Add new strnstr() function

Taken from FreeBSD.

COPYING

@@ -97,6 +97,7 @@ The rest of the licenses apply to code and/or man pages.
 
     Copyright © 1980, 1982, 1986, 1989-1994
 	The Regents of the University of California.  All rights reserved.
+    Copyright © 2001 Mike Barcroft <mike@FreeBSD.org>
 
     Some code is derived from software contributed to Berkeley by
     the American National Standards Committee X3, on Information
@@ -114,6 +115,9 @@ The rest of the licenses apply to code and/or man pages.
     Some code is derived from software contributed to Berkeley by
     Paul Vixie.
 
+    Some 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:

include/bsd/string.h

@@ -39,6 +39,7 @@
 __BEGIN_DECLS
 size_t strlcpy(char *dst, const char *src, size_t siz);
 size_t strlcat(char *dst, const char *src, size_t siz);
+char *strnstr(const char *str, const char *find, size_t str_len);
 void strmode(mode_t mode, char *str);
 __END_DECLS
 

man/Makefile.am

@@ -45,6 +45,7 @@ dist_man_MANS = \
 	sradixsort.3 \
 	strlcat.3 \
 	strlcpy.3 \
+	strnstr.3 \
 	strmode.3 \
 	strtonum.3 \
 	tree.3 \

man/strnstr.3

@@ -0,0 +1,110 @@
+.\" Copyright (c) 2001 Mike Barcroft <mike@FreeBSD.org>
+.\" Copyright (c) 1990, 1991, 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" This code is derived from software contributed to Berkeley by
+.\" Chris Torek and the American National Standards Committee X3,
+.\" on Information Processing Systems.
+.\"
+.\" 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. 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.
+.\"
+.\"     @(#)strstr.3	8.1 (Berkeley) 6/4/93
+.\" $FreeBSD$
+.\"
+.Dd October 11, 2001
+.Dt STRSTR 3
+.Os
+.Sh NAME
+.Nm strnstr
+.Nd locate a substring in a string
+.Sh LIBRARY
+.ds str-Lb-libbsd Utility functions from BSD systems (libbsd, \-lbsd)
+.Lb libbsd
+.Sh SYNOPSIS
+.In bsd/string.h
+.Ft char *
+.Fn strnstr "const char *big" "const char *little" "size_t len"
+.Sh DESCRIPTION
+The
+.Fn strnstr
+function
+locates the first occurrence of the null-terminated string
+.Fa little
+in the string
+.Fa big ,
+where not more than
+.Fa len
+characters are searched.
+Characters that appear after a
+.Ql \e0
+character are not searched.
+Since the
+.Fn strnstr
+function is a
+.Fx
+specific API, it should only be used when portability is not a concern.
+.Sh RETURN VALUES
+If
+.Fa little
+is an empty string,
+.Fa big
+is returned;
+if
+.Fa little
+occurs nowhere in
+.Fa big ,
+.Dv 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
+.Dv 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 strstr 3 ,
+.Xr strcasestr 3 ,
+.Xr memchr 3 ,
+.Xr memmem 3 ,
+.Xr strchr 3 ,
+.Xr strcspn 3 ,
+.Xr strpbrk 3 ,
+.Xr strrchr 3 ,
+.Xr strsep 3 ,
+.Xr strspn 3 ,
+.Xr strtok 3 ,
+.Xr wcsstr 3

src/Makefile.am

@@ -65,6 +65,7 @@ libbsd_la_SOURCES = \
 	strlcat.c \
 	strlcpy.c \
 	strmode.c \
+	strnstr.c \
 	strtonum.c \
 	unvis.c \
 	vis.c \

src/libbsd.map

@@ -96,6 +96,8 @@ LIBBSD_0.4 {
 } LIBBSD_0.3;
 
 LIBBSD_0.5 {
+    strnstr;
+
     wcslcat;
     wcslcpy;
 } LIBBSD_0.4;

src/strnstr.c

@@ -0,0 +1,65 @@
+/*-
+ * 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. 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.
+ */
+
+#if defined(LIBC_SCCS) && !defined(lint)
+static char sccsid[] = "@(#)strstr.c	8.1 (Berkeley) 6/4/93";
+#endif /* LIBC_SCCS and not lint */
+#include <sys/cdefs.h>
+__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(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 (slen-- < 1 || (sc = *s++) == '\0')
+					return (NULL);
+			} while (sc != c);
+			if (len > slen)
+				return (NULL);
+		} while (strncmp(s, find, len) != 0);
+		s--;
+	}
+	return ((char *)s);
+}