added SDL_strtokr() as a replacement for POSIX strtok_r (bug #4046.)

src/stdlib/SDL_strtokr.c

@@ -0,0 +1,103 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2019 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#if defined(__clang_analyzer__)
+#define SDL_DISABLE_ANALYZE_MACROS 1
+#endif
+
+#include "../SDL_internal.h"
+
+#include "SDL_stdinc.h"
+
+char *SDL_strtokr(char *s1, const char *s2, char **ptr)
+{
+#if defined(HAVE_STRTOK_R)
+    return strtok_r(s1, s2, ptr);
+
+#elif defined(_MSC_VER) && defined(HAVE_STRTOK_S)
+    return strtok_s(s1, s2, ptr);
+
+#else /* SDL implementation */
+/*
+ * Adapted from _PDCLIB_strtok() of PDClib library at
+ * https://github.com/DevSolar/pdclib.git
+ *
+ * The code was under CC0 license:
+ * https://creativecommons.org/publicdomain/zero/1.0/legalcode :
+ *
+ *                        No Copyright
+ *
+ * The person who associated a work with this deed has dedicated the
+ * work to the public domain by waiving all of his or her rights to
+ * the work worldwide under copyright law, including all related and
+ * neighboring rights, to the extent allowed by law.
+ *
+ * You can copy, modify, distribute and perform the work, even for
+ * commercial purposes, all without asking permission. See Other
+ * Information below.
+ */
+    const char *p = s2;
+
+    if (!s2 || !ptr || (!s1 && !*ptr)) return NULL;
+
+    if (s1 != NULL) {  /* new string */
+        *ptr = s1;
+    } else { /* old string continued */
+        if (*ptr == NULL) {
+        /* No old string, no new string, nothing to do */
+            return NULL;
+        }
+        s1 = *ptr;
+    }
+
+    /* skip leading s2 characters */
+    while (*p && *s1) {
+        if (*s1 == *p) {
+        /* found separator; skip and start over */
+            ++s1;
+            p = s2;
+            continue;
+        }
+        ++p;
+    }
+
+    if (! *s1) { /* no more to parse */
+        *ptr = s1;
+        return NULL;
+    }
+
+    /* skipping non-s2 characters */
+    *ptr = s1;
+    while (**ptr) {
+        p = s2;
+        while (*p) {
+            if (**ptr == *p++) {
+            /* found separator; overwrite with '\0', position *ptr, return */
+                *((*ptr)++) = '\0';
+                return s1;
+            }
+        }
+        ++(*ptr);
+    }
+
+    /* parsed to end of string */
+    return s1;
+#endif
+}