[GitHub] [incubator-nuttx] fjpanag opened a new issue #3915: Reopening a file does not clear I/O buffers.

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

fjpanag opened a new issue #3915:
URL: https://github.com/apache/incubator-nuttx/issues/3915


   If I use I/O buffering (CONFIG_STDIO_DISABLE_BUFFERING = n), then the following piece of code fails.
   
   ```c
   int c1;
   int c2;
   
   FILE * file = fopen("/file", "r");
   c1 = getc(file);
   
   file = freopen("/file", "rb");
   c2 = getc(file);
   
   assert(c1 == c2);
   ```
   
   When the file is re-opened, the file index does not return to zero. `c2` gets the *second* character in the file, as it was found in the buffer (the file is not re-read).
   
   Recompiling the code with `CONFIG_STDIO_DISABLE_BUFFERING` selected (no I/O buffering), the problem is solved.  
   When I reopen the file, I get the first character of the file, as expected.
   
   When a file is re-opened, shouldn't the I/O buffers be cleared?
   


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[GitHub] [incubator-nuttx] pkarashchenko commented on issue #3915: Reopening a file does not clear I/O buffers.

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

pkarashchenko commented on issue #3915:
URL: https://github.com/apache/incubator-nuttx/issues/3915#issuecomment-996888999


   From the example I see that `file = freopen("/file", "rb");` is used, but `FAR FILE *freopen(FAR const char *path, FAR const char *mode, FAR FILE *stream);`, so the last parameter is missing in the example. Is the case incomplete?


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