view contrib/chg/procutil.c @ 48598:a6f16ec07ed7

stream-clone: add a explicit test for format change during stream clone

They are different kind of requirements, the one which impact the data storage
and are relevant to the files being streamed and the one which does not. For
example some requirements are only relevant to the working copy, like sparse, or
dirstate-v2.

Since they are irrelevant to the content being streamed, they do not prevent the
receiving side to use streaming clone and mercurial skip adverting them over
the wire and, ideally, within the bundle.

In addition, this let the client decide to use whichever format it desire for
the part that does not affect the store itself. So the configuration related to
these format are used as normal when doing a streaming clone.

In practice, the feature was not really tested and is badly broken with bundle-2,
since the requirements are not filtered out from the stream bundle.

So we start with adding simple tests as a good base before the fix and adjust
the feature.

Differential Revision: https://phab.mercurial-scm.org/D12029

/*
 * Utilities about process handling - signal and subprocess (ex. pager)
 *
 * Copyright (c) 2011 Yuya Nishihara <[e-mail]>
 *
 * 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;
	}
}