From 2f9467cfd2574af44f97ee89b460c410a5a3c85a Mon Sep 17 00:00:00 2001
From: wm4 <wm4@nowhere>
Date: Mon, 17 Nov 2014 21:22:21 +0100
Subject: Provide a strndup() fallback

This standard function is not available everywhere, so we detect it and
provide a fallback if missing.
---
 configure.ac       |  2 +-
 libass/ass_utils.c | 14 ++++++++++++++
 libass/ass_utils.h |  7 +++++++
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 5575dfd..abcb474 100644
--- a/configure.ac
+++ b/configure.ac
@@ -28,7 +28,7 @@ AC_TYPE_UINT32_T
 AC_TYPE_UINT8_T
 
 # Checks for library functions.
-AC_CHECK_FUNCS([mkdir strcasecmp strdup strtol])
+AC_CHECK_FUNCS([mkdir strcasecmp strdup strndup strtol])
 
 # Checks for libraries.
 AC_SEARCH_LIBS([iconv_open], [iconv], AC_DEFINE(CONFIG_ICONV, 1, [use iconv]))
diff --git a/libass/ass_utils.c b/libass/ass_utils.c
index 593d787..b1c736c 100644
--- a/libass/ass_utils.c
+++ b/libass/ass_utils.c
@@ -62,6 +62,20 @@ int has_avx2(void)
 
 #endif // ASM
 
+#ifndef HAVE_STRNDUP
+char *ass_strndup(const char *s, size_t n)
+{
+    char *end = memchr(s, 0, n);
+    size_t len = end ? end - s : n;
+    char *new = len < SIZE_MAX ? malloc(len + 1) : NULL;
+    if (new) {
+        memcpy(new, s, len);
+        new[len] = 0;
+    }
+    return new;
+}
+#endif
+
 void *ass_aligned_alloc(size_t alignment, size_t size)
 {
     assert(!(alignment & (alignment - 1))); // alignment must be power of 2
diff --git a/libass/ass_utils.h b/libass/ass_utils.h
index 1ce451c..579ac40 100644
--- a/libass/ass_utils.h
+++ b/libass/ass_utils.h
@@ -27,6 +27,8 @@
 #include <assert.h>
 #include <errno.h>
 
+#include "config.h"
+
 #ifdef CONFIG_ENCA
 #include <enca.h>
 #endif
@@ -54,6 +56,11 @@ int has_avx(void);
 int has_avx2(void);
 #endif
 
+#ifndef HAVE_STRNDUP
+char *ass_strndup(const char *s, size_t n);
+#define strndup ass_strndup
+#endif
+
 void *ass_aligned_alloc(size_t alignment, size_t size);
 void ass_aligned_free(void *ptr);
 
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