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| author | Paul Eggert <eggert@cs.ucla.edu> | 2012-06-21 01:49:15 -0700 |
|---|---|---|
| committer | Paul Eggert <eggert@cs.ucla.edu> | 2012-06-21 01:49:39 -0700 |
| commit | bdb21d38b29f55d7266691007857697ecb2291b5 (patch) | |
| tree | 55817f8ee41dde27f04ab62d05758ed9efe0c671 /m4 | |
| parent | ebc6ce40ac3f349d69766e3b94db034a0245f3d7 (diff) | |
| download | gnulib-bdb21d38b29f55d7266691007857697ecb2291b5.tar.gz | |
mktime: fix integer overflow in 'configure'-time test
* m4/mktime.m4 (gl_FUNC_MKTIME): Do not rely on undefined behavior
after integer overflow. Problem reported by Rich Felker in
<http://lists.gnu.org/archive/html/bug-gnulib/2012-06/msg00257.html>.
Also, don't look for further instances of a bug if we've already
found one instance; this helps 'configure' run faster.
Diffstat (limited to 'm4')
| -rw-r--r-- | m4/mktime.m4 | 25 |
1 files changed, 14 insertions, 11 deletions
diff --git a/m4/mktime.m4 b/m4/mktime.m4 index 5e05dfa697..14fcf7fe56 100644 --- a/m4/mktime.m4 +++ b/m4/mktime.m4 @@ -1,4 +1,4 @@ -# serial 21 +# serial 22 dnl Copyright (C) 2002-2003, 2005-2007, 2009-2012 Free Software Foundation, dnl Inc. dnl This file is free software; the Free Software Foundation @@ -192,20 +192,23 @@ main () if (tz_strings[i]) putenv (tz_strings[i]); - for (t = 0; t <= time_t_max - delta; t += delta) + for (t = 0; t <= time_t_max - delta && (result & 1) == 0; t += delta) if (! mktime_test (t)) result |= 1; - if (! (mktime_test ((time_t) 1) - && mktime_test ((time_t) (60 * 60)) - && mktime_test ((time_t) (60 * 60 * 24)))) + if ((result & 2) == 0 + && ! (mktime_test ((time_t) 1) + && mktime_test ((time_t) (60 * 60)) + && mktime_test ((time_t) (60 * 60 * 24)))) result |= 2; - for (j = 1; ; j <<= 1) - if (! bigtime_test (j)) - result |= 4; - else if (INT_MAX / 2 < j) - break; - if (! bigtime_test (INT_MAX)) + for (j = 1; (result & 4) == 0; j <<= 1) + { + if (! bigtime_test (j)) + result |= 4; + if (INT_MAX / 2 < j) + break; + } + if ((result & 8) == 0 && ! bigtime_test (INT_MAX)) result |= 8; } if (! irix_6_4_bug ()) |