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Apparently setvbuf() size can be nonzero with _IONBF. That makes no sense, but is necessary if setbuf() is to work as it is defined at OpenGroup.org.

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This commit is contained in:
Gregory Nutt 2017-02-09 15:39:33 -06:00
parent ffbf6bc9a6
commit 98d072a1f7
2 changed files with 20 additions and 25 deletions
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23
libc/stdio/lib_setbuf.c
View File

@ -59,11 +59,7 @@
*
* setvbuf(stream, buf, _IONBF, BUFSIZ)
*
* if buf is a null pointer.
*
* EXCEPTION: Currently, the NuttX setvbuf() expects the size argument to
* be zero if the mode is __INOBF. That is a descrepancy! What would a
* non-zero size mean in that case?
* if buf is a null pointer.
*
* Input Parameters:
* stream - The stream whose buffer will be modified
@ -77,16 +73,15 @@
void setbuf(FAR FILE *stream, FAR char *buf)
{
#ifndef CONFIG_STDIO_DISABLE_BUFFERING
int mode;
DEBUGASSERT(stream != NULL);
#ifndef CONFIG_STDIO_DISABLE_BUFFERING
if (buf != NULL)
{
(void)setvbuf(stream, buf, _IOFBF, BUFSIZ);
}
else
{
(void)setvbuf(stream, NULL, _IONBF, 0);
}
mode = (buf != NULL) ? _IOFBF : _IONBF;
(void)setvbuf(stream, buf, mode, BUFSIZ);
#else
DEBUGASSERT(stream != NULL);
#endif
}

22
libc/stdio/lib_setvbuf.c
View File

@ -113,16 +113,6 @@ 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;
}
/* 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
@ -136,6 +126,17 @@ int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
size = BUFSIZ;
}
/* A non-zero size (or a non-NULL buffer) with mode = _IONBF makes no
* sense but is, apparently, permissible. We simply force the buffer to
* NULL and size to zero in this case without complaining.
*/
else if (mode == _IONBF)
{
buffer = NULL;
size = 0;
}
/* Make sure that we have exclusive access to the stream */
lib_take_semaphore(stream);
@ -229,7 +230,6 @@ int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
case _IONBF:
/* No buffer needed... We must be performing unbuffered I/O */
DEBUGASSERT(size == 0);
newbuf = NULL;
break;