Implement strcasestr() which many others (f.e. Linux) already have.

lib/libc/string/Makefile.inc

@@ -10,7 +10,7 @@ MISRCS+=bcmp.c bcopy.c bzero.c ffs.c index.c memccpy.c memchr.c memcmp.c \
 	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 \
+	strcasestr.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 \
@@ -37,6 +37,7 @@ MLINKS+=strcpy.3 strncpy.3
 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 strcasestr.3
 MLINKS+=strstr.3 strnstr.3
 MLINKS+=wmemchr.3 wmemcmp.3 wmemchr.3 wmemcpy.3 \
 	wmemchr.3 wmemmove.3 wmemchr.3 wmemset.3 \

lib/libc/string/strcasestr.c

@@ -0,0 +1,68 @@
+/*-
+ * 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.
+ */
+
+#ifndef lint
+static const char rcsid[] =
+  "$FreeBSD$";
+#endif
+
+#include <sys/cdefs.h>
+#include <ctype.h>
+#include <string.h>
+
+/*
+ * Find the first occurrence of find in s, ignore case.
+ */
+char *
+strcasestr(s, find)
+	register const char *s, *find;
+{
+	register char c, sc;
+	register size_t len;
+
+	if ((c = *find++) != 0) {
+		c = tolower((unsigned char)c);
+		len = strlen(find);
+		do {
+			do {
+				if ((sc = *s++) == 0)
+					return (NULL);
+			} while ((char)tolower((unsigned char)sc) != c);
+		} while (strncasecmp(s, find, len) != 0);
+		s--;
+	}
+	return ((char *)s);
+}

lib/libc/string/strstr.3

@@ -41,7 +41,7 @@
 .Dt STRSTR 3
 .Os
 .Sh NAME
-.Nm strstr , strnstr
+.Nm strstr , strcasestr , strnstr
 .Nd locate a substring in a string
 .Sh LIBRARY
 .Lb libc
@@ -50,6 +50,8 @@
 .Ft char *
 .Fn strstr "const char *big" "const char *little"
 .Ft char *
+.Fn strcasestr "const char *big" "const char *little"
+.Ft char *
 .Fn strnstr "const char *big" "const char *little" "size_t len"
 .Sh DESCRIPTION
 The
@@ -61,6 +63,12 @@ in the null-terminated string
 .Fa big .
 .Pp
 The
+.Fn strcasestr
+function is similar to
+.Fn strstr
+but ignores the case of both strings.
+.Pp
+The
 .Fn strnstr
 function
 locates the first occurrence of the null-terminated string