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Kill builds when we get EOF on the log FD

Browse source 
This closes a long-time bug that allowed builds to hang Nix
indefinitely (regardless of timeouts) simply by doing

  exec > /dev/null 2>&1; while true; do true; done

Now, on EOF, we just send SIGKILL to the child to make sure it's
really gone.
This commit is contained in:
Eelco Dolstra 2017-01-19 16:58:39 +01:00
parent 63e10b4d28
commit 21948deed9
No known key found for this signature in database
GPG key ID: 8170B4726D7198DE
6 changed files with 40 additions and 40 deletions
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33
src/libutil/util.cc
View file

@ -648,26 +648,25 @@ void Pipe::create()
Pid::Pid()
: pid(-1), separatePG(false), killSignal(SIGKILL)
{
}
Pid::Pid(pid_t pid)
: pid(pid), separatePG(false), killSignal(SIGKILL)
: pid(pid)
{
}
Pid::~Pid()
{
kill();
if (pid != -1) kill();
}
void Pid::operator =(pid_t pid)
{
if (this->pid != pid) kill();
if (this->pid != -1 && this->pid != pid) kill();
this->pid = pid;
killSignal = SIGKILL; // reset signal to default
}
@ -679,9 +678,9 @@ Pid::operator pid_t()
}
void Pid::kill(bool quiet)
int Pid::kill(bool quiet)
{
if (pid == -1 || pid == 0) return;
assert(pid != -1);
if (!quiet)
printError(format("killing process %1%") % pid);
@ -692,32 +691,20 @@ void Pid::kill(bool quiet)
if (::kill(separatePG ? -pid : pid, killSignal) != 0)
printError((SysError(format("killing process %1%") % pid).msg()));
/* Wait until the child dies, disregarding the exit status. */
int status;
while (waitpid(pid, &status, 0) == -1) {
checkInterrupt();
if (errno != EINTR) {
printError(
(SysError(format("waiting for process %1%") % pid).msg()));
break;
}
}
pid = -1;
return wait();
}
int Pid::wait(bool block)
int Pid::wait()
{
assert(pid != -1);
while (1) {
int status;
int res = waitpid(pid, &status, block ? 0 : WNOHANG);
int res = waitpid(pid, &status, 0);
if (res == pid) {
pid = -1;
return status;
}
if (res == 0 && !block) return -1;
if (errno != EINTR)
throw SysError("cannot get child exit status");
checkInterrupt();
@ -782,7 +769,7 @@ void killUser(uid_t uid)
_exit(0);
}, options);
int status = pid.wait(true);
int status = pid.wait();
if (status != 0)
throw Error(format("cannot kill processes for uid ‘%1%’: %2%") % uid % statusToString(status));
@ -893,7 +880,7 @@ string runProgram(Path program, bool searchPath, const Strings & args,
string result = drainFD(out.readSide.get());
/* Wait for the child to finish. */
int status = pid.wait(true);
int status = pid.wait();
if (!statusOk(status))
throw ExecError(status, format("program ‘%1%’ %2%")
% program % statusToString(status));