simplify/refactor fflush and make fflush_unlocked an alias for fflush

previously, fflush_unlocked was an alias for an internal backend that
was called by fflush, either for its argument or in a loop for each
file if a null pointer was passed. since the logic for the latter was
in the main fflush function, fflush_unlocked crashed when passed a
null pointer, rather than flushing all open files. since
fflush_unlocked is not a standard function and has no specification,
it's not clear whether it should be expected to accept null pointers
like fflush does, but a reasonable argument could be made that it
should.

this patch eliminates the helper function, simplifying fflush, and
makes fflush_unlocked an alias for fflush, which is valid because the
two functions agree in their behavior in all cases where their
behavior is defined (the unlocked version has undefined behavior if
another thread could hold locks).

diff --git a/src/stdio/fflush.c b/src/stdio/fflush.c
index 3f462c80e8d12f6efbecd144a144d430736ec6eb..c28810659aba7a6a6dd9148376314d251dc7bc69 100644 (file)
--- a/src/stdio/fflush.c
+++ b/src/stdio/fflush.c
@@ -1,11 +1,30 @@
 #include "stdio_impl.h"
 
-static int __fflush_unlocked(FILE *f)
+/* stdout.c will override this if linked */
+static FILE *volatile dummy = 0;
+weak_alias(dummy, __stdout_used);
+
+int fflush(FILE *f)
 {
+       if (!f) {
+               int r = __stdout_used ? fflush(__stdout_used) : 0;
+
+               for (f=*__ofl_lock(); f; f=f->next)
+                       if (f->wpos > f->wbase) r |= fflush(f);
+               __ofl_unlock();
+
+               return r;
+       }
+
+       FLOCK(f);
+
        /* If writing, flush output */
        if (f->wpos > f->wbase) {
                f->write(f, 0, 0);
-               if (!f->wpos) return EOF;
+               if (!f->wpos) {
+                       FUNLOCK(f);
+                       return EOF;
+               }
        }
 
        /* If reading, sync position, per POSIX */
@@ -15,34 +34,8 @@ static int __fflush_unlocked(FILE *f)
        f->wpos = f->wbase = f->wend = 0;
        f->rpos = f->rend = 0;
 
+       FUNLOCK(f);
        return 0;
 }
 
-/* stdout.c will override this if linked */
-static FILE *volatile dummy = 0;
-weak_alias(dummy, __stdout_used);
-
-int fflush(FILE *f)
-{
-       int r;
-
-       if (f) {
-               FLOCK(f);
-               r = __fflush_unlocked(f);
-               FUNLOCK(f);
-               return r;
-       }
-
-       r = __stdout_used ? fflush(__stdout_used) : 0;
-
-       for (f=*__ofl_lock(); f; f=f->next) {
-               FLOCK(f);
-               if (f->wpos > f->wbase) r |= __fflush_unlocked(f);
-               FUNLOCK(f);
-       }
-       __ofl_unlock();
-       
-       return r;
-}
-
-weak_alias(__fflush_unlocked, fflush_unlocked);
+weak_alias(fflush, fflush_unlocked);