[PATCH] Speed up gets

Corinna Vinschen vinschen@redhat.com
Mon Nov 24 19:08:00 GMT 2008


I'd like to propose the below patch.  The current code implements
gets/_gets_r in terms of _getchar_r calls.  That means, for every single
character of input the following sequence of functions is called:

  for each char

It should be much quicker to move the locking up into gets itself and to
call __sgetc_r right there, as FreeBSD does as well:

  for each char

That doesn't change the fact that gets is inherently unsecure, of
course :)

Ok to apply?


	* libc/stdio/gets.c (_gets_r): Lock stdin here and call
	__sgetc_r instead of _getchar_r.

Index: libc/stdio/gets.c
RCS file: /cvs/src/src/newlib/libc/stdio/gets.c,v
retrieving revision 1.2
diff -u -p -r1.2 gets.c
--- libc/stdio/gets.c	23 Apr 2004 20:01:55 -0000	1.2
+++ libc/stdio/gets.c	24 Nov 2008 17:25:27 -0000
@@ -79,15 +79,20 @@ _DEFUN(_gets_r, (ptr, buf),
   register int c;
   register char *s = buf;
-  while ((c = _getchar_r (ptr)) != '\n')
+  _flockfile (stdin);
+  while ((c = __sgetc_r (ptr, stdin)) != '\n')
     if (c == EOF)
       if (s == buf)
-	return NULL;
+	{
+	  _funlockfile (stdin);
+	  return NULL;
+	}
       *s++ = c;
   *s = 0;
+  _funlockfile (stdin);
   return buf;

Corinna Vinschen
Cygwin Project Co-Leader
Red Hat

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