forked from rpms/glibc
145 lines
4.3 KiB
Diff
145 lines
4.3 KiB
Diff
From 436a604b7dc741fc76b5a6704c6cd8bb178518e7 Mon Sep 17 00:00:00 2001
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From: Adam Yi <ayi@janestreet.com>
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Date: Tue, 7 Mar 2023 07:30:02 -0500
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Subject: posix: Fix system blocks SIGCHLD erroneously [BZ #30163]
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Fix bug that SIGCHLD is erroneously blocked forever in the following
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scenario:
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1. Thread A calls system but hasn't returned yet
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2. Thread B calls another system but returns
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SIGCHLD would be blocked forever in thread B after its system() returns,
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even after the system() in thread A returns.
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Although POSIX does not require, glibc system implementation aims to be
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thread and cancellation safe. This bug was introduced in
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5fb7fc96350575c9adb1316833e48ca11553be49 when we moved reverting signal
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mask to happen when the last concurrently running system returns,
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despite that signal mask is per thread. This commit reverts this logic
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and adds a test.
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Signed-off-by: Adam Yi <ayi@janestreet.com>
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Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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[DJ: Edited to use integer sleep() instead of nanosleep() dependency rabbit hole]
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diff --git a/stdlib/tst-system.c b/stdlib/tst-system.c
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index 634acfe264..47a0afe6bf 100644
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--- a/stdlib/tst-system.c
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+++ b/stdlib/tst-system.c
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@@ -25,6 +25,7 @@
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#include <support/check.h>
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#include <support/temp_file.h>
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#include <support/support.h>
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+#include <support/xthread.h>
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#include <support/xunistd.h>
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static char *tmpdir;
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@@ -71,6 +72,20 @@ call_system (void *closure)
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}
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}
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+static void *
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+sleep_and_check_sigchld (void *closure)
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+{
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+ double *seconds = (double *) closure;
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+ char cmd[namemax];
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+ sprintf (cmd, "sleep %lf" , *seconds);
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+ TEST_COMPARE (system (cmd), 0);
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+
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+ sigset_t blocked = {0};
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+ TEST_COMPARE (sigprocmask (SIG_BLOCK, NULL, &blocked), 0);
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+ TEST_COMPARE (sigismember (&blocked, SIGCHLD), 0);
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+ return NULL;
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+}
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+
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static int
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do_test (void)
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{
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@@ -154,6 +169,17 @@ do_test (void)
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xchmod (_PATH_BSHELL, st.st_mode);
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}
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+ {
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+ pthread_t long_sleep_thread = xpthread_create (NULL,
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+ sleep_and_check_sigchld,
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+ &(double) { 2 });
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+ pthread_t short_sleep_thread = xpthread_create (NULL,
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+ sleep_and_check_sigchld,
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+ &(double) { 1 });
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+ xpthread_join (short_sleep_thread);
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+ xpthread_join (long_sleep_thread);
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+ }
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+
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TEST_COMPARE (system (""), 0);
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return 0;
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diff --git a/support/shell-container.c b/support/shell-container.c
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index ffa3378b5e..b1f9e793c1 100644
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--- a/support/shell-container.c
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+++ b/support/shell-container.c
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@@ -169,6 +170,31 @@ kill_func (char **argv)
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return 0;
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}
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+/* Emulate the "/bin/sleep" command. No suffix support. Options are
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+ ignored. */
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+static int
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+sleep_func (char **argv)
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+{
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+ if (argv[0] == NULL)
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+ {
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+ fprintf (stderr, "sleep: missing operand\n");
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+ return 1;
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+ }
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+ char *endptr = NULL;
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+ long sec = strtol (argv[0], &endptr, 0);
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+ if (endptr == argv[0] || errno == ERANGE || sec < 0)
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+ {
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+ fprintf (stderr, "sleep: invalid time interval '%s'\n", argv[0]);
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+ return 1;
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+ }
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+ if (sleep (sec) < 0)
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+ {
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+ fprintf (stderr, "sleep: failed to nanosleep\n");
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+ return 1;
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+ }
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+ return 0;
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+}
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+
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/* This is a list of all the built-in commands we understand. */
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static struct {
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const char *name;
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@@ -179,6 +206,7 @@ static struct {
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{ "cp", copy_func },
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{ "exit", exit_func },
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{ "kill", kill_func },
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+ { "sleep", sleep_func },
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{ NULL, NULL }
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};
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diff --git a/sysdeps/posix/system.c b/sysdeps/posix/system.c
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index 2335a99184..d77720a625 100644
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--- a/sysdeps/posix/system.c
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+++ b/sysdeps/posix/system.c
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@@ -179,16 +179,16 @@ do_system (const char *line)
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as if the shell had terminated using _exit(127). */
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status = W_EXITCODE (127, 0);
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+ /* sigaction can not fail with SIGINT/SIGQUIT used with old
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+ disposition. Same applies for sigprocmask. */
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DO_LOCK ();
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if (SUB_REF () == 0)
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{
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- /* sigaction can not fail with SIGINT/SIGQUIT used with old
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- disposition. Same applies for sigprocmask. */
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__sigaction (SIGINT, &intr, NULL);
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__sigaction (SIGQUIT, &quit, NULL);
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- __sigprocmask (SIG_SETMASK, &omask, NULL);
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}
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DO_UNLOCK ();
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+ __sigprocmask (SIG_SETMASK, &omask, NULL);
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if (ret != 0)
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__set_errno (ret);
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