From e1b1fecaf26990c1a77d2a5d1e047fe469cd2212 Mon Sep 17 00:00:00 2001
From: Andrei Alexeyev <akari@taisei-project.org>
Date: Sat, 27 Aug 2022 02:40:55 +0300
Subject: [PATCH] util/stringops: add memmem() polyfill

---
 meson.build          |  2 +-
 src/util/stringops.c | 21 +++++++++++++++++++++
 src/util/stringops.h |  7 +++++++
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/meson.build b/meson.build
index 71faf224..363098df 100644
--- a/meson.build
+++ b/meson.build
@@ -272,7 +272,7 @@ config.set('TAISEI_BUILDCONF_HAVE_POSIX', have_posix)
 config.set('TAISEI_BUILDCONF_HAVE_SINCOS', cc.has_function('sincos', dependencies : dep_m))
 
 use_gnu_funcs = false
-gnu_funcs = ['sincos', 'strtok_r', 'memrchr']
+gnu_funcs = ['sincos', 'strtok_r', 'memrchr', 'memmem']
 
 foreach f : gnu_funcs
     have = cc.has_function(f, dependencies : dep_m)
diff --git a/src/util/stringops.c b/src/util/stringops.c
index 6709d01c..03e28cb0 100644
--- a/src/util/stringops.c
+++ b/src/util/stringops.c
@@ -431,3 +431,24 @@ void *memrchr(const void *s, int c, size_t n) {
 	return NULL;
 }
 #endif
+
+#ifndef TAISEI_BUILDCONF_HAVE_MEMMEM
+#undef memmem
+#define memmem _ts_memmem
+void *memmem(const void *haystack, size_t haystacklen, const void *needle, size_t needlelen) {
+	const char *p_haystack = haystack;
+	const char *e_haystack = p_haystack + haystacklen;
+
+	for(;;) {
+		if(needlelen > e_haystack - p_haystack) {
+			return NULL;
+		}
+
+		if(!memcmp(p_haystack, needle, needlelen)) {
+			return (void*)p_haystack;
+		}
+
+		++p_haystack;
+	}
+}
+#endif
diff --git a/src/util/stringops.h b/src/util/stringops.h
index 54bcdeba..a253a9ee 100644
--- a/src/util/stringops.h
+++ b/src/util/stringops.h
@@ -44,6 +44,13 @@ char *strtok_r(char *str, const char *delim, char **nextp);
 void *memrchr(const void *s, int c, size_t n);
 #endif
 
+#ifndef TAISEI_BUILDCONF_HAVE_MEMMEM
+#undef memmem
+#define memmem _ts_memmem
+void *memmem(const void *haystack, size_t haystacklen, const void *needle, size_t needlelen)
+	attr_nonnull_all;
+#endif
+
 #undef strcasecmp
 #define strcasecmp SDL_strcasecmp