lib: libc: string: Port strtok and strtok_r implementation from bionic

Port strtok and strtok_r implementation from bionic

Change-Id: I81afd1563d307dd09e99cf7565f4e98cb6558847

include/string.h

@@ -53,6 +53,7 @@ size_t      strspn(char const *, char const *) __PURE;
 size_t      strcspn(const char *s, const char *) __PURE;
 char       *strstr(char const *, char const *) __PURE;
 char       *strtok(char *, char const *);
+char       *strtok_r(char *s, const char *delim, char **last);
 int         strcoll(const char *s1, const char *s2) __PURE;
 size_t      strxfrm(char *dest, const char *src, size_t n) __PURE;
 char       *strdup(const char *str) __MALLOC;

lib/libc/string/strtok.c

@@ -0,0 +1,86 @@
+/*
+ * Copyright (c) 1988 Regents of the University of California.
+ * All rights reserved.
+ *
+ * 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.
+ */
+
+#include <string.h>
+
+char *
+strtok(char *s, const char *delim)
+{
+	static char *last;
+
+	return strtok_r(s, delim, &last);
+}
+
+char *
+strtok_r(char *s, const char *delim, char **last)
+{
+	char *spanp;
+	int c, sc;
+	char *tok;
+
+
+	if (s == NULL && (s = *last) == NULL)
+		return (NULL);
+
+	/*
+	 * Skip (span) leading delimiters (s += strspn(s, delim), sort of).
+	 */
+cont:
+	c = *s++;
+	for (spanp = (char *)delim; (sc = *spanp++) != 0;) {
+		if (c == sc)
+			goto cont;
+	}
+
+	if (c == 0) {		/* no non-delimiter characters */
+		*last = NULL;
+		return (NULL);
+	}
+	tok = s - 1;
+
+	/*
+	 * Scan token (scan for delimiters: s += strcspn(s, delim), sort of).
+	 * Note that delim must have one NUL; we stop if we see that, too.
+	 */
+	for (;;) {
+		c = *s++;
+		spanp = (char *)delim;
+		do {
+			if ((sc = *spanp++) == c) {
+				if (c == 0)
+					s = NULL;
+				else
+					s[-1] = 0;
+				*last = s;
+				return (tok);
+			}
+		} while (sc != 0);
+	}
+	/* NOTREACHED */
+}