banned.h: mark strncpy() as banned
authorJeff King <peff@peff.net>
Tue, 24 Jul 2018 09:28:28 +0000 (05:28 -0400)
committerJunio C Hamano <gitster@pobox.com>
Thu, 26 Jul 2018 17:12:51 +0000 (10:12 -0700)
The strncpy() function is less horrible than strcpy(), but
is still pretty easy to misuse because of its funny
termination semantics. Namely, that if it truncates it omits
the NUL terminator, and you must remember to add it
yourself. Even if you use it correctly, it's sometimes hard
for a reader to verify this without hunting through the
code. If you're thinking about using it, consider instead:

- strlcpy() if you really just need a truncated but
NUL-terminated string (we provide a compat version, so
it's always available)

- xsnprintf() if you're sure that what you're copying
should fit

- strbuf or xstrfmt() if you need to handle
arbitrary-length heap-allocated strings

Note that there is one instance of strncpy in
compat/regex/regcomp.c, which is fine (it allocates a
sufficiently large string before copying). But this doesn't
trigger the ban-list even when compiling with NO_REGEX=1,
because:

1. we don't use git-compat-util.h when compiling it
(instead we rely on the system includes from the
upstream library); and

2. It's in an "#ifdef DEBUG" block

Since it's doesn't trigger the banned.h code, we're better
off leaving it to keep our divergence from upstream minimal.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
banned.h
index ad0d36dc9ff75bc96f82a18fe3fc815f537d7582..28f5937035b762ad9fb091ea8fb7cc96f38fc92d 100644 (file)
--- a/banned.h
+++ b/banned.h
@@ -14,6 +14,8 @@
 #define strcpy(x,y) BANNED(strcpy)
 #undef strcat
 #define strcat(x,y) BANNED(strcat)
+#undef strncpy
+#define strncpy(x,y,n) BANNED(strncpy)
 
 #undef sprintf
 #undef vsprintf