sergiotarxz/nuttx
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

setvbuf: Correct some errors detected by code review.

Browse Source
This commit is contained in:
Gregory Nutt 2017-02-08 14:06:29 -06:00
parent ea53894e51
commit a92887c63d
2 changed files with 100 additions and 78 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
fs/vfs/fs_fdopen.c
View File

@ -249,7 +249,6 @@ FAR struct file_struct *fs_fdopen(int fd, int oflags, FAR struct tcb_s *tcb)
stream->fs_bufend = &stream->fs_bufstart[CONFIG_STDIO_BUFFER_SIZE];
stream->fs_bufpos = stream->fs_bufstart;
stream->fs_bufpos = stream->fs_bufstart;
stream->fs_bufread = stream->fs_bufstart;
/* Setup buffer flags */

177
libc/stdio/lib_setvbuf.c
View File

@ -98,11 +98,12 @@
int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
{
#if CONFIG_STDIO_BUFFER_SIZE > 0
FAR unsigned char *newbuf;
uint8_t flags;
int errcode;
int ret = OK;
/* Verify arguments */
/* Make sure that a valid mode was provided */
if (mode != _IOFBF && mode != _IOLBF && mode != _IONBF)
{
@ -110,24 +111,7 @@ int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
goto errout;
}
/* Make sure that the size argument agrees with the mode */
if (((mode == _IOFBF || mode == _IOLBF) && size == 0) ||
(mode == _IONBF && size > 0))
{
errcode = EINVAL;
goto errout;
}
/* Make sure that the buffer argument agrees with mode */
if (mode == _IONBF && buffer != NULL)
{
errcode = EINVAL;
goto errout;
}
/* Make sure that the buffer and size argeuments agree */
/* If a buffer pointer is provided, then it must have a non-zero size */
if (buffer != NULL && size == 0)
{
@ -135,6 +119,16 @@ int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
goto errout;
}
/* A non-zero size (or a non-NULL buffer) with mode = _IONBF makes no
* sense.
*/
if (mode == _IONBF && size > 0)
{
errcode = EINVAL;
goto errout;
}
#if 1 /* REVISIT: _IONBF not yet supported */
/* Not all features are be available. Without some additional logic,
* we cannot disable buffering if CONFIG_STDIO_BUFFER_SIZE > 0
@ -147,6 +141,19 @@ int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
}
#endif
/* My assumption is that if size is zero for modes {_IOFBF, _IOLBF} the
* caller is only attempting to change the buffering mode. In this case,
* the existing buffer should be re-used (if there is one). If there is no
* existing buffer, then I suppose we should allocate one of the default
* size?
*/
if ((mode == _IOFBF || mode == _IOLBF) && size == 0 &&
stream->fs_bufstart == NULL)
{
size = CONFIG_STDIO_BUFFER_SIZE;
}
/* Make sure that we have exclusive access to the stream */
lib_take_semaphore(stream);
@ -166,6 +173,8 @@ int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
/* Return EBUSY if operations have already been performed on the buffer.
* Here we really only verify that there is no valid data in the existing
* buffer.
*
* REVIST: There could be race conditions here, could there not?
*/
if (stream->fs_bufpos != stream->fs_bufstart)
@ -185,82 +194,96 @@ int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
flags = stream->fs_flags & ~(__FS_FLAG_LBF | __FS_FLAG_NBF | __FS_FLAG_UBF);
#endif
/* Allocate a new buffer if one is needed. We have already verified that:
*
* If a buffer is needed, then size > 0
* If a buffer is NOT needed, then buffer is NULL
* If buffer != NULL, then size > 0
*
* That simplifies the following check:
/* Allocate a new buffer if one is needed or reuse the existing buffer it
* is appropriate to do so.
*/
#if 0 /* REVISIT: _IONBF not yet supported */
if (size > 0)
#else
DEBUGASSERT(size > 0);
#endif
switch (mode)
{
FAR unsigned char *newbuf;
case _IOLBF:
flags |= __FS_FLAG_LBF;
/* A buffer is needed. Did the caller provide the buffer memory? */
/* Fall through */
DEBUGASSERT(mode == _IOFBF || mode == _IOLBF);
if (buffer != NULL)
{
newbuf = (FAR unsigned char *)buffer;
case _IOFBF:
/* Use the existing buffer if size == 0 */
/* Indicate that we have an I/O buffer managed by the caller of
* setvbuf.
*/
if (size > 0)
{
/* A new buffer is needed. Did the caller provide the buffer
* memory?
*/
flags |= __FS_FLAG_UBF;
}
else
{
newbuf = (FAR unsigned char *)lib_malloc(size);
if (newbuf == NULL)
{
errcode = ENOMEM;
goto errout_with_semaphore;
}
}
if (buffer != NULL)
{
newbuf = (FAR unsigned char *)buffer;
/* Do not release the previous buffer if it was allocated by the user
* on a previous call to setvbuf().
*/
/* Indicate that we have an I/O buffer managed by the caller of
* setvbuf.
*/
if ((stream->fs_flags & __FS_FLAG_UBF) != 0)
{
lib_free(stream->fs_bufstart);
}
flags |= __FS_FLAG_UBF;
}
else
{
newbuf = (FAR unsigned char *)lib_malloc(size);
if (newbuf == NULL)
{
errcode = ENOMEM;
goto errout_with_semaphore;
}
}
}
else
{
/* Re-use the existing buffer and retain some existing flags.
* This supports changing the buffering mode without changing
* the buffer.
*/
/* Use the new buffer */
DEBUGASSERT(stream->fs_bufstart != NULL);
flags |= stream->fs_flags & __FS_FLAG_UBF;
goto reuse_buffer;
}
stream->fs_bufstart = newbuf;
stream->fs_bufend = newbuf;
stream->fs_bufpos = newbuf;
stream->fs_bufread = newbuf;
break;
/* Check for line buffering */
if (mode == _IOLBF)
{
flags |= __FS_FLAG_LBF;
}
}
case _IONBF:
#if 0 /* REVISIT: _IONBF not yet supported */
else
{
/* No buffer needed... We must be performing unbuffered I/O */
/* No buffer needed... We must be performing unbuffered I/O */
DEBUGASSERT(mode == _IONBF);
flags |= __FS_FLAG_NBF;
}
DEBUGASSERT(size == 0);
newbuf = NULL;
flags |= __FS_FLAG_NBF;
break;
#endif
default:
PANIC();
}
/* Do not release the previous buffer if it was allocated by the user
* on a previous call to setvbuf().
*/
if (stream->fs_bufstart != NULL &&
(stream->fs_flags & __FS_FLAG_UBF) == 0)
{
lib_free(stream->fs_bufstart);
}
/* Set the new buffer information */
stream->fs_bufstart = newbuf;
stream->fs_bufpos = newbuf;
stream->fs_bufread = newbuf;
stream->fs_bufend = newbuf + size;
/* Update the stream flags and return success */
stream->fs_flags = flags;
reuse_buffer:
stream->fs_flags = flags;
lib_give_semaphore(stream);
return OK;