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libs/libc/stdio/lib_libfread.c: fread() should always set EOF if fewer than the requested number of bytes was not read. Per Anthony Merlino.

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This commit is contained in:
Gregory Nutt 2018-12-07 12:18:40 -06:00
parent a47224723e
commit 3def509f4e
1 changed files with 29 additions and 38 deletions
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67
libs/libc/stdio/lib_libfread.c
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@ -62,6 +62,7 @@ ssize_t lib_fread(FAR void *ptr, size_t count, FAR FILE *stream)
{
FAR unsigned char *dest = (FAR unsigned char*)ptr;
ssize_t bytes_read;
size_t remaining = count;
#ifndef CONFIG_STDIO_DISABLE_BUFFERING
int ret;
#endif
@ -82,7 +83,7 @@ ssize_t lib_fread(FAR void *ptr, size_t count, FAR FILE *stream)
#if CONFIG_NUNGET_CHARS > 0
/* First, re-read any previously ungotten characters */
while ((stream->fs_nungotten > 0) && (count > 0))
while (stream->fs_nungotten > 0 && remaining > 0)
{
/* Decrement the count of ungotten bytes to get an index */
@ -94,7 +95,7 @@ ssize_t lib_fread(FAR void *ptr, size_t count, FAR FILE *stream)
/* That's one less byte that we have to read */
count--;
remaining--;
}
#endif
@ -117,16 +118,16 @@ ssize_t lib_fread(FAR void *ptr, size_t count, FAR FILE *stream)
/* Now get any other needed chars from the buffer or the file. */
while (count > 0)
while (remaining > 0)
{
/* Is there readable data in the buffer? */
while ((count > 0) && (stream->fs_bufpos < stream->fs_bufread))
while (remaining > 0 && stream->fs_bufpos < stream->fs_bufread)
{
/* Yes, copy a byte into the user buffer */
*dest++ = *stream->fs_bufpos++;
count--;
remaining--;
}
/* The buffer is empty OR we have already supplied the number of
@ -134,7 +135,7 @@ ssize_t lib_fread(FAR void *ptr, size_t count, FAR FILE *stream)
* more from the file.
*/
if (count > 0)
if (remaining > 0)
{
size_t buffer_available;
@ -154,9 +155,9 @@ ssize_t lib_fread(FAR void *ptr, size_t count, FAR FILE *stream)
* directly into the user's buffer.
*/
if (count > buffer_available)
if (remaining > buffer_available)
{
bytes_read = _NX_READ(stream->fs_fd, dest, count);
bytes_read = _NX_READ(stream->fs_fd, dest, remaining);
if (bytes_read < 0)
{
/* An error occurred on the read. */
@ -175,24 +176,13 @@ ssize_t lib_fread(FAR void *ptr, size_t count, FAR FILE *stream)
}
else
{
/* Some bytes were read. Adjust the dest pointer */
/* Some (perhaps all) bytes were read. Adjust the dest
* pointer and remaining bytes to be read.
*/
dest += bytes_read;
/* Were all of the requested bytes read? */
if ((size_t)bytes_read < count)
{
/* No. We must be at the end of file. */
goto shortread;
}
else
{
/* Yes. We are done. */
count = 0;
}
DEBUGASSERT(bytes_read <= remaining);
dest += bytes_read;
remaining -= bytes_read;
}
}
else
@ -226,7 +216,7 @@ ssize_t lib_fread(FAR void *ptr, size_t count, FAR FILE *stream)
}
else
{
/* Some bytes were read */
/* Some (perhaps all) bytes were read */
stream->fs_bufread += bytes_read;
}
@ -239,9 +229,9 @@ ssize_t lib_fread(FAR void *ptr, size_t count, FAR FILE *stream)
{
/* Now get any other needed chars from the file. */
while (count > 0)
while (remaining > 0)
{
bytes_read = _NX_READ(stream->fs_fd, dest, count);
bytes_read = _NX_READ(stream->fs_fd, dest, remaining);
if (bytes_read < 0)
{
/* An error occurred on the read. The error code is
@ -262,26 +252,27 @@ ssize_t lib_fread(FAR void *ptr, size_t count, FAR FILE *stream)
}
else
{
dest += bytes_read;
count -= bytes_read;
DEBUGASSERT(bytes_read <= remaining);
dest += bytes_read;
remaining -= bytes_read;
}
}
}
/* Here after a successful (but perhaps short) read */
#ifndef CONFIG_STDIO_DISABLE_BUFFERING
shortread:
/* Here after a successful (but perhaps short) read. A short read can
* only occur is read() returns 0 (end-of-file).
*/
shortread:
#endif
bytes_read = dest - (FAR unsigned char *)ptr;
/* Set or clear the EOF indicator. If we get here because of a
* short read and the total number of* bytes read is zero, then
* short read and the total number of bytes read is zero, then
* we must be at the end-of-file.
*/
if (bytes_read > 0)
if (remaining == 0)
{
stream->fs_flags &= ~__FS_FLAG_EOF;
}
@ -293,7 +284,7 @@ ssize_t lib_fread(FAR void *ptr, size_t count, FAR FILE *stream)
lib_give_semaphore(stream);
}
return bytes_read;
return count - remaining;
/* Error exits */