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Restore default signal handling in child processes

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In particular, this fixes Ctrl-C in nix-shell sessions.
This commit is contained in:
Eelco Dolstra 2017-02-01 13:00:21 +01:00
parent 583ff4ec46
commit 7a65b2470e
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GPG key ID: 8170B4726D7198DE
7 changed files with 33 additions and 35 deletions
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24
src/libutil/util.cc
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@ -860,6 +860,8 @@ string runProgram(Path program, bool searchPath, const Strings & args,
Strings args_(args);
args_.push_front(program);
restoreSignals();
if (searchPath)
execvp(program.c_str(), stringsToCharPtrs(args_).data());
else
@ -909,16 +911,6 @@ void closeOnExec(int fd)
}
void restoreSIGPIPE()
{
struct sigaction act;
act.sa_handler = SIG_DFL;
act.sa_flags = 0;
sigemptyset(&act.sa_mask);
if (sigaction(SIGPIPE, &act, 0)) throw SysError("resetting SIGPIPE");
}
//////////////////////////////////////////////////////////////////////
@ -1218,19 +1210,31 @@ void triggerInterrupt()
}
}
static sigset_t savedSignalMask;
void startSignalHandlerThread()
{
if (sigprocmask(SIG_BLOCK, nullptr, &savedSignalMask))
throw SysError("quering signal mask");
sigset_t set;
sigemptyset(&set);
sigaddset(&set, SIGINT);
sigaddset(&set, SIGTERM);
sigaddset(&set, SIGHUP);
sigaddset(&set, SIGPIPE);
if (pthread_sigmask(SIG_BLOCK, &set, nullptr))
throw SysError("blocking signals");
std::thread(signalHandlerThread, set).detach();
}
void restoreSignals()
{
if (sigprocmask(SIG_SETMASK, &savedSignalMask, nullptr))
throw SysError("restoring signals");
}
/* RAII helper to automatically deregister a callback. */
struct InterruptCallbackImpl : InterruptCallback
{

7
src/libutil/util.hh
View file

@ -256,10 +256,6 @@ void closeMostFDs(const set<int> & exceptions);
/* Set the close-on-exec flag for the given file descriptor. */
void closeOnExec(int fd);
/* Restore default handling of SIGPIPE, otherwise some programs will
randomly say "Broken pipe". */
void restoreSIGPIPE();
/* User interruption. */
@ -423,6 +419,9 @@ void callSuccess(
on the current thread (and thus any threads created by it). */
void startSignalHandlerThread();
/* Restore default signal handling. */
void restoreSignals();
struct InterruptCallback
{
virtual ~InterruptCallback() { };