Mercurial > hg
view contrib/chg/chg.c @ 28085:c0d1bf1b26b7
chg: verify return value of sigaction() and sigemptyset()
They should never fail, but it couldn't hurt to be a paranoid.
author | Yuya Nishihara <yuya@tcha.org> |
---|---|
date | Fri, 29 Jan 2016 22:52:16 +0900 |
parents | 3fc45956c978 |
children | 65d24ca35496 |
line wrap: on
line source
/* * A fast client for Mercurial command server * * 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 <fcntl.h> #include <signal.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/stat.h> #include <sys/types.h> #include <sys/un.h> #include <sys/wait.h> #include <time.h> #include <unistd.h> #include "hgclient.h" #include "util.h" #ifndef UNIX_PATH_MAX #define UNIX_PATH_MAX (sizeof(((struct sockaddr_un *)NULL)->sun_path)) #endif struct cmdserveropts { char sockname[UNIX_PATH_MAX]; char lockfile[UNIX_PATH_MAX]; char pidfile[UNIX_PATH_MAX]; }; static void preparesockdir(const char *sockdir) { int r; r = mkdir(sockdir, 0700); if (r < 0 && errno != EEXIST) abortmsg("cannot create sockdir %s (errno = %d)", sockdir, errno); struct stat st; r = lstat(sockdir, &st); if (r < 0) abortmsg("cannot stat %s (errno = %d)", sockdir, errno); if (!S_ISDIR(st.st_mode)) abortmsg("cannot create sockdir %s (file exists)", sockdir); if (st.st_uid != geteuid() || st.st_mode & 0077) abortmsg("insecure sockdir %s", sockdir); } static void setcmdserveropts(struct cmdserveropts *opts) { int r; char sockdir[UNIX_PATH_MAX]; const char *envsockname = getenv("CHGSOCKNAME"); if (!envsockname) { /* by default, put socket file in secure directory * (permission of socket file may be ignored on some Unices) */ const char *tmpdir = getenv("TMPDIR"); if (!tmpdir) tmpdir = "/tmp"; r = snprintf(sockdir, sizeof(sockdir), "%s/chg%d", tmpdir, geteuid()); if (r < 0 || (size_t)r >= sizeof(sockdir)) abortmsg("too long TMPDIR (r = %d)", r); preparesockdir(sockdir); } const char *basename = (envsockname) ? envsockname : sockdir; const char *sockfmt = (envsockname) ? "%s" : "%s/server"; const char *lockfmt = (envsockname) ? "%s.lock" : "%s/lock"; const char *pidfmt = (envsockname) ? "%s.pid" : "%s/pid"; r = snprintf(opts->sockname, sizeof(opts->sockname), sockfmt, basename); if (r < 0 || (size_t)r >= sizeof(opts->sockname)) abortmsg("too long TMPDIR or CHGSOCKNAME (r = %d)", r); r = snprintf(opts->lockfile, sizeof(opts->lockfile), lockfmt, basename); if (r < 0 || (size_t)r >= sizeof(opts->lockfile)) abortmsg("too long TMPDIR or CHGSOCKNAME (r = %d)", r); r = snprintf(opts->pidfile, sizeof(opts->pidfile), pidfmt, basename); if (r < 0 || (size_t)r >= sizeof(opts->pidfile)) abortmsg("too long TMPDIR or CHGSOCKNAME (r = %d)", r); } /* * Make lock file that indicates cmdserver process is about to start. Created * lock file will be deleted by server. (0: success, -1: lock exists) */ static int lockcmdserver(const struct cmdserveropts *opts) { int r; char info[32]; r = snprintf(info, sizeof(info), "%d", getpid()); if (r < 0 || (size_t)r >= sizeof(info)) abortmsg("failed to format lock info"); r = symlink(info, opts->lockfile); if (r < 0 && errno != EEXIST) abortmsg("failed to make lock %s (errno = %d)", opts->lockfile, errno); return r; } static void execcmdserver(const struct cmdserveropts *opts) { const char *hgcmd = getenv("CHGHG"); if (!hgcmd || hgcmd[0] == '\0') hgcmd = getenv("HG"); if (!hgcmd || hgcmd[0] == '\0') hgcmd = "hg"; const char *argv[] = { hgcmd, "serve", "--cwd", "/", "--cmdserver", "chgunix", "--address", opts->sockname, "--daemon-pipefds", opts->lockfile, "--pid-file", opts->pidfile, "--config", "extensions.chgserver=", /* wrap root ui so that it can be disabled/enabled by config */ "--config", "progress.assume-tty=1", NULL, }; if (execvp(hgcmd, (char **)argv) < 0) abortmsg("failed to exec cmdserver (errno = %d)", errno); } /* * Sleep until lock file is deleted, i.e. cmdserver process starts listening. * If pid is given, it also checks if the child process fails to start. */ static void waitcmdserver(const struct cmdserveropts *opts, pid_t pid) { static const struct timespec sleepreq = {0, 10 * 1000000}; int pst = 0; for (unsigned int i = 0; i < 10 * 100; i++) { int r; struct stat lst; r = lstat(opts->lockfile, &lst); if (r < 0 && errno == ENOENT) return; /* lock file deleted by server */ if (r < 0) goto cleanup; if (pid > 0) { /* collect zombie if child process fails to start */ r = waitpid(pid, &pst, WNOHANG); if (r != 0) goto cleanup; } nanosleep(&sleepreq, NULL); } abortmsg("timed out waiting for cmdserver %s", opts->lockfile); return; cleanup: if (pid > 0) /* lockfile should be made by this process */ unlink(opts->lockfile); if (WIFEXITED(pst)) { abortmsg("cmdserver exited with status %d", WEXITSTATUS(pst)); } else if (WIFSIGNALED(pst)) { abortmsg("cmdserver killed by signal %d", WTERMSIG(pst)); } else { abortmsg("error white waiting cmdserver"); } } /* Spawn new background cmdserver */ static void startcmdserver(const struct cmdserveropts *opts) { debugmsg("start cmdserver at %s", opts->sockname); if (lockcmdserver(opts) < 0) { debugmsg("lock file exists, waiting..."); waitcmdserver(opts, 0); return; } /* remove dead cmdserver socket if any */ unlink(opts->sockname); pid_t pid = fork(); if (pid < 0) abortmsg("failed to fork cmdserver process"); if (pid == 0) { /* bypass uisetup() of pager extension */ int nullfd = open("/dev/null", O_WRONLY); if (nullfd >= 0) { dup2(nullfd, fileno(stdout)); close(nullfd); } execcmdserver(opts); } else { waitcmdserver(opts, pid); } } static void killcmdserver(const struct cmdserveropts *opts, int sig) { FILE *fp = fopen(opts->pidfile, "r"); if (!fp) abortmsg("cannot open %s (errno = %d)", opts->pidfile, errno); int pid = 0; int n = fscanf(fp, "%d", &pid); fclose(fp); if (n != 1 || pid <= 0) abortmsg("cannot read pid from %s", opts->pidfile); if (kill((pid_t)pid, sig) < 0) { if (errno == ESRCH) return; abortmsg("cannot kill %d (errno = %d)", pid, errno); } } static pid_t peerpid = 0; static void forwardsignal(int sig) { assert(peerpid > 0); if (kill(peerpid, sig) < 0) abortmsg("cannot kill %d (errno = %d)", peerpid, errno); debugmsg("forward signal %d", sig); } static void setupsignalhandler(pid_t pid) { if (pid <= 0) return; peerpid = pid; struct sigaction sa; memset(&sa, 0, sizeof(sa)); sa.sa_handler = forwardsignal; 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_flags |= SA_RESETHAND; if (sigaction(SIGTERM, &sa, NULL) < 0) goto error; return; error: abortmsg("failed to set up signal handlers (errno = %d)", errno); } /* This implementation is based on hgext/pager.py (pre 369741ef7253) */ static void setuppager(hgclient_t *hgc, const char *const args[], size_t argsize) { const char *pagercmd = hgc_getpager(hgc, args, argsize); if (!pagercmd) return; int pipefds[2]; if (pipe(pipefds) < 0) return; 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]); hgc_attachio(hgc); /* reattach to pager */ return; } else { dup2(pipefds[0], fileno(stdin)); close(pipefds[0]); close(pipefds[1]); int r = execlp("/bin/sh", "/bin/sh", "-c", pagercmd, NULL); if (r < 0) { abortmsg("cannot start pager '%s' (errno = %d)", pagercmd, errno); } return; } error: close(pipefds[0]); close(pipefds[1]); abortmsg("failed to prepare pager (errno = %d)", errno); } int main(int argc, const char *argv[], const char *envp[]) { if (getenv("CHGDEBUG")) enabledebugmsg(); struct cmdserveropts opts; setcmdserveropts(&opts); if (argc == 2) { int sig = 0; if (strcmp(argv[1], "--kill-chg-daemon") == 0) sig = SIGTERM; if (strcmp(argv[1], "--reload-chg-daemon") == 0) sig = SIGHUP; if (sig > 0) { killcmdserver(&opts, sig); return 0; } } hgclient_t *hgc = hgc_open(opts.sockname); if (!hgc) { startcmdserver(&opts); hgc = hgc_open(opts.sockname); } if (!hgc) abortmsg("cannot open hg client"); setupsignalhandler(hgc_peerpid(hgc)); hgc_setenv(hgc, envp); setuppager(hgc, argv + 1, argc - 1); int exitcode = hgc_runcommand(hgc, argv + 1, argc - 1); hgc_close(hgc); return exitcode; }