glibc/stdlib/tst-system.c
Adam Yi 48af2676a7 posix: Fix system blocks SIGCHLD erroneously [BZ #30163]
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
5fb7fc9635 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.

Signed-off-by: Adam Yi <ayi@janestreet.com>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
(cherry picked from commit 436a604b7d)
2023-04-28 16:16:40 +02:00

189 lines
5.2 KiB
C

/* Copyright (C) 2002-2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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
<https://www.gnu.org/licenses/>. */
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <paths.h>
#include <support/capture_subprocess.h>
#include <support/check.h>
#include <support/temp_file.h>
#include <support/support.h>
#include <support/xthread.h>
#include <support/xunistd.h>
static char *tmpdir;
static long int namemax;
static void
do_prepare (int argc, char *argv[])
{
tmpdir = support_create_temp_directory ("tst-system-");
/* Include the last '/0'. */
namemax = pathconf (tmpdir, _PC_NAME_MAX) + 1;
TEST_VERIFY_EXIT (namemax != -1);
}
#define PREPARE do_prepare
struct args
{
const char *command;
int exit_status;
int term_sig;
const char *path;
};
static void
call_system (void *closure)
{
struct args *args = (struct args *) closure;
int ret;
if (args->path != NULL)
TEST_COMPARE (setenv ("PATH", args->path, 1), 0);
ret = system (args->command);
if (args->term_sig == 0)
{
/* Expect regular termination. */
TEST_VERIFY (WIFEXITED (ret) != 0);
TEST_COMPARE (WEXITSTATUS (ret), args->exit_status);
}
else
{
/* status_or_signal < 0. Expect termination by signal. */
TEST_VERIFY (WIFSIGNALED (ret) != 0);
TEST_COMPARE (WTERMSIG (ret), args->term_sig);
}
}
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)
{
TEST_VERIFY (system (NULL) != 0);
{
char cmd[namemax];
memset (cmd, 'a', sizeof(cmd));
cmd[sizeof(cmd) - 1] = '\0';
struct support_capture_subprocess result;
result = support_capture_subprocess (call_system,
&(struct args) {
cmd, 127, 0, tmpdir
});
support_capture_subprocess_check (&result, "system", 0, sc_allow_stderr);
char *returnerr = xasprintf ("%s: execing %s failed: "
"No such file or directory",
basename(_PATH_BSHELL), cmd);
TEST_COMPARE_STRING (result.err.buffer, returnerr);
free (returnerr);
}
{
char cmd[namemax + 1];
memset (cmd, 'a', sizeof(cmd));
cmd[sizeof(cmd) - 1] = '\0';
struct support_capture_subprocess result;
result = support_capture_subprocess (call_system,
&(struct args) {
cmd, 127, 0, tmpdir
});
support_capture_subprocess_check (&result, "system", 0, sc_allow_stderr);
char *returnerr = xasprintf ("%s: execing %s failed: "
"File name too long",
basename(_PATH_BSHELL), cmd);
TEST_COMPARE_STRING (result.err.buffer, returnerr);
free (returnerr);
}
{
struct support_capture_subprocess result;
result = support_capture_subprocess (call_system,
&(struct args) {
"kill $$", 0, SIGTERM
});
support_capture_subprocess_check (&result, "system", 0, sc_allow_none);
}
{
struct support_capture_subprocess result;
result = support_capture_subprocess (call_system,
&(struct args) { "echo ...", 0 });
support_capture_subprocess_check (&result, "system", 0, sc_allow_stdout);
TEST_COMPARE_STRING (result.out.buffer, "...\n");
}
{
struct support_capture_subprocess result;
result = support_capture_subprocess (call_system,
&(struct args) { "exit 1", 1 });
support_capture_subprocess_check (&result, "system", 0, sc_allow_none);
}
{
struct stat64 st;
xstat (_PATH_BSHELL, &st);
mode_t mode = st.st_mode;
xchmod (_PATH_BSHELL, mode & ~(S_IXUSR | S_IXGRP | S_IXOTH));
struct support_capture_subprocess result;
result = support_capture_subprocess (call_system,
&(struct args) {
"exit 1", 127, 0
});
support_capture_subprocess_check (&result, "system", 0, sc_allow_none);
xchmod (_PATH_BSHELL, st.st_mode);
}
{
pthread_t long_sleep_thread = xpthread_create (NULL,
sleep_and_check_sigchld,
&(double) { 0.2 });
pthread_t short_sleep_thread = xpthread_create (NULL,
sleep_and_check_sigchld,
&(double) { 0.1 });
xpthread_join (short_sleep_thread);
xpthread_join (long_sleep_thread);
}
TEST_COMPARE (system (""), 0);
return 0;
}
#include <support/test-driver.c>