[BZ #6544]

	* libio/fmemopen.c: Implement binary mode.  In this mode no NUL
	byte gets added to writes and seeks from the end use the length of
	the buffer and not the currently terminating NUL byte.

ChangeLog

@@ -1,5 +1,10 @@
 2008-08-13  Ulrich Drepper  <drepper@redhat.com>
 
+	[BZ #6544]
+	* libio/fmemopen.c: Implement binary mode.  In this mode no NUL
+	byte gets added to writes and seeks from the end use the length of
+	the buffer and not the currently terminating NUL byte.
+
 	[BZ #6634]
 	* login/utmp_file.c (getutent_r_file): Take additional parameter.
 	Set to true if locking failed.

NEWS

@@ -28,6 +28,11 @@ Version 2.9
 * Implement "e" option for popen to open file descriptor with the
   close-on-exec flag set.  Implemented by Ulrich Drepper.
 
+* Implement "b" mode for fmemopen.  In this mode writes writes don't
+  implicitly add a NUL byte and seeks from the end of the buffer really
+  use the buffer end, not the string length as the basis.
+  Implemented by Ulrich Drepper.
+
 * Many functions, exported and internal, now atomically set the close-on-exec
   flag when run on a sufficiently new kernel.  Implemented by Ulrich Drepper.
 

libio/fmemopen.c

@@ -1,7 +1,7 @@
 /* Fmemopen implementation.
-   Copyright (C) 2000, 2002, 2005, 2006 Free Software Foundation, Inc.
+   Copyright (C) 2000, 2002, 2005, 2006, 2008 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
-   Contributed by  Hanno Mueller, kontakt@hanno.de, 2000.
+   Contributed by Hanno Mueller, kontakt@hanno.de, 2000.
 
    The GNU C Library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
@@ -82,6 +82,7 @@ struct fmemopen_cookie_struct
 {
   char *buffer;
   int mybuffer;
+  int binmode;
   size_t size;
   _IO_off64_t pos;
   size_t maxpos;
@@ -120,7 +121,7 @@ fmemopen_write (void *cookie, const char *b, size_t s)
 
   c = (fmemopen_cookie_t *) cookie;
 
-  addnullc = s == 0 || b[s - 1] != '\0';
+  addnullc = c->binmode == 0 && (s == 0 || b[s - 1] != '\0');
 
   if (c->pos + s + addnullc > c->size)
     {
@@ -165,7 +166,7 @@ fmemopen_seek (void *cookie, _IO_off64_t *p, int w)
       break;
 
     case SEEK_END:
-      np = c->maxpos - *p;
+      np = (c->binmode ? c->size : c->maxpos) - *p;
       break;
 
     default:
@@ -248,6 +249,8 @@ fmemopen (void *buf, size_t len, const char *mode)
   else
     c->pos = 0;
 
+  c->binmode = mode[0] != '\0' && mode[1] == 'b';
+
   iof.read = fmemopen_read;
   iof.write = fmemopen_write;
   iof.seek = fmemopen_seek;