Mercurial > hg
view contrib/chg/procutil.c @ 47471:aab064416f0c
censor: rename `rl` to `revlog` in the main function
Now that the bulk of the code moved to smaller function we are less restricted
on line length and we can use more explicite naming.
Differential Revision: https://phab.mercurial-scm.org/D10902
author | Pierre-Yves David <pierre-yves.david@octobus.net> |
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date | Tue, 22 Jun 2021 22:35:37 +0200 |
parents | 763b45bc4483 |
children |
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/* * Utilities about process handling - signal and subprocess (ex. pager) * * Copyright (c) 2011 Yuya Nishihara <yuya@tcha.org> * * This software may be used and distributed according to the terms of the * GNU General Public License version 2 or any later version. */ #include <assert.h> #include <errno.h> #include <signal.h> #include <stdio.h> #include <string.h> #include <sys/wait.h> #include <unistd.h> #include "procutil.h" #include "util.h" static pid_t pagerpid = 0; static pid_t peerpgid = 0; static pid_t peerpid = 0; static void forwardsignal(int sig) { assert(peerpid > 0); if (kill(peerpid, sig) < 0) { abortmsgerrno("cannot kill %d", peerpid); } debugmsg("forward signal %d", sig); } static void forwardsignaltogroup(int sig) { /* prefer kill(-pgid, sig), fallback to pid if pgid is invalid */ pid_t killpid = peerpgid > 1 ? -peerpgid : peerpid; if (kill(killpid, sig) < 0) { abortmsgerrno("cannot kill %d", killpid); } debugmsg("forward signal %d to %d", sig, killpid); } static void handlestopsignal(int sig) { sigset_t unblockset, oldset; struct sigaction sa, oldsa; if (sigemptyset(&unblockset) < 0) { goto error; } if (sigaddset(&unblockset, sig) < 0) { goto error; } memset(&sa, 0, sizeof(sa)); sa.sa_handler = SIG_DFL; sa.sa_flags = SA_RESTART; if (sigemptyset(&sa.sa_mask) < 0) { goto error; } forwardsignal(sig); if (raise(sig) < 0) { /* resend to self */ goto error; } if (sigaction(sig, &sa, &oldsa) < 0) { goto error; } if (sigprocmask(SIG_UNBLOCK, &unblockset, &oldset) < 0) { goto error; } /* resent signal will be handled before sigprocmask() returns */ if (sigprocmask(SIG_SETMASK, &oldset, NULL) < 0) { goto error; } if (sigaction(sig, &oldsa, NULL) < 0) { goto error; } return; error: abortmsgerrno("failed to handle stop signal"); } static void handlechildsignal(int sig UNUSED_) { if (peerpid == 0 || pagerpid == 0) { return; } /* if pager exits, notify the server with SIGPIPE immediately. * otherwise the server won't get SIGPIPE if it does not write * anything. (issue5278) */ if (waitpid(pagerpid, NULL, WNOHANG) == pagerpid) { kill(peerpid, SIGPIPE); } } void setupsignalhandler(pid_t pid, pid_t pgid) { if (pid <= 0) { return; } peerpid = pid; peerpgid = (pgid <= 1 ? 0 : pgid); struct sigaction sa; memset(&sa, 0, sizeof(sa)); /* deadly signals meant to be sent to a process group: * - SIGHUP: usually generated by the kernel, when termination of a * process causes that process group to become orphaned * - SIGINT: usually generated by the terminal */ sa.sa_handler = forwardsignaltogroup; sa.sa_flags = SA_RESTART; if (sigemptyset(&sa.sa_mask) < 0) { goto error; } if (sigaction(SIGHUP, &sa, NULL) < 0) { goto error; } if (sigaction(SIGINT, &sa, NULL) < 0) { goto error; } /* terminate frontend by double SIGTERM in case of server freeze */ sa.sa_handler = forwardsignal; sa.sa_flags |= SA_RESETHAND; if (sigaction(SIGTERM, &sa, NULL) < 0) { goto error; } /* notify the worker about window resize events */ sa.sa_flags = SA_RESTART; if (sigaction(SIGWINCH, &sa, NULL) < 0) { goto error; } /* forward user-defined signals */ if (sigaction(SIGUSR1, &sa, NULL) < 0) { goto error; } if (sigaction(SIGUSR2, &sa, NULL) < 0) { goto error; } /* propagate job control requests to worker */ sa.sa_handler = forwardsignal; sa.sa_flags = SA_RESTART; if (sigaction(SIGCONT, &sa, NULL) < 0) { goto error; } sa.sa_handler = handlestopsignal; sa.sa_flags = SA_RESTART; if (sigaction(SIGTSTP, &sa, NULL) < 0) { goto error; } /* get notified when pager exits */ sa.sa_handler = handlechildsignal; sa.sa_flags = SA_RESTART; if (sigaction(SIGCHLD, &sa, NULL) < 0) { goto error; } return; error: abortmsgerrno("failed to set up signal handlers"); } void restoresignalhandler(void) { struct sigaction sa; memset(&sa, 0, sizeof(sa)); sa.sa_handler = SIG_DFL; sa.sa_flags = SA_RESTART; if (sigemptyset(&sa.sa_mask) < 0) { goto error; } if (sigaction(SIGHUP, &sa, NULL) < 0) { goto error; } if (sigaction(SIGTERM, &sa, NULL) < 0) { goto error; } if (sigaction(SIGWINCH, &sa, NULL) < 0) { goto error; } if (sigaction(SIGCONT, &sa, NULL) < 0) { goto error; } if (sigaction(SIGTSTP, &sa, NULL) < 0) { goto error; } if (sigaction(SIGCHLD, &sa, NULL) < 0) { goto error; } /* ignore Ctrl+C while shutting down to make pager exits cleanly */ sa.sa_handler = SIG_IGN; if (sigaction(SIGINT, &sa, NULL) < 0) { goto error; } peerpid = 0; return; error: abortmsgerrno("failed to restore signal handlers"); } /* This implementation is based on hgext/pager.py (post 369741ef7253) * Return 0 if pager is not started, or pid of the pager */ pid_t setuppager(const char *pagercmd, const char *envp[]) { assert(pagerpid == 0); if (!pagercmd) { return 0; } int pipefds[2]; if (pipe(pipefds) < 0) { return 0; } pid_t pid = fork(); if (pid < 0) { goto error; } if (pid > 0) { close(pipefds[0]); if (dup2(pipefds[1], fileno(stdout)) < 0) { goto error; } if (isatty(fileno(stderr))) { if (dup2(pipefds[1], fileno(stderr)) < 0) { goto error; } } close(pipefds[1]); pagerpid = pid; return pid; } else { dup2(pipefds[0], fileno(stdin)); close(pipefds[0]); close(pipefds[1]); int r = execle("/bin/sh", "/bin/sh", "-c", pagercmd, NULL, envp); if (r < 0) { abortmsgerrno("cannot start pager '%s'", pagercmd); } return 0; } error: close(pipefds[0]); close(pipefds[1]); abortmsgerrno("failed to prepare pager"); return 0; } void waitpager(void) { if (pagerpid == 0) { return; } /* close output streams to notify the pager its input ends */ fclose(stdout); fclose(stderr); while (1) { pid_t ret = waitpid(pagerpid, NULL, 0); if (ret == -1 && errno == EINTR) { continue; } break; } }