Make fflush-after-ungetc POSIX compliant on glibc systems.

[gnulib.git] / lib / fseeko.c

diff --git a/lib/fseeko.c b/lib/fseeko.c
index ac0af57..47beac4 100644 (file)
--- a/lib/fseeko.c
+++ b/lib/fseeko.c
@@ -1,5 +1,5 @@
 /* An fseeko() function that, together with fflush(), is POSIX compliant.
-   Copyright (C) 2007-2008 Free Software Foundation, Inc.
+   Copyright (C) 2007-2009 Free Software Foundation, Inc.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -86,7 +86,14 @@ rpl_fseeko (FILE *fp, off_t offset, int whence)
   #error "Please port gnulib fseeko.c to your platform! Look at the code in fpurge.c, then report this to bug-gnulib."
 #endif
     {
-      off_t pos = lseek (fileno (fp), offset, whence);
+      /* We get here when an fflush() call immediately preceded this one.  We
+        know there are no buffers.
+        POSIX requires us to modify the file descriptor's position.
+        But we cannot position beyond end of file here.  */
+      off_t pos =
+       lseek (fileno (fp),
+              whence == SEEK_END && offset > 0 ? 0 : offset,
+              whence);
       if (pos == -1)
        {
 #if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
@@ -94,20 +101,22 @@ rpl_fseeko (FILE *fp, off_t offset, int whence)
 #endif
          return -1;
        }
-      else
-       {
-#if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
-         fp_->_offset = pos;
-         fp_->_flags |= __SOFF;
-         fp_->_flags &= ~__SEOF;
+
+#if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
+      fp->_flags &= ~_IO_EOF_SEEN;
+#elif defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
+      fp_->_offset = pos;
+      fp_->_flags |= __SOFF;
+      fp_->_flags &= ~__SEOF;
 #elif defined __EMX__               /* emx+gcc */
-          fp->_flags &= ~_IOEOF;
+      fp->_flags &= ~_IOEOF;
 #elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, mingw */
-          fp->_flag &= ~_IOEOF;
+      fp->_flag &= ~_IOEOF;
 #endif
-         return 0;
-       }
+      /* If we were not requested to position beyond end of file, we're
+        done.  */
+      if (!(whence == SEEK_END && offset > 0))
+       return 0;
     }
-  else
-    return fseeko (fp, offset, whence);
+  return fseeko (fp, offset, whence);
 }