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/fgets.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/fgets.c')
| -rw-r--r-- | src/stdio/fgets.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/src/stdio/fgets.c b/src/stdio/fgets.c index cf5b1039..d3f9819e 100644 --- a/src/stdio/fgets.c +++ b/src/stdio/fgets.c @@ -10,14 +10,16 @@ char *fgets(char *restrict s, int n, FILE *restrict f) size_t k; int c; + FLOCK(f); + if (n--<=1) { + f->mode |= f->mode-1; + FUNLOCK(f); if (n) return 0; *s = 0; return s; } - FLOCK(f); - while (n) { z = memchr(f->rpos, '\n', f->rend - f->rpos); k = z ? z - f->rpos + 1 : f->rend - f->rpos; |