# HG changeset patch
# User Bruno Haible <bruno@clisp.org>
# Date 1180360557 0
# Node ID d4d8703bfaae1dd643b40f436d32022706461fb4
# Parent  a8cf4cce248b6370eaf9c5b870295ebfc5560305
More comments.

diff --git a/ChangeLog b/ChangeLog
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2007-05-28  Bruno Haible  <bruno@clisp.org>
+
+	* lib/stdio_.h (fflush): More comments.
+
 2007-05-28  Bruno Haible  <bruno@clisp.org>
 
 	* m4/lseek.m4 (gl_FUNC_LSEEK): When not cross-compiling, perform a real
diff --git a/lib/stdio_.h b/lib/stdio_.h
--- a/lib/stdio_.h
+++ b/lib/stdio_.h
@@ -270,7 +270,11 @@
 # if @REPLACE_FFLUSH@
 #  define fflush rpl_fflush
   /* Flush all pending data on STREAM according to POSIX rules.  Both
-     output and seekable input streams are supported.  */
+     output and seekable input streams are supported.
+     Note! LOSS OF DATA can occur if fflush is applied on an input stream
+     that is _not_seekable_ or on an update stream that is _not_seekable_
+     and in which the most recent operation was input.  Seekability can
+     be tested with lseek(fileno(fp),0,SEEK_CUR).  */
   extern int fflush (FILE *gl_stream);
 # endif
 #elif defined GNULIB_POSIXCHECK