xutil: Implement xstrndup without relying on strndup.

Since we need to do this for portability, (some systems don't have a
strndup function), we might as well do it unconditionally. There's
almost no disadvantage to doing so, and this has the advantages of not
requiring a configure-time check nor having two different
implementations, one of which would often be less tested.

2 files changed, 6 insertions, 4 deletions

diff --git a/TODO b/TODO
index 1b8fb42a..87f84a42 100644
--- a/TODO
+++ b/TODO
@@ -41,8 +41,6 @@ Portability
 -----------
 Fix configure script to test each compiler warning we want to use.
 
-Implement strndup locally (or call talloc_strndup instead).
-
 Implement getline locally, (look at gnulib).
 
 Completion
diff --git a/lib/xutil.c b/lib/xutil.c
index 6fa5eb0d..268225b8 100644
--- a/lib/xutil.c
+++ b/lib/xutil.c
@@ -18,7 +18,6 @@
  * Author: Carl Worth <cworth@cworth.org>
  */
 
-#define _GNU_SOURCE /* For strndup */
 #include "notmuch-private.h"
 
 #include <stdio.h>
@@ -84,11 +83,16 @@ xstrndup (const char *s, size_t n)
 {
     char *ret;
 
-    ret = strndup (s, n);
+    if (strlen (s) <= n)
+	n = strlen (s);
+
+    ret = malloc (n + 1);
     if (ret == NULL) {
 	fprintf (stderr, "Out of memory.\n");
 	exit (1);
     }
+    memcpy (ret, s, n);
+    ret[n] = '\0';
 
     return ret;
 }