[git commit] hush: implement "wait %jobspec"
Denys Vlasenko
vda.linux at googlemail.com
Mon Nov 7 21:12:18 UTC 2016
commit: https://git.busybox.net/busybox/commit/?id=62b717b75ebff3ab00aae2fee0087a8106208a39
branch: https://git.busybox.net/busybox/commit/?id=refs/heads/master
function old new delta
parse_jobspec - 83 +83
job_exited_or_stopped - 79 +79
builtin_wait 236 302 +66
wait_for_child_or_signal 199 228 +29
checkjobs 142 158 +16
builtin_jobs 59 68 +9
process_wait_result 453 408 -45
builtin_fg_bg 272 203 -69
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 4/2 up/down: 282/-114) Total: 168 bytes
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
shell/hush.c | 117 ++++++++++++++++++++++++++++++++++++++++++++---------------
1 file changed, 88 insertions(+), 29 deletions(-)
diff --git a/shell/hush.c b/shell/hush.c
index 3b87d28..b842d6e 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -45,7 +45,6 @@
* 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
@@ -7065,6 +7064,27 @@ static void delete_finished_bg_job(struct pipe *pi)
}
#endif /* JOB */
+static int job_exited_or_stopped(struct pipe *pi)
+{
+ int rcode, i;
+
+ if (pi->alive_cmds != pi->stopped_cmds)
+ return -1;
+
+ /* All processes in fg pipe have exited or stopped */
+ rcode = 0;
+ i = pi->num_cmds;
+ while (--i >= 0) {
+ rcode = pi->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 (pi->pi_inverted) rcode = !rcode;)
+ return rcode;
+}
+
static int process_wait_result(struct pipe *fg_pipe, pid_t childpid, int status)
{
#if ENABLE_HUSH_JOB
@@ -7088,7 +7108,10 @@ static int process_wait_result(struct pipe *fg_pipe, pid_t childpid, int status)
/* Were we asked to wait for a fg pipe? */
if (fg_pipe) {
i = fg_pipe->num_cmds;
+
while (--i >= 0) {
+ int rcode;
+
debug_printf_jobs("check pid %d\n", fg_pipe->cmds[i].pid);
if (fg_pipe->cmds[i].pid != childpid)
continue;
@@ -7117,18 +7140,8 @@ static int process_wait_result(struct pipe *fg_pipe, pid_t childpid, int status)
}
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;)
+ rcode = job_exited_or_stopped(fg_pipe);
+ if (rcode >= 0) {
/* 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" */
@@ -7185,9 +7198,18 @@ static int process_wait_result(struct pipe *fg_pipe, pid_t childpid, int status)
/* 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).
+ *
+ * If non-NULL fg_pipe: wait for its completion or stop.
+ * Return its exitcode or zero if stopped.
+ *
+ * Alternatively (fg_pipe == NULL, waitfor_pid != 0):
+ * waitpid(WNOHANG), if waitfor_pid exits or stops, return exitcode+1,
+ * else return <0 if waitpid errors out (e.g. ECHILD: nothing to wait for)
+ * or 0 if no children changed status.
+ *
+ * Alternatively (fg_pipe == NULL, waitfor_pid == 0),
+ * return <0 if waitpid errors out (e.g. ECHILD: nothing to wait for)
+ * or 0 if no children changed status.
*/
static int checkjobs(struct pipe *fg_pipe, pid_t waitfor_pid)
{
@@ -7256,9 +7278,13 @@ static int checkjobs(struct pipe *fg_pipe, pid_t waitfor_pid)
break;
}
if (childpid == waitfor_pid) {
+ debug_printf_exec("childpid==waitfor_pid:%d status:0x%08x\n", childpid, status);
rcode = WEXITSTATUS(status);
if (WIFSIGNALED(status))
rcode = 128 + WTERMSIG(status);
+ if (WIFSTOPPED(status))
+ /* bash: "cmd & wait $!" and cmd stops: $? = 128 + stopsig */
+ rcode = 128 + WSTOPSIG(status);
rcode++;
break; /* "wait PID" called us, give it exitcode+1 */
}
@@ -9329,6 +9355,7 @@ static int FAST_FUNC builtin_jobs(char **argv UNUSED_PARAM)
struct pipe *job;
const char *status_string;
+ checkjobs(NULL, 0 /*(no pid to wait for)*/);
for (job = G.job_list; job; job = job->next) {
if (job->alive_cmds == job->stopped_cmds)
status_string = "Stopped";
@@ -9481,12 +9508,15 @@ 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)
+#if !ENABLE_HUSH_JOB
+# define wait_for_child_or_signal(pipe,pid) wait_for_child_or_signal(pid)
+#endif
+static int wait_for_child_or_signal(struct pipe *waitfor_pipe, pid_t waitfor_pid)
{
int ret = 0;
for (;;) {
int sig;
- sigset_t oldset, allsigs;
+ sigset_t oldset;
/* waitpid is not interruptible by SA_RESTARTed
* signals which we use. Thus, this ugly dance:
@@ -9495,10 +9525,10 @@ static int wait_for_child_or_signal(pid_t waitfor_pid)
/* 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...
+ * and get stuck in sigsuspend...
*/
- sigfillset(&allsigs);
- sigprocmask(SIG_SETMASK, &allsigs, &oldset);
+ sigfillset(&oldset); /* block all signals, remember old set */
+ sigprocmask(SIG_SETMASK, &oldset, &oldset);
if (!sigisemptyset(&G.pending_set)) {
/* Crap! we raced with some signal! */
@@ -9507,19 +9537,31 @@ static int wait_for_child_or_signal(pid_t waitfor_pid)
}
/*errno = 0; - checkjobs does this */
+/* Can't pass waitfor_pipe into checkjobs(): it won't be interruptible */
ret = checkjobs(NULL, waitfor_pid); /* waitpid(WNOHANG) inside */
+ debug_printf_exec("checkjobs:%d\n", ret);
+#if ENABLE_HUSH_JOB
+ if (waitfor_pipe) {
+ int rcode = job_exited_or_stopped(waitfor_pipe);
+ debug_printf_exec("job_exited_or_stopped:%d\n", rcode);
+ if (rcode >= 0) {
+ ret = rcode;
+ sigprocmask(SIG_SETMASK, &oldset, NULL);
+ break;
+ }
+ }
+#endif
/* 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 */
+ if (errno == ECHILD || ret) {
+ ret--;
+ if (ret < 0) /* if ECHILD, may need to fix "ret" */
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);
@@ -9544,6 +9586,7 @@ static int FAST_FUNC builtin_wait(char **argv)
{
int ret;
int status;
+ struct pipe *wait_pipe = NULL;
argv = skip_dash_dash(argv);
if (argv[0] == NULL) {
@@ -9563,18 +9606,27 @@ static int FAST_FUNC builtin_wait(char **argv)
* ^C <-- after ~4 sec from keyboard
* $
*/
- return wait_for_child_or_signal(0 /*(no pid to wait for)*/);
+ return wait_for_child_or_signal(NULL, 0 /*(no job and no pid to wait for)*/);
}
- /* TODO: support "wait %jobspec" */
do {
pid_t pid = bb_strtou(*argv, NULL, 10);
if (errno || pid <= 0) {
+#if ENABLE_HUSH_JOB
+ if (argv[0][0] == '%') {
+ wait_pipe = parse_jobspec(*argv);
+ if (wait_pipe) {
+ pid = - wait_pipe->pgrp;
+ goto do_wait;
+ }
+ }
+#endif
/* mimic bash message */
bb_error_msg("wait: '%s': not a pid or valid job spec", *argv);
ret = EXIT_FAILURE;
continue; /* bash checks all argv[] */
}
+ IF_HUSH_JOB(do_wait:)
/* Do we have such child? */
ret = waitpid(pid, &status, WNOHANG);
if (ret < 0) {
@@ -9599,13 +9651,20 @@ static int FAST_FUNC builtin_wait(char **argv)
}
if (ret == 0) {
/* Yes, and it still runs */
- ret = wait_for_child_or_signal(pid);
+ ret = wait_for_child_or_signal(wait_pipe, wait_pipe ? 0 : pid);
} else {
/* Yes, and it just exited */
- process_wait_result(NULL, pid, status);
+ process_wait_result(NULL, ret, status);
ret = WEXITSTATUS(status);
if (WIFSIGNALED(status))
ret = 128 + WTERMSIG(status);
+#if ENABLE_HUSH_JOB
+ if (wait_pipe) {
+ ret = job_exited_or_stopped(wait_pipe);
+ if (ret < 0)
+ goto do_wait;
+ }
+#endif
}
} while (*++argv);
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