From patchwork Fri Feb 24 15:27:41 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Adam Yi X-Patchwork-Id: 65778 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 467963858404 for ; Tue, 28 Feb 2023 14:53:00 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 467963858404 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1677595980; bh=U5+clEOjnr/C0jJM2ZuQeQExv8skL6CLDOCS+UwQ3wE=; h=In-Reply-To:References:Date:Subject:To:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From:Reply-To:From; b=MEMP0j6TKpslOa0ArZgDnXu/HPogdHi31pCC+3F10uYMxKwB6bOIDun4eXKQ4YRlN hro1djulLNIyHRubjR/D5oZcpYt0WtmJZhfAGF0qFyyXV3Iag0t1KyuO87qfL2BXyi LEBmzSh4wD/aiaI25ROyHnLgtY2QKl5rcUPWZco8= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mxout5.mail.janestreet.com (mxout5.mail.janestreet.com [64.215.233.18]) by sourceware.org (Postfix) with ESMTPS id 757373858D33 for ; Tue, 28 Feb 2023 14:52:35 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 757373858D33 In-Reply-To: References: Date: Fri, 24 Feb 2023 10:27:41 -0500 Subject: [PATCH v3] posix: Fix system blocks SIGCHLD erroneously [BZ #30163] To: libc-alpha@sourceware.org Cc: adhemerval.zanella@linaro.org, i@adamyi.com Message-Id: X-Spam-Status: No, score=-13.9 required=5.0 tests=BAYES_00, GIT_PATCH_0, KAM_DMARC_STATUS, KAM_SHORT, SPF_HELO_PASS, SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Adam Yi via Libc-alpha From: Adam Yi Reply-To: Adam Yi Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" Fix bug that SIGCHLD is erroneously blocked forever in the following scenario: 1. Thread A calls system but hasn't returned yet 2. Thread B calls another system but returns SIGCHLD would be blocked forever in thread B after its system() returns, even after the system() in thread A returns. Although POSIX does not require, glibc system implementation aims to be thread and cancellation safe. This bug was introduced in 5fb7fc96350575c9adb1316833e48ca11553be49 when we moved reverting signal mask to happen when the last concurrently running system returns, despite that signal mask is per thread. This commit reverts this logic and adds a test. --- stdlib/tst-system.c | 28 ++++++++++++++++++++ support/Makefile | 2 ++ support/dtotimespec-time64.c | 27 +++++++++++++++++++ support/dtotimespec.c | 50 ++++++++++++++++++++++++++++++++++++ support/shell-container.c | 13 ++++++++++ support/timespec.h | 4 +++ sysdeps/posix/system.c | 6 ++--- 7 files changed, 127 insertions(+), 3 deletions(-) create mode 100644 support/dtotimespec-time64.c create mode 100644 support/dtotimespec.c diff --git a/stdlib/tst-system.c b/stdlib/tst-system.c index 634acfe264..736d2bf95b 100644 --- a/stdlib/tst-system.c +++ b/stdlib/tst-system.c @@ -20,6 +20,8 @@ #include #include #include +#include +#include #include #include @@ -71,6 +73,20 @@ call_system (void *closure) } } +static void * +sleep_and_check_sigchld (void *closure) +{ + double *seconds = (double *) closure; + char cmd[namemax]; + sprintf (cmd, "sleep %lf" , *seconds); + TEST_COMPARE (system (cmd), 0); + + sigset_t blocked = {0}; + TEST_COMPARE (sigprocmask (SIG_BLOCK, NULL, &blocked), 0); + TEST_COMPARE (sigismember (&blocked, SIGCHLD), 0); + return NULL; +} + static int do_test (void) { @@ -154,6 +170,18 @@ do_test (void) xchmod (_PATH_BSHELL, st.st_mode); } + { + pthread_t long_sleep_thread, short_sleep_thread; + + TEST_COMPARE (pthread_create (&long_sleep_thread, NULL, + sleep_and_check_sigchld, &(double) { 0.2 }), 0); + TEST_COMPARE (pthread_create (&short_sleep_thread, NULL, + sleep_and_check_sigchld, &(double) { 0.1 }), 0); + + TEST_COMPARE (pthread_join (short_sleep_thread, NULL), 0); + TEST_COMPARE (pthread_join (long_sleep_thread, NULL), 0); + } + TEST_COMPARE (system (""), 0); return 0; diff --git a/support/Makefile b/support/Makefile index b29b7eb505..48cd74581d 100644 --- a/support/Makefile +++ b/support/Makefile @@ -32,6 +32,8 @@ libsupport-routines = \ check_hostent \ check_netent \ delayed_exit \ + dtotimespec \ + dtotimespec-time64 \ ignore_stderr \ next_to_fault \ oom_error \ diff --git a/support/dtotimespec-time64.c b/support/dtotimespec-time64.c new file mode 100644 index 0000000000..b3d5e351e3 --- /dev/null +++ b/support/dtotimespec-time64.c @@ -0,0 +1,27 @@ +/* Convert double to timespec. 64-bit time support. + Copyright (C) 2011-2023 Free Software Foundation, Inc. + This file is part of the GNU C Library and is also part of gnulib. + Patches to this file should be submitted to both projects. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#include + +#if __TIMESIZE != 64 +# define timespec __timespec64 +# define time_t __time64_t +# define dtotimespec dtotimespec_time64 +# include "dtotimespec.c" +#endif diff --git a/support/dtotimespec.c b/support/dtotimespec.c new file mode 100644 index 0000000000..860403b83c --- /dev/null +++ b/support/dtotimespec.c @@ -0,0 +1,50 @@ +/* Convert double to timespec. + Copyright (C) 2011-2023 Free Software Foundation, Inc. + This file is part of the GNU C Library and is also part of gnulib. + Patches to this file should be submitted to both projects. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +/* Convert the double value SEC to a struct timespec. Round toward + positive infinity. On overflow, return an extremal value. */ + +#include +#include + +struct timespec +dtotimespec (double sec) +{ + if (! (TYPE_MINIMUM (time_t) < sec)) + return make_timespec (TYPE_MINIMUM (time_t), 0); + else if (! (sec < 1.0 + TYPE_MAXIMUM (time_t))) + return make_timespec (TYPE_MAXIMUM (time_t), TIMESPEC_HZ - 1); + else + { + time_t s = sec; + double frac = TIMESPEC_HZ * (sec - s); + long ns = frac; + ns += ns < frac; + s += ns / TIMESPEC_HZ; + ns %= TIMESPEC_HZ; + + if (ns < 0) + { + s--; + ns += TIMESPEC_HZ; + } + + return make_timespec (s, ns); + } +} diff --git a/support/shell-container.c b/support/shell-container.c index e9ac9b6d04..a2be314ad9 100644 --- a/support/shell-container.c +++ b/support/shell-container.c @@ -39,6 +39,7 @@ #include #include +#include /* Design considerations @@ -171,6 +172,17 @@ kill_func (char **argv) return 0; } +/* Emulate the "/bin/sleep" command. No suffix support. Options are + ignored. */ +static int +sleep_func (char **argv) +{ + double sec = atof (argv[0]); + struct timespec ts = dtotimespec (sec); + nanosleep (&ts, NULL); + return 0; +} + /* This is a list of all the built-in commands we understand. */ static struct { const char *name; @@ -181,6 +193,7 @@ static struct { { "cp", copy_func }, { "exit", exit_func }, { "kill", kill_func }, + { "sleep", sleep_func }, { NULL, NULL } }; diff --git a/support/timespec.h b/support/timespec.h index 77b1e4e8d6..9559836d4c 100644 --- a/support/timespec.h +++ b/support/timespec.h @@ -57,6 +57,8 @@ int support_timespec_check_in_range (struct timespec expected, struct timespec observed, double lower_bound, double upper_bound); +struct timespec dtotimespec (double sec) __attribute__((const)); + #else struct timespec __REDIRECT (timespec_add, (struct timespec, struct timespec), timespec_add_time64); @@ -82,6 +84,8 @@ int __REDIRECT (support_timespec_check_in_range, (struct timespec expected, double lower_bound, double upper_bound), support_timespec_check_in_range_time64); + +struct timespec __REDIRECT (dtotimespec, (double sec), dtotimespec_time64); #endif /* Check that the timespec on the left represents a time before the diff --git a/sysdeps/posix/system.c b/sysdeps/posix/system.c index 2335a99184..d77720a625 100644 --- a/sysdeps/posix/system.c +++ b/sysdeps/posix/system.c @@ -179,16 +179,16 @@ do_system (const char *line) as if the shell had terminated using _exit(127). */ status = W_EXITCODE (127, 0); + /* sigaction can not fail with SIGINT/SIGQUIT used with old + disposition. Same applies for sigprocmask. */ DO_LOCK (); if (SUB_REF () == 0) { - /* sigaction can not fail with SIGINT/SIGQUIT used with old - disposition. Same applies for sigprocmask. */ __sigaction (SIGINT, &intr, NULL); __sigaction (SIGQUIT, &quit, NULL); - __sigprocmask (SIG_SETMASK, &omask, NULL); } DO_UNLOCK (); + __sigprocmask (SIG_SETMASK, &omask, NULL); if (ret != 0) __set_errno (ret);