Date: Thu, 4 Oct 2001 21:57:06 -0400 From: Mike Barcroft <mike@FreeBSD.org> To: audit@FreeBSD.org Subject: strnstr(3) - New libc function for review Message-ID: <20011004215706.B34530@coffee.q9media.com>
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--HcAYCG3uE/tztfnV Content-Type: text/plain; charset=us-ascii Content-Disposition: inline [BCC'd to -hackers for additional comments.] Hello, I would appreciate comments/reviews of the following new addition to libc. It is largely based off the current strstr(3) implementation. Patch attached and also available at: http://people.FreeBSD.org/~mike/patches/strnstr.diff Best regards, Mike Barcroft --HcAYCG3uE/tztfnV Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename="strnstr.diff" strnstr.diff Add a new libc function, strnstr(3), which allows one to limit the number of characters that are searched. This is especially useful with file operations and non-NUL terminated strings. Index: lib/libc/string/Makefile.inc =================================================================== RCS file: /cvs/src/lib/libc/string/Makefile.inc,v retrieving revision 1.23 diff -u -r1.23 Makefile.inc --- lib/libc/string/Makefile.inc 31 Jul 2001 16:34:52 -0000 1.23 +++ lib/libc/string/Makefile.inc 5 Oct 2001 00:30:43 -0000 @@ -10,6 +10,7 @@ memcpy.c memmove.c memset.c rindex.c strcasecmp.c strcat.c strchr.c \ strcmp.c strcoll.c strcpy.c strcspn.c strdup.c strerror.c \ strlcat.c strlcpy.c strlen.c strmode.c strncat.c strncmp.c strncpy.c \ + strnstr.c \ strpbrk.c strrchr.c strsep.c strsignal.c strspn.c strstr.c strtok.c \ strxfrm.c swab.c wcscat.c wcschr.c wcscmp.c wcscpy.c wcscspn.c \ wcslcat.c wcslcpy.c wcslen.c wcsncat.c wcsncmp.c wcsncpy.c wcspbrk.c \ @@ -36,6 +37,7 @@ MLINKS+=strerror.3 perror.3 strerror.3 sys_errlist.3 strerror.3 sys_nerr.3 MLINKS+=strlcpy.3 strlcat.3 MLINKS+=strtok.3 strtok_r.3 +MLINKS+=strstr.3 strnstr.3 MLINKS+=wmemchr.3 wmemcmp.3 wmemchr.3 wmemcpy.3 \ wmemchr.3 wmemmove.3 wmemchr.3 wmemset.3 \ wmemchr.3 wcscat.3 wmemchr.3 wcschr.3 \ --- /dev/null Thu Oct 4 21:11:00 2001 +++ lib/libc/string/strnstr.c Thu Oct 4 20:37:01 2001 @@ -0,0 +1,70 @@ +/*- + * Copyright (c) 2001 Mike Barcroft <mike@FreeBSD.org> + * Copyright (c) 1990, 1993 + * The Regents of the University of California. All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * Chris Torek. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <sys/cdefs.h> +__RCSID("@(#)strstr.c 8.1 (Berkeley) 6/4/93"); +__FBSDID("$FreeBSD$"); + +#include <string.h> + +/* + * Find the first occurrence of find in s, where the search is limited to the + * first slen characters of s. + */ +char * +strnstr(s, find, slen) + const char *s; + const char *find; + size_t slen; +{ + char c, sc; + size_t len; + + if ((c = *find++) != '\0') { + len = strlen(find); + do { + do { + if ((sc = *s++) == '\0' || slen-- < 1) + return (NULL); + } while (sc != c); + if (len > slen) + return (NULL); + } while (strncmp(s, find, len) != 0); + s--; + } + return ((char *)s); +} Index: lib/libc/string/strstr.3 =================================================================== RCS file: /cvs/src/lib/libc/string/strstr.3,v retrieving revision 1.7 diff -u -r1.7 strstr.3 --- lib/libc/string/strstr.3 1 Oct 2001 16:09:00 -0000 1.7 +++ lib/libc/string/strstr.3 5 Oct 2001 01:18:13 -0000 @@ -1,3 +1,4 @@ +.\" Copyright (c) 2001 Mike Barcroft <mike@FreeBSD.org> .\" Copyright (c) 1990, 1991, 1993 .\" The Regents of the University of California. All rights reserved. .\" @@ -40,7 +41,7 @@ .Dt STRSTR 3 .Os .Sh NAME -.Nm strstr +.Nm strstr , strnstr .Nd locate a substring in a string .Sh LIBRARY .Lb libc @@ -48,6 +49,8 @@ .In string.h .Ft char * .Fn strstr "const char *big" "const char *little" +.Ft char * +.Fn strnstr "const char *big" "const char *little" "size_t len" .Sh DESCRIPTION The .Fn strstr @@ -56,22 +59,58 @@ .Fa little in the null-terminated string .Fa big . +.Pp +The +.Fn strnstr +function +locates the first occurrence of the null-terminated string +.Fa little +in the string +.Fa big , +where only the first number of characters, identified by +.Fa len , +are searched. +.Sh RETURN VALUES If .Fa little -is the empty string, -.Fn strstr -returns -.Fa big ; +is an empty string, +.Fa big +is returned; if .Fa little occurs nowhere in .Fa big , -.Fn strstr -returns NULL; -otherwise -.Fn strstr -returns a pointer to the first character of the first occurrence of -.Fa little . +NULL is returned; +otherwise a pointer to the first character of the first occurrence of +.Fa little +is returned. +.Sh EXAMPLES +The following sets the pointer +.Va ptr +to the +.Dq Li Bar Baz +portion of +.Va largestring : +.Bd -literal -offset indent +const char *largestring = "Foo Bar Baz"; +const char *smallstring = "Bar"; +char *ptr; + +ptr = strstr(largestring, smallstring); +.Ed +.Pp +The following sets the pointer +.Va ptr +to NULL, because only the first 4 characters of +.Va largestring +are searched: +.Bd -literal -offset indent +const char *largestring = "Foo Bar Baz"; +const char *smallstring = "Bar"; +char *ptr; + +ptr = strnstr(largestring, smallstring, 4); +.Ed .Sh SEE ALSO .Xr memchr 3 , .Xr strchr 3 , Index: include/string.h =================================================================== RCS file: /cvs/src/include/string.h,v retrieving revision 1.6 diff -u -r1.6 string.h --- include/string.h 16 Aug 1999 06:53:13 -0000 1.6 +++ include/string.h 5 Oct 2001 00:34:03 -0000 @@ -87,6 +87,7 @@ size_t strlcpy __P((char *, const char *, size_t)); void strmode __P((int, char *)); int strncasecmp __P((const char *, const char *, size_t)); +char *strnstr __P((const char *, const char *, size_t)); char *strsep __P((char **, const char *)); char *strsignal __P((int)); char *strtok_r __P((char *, const char *, char **)); --HcAYCG3uE/tztfnV-- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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