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Posted to commits@nuttx.apache.org by GitBox <gi...@apache.org> on 2022/04/11 17:03:55 UTC

[GitHub] [incubator-nuttx] pkarashchenko commented on a diff in pull request #6029: libc:add strptime support

pkarashchenko commented on code in PR #6029:
URL: https://github.com/apache/incubator-nuttx/pull/6029#discussion_r847549566


##########
libs/libc/time/lib_strptime.c:
##########
@@ -0,0 +1,540 @@
+/****************************************************************************
+ * libs/libc/time/lib_strptime.c
+ *
+ *  $OpenBSD: strptime.c,v 1.11 2005/08/08 08:05:38 espie Exp $
+ *  $NetBSD: strptime.c,v 1.12 1998/01/20 21:39:40 mycroft Exp $
+ *
+ * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code was contributed to The NetBSD Foundation by Klaus Klein.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *        This product includes software developed by the NetBSD
+ *        Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+#include <nuttx/config.h>
+
+#include <ctype.h>
+#include <locale.h>
+#include <strings.h>
+#include <time.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define TM_YEAR_BASE        1900
+#define _ctloc(x)           (_defaulttimelocale.x)
+
+/* We do not implement alternate representations. However, we always
+ * check whether a given modifier is allowed for a certain conversion.
+ */
+
+#define _ALT_E              0x01
+#define _ALT_O              0x02
+#define _LEGAL_ALT(x)       { if (alt_format & ~(x)) return (0); }
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct
+{
+    const char *abday[7];
+    const char *day[7];
+    const char *abmon[12];
+    const char *mon[12];
+    const char *am_pm[2];
+    const char *d_t_fmt;
+    const char *d_fmt;
+    const char *t_fmt;
+    const char *t_fmt_ampm;
+} _defaulttimelocale =
+{
+  {
+    "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat",
+  },
+  {
+    "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday",
+    "Friday", "Saturday"
+  },
+  {
+    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+  },
+  {
+    "January", "February", "March", "April", "May", "June", "July",
+    "August", "September", "October", "November", "December"
+  },
+  {
+    "AM", "PM"
+  },
+  "%a %b %d %H:%M:%S %Y",
+  "%m/%d/%y",
+  "%H:%M:%S",
+  "%I:%M:%S %p"
+};
+
+struct century_relyear
+{
+    int century;
+    int relyear;
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static int _conv_num(const unsigned char **buf, int *dest,
+                     int llim, int ulim)
+{
+  int result = 0;
+  int rulim = ulim;
+
+  while (isspace(**buf))
+    (*buf)++;

Review Comment:
   ```suggestion
     while (isspace(**buf))
       {
         (*buf)++;
       }
   ```



##########
libs/libc/time/lib_strptime.c:
##########
@@ -0,0 +1,540 @@
+/****************************************************************************
+ * libs/libc/time/lib_strptime.c
+ *
+ *  $OpenBSD: strptime.c,v 1.11 2005/08/08 08:05:38 espie Exp $
+ *  $NetBSD: strptime.c,v 1.12 1998/01/20 21:39:40 mycroft Exp $
+ *
+ * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code was contributed to The NetBSD Foundation by Klaus Klein.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *        This product includes software developed by the NetBSD
+ *        Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+#include <nuttx/config.h>
+
+#include <ctype.h>
+#include <locale.h>
+#include <strings.h>
+#include <time.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define TM_YEAR_BASE        1900
+#define _ctloc(x)           (_defaulttimelocale.x)
+
+/* We do not implement alternate representations. However, we always
+ * check whether a given modifier is allowed for a certain conversion.
+ */
+
+#define _ALT_E              0x01
+#define _ALT_O              0x02
+#define _LEGAL_ALT(x)       { if (alt_format & ~(x)) return (0); }
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct
+{
+    const char *abday[7];
+    const char *day[7];
+    const char *abmon[12];
+    const char *mon[12];
+    const char *am_pm[2];
+    const char *d_t_fmt;
+    const char *d_fmt;
+    const char *t_fmt;
+    const char *t_fmt_ampm;
+} _defaulttimelocale =
+{
+  {
+    "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat",
+  },
+  {
+    "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday",
+    "Friday", "Saturday"
+  },
+  {
+    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+  },
+  {
+    "January", "February", "March", "April", "May", "June", "July",
+    "August", "September", "October", "November", "December"
+  },
+  {
+    "AM", "PM"
+  },
+  "%a %b %d %H:%M:%S %Y",
+  "%m/%d/%y",
+  "%H:%M:%S",
+  "%I:%M:%S %p"
+};
+
+struct century_relyear
+{
+    int century;
+    int relyear;
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static int _conv_num(const unsigned char **buf, int *dest,
+                     int llim, int ulim)
+{
+  int result = 0;
+  int rulim = ulim;
+
+  while (isspace(**buf))
+    (*buf)++;
+
+  if (**buf < '0' || **buf > '9')
+    {
+      return (0);
+    }
+
+  /* we use rulim to break out of the loop when we run out of digits */
+
+  do
+    {
+      result *= 10;
+      result += *(*buf)++ - '0';
+      rulim /= 10;
+    }
+      while ((result * 10 <= ulim) && rulim && **buf >= '0' && **buf <= '9');
+
+  if (result < llim || result > ulim)
+    {
+      return (0);
+    }
+
+  *dest = result;
+  return (1);
+}
+
+static unsigned char * _strptime(const unsigned char *buf,
+                                 const char *fmt,
+                                 struct tm *tm,
+                                 struct century_relyear *cr)
+{
+  unsigned char c;
+  const unsigned char *bp;
+  size_t len = 0;
+  int alt_format;
+  int i;
+
+  bp = (unsigned char *)buf;
+  while ((c = *fmt) != '\0')
+    {
+      /* Clear `alternate' modifier prior to new conversion. */
+
+      alt_format = 0;
+
+      /* Eat up white-space. */
+
+      if (isspace(c))
+        {
+          while (isspace(*bp))
+            bp++;
+
+          fmt++;
+          continue;
+        }
+
+      if ((c = *fmt++) != '%')
+        {
+          goto literal;
+        }
+
+    again:
+      switch (c = *fmt++)
+        {
+          case '%': /* "%%" is converted to "%". */
+          literal:
+            if (c != *bp++)
+              return (NULL);

Review Comment:
   ```suggestion
               if (c != *bp++)
                 {
                   return NULL;
                 }
   ```



##########
include/time.h:
##########
@@ -200,6 +200,8 @@ FAR struct tm *localtime_r(FAR const time_t *timep, FAR struct tm *result);
 
 size_t strftime(FAR char *s, size_t max, FAR const char *format,
                 FAR const struct tm *tm) strftimelike(3);
+FAR char *strptime(FAR const char *s, FAR const char *format,
+                FAR struct tm *tm);

Review Comment:
   ```suggestion
   FAR char *strptime(FAR const char *s, FAR const char *format,
                      FAR struct tm *tm);
   ```



##########
libs/libc/time/lib_strptime.c:
##########
@@ -0,0 +1,540 @@
+/****************************************************************************
+ * libs/libc/time/lib_strptime.c
+ *
+ *  $OpenBSD: strptime.c,v 1.11 2005/08/08 08:05:38 espie Exp $
+ *  $NetBSD: strptime.c,v 1.12 1998/01/20 21:39:40 mycroft Exp $
+ *
+ * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code was contributed to The NetBSD Foundation by Klaus Klein.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *        This product includes software developed by the NetBSD
+ *        Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+#include <nuttx/config.h>
+
+#include <ctype.h>
+#include <locale.h>
+#include <strings.h>
+#include <time.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define TM_YEAR_BASE        1900
+#define _ctloc(x)           (_defaulttimelocale.x)
+
+/* We do not implement alternate representations. However, we always
+ * check whether a given modifier is allowed for a certain conversion.
+ */
+
+#define _ALT_E              0x01
+#define _ALT_O              0x02
+#define _LEGAL_ALT(x)       { if (alt_format & ~(x)) return (0); }
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct
+{
+    const char *abday[7];
+    const char *day[7];
+    const char *abmon[12];
+    const char *mon[12];
+    const char *am_pm[2];
+    const char *d_t_fmt;
+    const char *d_fmt;
+    const char *t_fmt;
+    const char *t_fmt_ampm;
+} _defaulttimelocale =
+{
+  {
+    "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat",
+  },
+  {
+    "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday",
+    "Friday", "Saturday"
+  },
+  {
+    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+  },
+  {
+    "January", "February", "March", "April", "May", "June", "July",
+    "August", "September", "October", "November", "December"
+  },
+  {
+    "AM", "PM"
+  },
+  "%a %b %d %H:%M:%S %Y",
+  "%m/%d/%y",
+  "%H:%M:%S",
+  "%I:%M:%S %p"
+};
+
+struct century_relyear
+{
+    int century;
+    int relyear;

Review Comment:
   ```suggestion
     int century;
     int relyear;
   ```



##########
libs/libc/time/lib_strptime.c:
##########
@@ -0,0 +1,540 @@
+/****************************************************************************
+ * libs/libc/time/lib_strptime.c
+ *
+ *  $OpenBSD: strptime.c,v 1.11 2005/08/08 08:05:38 espie Exp $
+ *  $NetBSD: strptime.c,v 1.12 1998/01/20 21:39:40 mycroft Exp $
+ *
+ * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code was contributed to The NetBSD Foundation by Klaus Klein.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *        This product includes software developed by the NetBSD
+ *        Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+#include <nuttx/config.h>
+
+#include <ctype.h>
+#include <locale.h>
+#include <strings.h>
+#include <time.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define TM_YEAR_BASE        1900
+#define _ctloc(x)           (_defaulttimelocale.x)
+
+/* We do not implement alternate representations. However, we always
+ * check whether a given modifier is allowed for a certain conversion.
+ */
+
+#define _ALT_E              0x01
+#define _ALT_O              0x02
+#define _LEGAL_ALT(x)       { if (alt_format & ~(x)) return (0); }
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct
+{
+    const char *abday[7];
+    const char *day[7];
+    const char *abmon[12];
+    const char *mon[12];
+    const char *am_pm[2];
+    const char *d_t_fmt;
+    const char *d_fmt;
+    const char *t_fmt;
+    const char *t_fmt_ampm;
+} _defaulttimelocale =
+{
+  {
+    "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat",
+  },
+  {
+    "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday",
+    "Friday", "Saturday"
+  },
+  {
+    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+  },
+  {
+    "January", "February", "March", "April", "May", "June", "July",
+    "August", "September", "October", "November", "December"
+  },
+  {
+    "AM", "PM"
+  },
+  "%a %b %d %H:%M:%S %Y",
+  "%m/%d/%y",
+  "%H:%M:%S",
+  "%I:%M:%S %p"
+};
+
+struct century_relyear
+{
+    int century;
+    int relyear;
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static int _conv_num(const unsigned char **buf, int *dest,
+                     int llim, int ulim)
+{
+  int result = 0;
+  int rulim = ulim;
+
+  while (isspace(**buf))
+    (*buf)++;
+
+  if (**buf < '0' || **buf > '9')
+    {
+      return (0);

Review Comment:
   ```suggestion
         return 0;
   ```



##########
libs/libc/time/lib_strptime.c:
##########
@@ -0,0 +1,540 @@
+/****************************************************************************
+ * libs/libc/time/lib_strptime.c
+ *
+ *  $OpenBSD: strptime.c,v 1.11 2005/08/08 08:05:38 espie Exp $
+ *  $NetBSD: strptime.c,v 1.12 1998/01/20 21:39:40 mycroft Exp $
+ *
+ * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code was contributed to The NetBSD Foundation by Klaus Klein.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *        This product includes software developed by the NetBSD
+ *        Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+#include <nuttx/config.h>
+
+#include <ctype.h>
+#include <locale.h>
+#include <strings.h>
+#include <time.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define TM_YEAR_BASE        1900
+#define _ctloc(x)           (_defaulttimelocale.x)
+
+/* We do not implement alternate representations. However, we always
+ * check whether a given modifier is allowed for a certain conversion.
+ */
+
+#define _ALT_E              0x01
+#define _ALT_O              0x02
+#define _LEGAL_ALT(x)       { if (alt_format & ~(x)) return (0); }
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct
+{
+    const char *abday[7];
+    const char *day[7];
+    const char *abmon[12];
+    const char *mon[12];
+    const char *am_pm[2];
+    const char *d_t_fmt;
+    const char *d_fmt;
+    const char *t_fmt;
+    const char *t_fmt_ampm;
+} _defaulttimelocale =
+{
+  {
+    "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat",
+  },
+  {
+    "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday",
+    "Friday", "Saturday"
+  },
+  {
+    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+  },
+  {
+    "January", "February", "March", "April", "May", "June", "July",
+    "August", "September", "October", "November", "December"
+  },
+  {
+    "AM", "PM"
+  },
+  "%a %b %d %H:%M:%S %Y",
+  "%m/%d/%y",
+  "%H:%M:%S",
+  "%I:%M:%S %p"
+};
+
+struct century_relyear
+{
+    int century;
+    int relyear;
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static int _conv_num(const unsigned char **buf, int *dest,
+                     int llim, int ulim)

Review Comment:
   ```suggestion
   static int _conv_num(FAR const unsigned char **buf, FAR int *dest,
                        int llim, int ulim)
   ```



##########
libs/libc/time/lib_strptime.c:
##########
@@ -0,0 +1,540 @@
+/****************************************************************************
+ * libs/libc/time/lib_strptime.c
+ *
+ *  $OpenBSD: strptime.c,v 1.11 2005/08/08 08:05:38 espie Exp $
+ *  $NetBSD: strptime.c,v 1.12 1998/01/20 21:39:40 mycroft Exp $
+ *
+ * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code was contributed to The NetBSD Foundation by Klaus Klein.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *        This product includes software developed by the NetBSD
+ *        Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+#include <nuttx/config.h>
+
+#include <ctype.h>
+#include <locale.h>
+#include <strings.h>
+#include <time.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define TM_YEAR_BASE        1900
+#define _ctloc(x)           (_defaulttimelocale.x)
+
+/* We do not implement alternate representations. However, we always
+ * check whether a given modifier is allowed for a certain conversion.
+ */
+
+#define _ALT_E              0x01
+#define _ALT_O              0x02
+#define _LEGAL_ALT(x)       { if (alt_format & ~(x)) return (0); }
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct
+{
+    const char *abday[7];
+    const char *day[7];
+    const char *abmon[12];
+    const char *mon[12];
+    const char *am_pm[2];
+    const char *d_t_fmt;
+    const char *d_fmt;
+    const char *t_fmt;
+    const char *t_fmt_ampm;
+} _defaulttimelocale =
+{
+  {
+    "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat",
+  },
+  {
+    "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday",
+    "Friday", "Saturday"
+  },
+  {
+    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+  },
+  {
+    "January", "February", "March", "April", "May", "June", "July",
+    "August", "September", "October", "November", "December"
+  },
+  {
+    "AM", "PM"
+  },
+  "%a %b %d %H:%M:%S %Y",
+  "%m/%d/%y",
+  "%H:%M:%S",
+  "%I:%M:%S %p"
+};
+
+struct century_relyear
+{
+    int century;
+    int relyear;
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static int _conv_num(const unsigned char **buf, int *dest,
+                     int llim, int ulim)
+{
+  int result = 0;
+  int rulim = ulim;
+
+  while (isspace(**buf))
+    (*buf)++;
+
+  if (**buf < '0' || **buf > '9')
+    {
+      return (0);
+    }
+
+  /* we use rulim to break out of the loop when we run out of digits */
+
+  do
+    {
+      result *= 10;
+      result += *(*buf)++ - '0';
+      rulim /= 10;
+    }
+      while ((result * 10 <= ulim) && rulim && **buf >= '0' && **buf <= '9');

Review Comment:
   ```suggestion
     while ((result * 10 <= ulim) && rulim && **buf >= '0' && **buf <= '9');
   ```



##########
libs/libc/time/lib_strptime.c:
##########
@@ -0,0 +1,540 @@
+/****************************************************************************
+ * libs/libc/time/lib_strptime.c
+ *
+ *  $OpenBSD: strptime.c,v 1.11 2005/08/08 08:05:38 espie Exp $
+ *  $NetBSD: strptime.c,v 1.12 1998/01/20 21:39:40 mycroft Exp $
+ *
+ * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code was contributed to The NetBSD Foundation by Klaus Klein.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *        This product includes software developed by the NetBSD
+ *        Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+#include <nuttx/config.h>
+
+#include <ctype.h>
+#include <locale.h>
+#include <strings.h>
+#include <time.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define TM_YEAR_BASE        1900
+#define _ctloc(x)           (_defaulttimelocale.x)
+
+/* We do not implement alternate representations. However, we always
+ * check whether a given modifier is allowed for a certain conversion.
+ */
+
+#define _ALT_E              0x01
+#define _ALT_O              0x02
+#define _LEGAL_ALT(x)       { if (alt_format & ~(x)) return (0); }
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct
+{
+    const char *abday[7];
+    const char *day[7];
+    const char *abmon[12];
+    const char *mon[12];
+    const char *am_pm[2];
+    const char *d_t_fmt;
+    const char *d_fmt;
+    const char *t_fmt;
+    const char *t_fmt_ampm;
+} _defaulttimelocale =
+{
+  {
+    "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat",
+  },
+  {
+    "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday",
+    "Friday", "Saturday"
+  },
+  {
+    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+  },
+  {
+    "January", "February", "March", "April", "May", "June", "July",
+    "August", "September", "October", "November", "December"
+  },
+  {
+    "AM", "PM"
+  },
+  "%a %b %d %H:%M:%S %Y",
+  "%m/%d/%y",
+  "%H:%M:%S",
+  "%I:%M:%S %p"
+};
+
+struct century_relyear
+{
+    int century;
+    int relyear;
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static int _conv_num(const unsigned char **buf, int *dest,
+                     int llim, int ulim)
+{
+  int result = 0;
+  int rulim = ulim;
+
+  while (isspace(**buf))
+    (*buf)++;
+
+  if (**buf < '0' || **buf > '9')
+    {
+      return (0);
+    }
+
+  /* we use rulim to break out of the loop when we run out of digits */
+
+  do
+    {
+      result *= 10;
+      result += *(*buf)++ - '0';
+      rulim /= 10;
+    }
+      while ((result * 10 <= ulim) && rulim && **buf >= '0' && **buf <= '9');
+
+  if (result < llim || result > ulim)
+    {
+      return (0);

Review Comment:
   ```suggestion
         return 0;
   ```



##########
libs/libc/time/lib_strptime.c:
##########
@@ -0,0 +1,540 @@
+/****************************************************************************
+ * libs/libc/time/lib_strptime.c
+ *
+ *  $OpenBSD: strptime.c,v 1.11 2005/08/08 08:05:38 espie Exp $
+ *  $NetBSD: strptime.c,v 1.12 1998/01/20 21:39:40 mycroft Exp $
+ *
+ * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code was contributed to The NetBSD Foundation by Klaus Klein.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *        This product includes software developed by the NetBSD
+ *        Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+#include <nuttx/config.h>
+
+#include <ctype.h>
+#include <locale.h>
+#include <strings.h>
+#include <time.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define TM_YEAR_BASE        1900
+#define _ctloc(x)           (_defaulttimelocale.x)
+
+/* We do not implement alternate representations. However, we always
+ * check whether a given modifier is allowed for a certain conversion.
+ */
+
+#define _ALT_E              0x01
+#define _ALT_O              0x02
+#define _LEGAL_ALT(x)       { if (alt_format & ~(x)) return (0); }
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct
+{
+    const char *abday[7];
+    const char *day[7];
+    const char *abmon[12];
+    const char *mon[12];
+    const char *am_pm[2];
+    const char *d_t_fmt;
+    const char *d_fmt;
+    const char *t_fmt;
+    const char *t_fmt_ampm;
+} _defaulttimelocale =
+{
+  {
+    "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat",
+  },
+  {
+    "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday",
+    "Friday", "Saturday"
+  },
+  {
+    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+  },
+  {
+    "January", "February", "March", "April", "May", "June", "July",
+    "August", "September", "October", "November", "December"
+  },
+  {
+    "AM", "PM"
+  },
+  "%a %b %d %H:%M:%S %Y",
+  "%m/%d/%y",
+  "%H:%M:%S",
+  "%I:%M:%S %p"
+};
+
+struct century_relyear
+{
+    int century;
+    int relyear;
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static int _conv_num(const unsigned char **buf, int *dest,
+                     int llim, int ulim)
+{
+  int result = 0;
+  int rulim = ulim;
+
+  while (isspace(**buf))
+    (*buf)++;
+
+  if (**buf < '0' || **buf > '9')
+    {
+      return (0);
+    }
+
+  /* we use rulim to break out of the loop when we run out of digits */
+
+  do
+    {
+      result *= 10;
+      result += *(*buf)++ - '0';
+      rulim /= 10;
+    }
+      while ((result * 10 <= ulim) && rulim && **buf >= '0' && **buf <= '9');
+
+  if (result < llim || result > ulim)
+    {
+      return (0);
+    }
+
+  *dest = result;
+  return (1);

Review Comment:
   ```suggestion
     return 1;
   ```



##########
libs/libc/time/lib_strptime.c:
##########
@@ -0,0 +1,540 @@
+/****************************************************************************
+ * libs/libc/time/lib_strptime.c
+ *
+ *  $OpenBSD: strptime.c,v 1.11 2005/08/08 08:05:38 espie Exp $
+ *  $NetBSD: strptime.c,v 1.12 1998/01/20 21:39:40 mycroft Exp $
+ *
+ * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code was contributed to The NetBSD Foundation by Klaus Klein.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *        This product includes software developed by the NetBSD
+ *        Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+#include <nuttx/config.h>
+
+#include <ctype.h>
+#include <locale.h>
+#include <strings.h>
+#include <time.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define TM_YEAR_BASE        1900
+#define _ctloc(x)           (_defaulttimelocale.x)
+
+/* We do not implement alternate representations. However, we always
+ * check whether a given modifier is allowed for a certain conversion.
+ */
+
+#define _ALT_E              0x01
+#define _ALT_O              0x02
+#define _LEGAL_ALT(x)       { if (alt_format & ~(x)) return (0); }
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct
+{
+    const char *abday[7];
+    const char *day[7];
+    const char *abmon[12];
+    const char *mon[12];
+    const char *am_pm[2];
+    const char *d_t_fmt;
+    const char *d_fmt;
+    const char *t_fmt;
+    const char *t_fmt_ampm;
+} _defaulttimelocale =
+{
+  {
+    "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat",
+  },
+  {
+    "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday",
+    "Friday", "Saturday"
+  },
+  {
+    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+  },
+  {
+    "January", "February", "March", "April", "May", "June", "July",
+    "August", "September", "October", "November", "December"
+  },
+  {
+    "AM", "PM"
+  },
+  "%a %b %d %H:%M:%S %Y",
+  "%m/%d/%y",
+  "%H:%M:%S",
+  "%I:%M:%S %p"
+};
+
+struct century_relyear
+{
+    int century;
+    int relyear;
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static int _conv_num(const unsigned char **buf, int *dest,
+                     int llim, int ulim)
+{
+  int result = 0;
+  int rulim = ulim;
+
+  while (isspace(**buf))
+    (*buf)++;
+
+  if (**buf < '0' || **buf > '9')
+    {
+      return (0);
+    }
+
+  /* we use rulim to break out of the loop when we run out of digits */
+
+  do
+    {
+      result *= 10;
+      result += *(*buf)++ - '0';
+      rulim /= 10;
+    }
+      while ((result * 10 <= ulim) && rulim && **buf >= '0' && **buf <= '9');
+
+  if (result < llim || result > ulim)
+    {
+      return (0);
+    }
+
+  *dest = result;
+  return (1);
+}
+
+static unsigned char * _strptime(const unsigned char *buf,
+                                 const char *fmt,
+                                 struct tm *tm,
+                                 struct century_relyear *cr)
+{
+  unsigned char c;
+  const unsigned char *bp;
+  size_t len = 0;
+  int alt_format;
+  int i;
+
+  bp = (unsigned char *)buf;

Review Comment:
   ```suggestion
     bp = (const unsigned char *)buf;
   ```



##########
libs/libc/time/lib_strptime.c:
##########
@@ -0,0 +1,540 @@
+/****************************************************************************
+ * libs/libc/time/lib_strptime.c
+ *
+ *  $OpenBSD: strptime.c,v 1.11 2005/08/08 08:05:38 espie Exp $
+ *  $NetBSD: strptime.c,v 1.12 1998/01/20 21:39:40 mycroft Exp $
+ *
+ * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code was contributed to The NetBSD Foundation by Klaus Klein.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *        This product includes software developed by the NetBSD
+ *        Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+#include <nuttx/config.h>
+
+#include <ctype.h>
+#include <locale.h>
+#include <strings.h>
+#include <time.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define TM_YEAR_BASE        1900
+#define _ctloc(x)           (_defaulttimelocale.x)
+
+/* We do not implement alternate representations. However, we always
+ * check whether a given modifier is allowed for a certain conversion.
+ */
+
+#define _ALT_E              0x01
+#define _ALT_O              0x02
+#define _LEGAL_ALT(x)       { if (alt_format & ~(x)) return (0); }
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct
+{
+    const char *abday[7];
+    const char *day[7];
+    const char *abmon[12];
+    const char *mon[12];
+    const char *am_pm[2];
+    const char *d_t_fmt;
+    const char *d_fmt;
+    const char *t_fmt;
+    const char *t_fmt_ampm;
+} _defaulttimelocale =
+{
+  {
+    "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat",
+  },
+  {
+    "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday",
+    "Friday", "Saturday"
+  },
+  {
+    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+  },
+  {
+    "January", "February", "March", "April", "May", "June", "July",
+    "August", "September", "October", "November", "December"
+  },
+  {
+    "AM", "PM"
+  },
+  "%a %b %d %H:%M:%S %Y",
+  "%m/%d/%y",
+  "%H:%M:%S",
+  "%I:%M:%S %p"
+};
+
+struct century_relyear
+{
+    int century;
+    int relyear;
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static int _conv_num(const unsigned char **buf, int *dest,
+                     int llim, int ulim)
+{
+  int result = 0;
+  int rulim = ulim;
+
+  while (isspace(**buf))
+    (*buf)++;
+
+  if (**buf < '0' || **buf > '9')
+    {
+      return (0);
+    }
+
+  /* we use rulim to break out of the loop when we run out of digits */
+
+  do
+    {
+      result *= 10;
+      result += *(*buf)++ - '0';
+      rulim /= 10;
+    }
+      while ((result * 10 <= ulim) && rulim && **buf >= '0' && **buf <= '9');
+
+  if (result < llim || result > ulim)
+    {
+      return (0);
+    }
+
+  *dest = result;
+  return (1);
+}
+
+static unsigned char * _strptime(const unsigned char *buf,
+                                 const char *fmt,
+                                 struct tm *tm,
+                                 struct century_relyear *cr)
+{
+  unsigned char c;
+  const unsigned char *bp;

Review Comment:
   ```suggestion
     FAR const unsigned char *bp;
   ```



##########
libs/libc/time/lib_strptime.c:
##########
@@ -0,0 +1,540 @@
+/****************************************************************************
+ * libs/libc/time/lib_strptime.c
+ *
+ *  $OpenBSD: strptime.c,v 1.11 2005/08/08 08:05:38 espie Exp $
+ *  $NetBSD: strptime.c,v 1.12 1998/01/20 21:39:40 mycroft Exp $
+ *
+ * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code was contributed to The NetBSD Foundation by Klaus Klein.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *        This product includes software developed by the NetBSD
+ *        Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+#include <nuttx/config.h>
+
+#include <ctype.h>
+#include <locale.h>
+#include <strings.h>
+#include <time.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define TM_YEAR_BASE        1900
+#define _ctloc(x)           (_defaulttimelocale.x)
+
+/* We do not implement alternate representations. However, we always
+ * check whether a given modifier is allowed for a certain conversion.
+ */
+
+#define _ALT_E              0x01
+#define _ALT_O              0x02
+#define _LEGAL_ALT(x)       { if (alt_format & ~(x)) return (0); }
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct
+{
+    const char *abday[7];
+    const char *day[7];
+    const char *abmon[12];
+    const char *mon[12];
+    const char *am_pm[2];
+    const char *d_t_fmt;
+    const char *d_fmt;
+    const char *t_fmt;
+    const char *t_fmt_ampm;
+} _defaulttimelocale =
+{
+  {
+    "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat",
+  },
+  {
+    "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday",
+    "Friday", "Saturday"
+  },
+  {
+    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+  },
+  {
+    "January", "February", "March", "April", "May", "June", "July",
+    "August", "September", "October", "November", "December"
+  },
+  {
+    "AM", "PM"
+  },
+  "%a %b %d %H:%M:%S %Y",
+  "%m/%d/%y",
+  "%H:%M:%S",
+  "%I:%M:%S %p"
+};
+
+struct century_relyear
+{
+    int century;
+    int relyear;
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static int _conv_num(const unsigned char **buf, int *dest,
+                     int llim, int ulim)
+{
+  int result = 0;
+  int rulim = ulim;
+
+  while (isspace(**buf))
+    (*buf)++;
+
+  if (**buf < '0' || **buf > '9')
+    {
+      return (0);
+    }
+
+  /* we use rulim to break out of the loop when we run out of digits */
+
+  do
+    {
+      result *= 10;
+      result += *(*buf)++ - '0';
+      rulim /= 10;
+    }
+      while ((result * 10 <= ulim) && rulim && **buf >= '0' && **buf <= '9');
+
+  if (result < llim || result > ulim)
+    {
+      return (0);
+    }
+
+  *dest = result;
+  return (1);
+}
+
+static unsigned char * _strptime(const unsigned char *buf,
+                                 const char *fmt,
+                                 struct tm *tm,

Review Comment:
   ```suggestion
   static unsigned char * _strptime(FAR const unsigned char *buf,
                                    FAR const char *fmt,
                                    FAR struct tm *tm,
   ```



##########
libs/libc/time/lib_strptime.c:
##########
@@ -0,0 +1,540 @@
+/****************************************************************************
+ * libs/libc/time/lib_strptime.c
+ *
+ *  $OpenBSD: strptime.c,v 1.11 2005/08/08 08:05:38 espie Exp $
+ *  $NetBSD: strptime.c,v 1.12 1998/01/20 21:39:40 mycroft Exp $
+ *
+ * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code was contributed to The NetBSD Foundation by Klaus Klein.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *        This product includes software developed by the NetBSD
+ *        Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+#include <nuttx/config.h>
+
+#include <ctype.h>
+#include <locale.h>
+#include <strings.h>
+#include <time.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define TM_YEAR_BASE        1900
+#define _ctloc(x)           (_defaulttimelocale.x)
+
+/* We do not implement alternate representations. However, we always
+ * check whether a given modifier is allowed for a certain conversion.
+ */
+
+#define _ALT_E              0x01
+#define _ALT_O              0x02
+#define _LEGAL_ALT(x)       { if (alt_format & ~(x)) return (0); }
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static const struct
+{
+    const char *abday[7];
+    const char *day[7];
+    const char *abmon[12];
+    const char *mon[12];
+    const char *am_pm[2];
+    const char *d_t_fmt;
+    const char *d_fmt;
+    const char *t_fmt;
+    const char *t_fmt_ampm;
+} _defaulttimelocale =
+{
+  {
+    "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat",
+  },
+  {
+    "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday",
+    "Friday", "Saturday"
+  },
+  {
+    "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+  },
+  {
+    "January", "February", "March", "April", "May", "June", "July",
+    "August", "September", "October", "November", "December"
+  },
+  {
+    "AM", "PM"
+  },
+  "%a %b %d %H:%M:%S %Y",
+  "%m/%d/%y",
+  "%H:%M:%S",
+  "%I:%M:%S %p"
+};
+
+struct century_relyear
+{
+    int century;
+    int relyear;
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static int _conv_num(const unsigned char **buf, int *dest,
+                     int llim, int ulim)
+{
+  int result = 0;
+  int rulim = ulim;
+
+  while (isspace(**buf))
+    (*buf)++;
+
+  if (**buf < '0' || **buf > '9')
+    {
+      return (0);
+    }
+
+  /* we use rulim to break out of the loop when we run out of digits */
+
+  do
+    {
+      result *= 10;
+      result += *(*buf)++ - '0';
+      rulim /= 10;
+    }
+      while ((result * 10 <= ulim) && rulim && **buf >= '0' && **buf <= '9');
+
+  if (result < llim || result > ulim)
+    {
+      return (0);
+    }
+
+  *dest = result;
+  return (1);
+}
+
+static unsigned char * _strptime(const unsigned char *buf,
+                                 const char *fmt,
+                                 struct tm *tm,
+                                 struct century_relyear *cr)
+{
+  unsigned char c;
+  const unsigned char *bp;
+  size_t len = 0;
+  int alt_format;
+  int i;
+
+  bp = (unsigned char *)buf;
+  while ((c = *fmt) != '\0')
+    {
+      /* Clear `alternate' modifier prior to new conversion. */
+
+      alt_format = 0;
+
+      /* Eat up white-space. */
+
+      if (isspace(c))
+        {
+          while (isspace(*bp))
+            bp++;
+
+          fmt++;
+          continue;
+        }
+
+      if ((c = *fmt++) != '%')
+        {
+          goto literal;
+        }
+
+    again:
+      switch (c = *fmt++)
+        {
+          case '%': /* "%%" is converted to "%". */
+          literal:
+            if (c != *bp++)
+              return (NULL);
+
+            break;
+
+            /* "Alternative" modifiers. Just set the appropriate flag
+            * and start over again.
+            */
+
+          case 'E': /* "%E?" alternative conversion modifier. */
+            _LEGAL_ALT(0);
+            alt_format |= _ALT_E;
+            goto again;
+
+          case 'O': /* "%O?" alternative conversion modifier. */
+            _LEGAL_ALT(0);
+            alt_format |= _ALT_O;
+            goto again;
+
+            /* "Complex" conversion rules, implemented through recursion. */
+
+          case 'c': /* Date and time, using the locale's format. */
+            _LEGAL_ALT(_ALT_E);
+            if (!(bp = _strptime(bp, _ctloc(d_t_fmt), tm, cr)))
+              return (NULL);
+            break;
+
+          case 'D': /* The date as "%m/%d/%y". */
+            _LEGAL_ALT(0);
+            if (!(bp = _strptime(bp, "%m/%d/%y", tm, cr)))
+              return (NULL);
+            break;
+
+          case 'R': /* The time as "%H:%M". */
+            _LEGAL_ALT(0);
+            if (!(bp = _strptime(bp, "%H:%M", tm, cr)))
+              return (NULL);
+            break;
+
+          case 'r': /* The time as "%I:%M:%S %p". */
+            _LEGAL_ALT(0);
+            if (!(bp = _strptime(bp, "%I:%M:%S %p", tm, cr)))
+              return (NULL);
+            break;
+
+          case 'T': /* The time as "%H:%M:%S". */
+            _LEGAL_ALT(0);
+            if (!(bp = _strptime(bp, "%H:%M:%S", tm, cr)))
+              return (NULL);
+            break;
+
+          case 'X': /* The time, using the locale's format. */
+            _LEGAL_ALT(_ALT_E);
+            if (!(bp = _strptime(bp, _ctloc(t_fmt), tm, cr)))
+              return (NULL);
+            break;
+
+          case 'x': /* The date, using the locale's format. */
+            _LEGAL_ALT(_ALT_E);
+            if (!(bp = _strptime(bp, _ctloc(d_fmt), tm, cr)))
+              return (NULL);
+            break;
+
+            /* "Elementary" conversion rules. */
+
+          case 'A': /* The day of week, using the locale's form. */
+          case 'a':
+            _LEGAL_ALT(0);
+            for (i = 0; i < 7; i++)
+              {
+                /* Full name. */
+
+                len = strlen(_ctloc(day[i]));
+                if (strncasecmp(_ctloc(day[i]),
+                                (const char *)bp, len) == 0)
+                  break;
+
+                /* Abbreviated name. */
+
+                len = strlen(_ctloc(abday[i]));
+                if (strncasecmp(_ctloc(abday[i]),
+                                (const char *)bp, len) == 0)
+                  break;
+              }
+
+            /* Nothing matched. */
+
+            if (i == 7)
+              return (NULL);
+
+            tm->tm_wday = i;
+            bp += len;
+            break;
+
+          case 'B': /* The month, using the locale's form. */
+          case 'b':
+          case 'h':
+            _LEGAL_ALT(0);
+            for (i = 0; i < 12; i++)
+              {
+                /* Full name. */
+
+                len = strlen(_ctloc(mon[i]));
+                if (strncasecmp(_ctloc(mon[i]),
+                                (const char *)bp, len) == 0)
+                  break;
+
+                /* Abbreviated name. */
+
+                len = strlen(_ctloc(abmon[i]));
+                if (strncasecmp(_ctloc(abmon[i]),
+                                (const char *)bp, len) == 0)
+                  break;
+              }
+
+            /* Nothing matched. */
+
+            if (i == 12)
+              return (NULL);
+
+            tm->tm_mon = i;
+            bp += len;
+            break;
+
+          case 'C': /* The century number. */
+            _LEGAL_ALT(_ALT_E);
+            if (!(_conv_num(&bp, &i, 0, 99)))
+              return (NULL);
+
+            cr->century = i * 100;
+            break;
+
+          case 'd': /* The day of month. */
+          case 'e':
+            _LEGAL_ALT(_ALT_O);
+            if (!(_conv_num(&bp, &tm->tm_mday, 1, 31)))
+              return (NULL);
+            break;
+
+          case 'k': /* The hour (24-hour clock representation). */
+            _LEGAL_ALT(0);
+
+            /* FALLTHROUGH */
+
+          case 'H':
+            _LEGAL_ALT(_ALT_O);
+            if (!(_conv_num(&bp, &tm->tm_hour, 0, 23)))
+              return (NULL);
+            break;
+
+          case 'l': /* The hour (12-hour clock representation). */
+            _LEGAL_ALT(0);
+
+            /* FALLTHROUGH */
+
+          case 'I':
+            _LEGAL_ALT(_ALT_O);
+            if (!(_conv_num(&bp, &tm->tm_hour, 1, 12)))
+              return (NULL);
+            break;
+
+          case 'j': /* The day of year. */
+            _LEGAL_ALT(0);
+            if (!(_conv_num(&bp, &tm->tm_yday, 1, 366)))
+              return (NULL);
+            tm->tm_yday--;
+            break;
+
+          case 'M': /* The minute. */
+            _LEGAL_ALT(_ALT_O);
+            if (!(_conv_num(&bp, &tm->tm_min, 0, 59)))
+              return (NULL);
+            break;
+
+          case 'm': /* The month. */
+            _LEGAL_ALT(_ALT_O);
+            if (!(_conv_num(&bp, &tm->tm_mon, 1, 12)))
+              return (NULL);
+            tm->tm_mon--;
+            break;
+
+          case 'p': /* The locale's equivalent of AM/PM. */
+            _LEGAL_ALT(0);
+
+            /* AM? */
+
+            len = strlen(_ctloc(am_pm[0]));
+            if (strncasecmp(_ctloc(am_pm[0]), (const char *)bp, len) == 0)
+              {
+                if (tm->tm_hour > 12) /* i.e., 13:00 AM ?! */
+                  return (NULL);
+                else if (tm->tm_hour == 12)
+                  tm->tm_hour = 0;
+
+                bp += len;
+                break;
+              }
+
+            /* PM? */
+
+            len = strlen(_ctloc(am_pm[1]));
+            if (strncasecmp(_ctloc(am_pm[1]), (const char *)bp, len) == 0)
+              {
+                if (tm->tm_hour > 12) /* i.e., 13:00 PM ?! */
+                  return (NULL);
+                else if (tm->tm_hour < 12)
+                  tm->tm_hour += 12;
+
+                bp += len;
+                break;
+              }
+
+            /* Nothing matched. */
+
+            return (NULL);
+
+          case 'S': /* The seconds. */
+            _LEGAL_ALT(_ALT_O);
+            if (!(_conv_num(&bp, &tm->tm_sec, 0, 61)))
+              return (NULL);
+            break;
+
+          case 'U': /* The week of year, beginning on sunday. */
+          case 'W': /* The week of year, beginning on monday. */
+            _LEGAL_ALT(_ALT_O);
+            /* XXX This is bogus, as we can not assume any valid
+            * information present in the tm structure at this
+            * point to calculate a real value, so just check the
+            * range for now.
+            */
+
+            if (!(_conv_num(&bp, &i, 0, 53)))
+              return (NULL);
+            break;
+
+          case 'w': /* The day of week, beginning on sunday. */
+            _LEGAL_ALT(_ALT_O);
+            if (!(_conv_num(&bp, &tm->tm_wday, 0, 6)))
+              return (NULL);
+            break;
+
+          case 'Y': /* The year. */
+            _LEGAL_ALT(_ALT_E);
+            if (!(_conv_num(&bp, &i, 0, 9999)))
+              return (NULL);
+
+            cr->relyear = -1;
+            tm->tm_year = i - TM_YEAR_BASE;
+            break;
+
+          case 'y': /* The year within the century (2 digits). */
+            _LEGAL_ALT(_ALT_E | _ALT_O);
+            if (!(_conv_num(&bp, &cr->relyear, 0, 99)))
+              return (NULL);
+            break;
+
+            /* Miscellaneous conversions. */
+
+          case 'n': /* Any kind of white-space. */
+          case 't':
+            _LEGAL_ALT(0);
+            while (isspace(*bp))
+              bp++;
+            break;
+
+          default: /* Unknown/unsupported conversion. */
+            return (NULL);
+        }
+    }
+
+  /* We need to evaluate the two digit year spec (%y)
+   * last as we can get a century spec (%C) at any time.
+   */
+
+  if (cr->relyear != -1)
+  {
+    if (cr->century == TM_YEAR_BASE)
+    {
+      if (cr->relyear <= 68)
+        tm->tm_year = cr->relyear + 2000 - TM_YEAR_BASE;
+      else
+        tm->tm_year = cr->relyear + 1900 - TM_YEAR_BASE;
+    }
+    else
+    {
+      tm->tm_year = cr->relyear + cr->century - TM_YEAR_BASE;
+    }
+  }
+
+  return (unsigned char *)bp;

Review Comment:
   why `const` is discarded?



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