[PATCH] blame: prefer xsnprintf to strcpy for colors

[Jeff King <peff@peff.net>]

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>
---
Another option would just be color_parse(repeated_meta_color, "cyan").
The run-time cost is slightly higher, but it probably doesn't matter
here, and perhaps it's more readable.

This is a repost from:

  https://public-inbox.org/git/20180610204419.GA11273@sigill.intra.peff.net/

which I think just got overlooked as we were in the midst of the 2.18
release cycle.

 builtin/blame.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/builtin/blame.c b/builtin/blame.c
index 5a0388aaef..63bdf755bb 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -1069,7 +1069,9 @@ 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);
-- 
2.18.0.433.gb9621797ee