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Guard against pgid == 0

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This happens in firejail, and it means that we can't use it as an
argument to most pgid-taking functions.

E.g. `wait(0)` means to wait for the _current_ process group,
`tcsetpgrp(0)` doesn't work etc.

So we just stop doing this stuff and hope it works.

Fixes #5295.
This commit is contained in:
Fabian Homborg
2018-11-13 18:39:53 +01:00
parent 46db332be5
commit 0a0060481f
2 changed files with 12 additions and 7 deletions
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2
src/postfork.cpp
View File

@@ -158,8 +158,6 @@ bool set_child_group(job_t *j, pid_t child_pid) {
}
bool maybe_assign_terminal(const job_t *j) {
assert(j->pgid > 1 && "maybe_assign_terminal() called on job with invalid pgid!");
if (j->get_flag(job_flag_t::TERMINAL) && j->is_foreground()) { //!OCLINT(early exit)
if (tcgetpgrp(STDIN_FILENO) == j->pgid) {
// We've already assigned the process group control of the terminal when the first

17
src/proc.cpp
View File

@@ -442,7 +442,9 @@ static bool process_mark_finished_children(bool block_on_fg) {
options &= ~WNOHANG;
}
bool wait_by_process = !j->job_chain_is_fully_constructed();
// If the pgid is 0, we need to wait by process because that's invalid.
// This happens in firejail for reasons not entirely clear to me.
bool wait_by_process = !j->job_chain_is_fully_constructed() || j->pgid == 0;
process_list_t::iterator process = j->processes.begin();
// waitpid(2) returns 1 process each time, we need to keep calling it until we've reaped all
// children of the pgrp in question or else we can't reset the dirty_state flag. In all
@@ -975,10 +977,15 @@ bool terminal_give_to_job(const job_t *j, bool restore_attrs) {
}
pid_t terminal_acquire_before_builtin(int job_pgid) {
pid_t selfpid = getpid();
pid_t selfpgid = getpgrp();
if (selfpgid == 0) {
debug(2, L"Not acquiring terminal because we don't have a valid pgroup");
return -1;
}
pid_t current_owner = tcgetpgrp(STDIN_FILENO);
if (current_owner >= 0 && current_owner != selfpid && current_owner == job_pgid) {
if (tcsetpgrp(STDIN_FILENO, selfpid) == 0) {
if (current_owner >= 0 && current_owner != selfpgid && current_owner == job_pgid) {
if (tcsetpgrp(STDIN_FILENO, selfpgid) == 0) {
return current_owner;
}
}
@@ -989,7 +996,7 @@ pid_t terminal_acquire_before_builtin(int job_pgid) {
/// so that we can restore the terminal ownership to the job at a later time.
static bool terminal_return_from_job(job_t *j) {
errno = 0;
if (j->pgid == 0) {
if (j->pgid == 0 || getpgrp() == 0) {
debug(2, "terminal_return_from_job() returning early due to no process group");
return true;
}