public inbox for glibc-bugs@sourceware.org
help / color / mirror / Atom feed
* [Bug libc/18396] New: timezone internal code for time_t_max and time_t_min is UB
@ 2015-05-11 17:05 nszabolcs at gmail dot com
2015-05-11 17:41 ` [Bug libc/18396] " joseph at codesourcery dot com
2015-08-27 22:27 ` [Bug time/18396] " jsm28 at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: nszabolcs at gmail dot com @ 2015-05-11 17:05 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=18396
Bug ID: 18396
Summary: timezone internal code for time_t_max and time_t_min
is UB
Product: glibc
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: libc
Assignee: unassigned at sourceware dot org
Reporter: nszabolcs at gmail dot com
CC: drepper.fsp at gmail dot com
Target Milestone: ---
recent gcc change exposed an invalid -1 << n in timezone/private.h
if time_t is signed:
/* The minimum and maximum finite time values. */
static time_t const time_t_min =
(TYPE_SIGNED(time_t)
? (time_t) -1 << (CHAR_BIT * sizeof (time_t) - 1)
: 0);
static time_t const time_t_max =
(TYPE_SIGNED(time_t)
? - (~ 0 < 0) - ((time_t) -1 << (CHAR_BIT * sizeof (time_t) - 1))
: -1);
the gcc warning may get silenced as it caused other problems:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66066
but the UB should be fixed.
There is no simple solution: the above code seems to want to support
non-two's-complement signed int representations too.
I think a solution based on (uintmax_t)-1 >> n can work for time_t_max
with reasonable assumptions, otherwise arch specific soulution can be used.
--
You are receiving this mail because:
You are on the CC list for the bug.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug libc/18396] timezone internal code for time_t_max and time_t_min is UB
2015-05-11 17:05 [Bug libc/18396] New: timezone internal code for time_t_max and time_t_min is UB nszabolcs at gmail dot com
@ 2015-05-11 17:41 ` joseph at codesourcery dot com
2015-08-27 22:27 ` [Bug time/18396] " jsm28 at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: joseph at codesourcery dot com @ 2015-05-11 17:41 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=18396
--- Comment #1 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
This is already fixed in upstream tz git, we just need to import the next
tzcode release when it comes out.
--
You are receiving this mail because:
You are on the CC list for the bug.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug time/18396] timezone internal code for time_t_max and time_t_min is UB
2015-05-11 17:05 [Bug libc/18396] New: timezone internal code for time_t_max and time_t_min is UB nszabolcs at gmail dot com
2015-05-11 17:41 ` [Bug libc/18396] " joseph at codesourcery dot com
@ 2015-08-27 22:27 ` jsm28 at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: jsm28 at gcc dot gnu.org @ 2015-08-27 22:27 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=18396
Joseph Myers <jsm28 at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|libc |time
--
You are receiving this mail because:
You are on the CC list for the bug.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2015-08-27 22:27 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-05-11 17:05 [Bug libc/18396] New: timezone internal code for time_t_max and time_t_min is UB nszabolcs at gmail dot com
2015-05-11 17:41 ` [Bug libc/18396] " joseph at codesourcery dot com
2015-08-27 22:27 ` [Bug time/18396] " jsm28 at gcc dot gnu.org
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).