Thu Mar 14 06:01:07 1996 Roland McGrath <roland@charlie-brown.gnu.ai.mit.edu>

	* string/strnlen.c: New file.
	* string/Makefile (routines): Add strnlen.
	* string/string.h [__USE_GNU] (strnlen): Declare new function.
	[__OPTIMIZE__]: Define extern inline implementation of it.

3 files changed, 50 insertions, 2 deletions

diff --git a/string/Makefile b/string/Makefile
index 1fa63c24d2..5901c36594 100644
--- a/string/Makefile
+++ b/string/Makefile
@@ -1,4 +1,4 @@
-# Copyright (C) 1991, 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
+# Copyright (C) 1991, 92, 93, 94, 95, 96 Free Software Foundation, Inc.
 # This file is part of the GNU C Library.
 
 # The GNU C Library is free software; you can redistribute it and/or
@@ -24,7 +24,8 @@ subdir	:= string
 headers	:= string.h strings.h memory.h endian.h bytesex.h
 
 routines	:= strcat strchr strcmp strcoll strcpy strcspn strdup	\
-		   strerror _strerror strlen strncat strncmp strncpy 	\
+		   strerror _strerror strlen strnlen			\
+		   strncat strncmp strncpy				\
 		   strrchr strpbrk strsignal strspn strstr strtok	\
 		   strxfrm memchr memcmp memmove memset			\
 		   bcopy bzero ffs stpcpy stpncpy			\
diff --git a/string/string.h b/string/string.h
index 95dcba0041..49b29fd168 100644
--- a/string/string.h
+++ b/string/string.h
@@ -127,9 +127,26 @@ extern __ptr_t memmem __P ((__const __ptr_t __haystack, size_t __haystacklen,
 			    __const __ptr_t __needle, size_t __needlelen));
 #endif
 
+
 /* Return the length of S.  */
 extern size_t strlen __P ((__const char *__s));
 
+#ifdef	__USE_GNU
+/* Find the length of STRING, but scan at most MAXLEN characters.
+   If no '\0' terminator is found in that many characters, return MAXLEN.  */
+extern size_t strnlen __P ((__const char *__string, size_t __maxlen));
+
+#ifdef	__OPTIMIZE__
+extern __inline size_t
+strnlen (__const char *__string, size_t __maxlen)
+{
+  __const char *__end = memchr (__string, '\0', __maxlen);
+  return __end ? __end - __string : __maxlen;
+}
+#endif
+#endif
+
+
 /* Return a string describing the meaning of the `errno' code in ERRNUM.  */
 extern char *strerror __P ((int __errnum));
 #ifdef	__USE_REENTRANT
diff --git a/string/strnlen.c b/string/strnlen.c
new file mode 100644
index 0000000000..eb01a63692
--- /dev/null
+++ b/string/strnlen.c
@@ -0,0 +1,30 @@
+/* Find the length of STRING, but scan at most MAXLEN characters.
+Copyright (C) 1996 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <string.h>
+
+/* Find the length of STRING, but scan at most MAXLEN characters.
+   If no '\0' terminator is found in that many characters, return MAXLEN.  */
+
+size_t
+strnlen (const char *string, size_t maxlen)
+{
+  const char *end = memchr (string, '\0', maxlen);
+  return end ? end - string : maxlen;
+}