2 files changed, 52 insertions, 0 deletions
diff --git a/compat/compat.c b/compat/compat.c
new file mode 100644
index 0000000..1112146
--- /dev/null
+++ b/compat/compat.c
@@ -0,0 +1,31 @@
+#include "compat.h"
+
+#ifdef NO_STRDUP
+#include "moslib/safe.h"
+#include <string.h>
+char *strdup(const char *s) {
+    char *s2 = mos_safe_malloc(strlen(s) + 1);
+    strcpy(s2, s);
+    return s2;
+}
+#endif // NO_STRDUP
+
+#ifdef NO_MEMMEM
+void *memmem(const void *h, size_t h_size, const void *n, size_t n_size) {
+    if (n_size == 0)
+        return (void *)h;
+    if (n_size > h_size)
+        return NULL;
+
+    const unsigned char *p = h;
+    const unsigned char *end = p + h_size - n_size + 1;
+    unsigned char c = *(unsigned char *)n;
+    while ((p = memchr(p, c, end - p))) {
+        if (memcmp(p, n, n_size) == 0)
+            return (void *)p;
+        p++;
+    }
+
+    return NULL;
+}
+#endif // NO_MEMMEM
diff --git a/compat/compat.h b/compat/compat.h
new file mode 100644
index 0000000..b36b17f
--- /dev/null
+++ b/compat/compat.h
@@ -0,0 +1,21 @@
+// compat.h
+// Compatibility layer for functions not in standard C99
+
+#ifndef MOSLIB_COMPAT_H
+#define MOSLIB_COMPAT_H
+
+#define _XOPEN_SOURCE 500
+#define _GNU_SOURCE
+
+typedef void declaration;
+
+#ifdef NO_STRDUP
+extern char *strdup(const char *s);
+#endif // NO_STRDUP
+
+#ifdef NO_MEMMEM
+#include <stddef.h>
+extern void *memmem(const void *h, size_t h_size, const void *n, size_t n_size);
+#endif // NO_MEMMEM
+
+#endif // MOSLIB_COMPAT_H