diff options
| author | Rich Felker <dalias@aerifal.cx> | 2014-09-04 22:21:17 -0400 |
|---|---|---|
| committer | Rich Felker <dalias@aerifal.cx> | 2014-09-04 22:21:17 -0400 |
| commit | 6e2bb7acf42589fb7130b039d0623e2ca42503dd (patch) | |
| tree | 7af4719cfa84bc8cf0c6fa73fdca42035eaf03e9 /src/stdio/fread.c | |
| parent | 402611c3ba3be5b3b0486835d98e22ac7ced2722 (diff) | |
| download | musl-6e2bb7acf42589fb7130b039d0623e2ca42503dd.tar.gz | |
fix multiple stdio functions' behavior on zero-length operations
previously, fgets, fputs, fread, and fwrite completely omitted locking
and access to the FILE object when their arguments yielded a zero
length read or write operation independent of the FILE state. this
optimization was invalid; it wrongly skipped marking the stream as
byte-oriented (a C conformance bug) and exposed observably missing
synchronization (a POSIX conformance bug) where one of these functions
could wrongly complete despite another thread provably holding the
lock.
Diffstat (limited to 'src/stdio/fread.c')
| -rw-r--r-- | src/stdio/fread.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/src/stdio/fread.c b/src/stdio/fread.c index c461256c..33a65f58 100644 --- a/src/stdio/fread.c +++ b/src/stdio/fread.c @@ -8,11 +8,10 @@ size_t fread(void *restrict destv, size_t size, size_t nmemb, FILE *restrict f) unsigned char *dest = destv; size_t len = size*nmemb, l = len, k; - /* Never touch the file if length is zero.. */ - if (!l) return 0; - FLOCK(f); + f->mode |= f->mode-1; + if (f->rend - f->rpos > 0) { /* First exhaust the buffer. */ k = MIN(f->rend - f->rpos, l); |