From: Rich Felker <dalias@aerifal.cx>
Date: Thu, 23 May 2013 18:31:02 +0000 (-0400)
Subject: fix overflow behavior of clock() function
X-Git-Url: http://nsz.repo.hu/git/?p=musl;a=commitdiff_plain;h=05453b37fc0343e53bc7f332047e901b3e1abb84;hp=05453b37fc0343e53bc7f332047e901b3e1abb84

fix overflow behavior of clock() function

per Austin Group interpretation for issue #686, which cites the
requirements of ISO C, clock() cannot wrap. if the result is not
representable, it must return (clock_t)-1. in addition, the old code
was performing wrapping via signed overflow and thus invoking
undefined behavior.

since it seems impossible to accurately check for overflow with the
old times()-based fallback code, I have simply dropped the fallback
code for now, thus always returning -1 on ancient systems. if there's
a demand for making it work and somebody comes up with a way, it could
be reinstated, but the clock() function is essentially useless on
32-bit system anyway (it overflows in less than an hour).

it should be noted that I used LONG_MAX rather than ULONG_MAX, despite
32-bit archs using an unsigned type for clock_t. this discrepency with
the glibc/LSB type definitions will be fixed now; since wrapping of
clock_t is no longer supported, there's no use in it being unsigned.
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