Libc-1439.100.3.tar.gz

[apple/libc.git] / stdio / FreeBSD / fflush.c

diff --git a/stdio/FreeBSD/fflush.c b/stdio/FreeBSD/fflush.c
index 5db1a1c61fd4636c32eb1e736f92ab1f1a3ba2e3..db6761da81694375e855f270af2be747faf42a9f 100644 (file)
--- a/stdio/FreeBSD/fflush.c
+++ b/stdio/FreeBSD/fflush.c
@@ -53,34 +53,14 @@ static int  sflush_locked(FILE *);
 int
 fflush(FILE *fp)
 {
-       int retval;
+       int retval = 0;
 
-       if (fp == NULL)
+       if (fp == NULL) {
                return (_fwalk(sflush_locked));
-       FLOCKFILE(fp);
+       }
 
-       /*
-        * 11103146: Conformance change:
-        * --- Begin History ---
-        * There is disagreement about the correct behaviour of fflush()
-        * when passed a file which is not open for writing.  According to
-        * the ISO C standard, the behaviour is undefined.
-        * Under linux, such an fflush returns success and has no effect;
-        * under Windows, such an fflush is documented as behaving instead
-        * as fpurge().
-        * Given that applications may be written with the expectation of
-        * either of these two behaviours, the only safe (non-astonishing)
-        * option is to return EBADF and ask that applications be fixed.
-        * --- End History ---
-        * SUSv3 now requires that fflush() returns success on a read-only
-        * stream.  In addition, the conformance tests will warn if a fflush
-        * on a read-only stream does not set the file descriptor's file offset
-        * to the real position.  We won't be fixing the warning at this time.
-        */
-       if ((fp->_flags & (__SWR | __SRW)) == 0) {
-               retval = 0;
-       } else
-               retval = __sflush(fp);
+       FLOCKFILE(fp);
+       retval = __sflush(fp);
        FUNLOCKFILE(fp);
        return (retval);
 }
@@ -110,34 +90,77 @@ __sflush(FILE *fp)
        int n, t;
 
        t = fp->_flags;
-       if ((t & __SWR) == 0)
-               return (0);
 
        if ((p = fp->_bf._base) == NULL)
                return (0);
 
-       n = fp->_p - p;         /* write this much */
-
        /*
-        * Set these immediately to avoid problems with longjmp and to allow
-        * exchange buffering (via setvbuf) in user write function.
+        * SUSv3 requires that fflush() on a seekable input stream updates the file
+        * position indicator with the underlying seek function.  Use a dumb fseek
+        * for this (don't attempt to preserve the buffers).
         */
-       fp->_p = p;
-       fp->_w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size;
-
-       for (; n > 0; n -= t, p += t) {
-               t = _swrite(fp, (char *)p, n);
-               if (t <= 0) {
-                       /* 5340694: reset _p and _w on EAGAIN */
-                       if (t < 0 && errno == EAGAIN) {
-                               if (p > fp->_p) /* some was written */
-                                       memmove(fp->_p, p, n);
-                               fp->_p += n;
-                               if (!(fp->_flags & (__SLBF|__SNBF)))
-                                       fp->_w -= n;
+       if ((t & __SRD) != 0) {
+               if (fp->_seek == NULL) {
+                       /*
+                        * No way to seek this file -- just return "success."
+                        */
+                       return (0);
+               }
+
+               n = fp->_r;
+
+               if (n > 0) {
+                       /*
+                        * See _fseeko's dumb path.
+                        */
+                       if (_sseek(fp, (fpos_t)-n, SEEK_CUR) == -1) {
+                               if (errno == ESPIPE) {
+                                       /*
+                                        * Ignore ESPIPE errors, since there's no way to put the bytes
+                                        * back into the pipe.
+                                        */
+                                       return (0);
+                               }
+                               return (EOF);
+                       }
+
+                       if (HASUB(fp)) {
+                               FREEUB(fp);
+                       }
+                       fp->_p = fp->_bf._base;
+                       fp->_r = 0;
+                       fp->_flags &= ~__SEOF;
+                       memset(&fp->_mbstate, 0, sizeof(mbstate_t));
+               }
+               return (0);
+       }
+
+       if ((t & __SWR) != 0) {
+               n = fp->_p - p;         /* write this much */
+
+               /*
+                * Set these immediately to avoid problems with longjmp and to allow
+                * exchange buffering (via setvbuf) in user write function.
+                */
+               fp->_p = p;
+               fp->_w = t & (__SLBF|__SNBF) ? 0 : fp->_bf._size;
+
+               for (; n > 0; n -= t, p += t) {
+                       t = _swrite(fp, (char *)p, n);
+                       if (t <= 0) {
+                               /* 5340694: reset _p and _w on EAGAIN */
+                               if (t < 0 && errno == EAGAIN) {
+                                       if (p > fp->_p) {
+                                               /* some was written */
+                                               memmove(fp->_p, p, n);
+                                               fp->_p += n;
+                                               if (!(fp->_flags & (__SLBF|__SNBF)))
+                                                       fp->_w -= n;
+                                       }
+                               }
+                               fp->_flags |= __SERR;
+                               return (EOF);
                        }
-                       fp->_flags |= __SERR;
-                       return (EOF);
                }
        }
        return (0);