X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Ffflush.m4;h=da30e1fe6788494162dabc19553f4c91c2bc5ff1;hb=740cb7248fef99fc09b575deb650cfe9ecabafbf;hp=f796a55415d2a0744b7d594e6ad21aacb332aed1;hpb=27de795dd766ae4dd5627b8d5a612807879b735a;p=gnulib.git

diff --git a/m4/fflush.m4 b/m4/fflush.m4
index f796a5541..da30e1fe6 100644
--- a/m4/fflush.m4
+++ b/m4/fflush.m4
@@ -1,6 +1,6 @@
-# fflush.m4 serial 4
+# fflush.m4 serial 7
 
-# Copyright (C) 2007 Free Software Foundation, Inc.
+# Copyright (C) 2007-2009 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
@@ -21,19 +21,41 @@ AC_DEFUN([gl_FUNC_FFLUSH],
 #include <unistd.h>
        ]], [[FILE *f = fopen ("conftest.txt", "r");
 	 char buffer[10];
-	 int fd = fileno (f);
-	 if (!f || 0 > fd || fread (buffer, 1, 5, f) != 5)
+	 int fd;
+	 int c;
+	 if (f == NULL)
+	   return 1;
+	 fd = fileno (f);
+	 if (fd < 0 || fread (buffer, 1, 5, f) != 5)
 	   return 2;
 	 /* For deterministic results, ensure f read a bigger buffer.  */
 	 if (lseek (fd, 0, SEEK_CUR) == 5)
 	   return 3;
-	 /* POSIX requires fflush-fseek to set file offset of fd.  */
+	 /* POSIX requires fflush-fseek to set file offset of fd.  This fails
+	    on BSD systems and on mingw.  */
 	 if (fflush (f) != 0 || fseek (f, 0, SEEK_CUR) != 0)
 	   return 4;
-	 return !(lseek (fd, 0, SEEK_CUR) == 5);
+	 if (lseek (fd, 0, SEEK_CUR) != 5)
+	   return 5;
+	 /* Verify behaviour of fflush after ungetc. See
+	    <http://www.opengroup.org/austin/aardvark/latest/xshbug3.txt>  */
+	 /* Verify behaviour of fflush after a backup ungetc.  This fails on
+	    mingw.  */
+	 c = fgetc (f);
+	 ungetc (c, f);
+	 fflush (f);
+	 if (fgetc (f) != c)
+	   return 6;
+	 /* Verify behaviour of fflush after a non-backup ungetc.  This fails
+	    on glibc 2.8 and on BSD systems.  */
+	 c = fgetc (f);
+	 ungetc ('@', f);
+	 fflush (f);
+	 if (fgetc (f) != c)
+	   return 7;
+	 return 0;
        ]])], [gl_cv_func_fflush_stdin=yes], [gl_cv_func_fflush_stdin=no],
-     [dnl Pessimistically assume fflush is broken.  This is wrong for
-      dnl at least glibc and cygwin; but lib/fflush.c takes this into account.
+     [dnl Pessimistically assume fflush is broken.
       gl_cv_func_fflush_stdin=no])
      rm conftest.txt
     ])
@@ -49,4 +71,12 @@ AC_DEFUN([gl_REPLACE_FFLUSH],
   AC_REQUIRE([gl_STDIO_H_DEFAULTS])
   REPLACE_FFLUSH=1
   REPLACE_FSEEKO=1
+  gl_PREREQ_FFLUSH
+])
+
+# Prerequisites of lib/fflush.c.
+AC_DEFUN([gl_PREREQ_FFLUSH],
+[
+  AC_REQUIRE([AC_C_INLINE])
+  :
 ])