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| author | Paul Eggert <eggert@cs.ucla.edu> | 2011-01-29 23:59:31 -0800 |
|---|---|---|
| committer | Paul Eggert <eggert@cs.ucla.edu> | 2011-01-30 00:00:00 -0800 |
| commit | ee9e39c014e2880179c91960ce1f69309d0c1500 (patch) | |
| tree | 11654c2892678ea15c6fa939af91e1062bb1eb31 /lib/intprops.h | |
| parent | 56887e878833f53c8ca55371c0e4be66388e157b (diff) | |
| download | gnulib-ee9e39c014e2880179c91960ce1f69309d0c1500.tar.gz | |
TYPE_MAXIMUM: avoid theoretically undefined behavior
* lib/intprops.h (TYPE_MINIMUM, TYPE_MAXIMUM): Do not shift a
negative number, which the C Standard says has undefined behavior.
In practice this is not a problem, but might as well do it by the book.
Reported by Rich Felker and Eric Blake; see
<http://lists.gnu.org/archive/html/bug-gnulib/2011-01/msg00493.html>.
* lib/strtol.c (TYPE_MINIMUM, TYPE_MAXIMUM): Likewise.
* m4/mktime.m4 (AC_FUNC_MKTIME): Likewise.
* m4/nanosleep.m4 (gl_FUNC_NANOSLEEP): Likewise.
* m4/parse-datetime.m4 (gl_PARSE_DATETIME): Likewise.
* m4/stdint.m4 (gl_STDINT_H): Likewise.
* lib/mktime.c (TYPE_MAXIMUM): Redo slightly to match the others.
Diffstat (limited to 'lib/intprops.h')
| -rw-r--r-- | lib/intprops.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/lib/intprops.h b/lib/intprops.h index 511a5aa989..58b1b3fbf4 100644 --- a/lib/intprops.h +++ b/lib/intprops.h @@ -49,11 +49,11 @@ ? (t) 0 \ : TYPE_SIGNED_MAGNITUDE (t) \ ? ~ (t) 0 \ - : ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1))) + : ~ TYPE_MAXIMUM (t))) # define TYPE_MAXIMUM(t) \ ((t) (! TYPE_SIGNED (t) \ ? (t) -1 \ - : ~ (~ (t) 0 << (sizeof (t) * CHAR_BIT - 1)))) + : ((((t) 1 << (sizeof (t) * CHAR_BIT - 2)) - 1) * 2 + 1))) /* Return zero if T can be determined to be an unsigned type. Otherwise, return 1. |