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OS X EINVAL compatibility for waitpid

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The return value on OS X is more along the lines of the documented
waitpid behavior; EINVAL is returned if the group no longer exists.
This commit is contained in:
Mahmoud Al-Qudsi 2017-07-29 16:42:06 -05:00 committed by Kurtis Rader
parent 8e63386203
commit 628db65504
2 changed files with 25 additions and 7 deletions
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9
src/exec.cpp
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@ -1163,7 +1163,14 @@ void exec_job(parser_t &parser, job_t *j) {
//but we only need to call set_child_group for the first process in the group.
//If needs_keepalive is set, this has already been called for the keepalive process
pid_t pid_status{};
if (waitpid(p->pid, &pid_status, WUNTRACED) == -1) {
int result;
while ((result = waitpid(p->pid, &pid_status, WUNTRACED)) == -1 && errno == EINTR) {
//This could be a superfluous interrupt or Ctrl+C at the terminal
//In all cases, it is OK to retry since the forking code above is specifically designed
//to never, ever hang/block in a child process before the SIGSTOP call is reached.
continue;
}
if (result == -1) {
exec_error = true;
debug(1, L"waitpid(%d) call in unblock_pid failed:!\n", p->pid);
wperror(L"waitpid");

23
src/proc.cpp
View file

@ -819,22 +819,33 @@ bool terminal_give_to_job(job_t *j, int cont) {
//thing is that we can guarantee the process isn't going to exit while we wait (which would cause us to
//possibly block indefinitely).
auto pgroupTerminated = [&j]() {
//everyone in the process group has exited
//The only way that can happen is if the very last process in the group terminated, and didn't need
//to access the terminal, otherwise it would have hung waiting for terminal IO. We can ignore this.
debug(3, L"terminal_give_to_job(): tcsetpgrp called but process group %d has terminated.\n", j->pgid);
};
while (tcsetpgrp(STDIN_FILENO, j->pgid) != 0) {
if (errno == EINTR) {
//always retry on EINTR
}
else if (errno == EINVAL) {
//OS X returns EINVAL if the process group no longer lives. Probably other OSes, too.
//See comments in pgroupTerminated() above.
pgroupTerminated();
break;
}
else if (errno == EPERM) {
//so long as this isn't because the process group is dead
//retry so long as this isn't because the process group is dead
int wait_result = waitpid(-1 * j->pgid, &wait_result, WNOHANG);
if (wait_result == -1) {
//everyone in the process group has exited
//The only way that can happen is if the very last process in the group terminated, and didn't need
//to access the terminal, otherwise it would have hung waiting for terminal IO. We can ignore this.
//Note that -1 is technically an "error" for waitpid in the sense that an invalid argument was specified
//because no such process group exists any longer.
//because no such process group exists any longer. This is the observed behavior on Linux 4.4.0.
//a "success" result would mean processes from the group still exist but is still running in some state
//or the other.
debug(3, L"terminal_give_to_job(): tcsetpgrp called but process group %d has terminated.\n", j->pgid);
//See comments in pgroupTerminated() above.
pgroupTerminated();
break;
}
debug(2, L"terminal_give_to_job(): EPERM.\n", j->pgid);