blame: prefer xsnprintf to strcpy for colors

Our color buffers are all COLOR_MAXLEN, which fits the
largest possible color. So we can never overflow the buffer
by copying an existing color. However, using strcpy() makes
it harder to audit the code-base for calls that _are_
problems. We should use something like xsnprintf(), which
shows the reader that we expect this never to fail (and
provides a run-time assertion if it does, just in case).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: peff

builtin/blame.c

@@ -1060,7 +1060,9 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
 		find_alignment(&sb, &output_option);
 		if (!*repeated_meta_color &&
 		    (output_option & OUTPUT_COLOR_LINE))
-			strcpy(repeated_meta_color, GIT_COLOR_CYAN);
+			xsnprintf(repeated_meta_color,
+				  sizeof(repeated_meta_color),
+				  "%s", GIT_COLOR_CYAN);
 	}
 	if (output_option & OUTPUT_ANNOTATE_COMPAT)
 		output_option &= ~(OUTPUT_COLOR_LINE | OUTPUT_SHOW_AGE_WITH_COLOR);