Added test driver, fixed off-by-one bug.

[pdclib] / functions / string / strncpy.c

diff --git a/functions/string/strncpy.c b/functions/string/strncpy.c
index 614ca13e097384fbf1d4e8bf52bc2d3874ad8e20..31602ec8a9fef4709ce87b2904c821fb6256d2f4 100644 (file)
--- a/functions/string/strncpy.c
+++ b/functions/string/strncpy.c
@@ -8,6 +8,7 @@
    Permission is granted to use, modify, and / or redistribute at will.
 */
 
+#include <_PDCLIB_aux.h>
 #include <string.h>
 
 char * strncpy( char * _PDCLIB_restrict s1, const char * _PDCLIB_restrict s2, size_t n )
@@ -16,13 +17,34 @@ char * strncpy( char * _PDCLIB_restrict s1, const char * _PDCLIB_restrict s2, si
     while ( ( n > 0 ) && ( *s1++ = *s2++ ) )
     {
         /* Cannot do "n--" in the conditional as size_t is unsigned and we have
-           to check it again for >0 in the next loop.
+        to check it again for >0 in the next loop.
         */
         --n;
     }
-    while ( n-- )
+    while ( --n )
     {
         *s1++ = '\0';
     }
     return rc;
 }
+
+#ifdef TEST
+#include <_PDCLIB_test.h>
+
+int main()
+{
+    char s[] = "xxxxxxx";
+    BEGIN_TESTS;
+    TESTCASE( strncpy( s, "", 1 ) == s );
+    TESTCASE( s[0] == '\0' );
+    TESTCASE( s[1] == 'x' );
+    TESTCASE( strncpy( s, abcde, 6 ) == s );
+    TESTCASE( s[0] == 'a' );
+    TESTCASE( s[4] == 'e' );
+    TESTCASE( s[5] == '\0' );
+    TESTCASE( s[6] == 'x' );
+    TESTCASE( strncpy( s, abcde, 7 ) == s );
+    TESTCASE( s[6] == '\0' );
+    return TEST_RESULTS;
+}
+#endif