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commit 567f7413fb1179acd936766b542ea72f7ef60d8b
Author: Adam Yi <ayi@janestreet.com>
Date: Tue Mar 7 07:30:02 2023 -0500
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
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.
Signed-off-by: Adam Yi <ayi@janestreet.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
(cherry picked from commit 436a604b7dc741fc76b5a6704c6cd8bb178518e7)
diff --git a/stdlib/tst-system.c b/stdlib/tst-system.c
index 178808e048a9b3bc..d1413d7c6a4cb82c 100644
--- a/stdlib/tst-system.c
+++ b/stdlib/tst-system.c
@@ -26,6 +26,7 @@
#include <support/check.h>
#include <support/temp_file.h>
#include <support/support.h>
+#include <support/xthread.h>
#include <support/xunistd.h>
static char *tmpdir;
@@ -72,6 +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)
{
@@ -155,6 +170,17 @@ do_test (void)
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;
diff --git a/support/Makefile b/support/Makefile
index 0aa9d41c5a890087..e7f66920f1abbb48 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 0000000000000000..b3d5e351e3a631ac
--- /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
+ <https://www.gnu.org/licenses/>. */
+
+#include <time.h>
+
+#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 0000000000000000..cde5b4d74cba1932
--- /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
+ <https://www.gnu.org/licenses/>. */
+
+/* Convert the double value SEC to a struct timespec. Round toward
+ positive infinity. On overflow, return an extremal value. */
+
+#include <support/timespec.h>
+#include <intprops.h>
+
+struct timespec
+dtotimespec (double sec)
+{
+ if (sec <= TYPE_MINIMUM (time_t))
+ 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 b2a4324dc7444be5..6fe925dc49075848 100644
--- a/support/shell-container.c
+++ b/support/shell-container.c
@@ -39,6 +39,7 @@
#include <error.h>
#include <support/support.h>
+#include <support/timespec.h>
/* Design considerations
@@ -171,6 +172,32 @@ kill_func (char **argv)
return 0;
}
+/* Emulate the "/bin/sleep" command. No suffix support. Options are
+ ignored. */
+static int
+sleep_func (char **argv)
+{
+ if (argv[0] == NULL)
+ {
+ fprintf (stderr, "sleep: missing operand\n");
+ return 1;
+ }
+ char *endptr = NULL;
+ double sec = strtod (argv[0], &endptr);
+ if (endptr == argv[0] || errno == ERANGE || sec < 0)
+ {
+ fprintf (stderr, "sleep: invalid time interval '%s'\n", argv[0]);
+ return 1;
+ }
+ struct timespec ts = dtotimespec (sec);
+ if (nanosleep (&ts, NULL) < 0)
+ {
+ fprintf (stderr, "sleep: failed to nanosleep: %s\n", strerror (errno));
+ return 1;
+ }
+ return 0;
+}
+
/* This is a list of all the built-in commands we understand. */
static struct {
const char *name;
@@ -181,6 +208,7 @@ 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 0478aef51fdcc5ae..843a90d60675f37d 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 48668fb392e67d1a..b9676abb1c6f35eb 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);