From patchwork Tue Aug 20 13:21:50 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Zack Weinberg X-Patchwork-Id: 34194 Received: (qmail 41437 invoked by alias); 20 Aug 2019 13:56:54 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 41429 invoked by uid 89); 20 Aug 2019 13:56:53 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-17.9 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, SPF_HELO_PASS, SPF_PASS autolearn=ham version=3.3.1 spammy=Minutes X-HELO: l2mail1.panix.com From: Zack Weinberg To: libc-alpha@sourceware.org Cc: Joseph Myers , Florian Weimer , Lukasz Majewski , Alistair Francis , Stepan Golosunov , Arnd Bergmann Subject: [PATCH 10/12] Warn when gettimeofday is called with non-null tzp argument. Date: Tue, 20 Aug 2019 09:21:50 -0400 Message-Id: <20190820132152.24100-11-zackw@panix.com> In-Reply-To: <20190820132152.24100-1-zackw@panix.com> References: <20190820132152.24100-1-zackw@panix.com> MIME-Version: 1.0 At this stage I don’t 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 ‘void *’. 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 ‘void *’. --- 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 22a996a220..bd1fc3cb5e 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 5dbc7fc627..1b6c112274 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 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;