[GitHub] [incubator-nuttx] pkarashchenko commented on a diff in pull request #7198: libs/libc: add obstack

[GitBox <gi...@apache.org>]

pkarashchenko commented on code in PR #7198:
URL: https://github.com/apache/incubator-nuttx/pull/7198#discussion_r985290481


##########
include/obstack.h:
##########
@@ -0,0 +1,459 @@
+/****************************************************************************
+ * include/obstack.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/* This is based on the GlibC API but the implementation is not exactly same.
+ * The major difference is how required memory is allocated. The GlibC
+ * implementation starts with 4KB of allocated space. That would make it
+ * impossible to use this on MCUs. This implementation rather tries to
+ * allocated only required amount of space and it won't allocate chunk unless
+ * grow functions are used and even then it uses realloc to release unused
+ * space. It also in default won't use 4KB per chunk but rather just BUFSIZ.
+ *
+ * Not implemented interface:
+ *   obstack_alignment_mask:
+ *     The current implementation does not provide any alignment guaranties.
+ *   obstack_chunk_alloc and obstack_chunk_free:
+ *     Internal implementation uses not only alloc and free but also realloc
+ *     and thus standard implementations are used unconditionally instead of
+ *     requiring users to provide declaration for these functions.
+ */
+
+#ifndef __INCLUDE_OBSTACK_H
+#define __INCLUDE_OBSTACK_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <stddef.h>
+#include <stdarg.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: obstack_chunk_size
+ *
+ * Description:
+ *   The access to the obstack configuration specifying the size of the
+ *   single chunk used when growing object.
+ *   It is documented t hat this is macro and that it is possible to use
+ *   assignment to change the chunk size (eq.: obstack_chunk_size(h) = 1024).
+ *
+ *   The default chunk size is set to BUFSIZ.
+ *
+ *   The chunks size has to be always power of two due to the limitations of
+ *   the obstack_make_room implementation!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Size of the single chunk.
+ *
+ ****************************************************************************/
+#define obstack_chunk_size(h) ((h)->chunk_size)
+
+/****************************************************************************
+ * Name: obstack_base
+ *
+ * Description:
+ *   Provides access to the tentative starting address of the
+ *   currently growing object.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Tentative starting address of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_base(h) ((h)->object_base)
+
+/****************************************************************************
+ * Name: obstack_next_free
+ *
+ * Description:
+ *   Provides access to the tentative address just after the end of the
+ *   currently growing object.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Address just after the end of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_next_free(h) ((h)->next_free)
+
+/****************************************************************************
+ * Name: obstack_blank_fast
+ *
+ * Description:
+ *   Moves the end of the currently growing object by given size and thus
+ *   adding given number of uninitialized bytes to the growing object.
+ *   There is no check if there is enough room and thus it is easy to cause
+ *   buffer overrun. Use only when you are sure that there is enough room!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *   size: number of bytes
+ *
+ * Returned Value:
+ *   The new address just after the end of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_blank_fast(h, size) ((h)->next_free += size)
+
+/****************************************************************************
+ * Name: obstack_1grow_fast
+ *
+ * Description:
+ *   Adds one byte to the currently growing object.
+ *   There is no check if there is enough room and thus it is easy to cause
+ *   buffer overrun. Use only when you are sure that there is enough room!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *   data: byte to be added
+ *
+ * Returned Value:
+ *   Added byte.
+ *
+ ****************************************************************************/
+#define obstack_1grow_fast(h, data) (*((h)->next_free++) = data)
+
+/****************************************************************************
+ * Public Type Definitions
+ ****************************************************************************/
+
+struct _obstack_chunk           /* Chunk head. */
+{
+  char *limit;                  /* address of char after this chunk */

Review Comment:
   ```suggestion
     FAR char *limit;              /* address of char after this chunk */
   ```



##########
include/obstack.h:
##########
@@ -0,0 +1,459 @@
+/****************************************************************************
+ * include/obstack.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/* This is based on the GlibC API but the implementation is not exactly same.
+ * The major difference is how required memory is allocated. The GlibC
+ * implementation starts with 4KB of allocated space. That would make it
+ * impossible to use this on MCUs. This implementation rather tries to
+ * allocated only required amount of space and it won't allocate chunk unless
+ * grow functions are used and even then it uses realloc to release unused
+ * space. It also in default won't use 4KB per chunk but rather just BUFSIZ.
+ *
+ * Not implemented interface:
+ *   obstack_alignment_mask:
+ *     The current implementation does not provide any alignment guaranties.
+ *   obstack_chunk_alloc and obstack_chunk_free:
+ *     Internal implementation uses not only alloc and free but also realloc
+ *     and thus standard implementations are used unconditionally instead of
+ *     requiring users to provide declaration for these functions.
+ */
+
+#ifndef __INCLUDE_OBSTACK_H
+#define __INCLUDE_OBSTACK_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <stddef.h>
+#include <stdarg.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: obstack_chunk_size
+ *
+ * Description:
+ *   The access to the obstack configuration specifying the size of the
+ *   single chunk used when growing object.
+ *   It is documented t hat this is macro and that it is possible to use
+ *   assignment to change the chunk size (eq.: obstack_chunk_size(h) = 1024).
+ *
+ *   The default chunk size is set to BUFSIZ.
+ *
+ *   The chunks size has to be always power of two due to the limitations of
+ *   the obstack_make_room implementation!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Size of the single chunk.
+ *
+ ****************************************************************************/
+#define obstack_chunk_size(h) ((h)->chunk_size)
+
+/****************************************************************************
+ * Name: obstack_base
+ *
+ * Description:
+ *   Provides access to the tentative starting address of the
+ *   currently growing object.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Tentative starting address of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_base(h) ((h)->object_base)
+
+/****************************************************************************
+ * Name: obstack_next_free
+ *
+ * Description:
+ *   Provides access to the tentative address just after the end of the
+ *   currently growing object.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Address just after the end of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_next_free(h) ((h)->next_free)
+
+/****************************************************************************
+ * Name: obstack_blank_fast
+ *
+ * Description:
+ *   Moves the end of the currently growing object by given size and thus
+ *   adding given number of uninitialized bytes to the growing object.
+ *   There is no check if there is enough room and thus it is easy to cause
+ *   buffer overrun. Use only when you are sure that there is enough room!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *   size: number of bytes
+ *
+ * Returned Value:
+ *   The new address just after the end of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_blank_fast(h, size) ((h)->next_free += size)
+
+/****************************************************************************
+ * Name: obstack_1grow_fast
+ *
+ * Description:
+ *   Adds one byte to the currently growing object.
+ *   There is no check if there is enough room and thus it is easy to cause
+ *   buffer overrun. Use only when you are sure that there is enough room!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *   data: byte to be added
+ *
+ * Returned Value:
+ *   Added byte.
+ *
+ ****************************************************************************/
+#define obstack_1grow_fast(h, data) (*((h)->next_free++) = data)
+
+/****************************************************************************
+ * Public Type Definitions
+ ****************************************************************************/
+
+struct _obstack_chunk           /* Chunk head. */
+{
+  char *limit;                  /* address of char after this chunk */
+  struct _obstack_chunk *prev;  /* address of prior chunk or NULL */
+};
+
+struct obstack
+{
+  size_t chunk_size;            /* preferred size to allocate chunks in */
+  struct _obstack_chunk *chunk; /* address of current struct _obstack_chunk */
+  char *object_base;            /* address of object we are building */
+  char *next_free;              /* where to add next char to current object */

Review Comment:
   ```suggestion
     FAR char *object_base;        /* address of object we are building */
     FAR char *next_free;          /* where to add next char to current object */
   ```



##########
include/obstack.h:
##########
@@ -0,0 +1,459 @@
+/****************************************************************************
+ * include/obstack.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/* This is based on the GlibC API but the implementation is not exactly same.
+ * The major difference is how required memory is allocated. The GlibC
+ * implementation starts with 4KB of allocated space. That would make it
+ * impossible to use this on MCUs. This implementation rather tries to
+ * allocated only required amount of space and it won't allocate chunk unless
+ * grow functions are used and even then it uses realloc to release unused
+ * space. It also in default won't use 4KB per chunk but rather just BUFSIZ.
+ *
+ * Not implemented interface:
+ *   obstack_alignment_mask:
+ *     The current implementation does not provide any alignment guaranties.
+ *   obstack_chunk_alloc and obstack_chunk_free:
+ *     Internal implementation uses not only alloc and free but also realloc
+ *     and thus standard implementations are used unconditionally instead of
+ *     requiring users to provide declaration for these functions.
+ */
+
+#ifndef __INCLUDE_OBSTACK_H
+#define __INCLUDE_OBSTACK_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <stddef.h>
+#include <stdarg.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: obstack_chunk_size
+ *
+ * Description:
+ *   The access to the obstack configuration specifying the size of the
+ *   single chunk used when growing object.
+ *   It is documented t hat this is macro and that it is possible to use
+ *   assignment to change the chunk size (eq.: obstack_chunk_size(h) = 1024).
+ *
+ *   The default chunk size is set to BUFSIZ.
+ *
+ *   The chunks size has to be always power of two due to the limitations of
+ *   the obstack_make_room implementation!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Size of the single chunk.
+ *
+ ****************************************************************************/
+#define obstack_chunk_size(h) ((h)->chunk_size)
+
+/****************************************************************************
+ * Name: obstack_base
+ *
+ * Description:
+ *   Provides access to the tentative starting address of the
+ *   currently growing object.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Tentative starting address of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_base(h) ((h)->object_base)
+
+/****************************************************************************
+ * Name: obstack_next_free
+ *
+ * Description:
+ *   Provides access to the tentative address just after the end of the
+ *   currently growing object.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Address just after the end of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_next_free(h) ((h)->next_free)
+
+/****************************************************************************
+ * Name: obstack_blank_fast
+ *
+ * Description:
+ *   Moves the end of the currently growing object by given size and thus
+ *   adding given number of uninitialized bytes to the growing object.
+ *   There is no check if there is enough room and thus it is easy to cause
+ *   buffer overrun. Use only when you are sure that there is enough room!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *   size: number of bytes
+ *
+ * Returned Value:
+ *   The new address just after the end of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_blank_fast(h, size) ((h)->next_free += size)
+
+/****************************************************************************
+ * Name: obstack_1grow_fast
+ *
+ * Description:
+ *   Adds one byte to the currently growing object.
+ *   There is no check if there is enough room and thus it is easy to cause
+ *   buffer overrun. Use only when you are sure that there is enough room!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *   data: byte to be added
+ *
+ * Returned Value:
+ *   Added byte.
+ *
+ ****************************************************************************/
+#define obstack_1grow_fast(h, data) (*((h)->next_free++) = data)
+
+/****************************************************************************
+ * Public Type Definitions
+ ****************************************************************************/
+
+struct _obstack_chunk           /* Chunk head. */
+{
+  char *limit;                  /* address of char after this chunk */
+  struct _obstack_chunk *prev;  /* address of prior chunk or NULL */
+};
+
+struct obstack
+{
+  size_t chunk_size;            /* preferred size to allocate chunks in */
+  struct _obstack_chunk *chunk; /* address of current struct _obstack_chunk */
+  char *object_base;            /* address of object we are building */
+  char *next_free;              /* where to add next char to current object */
+};
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#if defined(__cplusplus)
+extern "C"
+{
+#endif
+
+/****************************************************************************
+ * Name: obstack_init
+ *
+ * Description:
+ *   Initialize obstack for allocation of objects.
+ *   Compared to the GlibC version this won't initialize a first chunk.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle to initialize
+ *
+ ****************************************************************************/
+
+void obstack_init (FAR struct obstack *h);
+
+/****************************************************************************
+ * Name: obstack_alloc
+ *
+ * Description:
+ *   Allocate an object of given size with uninitialized bytes.
+ *   Compared to the GlibC version this uses malloc to allocate exactly
+ *   required space (plus overhead) and nothing more.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle to allocate an object in
+ *   size: number of bytes to allocate
+ *
+ ****************************************************************************/
+
+FAR void *obstack_alloc (FAR struct obstack *h, size_t size);

Review Comment:
   ```suggestion
   FAR void *obstack_alloc(FAR struct obstack *h, size_t size);
   ```



##########
libs/libc/obstack/lib_obstack_alloc.c:
##########
@@ -0,0 +1,55 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_alloc.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+
+#include <stdlib.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+FAR void *obstack_alloc (FAR struct obstack *h, size_t size)

Review Comment:
   ```suggestion
   FAR void *obstack_alloc(FAR struct obstack *h, size_t size)
   ```



##########
include/obstack.h:
##########
@@ -0,0 +1,459 @@
+/****************************************************************************
+ * include/obstack.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/* This is based on the GlibC API but the implementation is not exactly same.
+ * The major difference is how required memory is allocated. The GlibC
+ * implementation starts with 4KB of allocated space. That would make it
+ * impossible to use this on MCUs. This implementation rather tries to
+ * allocated only required amount of space and it won't allocate chunk unless
+ * grow functions are used and even then it uses realloc to release unused
+ * space. It also in default won't use 4KB per chunk but rather just BUFSIZ.
+ *
+ * Not implemented interface:
+ *   obstack_alignment_mask:
+ *     The current implementation does not provide any alignment guaranties.
+ *   obstack_chunk_alloc and obstack_chunk_free:
+ *     Internal implementation uses not only alloc and free but also realloc
+ *     and thus standard implementations are used unconditionally instead of
+ *     requiring users to provide declaration for these functions.
+ */
+
+#ifndef __INCLUDE_OBSTACK_H
+#define __INCLUDE_OBSTACK_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <stddef.h>
+#include <stdarg.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: obstack_chunk_size
+ *
+ * Description:
+ *   The access to the obstack configuration specifying the size of the
+ *   single chunk used when growing object.
+ *   It is documented t hat this is macro and that it is possible to use
+ *   assignment to change the chunk size (eq.: obstack_chunk_size(h) = 1024).
+ *
+ *   The default chunk size is set to BUFSIZ.
+ *
+ *   The chunks size has to be always power of two due to the limitations of
+ *   the obstack_make_room implementation!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Size of the single chunk.
+ *
+ ****************************************************************************/
+#define obstack_chunk_size(h) ((h)->chunk_size)
+
+/****************************************************************************
+ * Name: obstack_base
+ *
+ * Description:
+ *   Provides access to the tentative starting address of the
+ *   currently growing object.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Tentative starting address of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_base(h) ((h)->object_base)
+
+/****************************************************************************
+ * Name: obstack_next_free
+ *
+ * Description:
+ *   Provides access to the tentative address just after the end of the
+ *   currently growing object.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Address just after the end of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_next_free(h) ((h)->next_free)
+
+/****************************************************************************
+ * Name: obstack_blank_fast
+ *
+ * Description:
+ *   Moves the end of the currently growing object by given size and thus
+ *   adding given number of uninitialized bytes to the growing object.
+ *   There is no check if there is enough room and thus it is easy to cause
+ *   buffer overrun. Use only when you are sure that there is enough room!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *   size: number of bytes
+ *
+ * Returned Value:
+ *   The new address just after the end of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_blank_fast(h, size) ((h)->next_free += size)
+
+/****************************************************************************
+ * Name: obstack_1grow_fast
+ *
+ * Description:
+ *   Adds one byte to the currently growing object.
+ *   There is no check if there is enough room and thus it is easy to cause
+ *   buffer overrun. Use only when you are sure that there is enough room!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *   data: byte to be added
+ *
+ * Returned Value:
+ *   Added byte.
+ *
+ ****************************************************************************/
+#define obstack_1grow_fast(h, data) (*((h)->next_free++) = data)
+
+/****************************************************************************
+ * Public Type Definitions
+ ****************************************************************************/
+
+struct _obstack_chunk           /* Chunk head. */
+{
+  char *limit;                  /* address of char after this chunk */
+  struct _obstack_chunk *prev;  /* address of prior chunk or NULL */
+};
+
+struct obstack
+{
+  size_t chunk_size;            /* preferred size to allocate chunks in */
+  struct _obstack_chunk *chunk; /* address of current struct _obstack_chunk */
+  char *object_base;            /* address of object we are building */
+  char *next_free;              /* where to add next char to current object */
+};
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#if defined(__cplusplus)
+extern "C"
+{
+#endif
+
+/****************************************************************************
+ * Name: obstack_init
+ *
+ * Description:
+ *   Initialize obstack for allocation of objects.
+ *   Compared to the GlibC version this won't initialize a first chunk.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle to initialize
+ *
+ ****************************************************************************/
+
+void obstack_init (FAR struct obstack *h);
+
+/****************************************************************************
+ * Name: obstack_alloc
+ *
+ * Description:
+ *   Allocate an object of given size with uninitialized bytes.
+ *   Compared to the GlibC version this uses malloc to allocate exactly
+ *   required space (plus overhead) and nothing more.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle to allocate an object in
+ *   size: number of bytes to allocate
+ *
+ ****************************************************************************/
+
+FAR void *obstack_alloc (FAR struct obstack *h, size_t size);
+
+/****************************************************************************
+ * Name: obstack_copy
+ *
+ * Description:
+ *   Allocate an object of given size with contents copied from address.
+ *   The same remarks regarding the allocation apply here as for
+ *   obstack_alloc.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle to allocate an object in
+ *   address: pointer to the bytes to be used to initialize new object
+ *   size: number of bytes to allocate
+ *
+ ****************************************************************************/
+
+FAR void *obstack_copy (FAR struct obstack *h,

Review Comment:
   ```suggestion
   FAR void *obstack_copy(FAR struct obstack *h,
   ```



##########
libs/libc/obstack/lib_obstack_alloc.c:
##########
@@ -0,0 +1,55 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_alloc.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+
+#include <stdlib.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+FAR void *obstack_alloc (FAR struct obstack *h, size_t size)
+{
+  FAR struct _obstack_chunk *prev;
+  FAR void *res;
+
+  if (h->chunk == NULL || (h->chunk->limit - h->object_base) < size)
+    {
+      /* TODO: could we just expand current allocation? */
+
+      prev = h->chunk;
+      h->chunk = malloc(size + sizeof(struct _obstack_chunk));
+      h->chunk->limit =
+        (void *)h->chunk + sizeof(struct _obstack_chunk) + size;
+      h->chunk->prev = prev;
+      h->object_base = (void *)h->chunk + sizeof(struct _obstack_chunk);

Review Comment:
   ```suggestion
         h->object_base = (FAR void *)h->chunk + sizeof(struct _obstack_chunk);
   ```



##########
include/obstack.h:
##########
@@ -0,0 +1,459 @@
+/****************************************************************************
+ * include/obstack.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/* This is based on the GlibC API but the implementation is not exactly same.
+ * The major difference is how required memory is allocated. The GlibC
+ * implementation starts with 4KB of allocated space. That would make it
+ * impossible to use this on MCUs. This implementation rather tries to
+ * allocated only required amount of space and it won't allocate chunk unless
+ * grow functions are used and even then it uses realloc to release unused
+ * space. It also in default won't use 4KB per chunk but rather just BUFSIZ.
+ *
+ * Not implemented interface:
+ *   obstack_alignment_mask:
+ *     The current implementation does not provide any alignment guaranties.
+ *   obstack_chunk_alloc and obstack_chunk_free:
+ *     Internal implementation uses not only alloc and free but also realloc
+ *     and thus standard implementations are used unconditionally instead of
+ *     requiring users to provide declaration for these functions.
+ */
+
+#ifndef __INCLUDE_OBSTACK_H
+#define __INCLUDE_OBSTACK_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <stddef.h>
+#include <stdarg.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: obstack_chunk_size
+ *
+ * Description:
+ *   The access to the obstack configuration specifying the size of the
+ *   single chunk used when growing object.
+ *   It is documented t hat this is macro and that it is possible to use
+ *   assignment to change the chunk size (eq.: obstack_chunk_size(h) = 1024).
+ *
+ *   The default chunk size is set to BUFSIZ.
+ *
+ *   The chunks size has to be always power of two due to the limitations of
+ *   the obstack_make_room implementation!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Size of the single chunk.
+ *
+ ****************************************************************************/
+#define obstack_chunk_size(h) ((h)->chunk_size)
+
+/****************************************************************************
+ * Name: obstack_base
+ *
+ * Description:
+ *   Provides access to the tentative starting address of the
+ *   currently growing object.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Tentative starting address of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_base(h) ((h)->object_base)
+
+/****************************************************************************
+ * Name: obstack_next_free
+ *
+ * Description:
+ *   Provides access to the tentative address just after the end of the
+ *   currently growing object.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Address just after the end of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_next_free(h) ((h)->next_free)
+
+/****************************************************************************
+ * Name: obstack_blank_fast
+ *
+ * Description:
+ *   Moves the end of the currently growing object by given size and thus
+ *   adding given number of uninitialized bytes to the growing object.
+ *   There is no check if there is enough room and thus it is easy to cause
+ *   buffer overrun. Use only when you are sure that there is enough room!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *   size: number of bytes
+ *
+ * Returned Value:
+ *   The new address just after the end of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_blank_fast(h, size) ((h)->next_free += size)
+
+/****************************************************************************
+ * Name: obstack_1grow_fast
+ *
+ * Description:
+ *   Adds one byte to the currently growing object.
+ *   There is no check if there is enough room and thus it is easy to cause
+ *   buffer overrun. Use only when you are sure that there is enough room!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *   data: byte to be added
+ *
+ * Returned Value:
+ *   Added byte.
+ *
+ ****************************************************************************/
+#define obstack_1grow_fast(h, data) (*((h)->next_free++) = data)
+
+/****************************************************************************
+ * Public Type Definitions
+ ****************************************************************************/
+
+struct _obstack_chunk           /* Chunk head. */
+{
+  char *limit;                  /* address of char after this chunk */
+  struct _obstack_chunk *prev;  /* address of prior chunk or NULL */
+};
+
+struct obstack
+{
+  size_t chunk_size;            /* preferred size to allocate chunks in */
+  struct _obstack_chunk *chunk; /* address of current struct _obstack_chunk */
+  char *object_base;            /* address of object we are building */
+  char *next_free;              /* where to add next char to current object */
+};
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#if defined(__cplusplus)
+extern "C"
+{
+#endif
+
+/****************************************************************************
+ * Name: obstack_init
+ *
+ * Description:
+ *   Initialize obstack for allocation of objects.
+ *   Compared to the GlibC version this won't initialize a first chunk.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle to initialize
+ *
+ ****************************************************************************/
+
+void obstack_init (FAR struct obstack *h);
+
+/****************************************************************************
+ * Name: obstack_alloc
+ *
+ * Description:
+ *   Allocate an object of given size with uninitialized bytes.
+ *   Compared to the GlibC version this uses malloc to allocate exactly
+ *   required space (plus overhead) and nothing more.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle to allocate an object in
+ *   size: number of bytes to allocate
+ *
+ ****************************************************************************/
+
+FAR void *obstack_alloc (FAR struct obstack *h, size_t size);
+
+/****************************************************************************
+ * Name: obstack_copy
+ *
+ * Description:
+ *   Allocate an object of given size with contents copied from address.
+ *   The same remarks regarding the allocation apply here as for
+ *   obstack_alloc.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle to allocate an object in
+ *   address: pointer to the bytes to be used to initialize new object
+ *   size: number of bytes to allocate
+ *
+ ****************************************************************************/
+
+FAR void *obstack_copy (FAR struct obstack *h,
+    FAR const void *address, size_t size);
+
+/****************************************************************************
+ * Name: obstack_copy0
+ *
+ * Description:
+ *   Allocate an object of given size+1 with contents copied from address and
+ *   append null byte at the end.
+ *   The same remarks regarding the allocation apply here as for
+ *   obstack_alloc.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle to allocate an object in
+ *   address: pointer to the bytes to be used to initialize new object
+ *   size: number of bytes to allocate (excluding the null byte)
+ *
+ ****************************************************************************/
+
+FAR void *obstack_copy0 (FAR struct obstack *h,
+    FAR const void *address, size_t size);
+
+/****************************************************************************
+ * Name: obstack_free
+ *
+ * Description:
+ *   Free objects (and everything allocated in the specified obstack more
+ *   recently than object). You can pass NULL to free everything.
+ *   The buffer the allocated object was preset is kept and thus can be
+ *   immediately reused for growing. The only exception for this is when NULL
+ *   is passed as in such case even the last buffer is freed.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle object belongs to
+ *   object: the pointer to the object or NULL
+ *
+ ****************************************************************************/
+
+void obstack_free (FAR struct obstack *h, FAR void *object);
+
+/****************************************************************************
+ * Name: obstack_make_room
+ *
+ * Description:
+ *   This is non-standard function that is probably available only on NuttX!
+ *   Make sure that there is room in the buffer to fit object with given
+ *   size. The allocation performed is in multiples of chunk_size specified
+ *   for the obstack.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle where room should be made
+ *   size: number of bytes to be free for growth
+ *
+ * Assumptions/Limitations:
+ *   The obstack's chunk_size is expected to be power of two. This helps to
+ *   eliminate division that might not be implemented in the HW and thus
+ *   inefficient.
+ *
+ ****************************************************************************/
+
+void obstack_make_room(struct obstack *h, size_t size);
+
+/****************************************************************************
+ * Name: obstack_blank
+ *
+ * Description:
+ *   Grow object by given size. The bytes are uninitialized.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle to allocated object to
+ *   size: number of bytes to grow object
+ *
+ ****************************************************************************/
+
+void obstack_blank (FAR struct obstack *h, size_t size);
+
+/****************************************************************************
+ * Name: obstack_grow
+ *
+ * Description:
+ *   Grow object by given size and allocated it with bytes from address.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle to allocated object to
+ *   address: pointer to the bytes to be used to initialize the new object
+ *   size: number of bytes to grow object
+ *
+ ****************************************************************************/
+
+void obstack_grow (FAR struct obstack *h,
+    FAR const void *address, size_t size);
+
+/****************************************************************************
+ * Name: obstack_grow0
+ *
+ * Description:
+ *   Grow object by given size+1 and allocated it with bytes from address
+ *   plus null byte at the end.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle to allocated object to
+ *   address: pointer to the bytes to be used to initialize the new object
+ *   size: number of bytes to grow object (excluding the null byte)
+ *
+ ****************************************************************************/
+
+void obstack_grow0 (FAR struct obstack *h,
+    FAR const void *address, size_t size);
+
+/****************************************************************************
+ * Name: obstack_1grow
+ *
+ * Description:
+ *   Grow object by single data byte.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle to allocated object to
+ *   data: byte to be added to the growing object
+ *
+ ****************************************************************************/
+
+void obstack_1grow (FAR struct obstack *h, char data);
+
+/****************************************************************************
+ * Name: obstack_finish
+ *
+ * Description:
+ *   Finish growing object and receive address to it.
+ *   Compared to the GlibC version this uses realloc to reduce buffer size to
+ *   only allocated amount. The non-standard obstack_finish_norealloc can be
+ *   used if you want the standard behavior for ever reason.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Permanent address to the object.
+ *
+ ****************************************************************************/
+
+FAR void *obstack_finish (FAR struct obstack *h);
+
+/****************************************************************************
+ * Name: obstack_finish_norealloc
+ *
+ * Description:
+ *   Finish growing object and receive address to it without reallocating
+ *   buffer to fit the object (keeping space for more growth).
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Permanent address to the object.
+ *
+ ****************************************************************************/
+
+FAR void *obstack_finish_norealloc (FAR struct obstack *h);
+
+/****************************************************************************
+ * Name: obstack_object_size
+ *
+ * Description:
+ *   Calculate the size of the currently growing object.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Size of the object.
+ *
+ ****************************************************************************/
+
+size_t obstack_object_size (FAR struct obstack *h);
+
+/****************************************************************************
+ * Name: obstack_room
+ *
+ * Description:
+ *   Calculate the number of bytes available for growth before reallocation
+ *   is required.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Number of free bytes.
+ *
+ ****************************************************************************/
+
+size_t obstack_room (FAR struct obstack *h);
+
+/****************************************************************************
+ * Name: obstack_printf
+ *
+ * Description:
+ *   This is similar to the asprintf except it uses obstack to allocate
+ *   string on. The characters are written onto the end of the currently
+ *   growing object and terminated by null byte.
+ *
+ *   This function is defined in stdio.h in GlibC. There is no definition
+ *   that would be in stdio.h required for these here and thus it is easier
+ *   to just keep these functions here as user has to include obstack anyway
+ *   to get the full functionality.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *   fmt: format string with its format inputs followed.
+ *
+ * Returned Value:
+ *   Number of characters added to the obstack excluding the null byte.
+ *
+ ****************************************************************************/
+
+int obstack_printf(FAR struct obstack *h, FAR const char *fmt, ...);
+
+/****************************************************************************
+ * Name: obstack_vprintf
+ *
+ * Description:
+ *   This is similar to the vasprintf except it uses obstack to allocate
+ *   string on. The characters are written onto the end of the currently
+ *   growing object and terminated by null byte.
+ *
+ *   The same remarks are applied here as for obstack_printf regarding the
+ *   definition location in GlibC.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *   fmt: format string
+ *   ap: format string input as a variable argument list
+ *
+ * Returned Value:
+ *   Number of characters added to the obstack excluding the null byte.
+ *
+ ****************************************************************************/
+
+int obstack_vprintf(FAR struct obstack *h, FAR const char *fmt, va_list ap);
+
+#if defined(__cplusplus)
+}
+#endif

Review Comment:
   ```suggestion
   #undef EXTERN
   #if defined(__cplusplus)
   }
   #endif
   ```



##########
libs/libc/obstack/lib_obstack_alloc.c:
##########
@@ -0,0 +1,55 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_alloc.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+
+#include <stdlib.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+FAR void *obstack_alloc (FAR struct obstack *h, size_t size)
+{
+  FAR struct _obstack_chunk *prev;
+  FAR void *res;
+
+  if (h->chunk == NULL || (h->chunk->limit - h->object_base) < size)
+    {
+      /* TODO: could we just expand current allocation? */
+
+      prev = h->chunk;
+      h->chunk = malloc(size + sizeof(struct _obstack_chunk));

Review Comment:
   ```suggestion
         h->chunk = lib_malloc(size + sizeof(struct _obstack_chunk));
   ```



##########
libs/libc/obstack/lib_obstack_make_room.c:
##########
@@ -0,0 +1,77 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_make_room.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+
+#include <stdlib.h>
+#include <assert.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+void obstack_make_room(FAR struct obstack *h, size_t size)
+{
+  unsigned i;
+  size_t mask;
+
+  DEBUGASSERT(h);
+
+  if (obstack_room(h) >= size)
+    return; /* No need to allocate anything */
+
+  size_t object_size = obstack_object_size(h);
+
+  size += object_size + sizeof(struct _obstack_chunk);
+
+  /* Note: this is rounding up to the multiple of chunk size that is power of
+   * two. Thus this creates limitation that chunks can be only power of two.
+   */
+
+  mask = h->chunk_size;
+  for (i = 1; i < sizeof(size_t); i = i << 1)
+      mask |= mask >> i;
+  size = (size + mask) & ~mask;
+
+  if (h->chunk == NULL ||
+      h->object_base != (void *)h->chunk + sizeof(struct _obstack_chunk))
+    {
+      /* Allocate new chunk if there is something in the chunk already or if
+       * there is no chunk yet.
+       */
+
+      struct _obstack_chunk *prev = h->chunk;
+      h->chunk = malloc(size);
+      h->chunk->prev = prev;
+    }
+
+  else
+    {
+      h->chunk = realloc(h->chunk, size);

Review Comment:
   ```suggestion
         h->chunk = lib_realloc(h->chunk, size);
   ```



##########
libs/libc/obstack/lib_obstack_make_room.c:
##########
@@ -0,0 +1,77 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_make_room.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+
+#include <stdlib.h>
+#include <assert.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+void obstack_make_room(FAR struct obstack *h, size_t size)
+{
+  unsigned i;
+  size_t mask;
+
+  DEBUGASSERT(h);
+
+  if (obstack_room(h) >= size)
+    return; /* No need to allocate anything */

Review Comment:
   ```suggestion
     if (obstack_room(h) >= size)
       {
         return; /* No need to allocate anything */
       }
   ```



##########
include/obstack.h:
##########
@@ -0,0 +1,459 @@
+/****************************************************************************
+ * include/obstack.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/* This is based on the GlibC API but the implementation is not exactly same.
+ * The major difference is how required memory is allocated. The GlibC
+ * implementation starts with 4KB of allocated space. That would make it
+ * impossible to use this on MCUs. This implementation rather tries to
+ * allocated only required amount of space and it won't allocate chunk unless
+ * grow functions are used and even then it uses realloc to release unused
+ * space. It also in default won't use 4KB per chunk but rather just BUFSIZ.
+ *
+ * Not implemented interface:
+ *   obstack_alignment_mask:
+ *     The current implementation does not provide any alignment guaranties.
+ *   obstack_chunk_alloc and obstack_chunk_free:
+ *     Internal implementation uses not only alloc and free but also realloc
+ *     and thus standard implementations are used unconditionally instead of
+ *     requiring users to provide declaration for these functions.
+ */
+
+#ifndef __INCLUDE_OBSTACK_H
+#define __INCLUDE_OBSTACK_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <stddef.h>
+#include <stdarg.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: obstack_chunk_size
+ *
+ * Description:
+ *   The access to the obstack configuration specifying the size of the
+ *   single chunk used when growing object.
+ *   It is documented t hat this is macro and that it is possible to use
+ *   assignment to change the chunk size (eq.: obstack_chunk_size(h) = 1024).
+ *
+ *   The default chunk size is set to BUFSIZ.
+ *
+ *   The chunks size has to be always power of two due to the limitations of
+ *   the obstack_make_room implementation!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Size of the single chunk.
+ *
+ ****************************************************************************/
+#define obstack_chunk_size(h) ((h)->chunk_size)
+
+/****************************************************************************
+ * Name: obstack_base
+ *
+ * Description:
+ *   Provides access to the tentative starting address of the
+ *   currently growing object.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Tentative starting address of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_base(h) ((h)->object_base)
+
+/****************************************************************************
+ * Name: obstack_next_free
+ *
+ * Description:
+ *   Provides access to the tentative address just after the end of the
+ *   currently growing object.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Address just after the end of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_next_free(h) ((h)->next_free)
+
+/****************************************************************************
+ * Name: obstack_blank_fast
+ *
+ * Description:
+ *   Moves the end of the currently growing object by given size and thus
+ *   adding given number of uninitialized bytes to the growing object.
+ *   There is no check if there is enough room and thus it is easy to cause
+ *   buffer overrun. Use only when you are sure that there is enough room!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *   size: number of bytes
+ *
+ * Returned Value:
+ *   The new address just after the end of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_blank_fast(h, size) ((h)->next_free += size)
+
+/****************************************************************************
+ * Name: obstack_1grow_fast
+ *
+ * Description:
+ *   Adds one byte to the currently growing object.
+ *   There is no check if there is enough room and thus it is easy to cause
+ *   buffer overrun. Use only when you are sure that there is enough room!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *   data: byte to be added
+ *
+ * Returned Value:
+ *   Added byte.
+ *
+ ****************************************************************************/
+#define obstack_1grow_fast(h, data) (*((h)->next_free++) = data)
+
+/****************************************************************************
+ * Public Type Definitions
+ ****************************************************************************/
+
+struct _obstack_chunk           /* Chunk head. */
+{
+  char *limit;                  /* address of char after this chunk */
+  struct _obstack_chunk *prev;  /* address of prior chunk or NULL */
+};
+
+struct obstack
+{
+  size_t chunk_size;            /* preferred size to allocate chunks in */
+  struct _obstack_chunk *chunk; /* address of current struct _obstack_chunk */
+  char *object_base;            /* address of object we are building */
+  char *next_free;              /* where to add next char to current object */
+};
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#if defined(__cplusplus)
+extern "C"
+{
+#endif
+
+/****************************************************************************
+ * Name: obstack_init
+ *
+ * Description:
+ *   Initialize obstack for allocation of objects.
+ *   Compared to the GlibC version this won't initialize a first chunk.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle to initialize
+ *
+ ****************************************************************************/
+
+void obstack_init (FAR struct obstack *h);
+
+/****************************************************************************
+ * Name: obstack_alloc
+ *
+ * Description:
+ *   Allocate an object of given size with uninitialized bytes.
+ *   Compared to the GlibC version this uses malloc to allocate exactly
+ *   required space (plus overhead) and nothing more.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle to allocate an object in
+ *   size: number of bytes to allocate
+ *
+ ****************************************************************************/
+
+FAR void *obstack_alloc (FAR struct obstack *h, size_t size);
+
+/****************************************************************************
+ * Name: obstack_copy
+ *
+ * Description:
+ *   Allocate an object of given size with contents copied from address.
+ *   The same remarks regarding the allocation apply here as for
+ *   obstack_alloc.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle to allocate an object in
+ *   address: pointer to the bytes to be used to initialize new object
+ *   size: number of bytes to allocate
+ *
+ ****************************************************************************/
+
+FAR void *obstack_copy (FAR struct obstack *h,
+    FAR const void *address, size_t size);
+
+/****************************************************************************
+ * Name: obstack_copy0
+ *
+ * Description:
+ *   Allocate an object of given size+1 with contents copied from address and
+ *   append null byte at the end.
+ *   The same remarks regarding the allocation apply here as for
+ *   obstack_alloc.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle to allocate an object in
+ *   address: pointer to the bytes to be used to initialize new object
+ *   size: number of bytes to allocate (excluding the null byte)
+ *
+ ****************************************************************************/
+
+FAR void *obstack_copy0 (FAR struct obstack *h,

Review Comment:
   ```suggestion
   FAR void *obstack_copy0(FAR struct obstack *h,
   ```



##########
libs/libc/obstack/lib_obstack_make_room.c:
##########
@@ -0,0 +1,77 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_make_room.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+
+#include <stdlib.h>
+#include <assert.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+void obstack_make_room(FAR struct obstack *h, size_t size)
+{
+  unsigned i;
+  size_t mask;
+
+  DEBUGASSERT(h);
+
+  if (obstack_room(h) >= size)
+    return; /* No need to allocate anything */
+
+  size_t object_size = obstack_object_size(h);
+
+  size += object_size + sizeof(struct _obstack_chunk);
+
+  /* Note: this is rounding up to the multiple of chunk size that is power of
+   * two. Thus this creates limitation that chunks can be only power of two.
+   */
+
+  mask = h->chunk_size;
+  for (i = 1; i < sizeof(size_t); i = i << 1)
+      mask |= mask >> i;
+  size = (size + mask) & ~mask;
+
+  if (h->chunk == NULL ||
+      h->object_base != (void *)h->chunk + sizeof(struct _obstack_chunk))
+    {
+      /* Allocate new chunk if there is something in the chunk already or if
+       * there is no chunk yet.
+       */
+
+      struct _obstack_chunk *prev = h->chunk;
+      h->chunk = malloc(size);

Review Comment:
   ```suggestion
         h->chunk = lib_malloc(size);
   ```



##########
libs/libc/obstack/lib_obstack_object_size.c:
##########
@@ -0,0 +1,41 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_object_size.c
+ *
+ * This file is a part of NuttX:
+ *
+ *   Copyright (C) 2012 Gregory Nutt. All rights reserved.
+ *   Ported by: Darcy Gong
+ *
+ * It derives from the Rhombus OS math library by Nick Johnson which has
+ * a compatible, MIT-style license:
+ *
+ * Copyright (C) 2009, 2010 Nick Johnson <nickbjohnson4224 at gmail.com>

Review Comment:
   Where this license comes from?



##########
libs/libc/obstack/lib_obstack_room.c:
##########
@@ -0,0 +1,41 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_room.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+
+#include <assert.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+size_t obstack_room (FAR struct obstack *h)
+{
+  DEBUGASSERT(h);
+
+  if (h->chunk)
+      return h->chunk->limit - h->next_free;
+
+  return 0;

Review Comment:
   ```suggestion
     return h->chunk != NULL ? h->chunk->limit - h->next_free : 0;
   ```
   Or maybe even a macro



##########
libs/libc/obstack/lib_obstack_alloc.c:
##########
@@ -0,0 +1,55 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_alloc.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+
+#include <stdlib.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+FAR void *obstack_alloc (FAR struct obstack *h, size_t size)
+{
+  FAR struct _obstack_chunk *prev;
+  FAR void *res;
+
+  if (h->chunk == NULL || (h->chunk->limit - h->object_base) < size)
+    {
+      /* TODO: could we just expand current allocation? */
+
+      prev = h->chunk;
+      h->chunk = malloc(size + sizeof(struct _obstack_chunk));
+      h->chunk->limit =
+        (void *)h->chunk + sizeof(struct _obstack_chunk) + size;

Review Comment:
   ```suggestion
           (FAR void *)h->chunk + sizeof(struct _obstack_chunk) + size;
   ```



##########
libs/libc/obstack/lib_obstack_blank.c:
##########
@@ -0,0 +1,35 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_blank.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+void obstack_blank (struct obstack *h, size_t size)

Review Comment:
   ```suggestion
   void obstack_blank(FAR struct obstack *h, size_t size)
   ```



##########
include/obstack.h:
##########
@@ -0,0 +1,459 @@
+/****************************************************************************
+ * include/obstack.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/* This is based on the GlibC API but the implementation is not exactly same.
+ * The major difference is how required memory is allocated. The GlibC
+ * implementation starts with 4KB of allocated space. That would make it
+ * impossible to use this on MCUs. This implementation rather tries to
+ * allocated only required amount of space and it won't allocate chunk unless
+ * grow functions are used and even then it uses realloc to release unused
+ * space. It also in default won't use 4KB per chunk but rather just BUFSIZ.
+ *
+ * Not implemented interface:
+ *   obstack_alignment_mask:
+ *     The current implementation does not provide any alignment guaranties.
+ *   obstack_chunk_alloc and obstack_chunk_free:
+ *     Internal implementation uses not only alloc and free but also realloc
+ *     and thus standard implementations are used unconditionally instead of
+ *     requiring users to provide declaration for these functions.
+ */
+
+#ifndef __INCLUDE_OBSTACK_H
+#define __INCLUDE_OBSTACK_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <stddef.h>
+#include <stdarg.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: obstack_chunk_size
+ *
+ * Description:
+ *   The access to the obstack configuration specifying the size of the
+ *   single chunk used when growing object.
+ *   It is documented t hat this is macro and that it is possible to use
+ *   assignment to change the chunk size (eq.: obstack_chunk_size(h) = 1024).
+ *
+ *   The default chunk size is set to BUFSIZ.
+ *
+ *   The chunks size has to be always power of two due to the limitations of
+ *   the obstack_make_room implementation!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Size of the single chunk.
+ *
+ ****************************************************************************/
+#define obstack_chunk_size(h) ((h)->chunk_size)
+
+/****************************************************************************
+ * Name: obstack_base
+ *
+ * Description:
+ *   Provides access to the tentative starting address of the
+ *   currently growing object.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Tentative starting address of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_base(h) ((h)->object_base)
+
+/****************************************************************************
+ * Name: obstack_next_free
+ *
+ * Description:
+ *   Provides access to the tentative address just after the end of the
+ *   currently growing object.
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *
+ * Returned Value:
+ *   Address just after the end of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_next_free(h) ((h)->next_free)
+
+/****************************************************************************
+ * Name: obstack_blank_fast
+ *
+ * Description:
+ *   Moves the end of the currently growing object by given size and thus
+ *   adding given number of uninitialized bytes to the growing object.
+ *   There is no check if there is enough room and thus it is easy to cause
+ *   buffer overrun. Use only when you are sure that there is enough room!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *   size: number of bytes
+ *
+ * Returned Value:
+ *   The new address just after the end of the currently growing object.
+ *
+ ****************************************************************************/
+#define obstack_blank_fast(h, size) ((h)->next_free += size)
+
+/****************************************************************************
+ * Name: obstack_1grow_fast
+ *
+ * Description:
+ *   Adds one byte to the currently growing object.
+ *   There is no check if there is enough room and thus it is easy to cause
+ *   buffer overrun. Use only when you are sure that there is enough room!
+ *
+ * Input Parameters:
+ *   h: pointer to the handle used to grow the object.
+ *   data: byte to be added
+ *
+ * Returned Value:
+ *   Added byte.
+ *
+ ****************************************************************************/
+#define obstack_1grow_fast(h, data) (*((h)->next_free++) = data)
+
+/****************************************************************************
+ * Public Type Definitions
+ ****************************************************************************/
+
+struct _obstack_chunk           /* Chunk head. */
+{
+  char *limit;                  /* address of char after this chunk */
+  struct _obstack_chunk *prev;  /* address of prior chunk or NULL */
+};
+
+struct obstack
+{
+  size_t chunk_size;            /* preferred size to allocate chunks in */
+  struct _obstack_chunk *chunk; /* address of current struct _obstack_chunk */
+  char *object_base;            /* address of object we are building */
+  char *next_free;              /* where to add next char to current object */
+};
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#if defined(__cplusplus)
+extern "C"
+{
+#endif

Review Comment:
   ```suggestion
   #undef EXTERN
   #if defined(__cplusplus)
   #define EXTERN extern "C"
   extern "C"
   {
   #else
   #define EXTERN extern
   #endif
   ```



##########
libs/libc/obstack/lib_obstack_copy.c:
##########
@@ -0,0 +1,48 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_copy.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+
+#include <string.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+FAR void *obstack_copy (FAR struct obstack *h,

Review Comment:
   ```suggestion
   FAR void *obstack_copy(FAR struct obstack *h,
   ```



##########
libs/libc/obstack/lib_obstack_copy.c:
##########
@@ -0,0 +1,48 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_copy.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+
+#include <string.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+FAR void *obstack_copy (FAR struct obstack *h,
+    FAR const void *address, size_t size)
+{
+  void *res = obstack_alloc(h, size);

Review Comment:
   ```suggestion
     FAR void *res = obstack_alloc(h, size);
   ```



##########
libs/libc/obstack/lib_obstack_finish.c:
##########
@@ -0,0 +1,56 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_finish.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+
+#include <stdlib.h>
+#include <assert.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+FAR void *obstack_finish (FAR struct obstack *h)
+{
+  size_t chsize;
+
+  if (((void *)h->chunk + sizeof(struct _obstack_chunk)) == h->object_base)
+    {
+      chsize = h->next_free - (char *)h->chunk;

Review Comment:
   ```suggestion
         chsize = h->next_free - (FAR char *)h->chunk;
   ```



##########
libs/libc/obstack/lib_obstack_free.c:
##########
@@ -0,0 +1,60 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_free.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+#include <stdlib.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+void obstack_free (FAR struct obstack *h, FAR void *object)

Review Comment:
   ```suggestion
   void obstack_free(FAR struct obstack *h, FAR void *object)
   ```



##########
libs/libc/obstack/lib_obstack_finish.c:
##########
@@ -0,0 +1,56 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_finish.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+
+#include <stdlib.h>
+#include <assert.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+FAR void *obstack_finish (FAR struct obstack *h)
+{
+  size_t chsize;
+
+  if (((void *)h->chunk + sizeof(struct _obstack_chunk)) == h->object_base)

Review Comment:
   ```suggestion
     if (((FAR void *)h->chunk + sizeof(struct _obstack_chunk)) == h->object_base)
   ```



##########
libs/libc/obstack/lib_obstack_make_room.c:
##########
@@ -0,0 +1,77 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_make_room.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+
+#include <stdlib.h>
+#include <assert.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+void obstack_make_room(FAR struct obstack *h, size_t size)
+{
+  unsigned i;
+  size_t mask;
+
+  DEBUGASSERT(h);
+
+  if (obstack_room(h) >= size)
+    return; /* No need to allocate anything */
+
+  size_t object_size = obstack_object_size(h);
+
+  size += object_size + sizeof(struct _obstack_chunk);
+
+  /* Note: this is rounding up to the multiple of chunk size that is power of
+   * two. Thus this creates limitation that chunks can be only power of two.
+   */
+
+  mask = h->chunk_size;
+  for (i = 1; i < sizeof(size_t); i = i << 1)
+      mask |= mask >> i;
+  size = (size + mask) & ~mask;
+
+  if (h->chunk == NULL ||
+      h->object_base != (void *)h->chunk + sizeof(struct _obstack_chunk))
+    {
+      /* Allocate new chunk if there is something in the chunk already or if
+       * there is no chunk yet.
+       */
+
+      struct _obstack_chunk *prev = h->chunk;
+      h->chunk = malloc(size);
+      h->chunk->prev = prev;
+    }
+
+  else
+    {
+      h->chunk = realloc(h->chunk, size);
+    }
+
+  h->chunk->limit = (void *)h->chunk + sizeof(struct _obstack_chunk) + size;
+  h->object_base = (void *)h->chunk + sizeof(struct _obstack_chunk);

Review Comment:
   ```suggestion
     h->chunk->limit = (FAR void *)h->chunk + sizeof(struct _obstack_chunk) + size;
     h->object_base = (FAR void *)h->chunk + sizeof(struct _obstack_chunk);
   ```
   `void` pointer increment is not defined by C standard if I recall correctly, so better to use `uint8_t *` here.



##########
libs/libc/obstack/lib_obstack_free.c:
##########
@@ -0,0 +1,60 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_free.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+#include <stdlib.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+void obstack_free (FAR struct obstack *h, FAR void *object)
+{
+  FAR struct _obstack_chunk *prev;
+
+  while (h->chunk)
+    {
+      if (object >= (void *)&h->chunk + sizeof(struct _obstack_chunk)
+          && object < (void *)h->chunk->limit)
+        {
+          /* The obect is in this chunk so just move object base.
+           * Note: this keeps the last chunk allocated. This is desirable
+           * behavior as we can decide if we want to reuse it by either
+           * passing NULL to free everything or the first returned object to
+           * keep the chunk allocated.
+           */
+
+          h->object_base = object;
+          h->next_free = object;
+          return;
+        }
+
+      prev = h->chunk->prev;
+      free(h->chunk);

Review Comment:
   ```suggestion
         lib_free(h->chunk);
   ```



##########
libs/libc/obstack/lib_obstack_finish.c:
##########
@@ -0,0 +1,56 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_finish.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+
+#include <stdlib.h>
+#include <assert.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+FAR void *obstack_finish (FAR struct obstack *h)
+{
+  size_t chsize;
+
+  if (((void *)h->chunk + sizeof(struct _obstack_chunk)) == h->object_base)
+    {
+      chsize = h->next_free - (char *)h->chunk;
+      h->chunk = realloc(h->chunk, chsize);
+      h->chunk->limit = (void *)h->chunk + chsize;
+      h->object_base = h->chunk->limit;
+      h->next_free = h->chunk->limit;
+      return (void *)h->chunk + sizeof(struct _obstack_chunk);
+    }
+
+  return obstack_finish_norealloc(h);
+}
+
+FAR void *obstack_finish_norealloc (FAR struct obstack *h)
+{
+  char *res = h->object_base;

Review Comment:
   ```suggestion
     FAR char *res = h->object_base;
   ```



##########
libs/libc/obstack/lib_obstack_finish.c:
##########
@@ -0,0 +1,56 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_finish.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+
+#include <stdlib.h>
+#include <assert.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+FAR void *obstack_finish (FAR struct obstack *h)
+{
+  size_t chsize;
+
+  if (((void *)h->chunk + sizeof(struct _obstack_chunk)) == h->object_base)
+    {
+      chsize = h->next_free - (char *)h->chunk;
+      h->chunk = realloc(h->chunk, chsize);

Review Comment:
   ```suggestion
         h->chunk = lib_realloc(h->chunk, chsize);
   ```



##########
libs/libc/obstack/lib_obstack_room.c:
##########
@@ -0,0 +1,41 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_room.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+
+#include <assert.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+size_t obstack_room (FAR struct obstack *h)

Review Comment:
   ```suggestion
   size_t obstack_room(FAR struct obstack *h)
   ```



##########
libs/libc/obstack/lib_obstack_make_room.c:
##########
@@ -0,0 +1,77 @@
+/****************************************************************************
+ * libs/libc/obstack/lib_obstack_make_room.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <obstack.h>
+
+#include <stdlib.h>
+#include <assert.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+void obstack_make_room(FAR struct obstack *h, size_t size)
+{
+  unsigned i;
+  size_t mask;
+
+  DEBUGASSERT(h);
+
+  if (obstack_room(h) >= size)
+    return; /* No need to allocate anything */
+
+  size_t object_size = obstack_object_size(h);
+
+  size += object_size + sizeof(struct _obstack_chunk);
+
+  /* Note: this is rounding up to the multiple of chunk size that is power of
+   * two. Thus this creates limitation that chunks can be only power of two.
+   */
+
+  mask = h->chunk_size;
+  for (i = 1; i < sizeof(size_t); i = i << 1)
+      mask |= mask >> i;
+  size = (size + mask) & ~mask;
+
+  if (h->chunk == NULL ||
+      h->object_base != (void *)h->chunk + sizeof(struct _obstack_chunk))
+    {
+      /* Allocate new chunk if there is something in the chunk already or if
+       * there is no chunk yet.
+       */
+
+      struct _obstack_chunk *prev = h->chunk;

Review Comment:
   ```suggestion
         FAR struct _obstack_chunk *prev = h->chunk;
   ```



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