Re: [PATCH] strtoul_ui: actually report error in case of negative input
From: Matthieu Moy <hidden>
Date: 2016-06-15 23:06:32
Max Kirillov [off-list ref] writes:
If s == "-1" and CPU is i386, then none of the checks is triggered, including the last "(unsigned int) ul != ul", because ul == 2**32 - 1, which fits into "unsigned int".
Thanks for noticing and reporting.
Fix it by changing the last check to trigger earlier, as soon as it becomes bigger than INT_MAX.
What if the value is actually greater than INT_MAX? The function is returning an unsigned long (64 bits on 64bits architectures), and your version is restricting it to integers smaller than 2^31, right?
quoted hunk
--- a/git-compat-util.h +++ b/git-compat-util.h@@ -815,7 +815,7 @@ static inline int strtoul_ui(char const *s, int base, unsigned int *result) errno = 0; ul = strtoul(s, &p, base); - if (errno || *p || p == s || (unsigned int) ul != ul) + if (errno || *p || p == s || ul > (unsigned long) INT_MAX)
I think you at least want to use LONG_MAX and drop the cast here (untested, and beware of my advices when given before coffee). That would restrict to values smaller than 2^63, and I guess no one is interested in the interval ]2^63, 2^64]. The other option would be to look for a leading '-' before calling strtoul. (Actually, this makes me wonder why strtoul happily returns a big positive when fed with the string "-1", but we can't change it) -- Matthieu Moy http://www-verimag.imag.fr/~moy/