libs/libc/string/lib_strsep.c: Add strsep BSD/Linux function.

include/string.h

@@ -83,6 +83,7 @@ size_t     strspn(FAR const char *, FAR const char *);
 size_t     strcspn(FAR const char *, FAR const char *);
 FAR char  *strstr(FAR const char *, FAR const char *);
 FAR char  *strcasestr(FAR const char *, FAR const char *);
+FAR char  *strsep(FAR char **, FAR const char *);
 FAR char  *strsignal(int signum);
 FAR char  *strtok(FAR char *, FAR const char *);
 FAR char  *strtok_r(FAR char *, FAR const char *, FAR char **);

libs/libc/string/Make.defs

@@ -44,7 +44,7 @@ CSRCS += lib_strdup.c lib_strerror.c lib_strlen.c lib_strnlen.c
 CSRCS += lib_strncasecmp.c lib_strncat.c lib_strncmp.c lib_strncpy.c
 CSRCS += lib_strndup.c lib_strcasestr.c lib_strpbrk.c lib_strrchr.c
 CSRCS += lib_strspn.c lib_strstr.c lib_strtok.c lib_strtokr.c
-CSRCS += lib_strerrorr.c lib_explicit_bzero.c
+CSRCS += lib_strsep.c lib_strerrorr.c lib_explicit_bzero.c
 
 ifneq ($(CONFIG_LIBC_ARCH_MEMCPY),y)
 ifeq ($(CONFIG_MEMCPY_VIK),y)

libs/libc/string/lib_strsep.c

@@ -0,0 +1,82 @@
+/****************************************************************************
+ * libs/libc/string/lib_strsep.c
+ *
+ *   Copyright (C) 2019 Pinecone Inc. All rights reserved.
+ *   Author: Xiang Xiao <xiaoxiang@pinecon.net>
+ *
+ * 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 NuttX 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 COPYRIGHT HOLDERS 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
+ * COPYRIGHT OWNER 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <string.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: strsep
+ *
+ * Description:
+ *    If *strp is NULL, the strsep() function returns NULL and does
+ *    nothing else.  Otherwise, this function finds the first token in the
+ *    string *strp, that is delimited by one of the bytes in the string
+ *    delim.  This token is terminated by overwriting the delimiter with a
+ *    null byte ('\0'), and *strp is updated to point past the token.
+ *    In case no delimiter was found, the token is taken to be the entire
+ *    string *strp, and *strp is made NULL.
+ *
+ * Returned Value:
+ *    The strsep() function returns a pointer to the token, that is, it
+ *    returns the original value of *strp.
+ *
+ ****************************************************************************/
+
+FAR char *strsep(FAR char **strp, FAR const char *delim)
+{
+  FAR char *sbegin = *strp;
+  FAR char *end;
+
+  if !sbegin == NULL)
+    {
+      return NULL;
+    }
+
+  end = strpbrk(sbegin, delim);
+  if (end != NULL)
+    {
+      *end++ = '\0';
+    }
+
+  *strp = end;
+  return sbegin;
+}