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From: Zack Weinberg <zack@sourceware.org> To: glibc-cvs@sourceware.org Subject: [glibc/zack/y2038-preliminaries] Warn when gettimeofday is called with non-null tzp argument. Date: Thu, 22 Aug 2019 23:04:00 -0000 [thread overview] Message-ID: <20190822230410.9251.qmail@sourceware.org> (raw) [-- Warning: decoded text below may be mangled, UTF-8 assumed --] [-- Attachment #1: Type: text/plain; charset="us-ascii", Size: 4001 bytes --] https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=53df1cd2811b71aa4193cb250b95fc14b7f310a3 commit 53df1cd2811b71aa4193cb250b95fc14b7f310a3 Author: Zack Weinberg <zackw@panix.com> Date: Mon Aug 19 13:51:25 2019 -0400 Warn when gettimeofday is called with non-null tzp argument. At this stage I donât think we can issue warnings for settimeofday with a non-null tzp argument, nor for arbitrary use of struct timezone. But we can warn about gettimeofday with non-null tzp. This uses a macro instead of an inline (fortify-style) function because I got false positives with an inline, even with GCC 9. * time/sys/time.h (__timezone_ptr_t): Delete. (gettimeofday): Always declare second argument with type âvoid *â. When possible, wrap with a macro that detects non-null and non-constant second argument and issues a warning. Improve commentary. (settimeofday): Improve commentary. * time/gettimeofday.c (gettimeofday): Declare second argument as type âvoid *â. Diff: --- time/gettimeofday.c | 4 ++-- time/sys/time.h | 36 +++++++++++++++++++++++++----------- 2 files changed, 27 insertions(+), 13 deletions(-) diff --git a/time/gettimeofday.c b/time/gettimeofday.c index 22a996a..bd1fc3c 100644 --- a/time/gettimeofday.c +++ b/time/gettimeofday.c @@ -23,10 +23,10 @@ If *TZ is not NULL, clear it. Returns 0 on success, -1 on errors. */ int -__gettimeofday (struct timeval *tv, struct timezone *tz) +__gettimeofday (struct timeval *restrict tv, void *restrict tz) { if (__glibc_unlikely (tz != 0)) - memset (tz, 0, sizeof *tz); + memset (tz, 0, sizeof (struct timezone)); struct timespec ts; if (__clock_gettime (CLOCK_REALTIME, &ts)) diff --git a/time/sys/time.h b/time/sys/time.h index 5dbc7fc..1b6c112 100644 --- a/time/sys/time.h +++ b/time/sys/time.h @@ -54,23 +54,37 @@ struct timezone int tz_minuteswest; /* Minutes west of GMT. */ int tz_dsttime; /* Nonzero if DST is ever in effect. */ }; - -typedef struct timezone *__restrict __timezone_ptr_t; -#else -typedef void *__restrict __timezone_ptr_t; #endif -/* Get the current time of day and timezone information, - putting it into *TV and *TZ. If TZ is NULL, *TZ is not filled. - Returns 0 on success, -1 on errors. - NOTE: This form of timezone information is obsolete. - Use the functions and variables declared in <time.h> instead. */ +/* Get the current time of day, putting it into *TV. + If TZ is not null, *TZ must be a struct timezone, and both fields + will be set to zero. + Calling this function with a non-null TZ is obsolete; + use localtime etc. instead. + This function itself is semi-obsolete; + most callers should use time or clock_gettime instead. */ extern int gettimeofday (struct timeval *__restrict __tv, - __timezone_ptr_t __tz) __THROW __nonnull ((1)); + void *__restrict __tz) __THROW __nonnull ((1)); + +#if __GNUC_PREREQ (4,3) +/* Issue a warning for use of gettimeofday with a non-null __tz argument. */ +__warndecl (__warn_gettimeofday_timezone, + "gettimeofday with non-null or non-constant timezone parameter;" + " this is obsolete and inaccurate, use localtime instead"); + +#define gettimeofday(__tv, __tz) \ + (((!__builtin_constant_p (__tz) || (__tz) != 0) \ + ? __warn_gettimeofday_timezone () \ + : (void) 0), \ + (gettimeofday) (__tv, __tz)) +#endif #ifdef __USE_MISC /* Set the current time of day and timezone information. - This call is restricted to the super-user. */ + This call is restricted to the super-user. + Setting the timezone in this way is obsolete, but we don't yet + warn about it because it still has some uses for which there is + no alternative. */ extern int settimeofday (const struct timeval *__tv, const struct timezone *__tz) __THROW;
next reply other threads:[~2019-08-22 23:04 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-08-22 23:04 Zack Weinberg [this message] -- strict thread matches above, loose matches on Subject: below -- 2019-08-28 13:05 Zack Weinberg 2019-08-21 12:28 Zack Weinberg 2019-08-20 13:25 Zack Weinberg 2019-08-20 12:32 Zack Weinberg 2019-08-20 12:08 Zack Weinberg 2019-08-19 18:31 Zack Weinberg
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