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hush: fix "wait PID"

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It was not properly interruptible, and did not update job status
(the exited processes were still thought of as running).

function                                             old     new   delta
process_wait_result                                    -     453    +453
wait_for_child_or_signal                               -     199    +199
run_list                                             996    1002      +6
checkjobs_and_fg_shell                                41      43      +2
builtin_wait                                         328     215    -113
checkjobs                                            516     142    -374
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 2/2 up/down: 660/-487)          Total: 173 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2016-10-28 21:57:31 +02:00
parent 8f7b0248ad
commit 7e6753609d
7 changed files with 246 additions and 174 deletions
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404
shell/hush.c
View File

@ -44,6 +44,8 @@
* special variables (done: PWD, PPID, RANDOM)
* tilde expansion
* aliases
* kill %jobspec
* wait %jobspec
* follow IFS rules more precisely, including update semantics
* builtins mandated by standards we don't support:
* [un]alias, command, fc, getopts, newgrp, readonly, times
@ -7041,16 +7043,134 @@ static void delete_finished_bg_job(struct pipe *pi)
}
#endif /* JOB */
/* Check to see if any processes have exited -- if they
* have, figure out why and see if a job has completed */
static int checkjobs(struct pipe *fg_pipe)
static int process_wait_result(struct pipe *fg_pipe, pid_t childpid, int status)
{
int attributes;
int status;
#if ENABLE_HUSH_JOB
struct pipe *pi;
#endif
pid_t childpid;
int i, dead;
dead = WIFEXITED(status) || WIFSIGNALED(status);
#if DEBUG_JOBS
if (WIFSTOPPED(status))
debug_printf_jobs("pid %d stopped by sig %d (exitcode %d)\n",
childpid, WSTOPSIG(status), WEXITSTATUS(status));
if (WIFSIGNALED(status))
debug_printf_jobs("pid %d killed by sig %d (exitcode %d)\n",
childpid, WTERMSIG(status), WEXITSTATUS(status));
if (WIFEXITED(status))
debug_printf_jobs("pid %d exited, exitcode %d\n",
childpid, WEXITSTATUS(status));
#endif
/* Were we asked to wait for a fg pipe? */
if (fg_pipe) {
i = fg_pipe->num_cmds;
while (--i >= 0) {
debug_printf_jobs("check pid %d\n", fg_pipe->cmds[i].pid);
if (fg_pipe->cmds[i].pid != childpid)
continue;
if (dead) {
int ex;
fg_pipe->cmds[i].pid = 0;
fg_pipe->alive_cmds--;
ex = WEXITSTATUS(status);
/* bash prints killer signal's name for *last*
* process in pipe (prints just newline for SIGINT/SIGPIPE).
* Mimic this. Example: "sleep 5" + (^\ or kill -QUIT)
*/
if (WIFSIGNALED(status)) {
int sig = WTERMSIG(status);
if (i == fg_pipe->num_cmds-1)
/* TODO: use strsignal() instead for bash compat? but that's bloat... */
puts(sig == SIGINT || sig == SIGPIPE ? "" : get_signame(sig));
/* TODO: if (WCOREDUMP(status)) + " (core dumped)"; */
/* TODO: MIPS has 128 sigs (1..128), what if sig==128 here?
* Maybe we need to use sig | 128? */
ex = sig + 128;
}
fg_pipe->cmds[i].cmd_exitcode = ex;
} else {
fg_pipe->stopped_cmds++;
}
debug_printf_jobs("fg_pipe: alive_cmds %d stopped_cmds %d\n",
fg_pipe->alive_cmds, fg_pipe->stopped_cmds);
if (fg_pipe->alive_cmds == fg_pipe->stopped_cmds) {
/* All processes in fg pipe have exited or stopped */
int rcode = 0;
i = fg_pipe->num_cmds;
while (--i >= 0) {
rcode = fg_pipe->cmds[i].cmd_exitcode;
/* usually last process gives overall exitstatus,
* but with "set -o pipefail", last *failed* process does */
if (G.o_opt[OPT_O_PIPEFAIL] == 0 || rcode != 0)
break;
}
IF_HAS_KEYWORDS(if (fg_pipe->pi_inverted) rcode = !rcode;)
/* Note: *non-interactive* bash does not continue if all processes in fg pipe
* are stopped. Testcase: "cat | cat" in a script (not on command line!)
* and "killall -STOP cat" */
if (G_interactive_fd) {
#if ENABLE_HUSH_JOB
if (fg_pipe->alive_cmds != 0)
insert_bg_job(fg_pipe);
#endif
return rcode;
}
if (fg_pipe->alive_cmds == 0)
return rcode;
}
/* There are still running processes in the fg_pipe */
return -1;
}
/* It wasnt in fg_pipe, look for process in bg pipes */
}
#if ENABLE_HUSH_JOB
/* We were asked to wait for bg or orphaned children */
/* No need to remember exitcode in this case */
for (pi = G.job_list; pi; pi = pi->next) {
for (i = 0; i < pi->num_cmds; i++) {
if (pi->cmds[i].pid == childpid)
goto found_pi_and_prognum;
}
}
/* Happens when shell is used as init process (init=/bin/sh) */
debug_printf("checkjobs: pid %d was not in our list!\n", childpid);
return -1; /* this wasn't a process from fg_pipe */
found_pi_and_prognum:
if (dead) {
/* child exited */
pi->cmds[i].pid = 0;
pi->cmds[i].cmd_exitcode = WEXITSTATUS(status);
if (WIFSIGNALED(status))
pi->cmds[i].cmd_exitcode = 128 + WTERMSIG(status);
pi->alive_cmds--;
if (!pi->alive_cmds) {
if (G_interactive_fd)
printf(JOB_STATUS_FORMAT, pi->jobid,
"Done", pi->cmdtext);
delete_finished_bg_job(pi);
}
} else {
/* child stopped */
pi->stopped_cmds++;
}
#endif
return -1; /* this wasn't a process from fg_pipe */
}
/* Check to see if any processes have exited -- if they have,
* figure out why and see if a job has completed.
* Alternatively (fg_pipe == NULL, waitfor_pid != 0),
* wait for a specific pid to complete, return exitcode+1
* (this allows to distinguish zero as "no children exited" result).
*/
static int checkjobs(struct pipe *fg_pipe, pid_t waitfor_pid)
{
int attributes;
int status;
int rcode = 0;
debug_printf_jobs("checkjobs %p\n", fg_pipe);
@ -7087,12 +7207,10 @@ static int checkjobs(struct pipe *fg_pipe)
* 1 <========== bg pipe is not fully done, but exitcode is already known!
* [hush 1.14.0: yes we do it right]
*/
wait_more:
while (1) {
int i;
int dead;
pid_t childpid;
#if ENABLE_HUSH_FAST
int i;
i = G.count_SIGCHLD;
#endif
childpid = waitpid(-1, &status, attributes);
@ -7106,112 +7224,24 @@ static int checkjobs(struct pipe *fg_pipe)
//bb_error_msg("[%d] checkjobs: waitpid returned <= 0, G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
}
#endif
/* ECHILD (no children), or 0 (no change in children status) */
rcode = childpid;
break;
}
dead = WIFEXITED(status) || WIFSIGNALED(status);
#if DEBUG_JOBS
if (WIFSTOPPED(status))
debug_printf_jobs("pid %d stopped by sig %d (exitcode %d)\n",
childpid, WSTOPSIG(status), WEXITSTATUS(status));
if (WIFSIGNALED(status))
debug_printf_jobs("pid %d killed by sig %d (exitcode %d)\n",
childpid, WTERMSIG(status), WEXITSTATUS(status));
if (WIFEXITED(status))
debug_printf_jobs("pid %d exited, exitcode %d\n",
childpid, WEXITSTATUS(status));
#endif
/* Were we asked to wait for fg pipe? */
if (fg_pipe) {
i = fg_pipe->num_cmds;
while (--i >= 0) {
debug_printf_jobs("check pid %d\n", fg_pipe->cmds[i].pid);
if (fg_pipe->cmds[i].pid != childpid)
continue;
if (dead) {
int ex;
fg_pipe->cmds[i].pid = 0;
fg_pipe->alive_cmds--;
ex = WEXITSTATUS(status);
/* bash prints killer signal's name for *last*
* process in pipe (prints just newline for SIGINT/SIGPIPE).
* Mimic this. Example: "sleep 5" + (^\ or kill -QUIT)
*/
if (WIFSIGNALED(status)) {
int sig = WTERMSIG(status);
if (i == fg_pipe->num_cmds-1)
/* TODO: use strsignal() instead for bash compat? but that's bloat... */
puts(sig == SIGINT || sig == SIGPIPE ? "" : get_signame(sig));
/* TODO: if (WCOREDUMP(status)) + " (core dumped)"; */
/* TODO: MIPS has 128 sigs (1..128), what if sig==128 here?
* Maybe we need to use sig | 128? */
ex = sig + 128;
}
fg_pipe->cmds[i].cmd_exitcode = ex;
} else {
fg_pipe->stopped_cmds++;
}
debug_printf_jobs("fg_pipe: alive_cmds %d stopped_cmds %d\n",
fg_pipe->alive_cmds, fg_pipe->stopped_cmds);
if (fg_pipe->alive_cmds == fg_pipe->stopped_cmds) {
/* All processes in fg pipe have exited or stopped */
i = fg_pipe->num_cmds;
while (--i >= 0) {
rcode = fg_pipe->cmds[i].cmd_exitcode;
/* usually last process gives overall exitstatus,
* but with "set -o pipefail", last *failed* process does */
if (G.o_opt[OPT_O_PIPEFAIL] == 0 || rcode != 0)
break;
}
IF_HAS_KEYWORDS(if (fg_pipe->pi_inverted) rcode = !rcode;)
/* Note: *non-interactive* bash does not continue if all processes in fg pipe
* are stopped. Testcase: "cat | cat" in a script (not on command line!)
* and "killall -STOP cat" */
if (G_interactive_fd) {
#if ENABLE_HUSH_JOB
if (fg_pipe->alive_cmds != 0)
insert_bg_job(fg_pipe);
#endif
return rcode;
}
if (fg_pipe->alive_cmds == 0)
return rcode;
}
/* There are still running processes in the fg pipe */
goto wait_more; /* do waitpid again */
}
/* it wasnt fg_pipe, look for process in bg pipes */
rcode = process_wait_result(fg_pipe, childpid, status);
if (rcode >= 0) {
/* fg_pipe exited or stopped */
break;
}
#if ENABLE_HUSH_JOB
/* We asked to wait for bg or orphaned children */
/* No need to remember exitcode in this case */
for (pi = G.job_list; pi; pi = pi->next) {
for (i = 0; i < pi->num_cmds; i++) {
if (pi->cmds[i].pid == childpid)
goto found_pi_and_prognum;
}
if (childpid == waitfor_pid) {
rcode = WEXITSTATUS(status);
if (WIFSIGNALED(status))
rcode = 128 + WTERMSIG(status);
rcode++;
break; /* "wait PID" called us, give it exitcode+1 */
}
/* Happens when shell is used as init process (init=/bin/sh) */
debug_printf("checkjobs: pid %d was not in our list!\n", childpid);
continue; /* do waitpid again */
found_pi_and_prognum:
if (dead) {
/* child exited */
pi->cmds[i].pid = 0;
pi->alive_cmds--;
if (!pi->alive_cmds) {
if (G_interactive_fd)
printf(JOB_STATUS_FORMAT, pi->jobid,
"Done", pi->cmdtext);
delete_finished_bg_job(pi);
}
} else {
/* child stopped */
pi->stopped_cmds++;
}
#endif
/* This wasn't one of our processes, or */
/* fg_pipe still has running processes, do waitpid again */
} /* while (waitpid succeeds)... */
return rcode;
@ -7221,7 +7251,7 @@ static int checkjobs(struct pipe *fg_pipe)
static int checkjobs_and_fg_shell(struct pipe *fg_pipe)
{
pid_t p;
int rcode = checkjobs(fg_pipe);
int rcode = checkjobs(fg_pipe, 0 /*(no pid to wait for)*/);
if (G_saved_tty_pgrp) {
/* Job finished, move the shell to the foreground */
p = getpgrp(); /* our process group id */
@ -7893,7 +7923,7 @@ static int run_list(struct pipe *pi)
/* else: e.g. "continue 2" should *break* once, *then* continue */
} /* else: "while... do... { we are here (innermost list is not a loop!) };...done" */
if (G.depth_break_continue != 0 || fbc == BC_BREAK) {
checkjobs(NULL);
checkjobs(NULL, 0 /*(no pid to wait for)*/);
break;
}
/* "continue": simulate end of loop */
@ -7902,7 +7932,7 @@ static int run_list(struct pipe *pi)
}
#endif
if (G_flag_return_in_progress == 1) {
checkjobs(NULL);
checkjobs(NULL, 0 /*(no pid to wait for)*/);
break;
}
} else if (pi->followup == PIPE_BG) {
@ -7929,7 +7959,7 @@ static int run_list(struct pipe *pi)
} else
#endif
{ /* This one just waits for completion */
rcode = checkjobs(pi);
rcode = checkjobs(pi, 0 /*(no pid to wait for)*/);
debug_printf_exec(": checkjobs exitcode %d\n", rcode);
check_and_run_traps();
}
@ -7943,7 +7973,7 @@ static int run_list(struct pipe *pi)
cond_code = rcode;
#endif
check_jobs_and_continue:
checkjobs(NULL);
checkjobs(NULL, 0 /*(no pid to wait for)*/);
dont_check_jobs_but_continue: ;
#if ENABLE_HUSH_LOOPS
/* Beware of "while false; true; do ..."! */
@ -9408,9 +9438,68 @@ static int FAST_FUNC builtin_umask(char **argv)
}
/* http://www.opengroup.org/onlinepubs/9699919799/utilities/wait.html */
static int wait_for_child_or_signal(pid_t waitfor_pid)
{
int ret = 0;
for (;;) {
int sig;
sigset_t oldset, allsigs;
/* waitpid is not interruptible by SA_RESTARTed
* signals which we use. Thus, this ugly dance:
*/
/* Make sure possible SIGCHLD is stored in kernel's
* pending signal mask before we call waitpid.
* Or else we may race with SIGCHLD, lose it,
* and get stuck in sigwaitinfo...
*/
sigfillset(&allsigs);
sigprocmask(SIG_SETMASK, &allsigs, &oldset);
if (!sigisemptyset(&G.pending_set)) {
/* Crap! we raced with some signal! */
// sig = 0;
goto restore;
}
/*errno = 0; - checkjobs does this */
ret = checkjobs(NULL, waitfor_pid); /* waitpid(WNOHANG) inside */
/* if ECHILD, there are no children (ret is -1 or 0) */
/* if ret == 0, no children changed state */
/* if ret != 0, it's exitcode+1 of exited waitfor_pid child */
if (errno == ECHILD || ret--) {
if (ret < 0) /* if ECHILD, may need to fix */
ret = 0;
sigprocmask(SIG_SETMASK, &oldset, NULL);
break;
}
/* Wait for SIGCHLD or any other signal */
//sig = sigwaitinfo(&allsigs, NULL);
/* It is vitally important for sigsuspend that SIGCHLD has non-DFL handler! */
/* Note: sigsuspend invokes signal handler */
sigsuspend(&oldset);
restore:
sigprocmask(SIG_SETMASK, &oldset, NULL);
/* So, did we get a signal? */
//if (sig > 0)
// raise(sig); /* run handler */
sig = check_and_run_traps();
if (sig /*&& sig != SIGCHLD - always true */) {
/* see note 2 */
ret = 128 + sig;
break;
}
/* SIGCHLD, or no signal, or ignored one, such as SIGQUIT. Repeat */
}
return ret;
}
static int FAST_FUNC builtin_wait(char **argv)
{
int ret = EXIT_SUCCESS;
int ret;
int status;
argv = skip_dash_dash(argv);
@ -9431,74 +9520,41 @@ static int FAST_FUNC builtin_wait(char **argv)
* ^C <-- after ~4 sec from keyboard
* $
*/
while (1) {
int sig;
sigset_t oldset, allsigs;
/* waitpid is not interruptible by SA_RESTARTed
* signals which we use. Thus, this ugly dance:
*/
/* Make sure possible SIGCHLD is stored in kernel's
* pending signal mask before we call waitpid.
* Or else we may race with SIGCHLD, lose it,
* and get stuck in sigwaitinfo...
*/
sigfillset(&allsigs);
sigprocmask(SIG_SETMASK, &allsigs, &oldset);
if (!sigisemptyset(&G.pending_set)) {
/* Crap! we raced with some signal! */
// sig = 0;
goto restore;
}
checkjobs(NULL); /* waitpid(WNOHANG) inside */
if (errno == ECHILD) {
sigprocmask(SIG_SETMASK, &oldset, NULL);
break;
}
/* Wait for SIGCHLD or any other signal */
//sig = sigwaitinfo(&allsigs, NULL);
/* It is vitally important for sigsuspend that SIGCHLD has non-DFL handler! */
/* Note: sigsuspend invokes signal handler */
sigsuspend(&oldset);
restore:
sigprocmask(SIG_SETMASK, &oldset, NULL);
/* So, did we get a signal? */
//if (sig > 0)
// raise(sig); /* run handler */
sig = check_and_run_traps();
if (sig /*&& sig != SIGCHLD - always true */) {
/* see note 2 */
ret = 128 + sig;
break;
}
/* SIGCHLD, or no signal, or ignored one, such as SIGQUIT. Repeat */
}
return ret;
return wait_for_child_or_signal(0 /*(no pid to wait for)*/);
}
/* This is probably buggy wrt interruptible-ness */
while (*argv) {
/* TODO: support "wait %jobspec" */
do {
pid_t pid = bb_strtou(*argv, NULL, 10);
if (errno) {
if (errno || pid <= 0) {
/* mimic bash message */
bb_error_msg("wait: '%s': not a pid or valid job spec", *argv);
return EXIT_FAILURE;
}
if (waitpid(pid, &status, 0) == pid) {
/* Do we have such child? */
ret = waitpid(pid, &status, WNOHANG);
if (ret < 0) {
/* No */
if (errno == ECHILD) {
/* Example: "wait 1". mimic bash message */
bb_error_msg("wait: pid %d is not a child of this shell", (int)pid);
} else {
/* ??? */
bb_perror_msg("wait %s", *argv);
}
ret = 127;
} else if (ret == 0) {
/* Yes, and it still runs */
ret = wait_for_child_or_signal(pid);
} else {
/* Yes, and it just exited */
process_wait_result(NULL, pid, status);
ret = WEXITSTATUS(status);
if (WIFSIGNALED(status))
ret = 128 + WTERMSIG(status);
} else {
bb_perror_msg("wait %s", *argv);
ret = 127;
}
argv++;
}
} while (*argv);
return ret;
}

2
shell/hush_test/hush-misc/wait1.right Normal file
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@ -0,0 +1,2 @@
0
[1] Running sleep 2

3
shell/hush_test/hush-misc/wait1.tests Executable file
View File

@ -0,0 +1,3 @@
sleep 2 & sleep 1 & wait $!
echo $?
jobs

2
shell/hush_test/hush-misc/wait2.right Normal file
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@ -0,0 +1,2 @@
0
[1] Running sleep 3

4
shell/hush_test/hush-misc/wait2.tests Executable file
View File

@ -0,0 +1,4 @@
sleep 3 & sleep 2 & sleep 1
wait $!
echo $?
jobs

2
shell/hush_test/hush-misc/wait3.right Normal file
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@ -0,0 +1,2 @@
3
[1] Running sleep 2

3
shell/hush_test/hush-misc/wait3.tests Executable file
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@ -0,0 +1,3 @@
sleep 2 & (sleep 1;exit 3) & wait $!
echo $?
jobs