bsdstubs: implement strndup() stub implementation if none exists

bsdstubs.c

@@ -96,3 +96,40 @@ strlcat(char *dst, const char *src, size_t siz)
 }
 
 #endif
+
+/*
+ * Copyright (c) 2012 William Pitcock <nenolod@dereferenced.org>.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef HAVE_STRNDUP
+
+/*
+ * Creates a memory buffer and copies at most 'len' characters to it.
+ * If 'len' is less than the length of the source string, truncation occured.
+ */
+char *strndup(const char *src, size_t len)
+{
+	char *out = malloc(len + 1);
+
+	strlcpy(out, src, len + 1);
+
+	return out;
+}
+
+#endif

bsdstubs.h

@@ -30,3 +30,8 @@ extern size_t strlcpy(char *dst, const char *src, size_t siz);
 #ifndef HAVE_STRLCAT
 extern size_t strlcat(char *dst, const char *src, size_t siz);
 #endif
+
+#ifndef HAVE_STRNDUP
+extern char *strndup(const char *src, size_t len);
+#endif
+