1 files changed, 49 insertions, 0 deletions
diff --git a/strnstarts.c b/strnstarts.c
new file mode 100644
index 0000000..727cf3e
--- /dev/null
+++ b/strnstarts.c
@@ -0,0 +1,49 @@
+/* See LICENSE file for copyright and license details. */
+#include "libsimple.h"
+#ifndef TEST
+
+
+int
+libsimple_strnstarts(const char *s_, const char *t, size_t n)
+{
+	char *s = *(char **)(void *)&s_;
+	size_t len = strlen(t);
+	n = strnlen(s, n);
+	if (n < len)
+		return 0;
+	return !strncmp(s, t, len);
+}
+
+
+#else
+#include "test.h"
+
+int
+main(void)
+{
+	size_t n, i, j;
+	char buf[10];
+	for (n = 0; n <= 8; n++) {
+		assert(libsimple_strnstarts("abcABC", "", n) == 1);
+		assert(libsimple_strnstarts("ABCabc", "", n) == 1);
+		assert(libsimple_strnstarts("123456", "", n) == 1);
+		for (i = 0; i < 7; i++) {
+			for (j = 1; j < 8 - i; j++) {
+				strcpy(buf, &"abcABCx"[i])[j] = '\0';
+				assert(libsimple_strnstarts("abcABC", buf, n) == (i == 0 && j < 7 && n >= j));
+				assert(libsimple_strnstarts("ABCabc", buf, n) == (i == 3 && j < 4 && n >= j));
+				strcpy(buf, &"ABCabcx"[i])[j] = '\0';
+				assert(libsimple_strnstarts("abcABC", buf, n) == (i == 3 && j < 4 && n >= j));
+				assert(libsimple_strnstarts("ABCabc", buf, n) == (i == 0 && j < 7 && n >= j));
+				strcpy(buf, &"1234567"[i])[j] = '\0';
+				assert(libsimple_strnstarts("123456", buf, n) == (i == 0 && j < 7 && n >= j));
+				assert(libsimple_strnstarts("zzzzzz", buf, n) == 0);
+				strcpy(buf, &"aaaaaaa"[i])[j] = '\0';
+				assert(libsimple_strnstarts("zzzzzz", buf, n) == 0);
+			}
+		}
+	}
+	return 0;
+}
+
+#endif