misc: Add strndup implementation if not provides by the OS

Fixes T112

Signed-off-by: Andreas Schneider <asn@cryptomilk.org>
(cherry picked from commit 247983e982)

ConfigureChecks.cmake

@@ -115,6 +115,7 @@ endif (NOT WITH_GCRYPT)
 
 check_function_exists(isblank HAVE_ISBLANK)
 check_function_exists(strncpy HAVE_STRNCPY)
+check_function_exists(strndup HAVE_STRNDUP)
 check_function_exists(strtoull HAVE_STRTOULL)
 
 if (NOT WIN32)

config.h.cmake

@@ -103,6 +103,9 @@
 /* Define to 1 if you have the `strncpy' function. */
 #cmakedefine HAVE_STRNCPY 1
 
+/* Define to 1 if you have the `strndup' function. */
+#cmakedefine HAVE_STRNDUP 1
+
 /* Define to 1 if you have the `cfmakeraw' function. */
 #cmakedefine HAVE_CFMAKERAW 1
 

include/libssh/priv.h

@@ -43,6 +43,10 @@
 # endif
 #endif /* !defined(HAVE_STRTOULL) */
 
+#if !defined(HAVE_STRNDUP)
+char *strndup(const char *s, size_t n);
+#endif /* ! HAVE_STRNDUP */
+
 #ifdef HAVE_BYTESWAP_H
 #include <byteswap.h>
 #endif

src/misc.c

@@ -1028,6 +1028,27 @@ int ssh_match_group(const char *group, const char *object)
     return 0;
 }
 
+#if !defined(HAVE_STRNDUP)
+char *strndup(const char *s, size_t n)
+{
+    char *x = NULL;
+
+    if (n + 1 < n) {
+        return NULL;
+    }
+
+    x = malloc(n + 1);
+    if (x == NULL) {
+        return NULL;
+    }
+
+    memcpy(x, s, n);
+    x[n] = '\0';
+
+    return x;
+}
+#endif /* ! HAVE_STRNDUP */
+
 /** @} */
 
 /* vim: set ts=4 sw=4 et cindent: */