/*
* 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/file.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 redirectsockname[UNIX_PATH_MAX];
char lockfile[UNIX_PATH_MAX];
size_t argsize;
const char **args;
int lockfd;
};
static void initcmdserveropts(struct cmdserveropts *opts) {
memset(opts, 0, sizeof(struct cmdserveropts));
opts->lockfd = -1;
}
static void freecmdserveropts(struct cmdserveropts *opts) {
free(opts->args);
opts->args = NULL;
opts->argsize = 0;
}
/*
* Test if an argument is a sensitive flag that should be passed to the server.
* Return 0 if not, otherwise the number of arguments starting from the current
* one that should be passed to the server.
*/
static size_t testsensitiveflag(const char *arg)
{
static const struct {
const char *name;
size_t narg;
} flags[] = {
{"--config", 1},
{"--cwd", 1},
{"--repo", 1},
{"--repository", 1},
{"--traceback", 0},
{"-R", 1},
};
size_t i;
for (i = 0; i < sizeof(flags) / sizeof(flags[0]); ++i) {
size_t len = strlen(flags[i].name);
size_t narg = flags[i].narg;
if (memcmp(arg, flags[i].name, len) == 0) {
if (arg[len] == '\0') { /* --flag (value) */
return narg + 1;
} else if (arg[len] == '=' && narg > 0) { /* --flag=value */
return 1;
} else if (flags[i].name[1] != '-') { /* short flag */
return 1;
}
}
}
return 0;
}
/*
* Parse argv[] and put sensitive flags to opts->args
*/
static void setcmdserverargs(struct cmdserveropts *opts,
int argc, const char *argv[])
{
size_t i, step;
opts->argsize = 0;
for (i = 0, step = 1; i < (size_t)argc; i += step, step = 1) {
if (!argv[i])
continue; /* pass clang-analyse */
if (strcmp(argv[i], "--") == 0)
break;
size_t n = testsensitiveflag(argv[i]);
if (n == 0 || i + n > (size_t)argc)
continue;
opts->args = reallocx(opts->args,
(n + opts->argsize) * sizeof(char *));
memcpy(opts->args + opts->argsize, argv + i,
sizeof(char *) * n);
opts->argsize += n;
step = n;
}
}
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";
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);
}
/*
* Acquire a file lock that indicates a client is trying to start and connect
* to a server, before executing a command. The lock is released upon exit or
* explicit unlock. Will block if the lock is held by another process.
*/
static void lockcmdserver(struct cmdserveropts *opts)
{
if (opts->lockfd == -1) {
opts->lockfd = open(opts->lockfile, O_RDWR | O_CREAT | O_NOFOLLOW, 0600);
if (opts->lockfd == -1)
abortmsg("cannot create lock file %s", opts->lockfile);
}
int r = flock(opts->lockfd, LOCK_EX);
if (r == -1)
abortmsg("cannot acquire lock");
}
/*
* Release the file lock held by calling lockcmdserver. Will do nothing if
* lockcmdserver is not called.
*/
static void unlockcmdserver(struct cmdserveropts *opts)
{
if (opts->lockfd == -1)
return;
flock(opts->lockfd, LOCK_UN);
close(opts->lockfd);
opts->lockfd = -1;
}
static const char *gethgcmd(void)
{
static const char *hgcmd = NULL;
if (!hgcmd) {
hgcmd = getenv("CHGHG");
if (!hgcmd || hgcmd[0] == '\0')
hgcmd = getenv("HG");
if (!hgcmd || hgcmd[0] == '\0')
#ifdef HGPATH
hgcmd = (HGPATH);
#else
hgcmd = "hg";
#endif
}
return hgcmd;
}
static void execcmdserver(const struct cmdserveropts *opts)
{
const char *hgcmd = gethgcmd();
const char *baseargv[] = {
hgcmd,
"serve",
"--cmdserver", "chgunix",
"--address", opts->sockname,
"--daemon-postexec", "chdir:/",
"--config", "extensions.chgserver=",
};
size_t baseargvsize = sizeof(baseargv) / sizeof(baseargv[0]);
size_t argsize = baseargvsize + opts->argsize + 1;
const char **argv = mallocx(sizeof(char *) * argsize);
memcpy(argv, baseargv, sizeof(baseargv));
memcpy(argv + baseargvsize, opts->args, sizeof(char *) * opts->argsize);
argv[argsize - 1] = NULL;
if (putenv("CHGINTERNALMARK=") != 0)
abortmsg("failed to putenv (errno = %d)", errno);
if (execvp(hgcmd, (char **)argv) < 0)
abortmsg("failed to exec cmdserver (errno = %d)", errno);
free(argv);
}
/* Retry until we can connect to the server. Give up after some time. */
static hgclient_t *retryconnectcmdserver(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++) {
hgclient_t *hgc = hgc_open(opts->sockname);
if (hgc)
return hgc;
if (pid > 0) {
/* collect zombie if child process fails to start */
int r = waitpid(pid, &pst, WNOHANG);
if (r != 0)
goto cleanup;
}
nanosleep(&sleepreq, NULL);
}
abortmsg("timed out waiting for cmdserver %s", opts->sockname);
return NULL;
cleanup:
if (WIFEXITED(pst)) {
debugmsg("cmdserver exited with status %d", WEXITSTATUS(pst));
exit(WEXITSTATUS(pst));
} else if (WIFSIGNALED(pst)) {
abortmsg("cmdserver killed by signal %d", WTERMSIG(pst));
} else {
abortmsg("error white waiting cmdserver");
}
return NULL;
}
/* Connect to a cmdserver. Will start a new server on demand. */
static hgclient_t *connectcmdserver(struct cmdserveropts *opts)
{
const char *sockname = opts->redirectsockname[0] ?
opts->redirectsockname : opts->sockname;
hgclient_t *hgc = hgc_open(sockname);
if (hgc)
return hgc;
lockcmdserver(opts);
hgc = hgc_open(sockname);
if (hgc) {
unlockcmdserver(opts);
debugmsg("cmdserver is started by another process");
return hgc;
}
/* prevent us from being connected to an outdated server: we were
* told by a server to redirect to opts->redirectsockname and that
* address does not work. we do not want to connect to the server
* again because it will probably tell us the same thing. */
if (sockname == opts->redirectsockname)
unlink(opts->sockname);
debugmsg("start cmdserver at %s", opts->sockname);
pid_t pid = fork();
if (pid < 0)
abortmsg("failed to fork cmdserver process");
if (pid == 0) {
/* do not leak lockfd to hg */
close(opts->lockfd);
execcmdserver(opts);
} else {
hgc = retryconnectcmdserver(opts, pid);
}
unlockcmdserver(opts);
return hgc;
}
static void killcmdserver(const struct cmdserveropts *opts)
{
/* resolve config hash */
char *resolvedpath = realpath(opts->sockname, NULL);
if (resolvedpath) {
unlink(resolvedpath);
free(resolvedpath);
}
}
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 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:
abortmsg("failed to handle stop signal (errno = %d)", errno);
}
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;
/* 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;
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);
}
/* Run instructions sent from the server like unlink and set redirect path
* Return 1 if reconnect is needed, otherwise 0 */
static int runinstructions(struct cmdserveropts *opts, const char **insts)
{
int needreconnect = 0;
if (!insts)
return needreconnect;
assert(insts);
opts->redirectsockname[0] = '\0';
const char **pinst;
for (pinst = insts; *pinst; pinst++) {
debugmsg("instruction: %s", *pinst);
if (strncmp(*pinst, "unlink ", 7) == 0) {
unlink(*pinst + 7);
} else if (strncmp(*pinst, "redirect ", 9) == 0) {
int r = snprintf(opts->redirectsockname,
sizeof(opts->redirectsockname),
"%s", *pinst + 9);
if (r < 0 || r >= (int)sizeof(opts->redirectsockname))
abortmsg("redirect path is too long (%d)", r);
needreconnect = 1;
} else if (strncmp(*pinst, "exit ", 5) == 0) {
int n = 0;
if (sscanf(*pinst + 5, "%d", &n) != 1)
abortmsg("cannot read the exit code");
exit(n);
} else if (strcmp(*pinst, "reconnect") == 0) {
needreconnect = 1;
} else {
abortmsg("unknown instruction: %s", *pinst);
}
}
return needreconnect;
}
/*
* Test whether the command is unsupported or not. This is not designed to
* cover all cases. But it's fast, does not depend on the server and does
* not return false positives.
*/
static int isunsupported(int argc, const char *argv[])
{
enum {
SERVE = 1,
DAEMON = 2,
SERVEDAEMON = SERVE | DAEMON,
TIME = 4,
};
unsigned int state = 0;
int i;
for (i = 0; i < argc; ++i) {
if (strcmp(argv[i], "--") == 0)
break;
if (i == 0 && strcmp("serve", argv[i]) == 0)
state |= SERVE;
else if (strcmp("-d", argv[i]) == 0 ||
strcmp("--daemon", argv[i]) == 0)
state |= DAEMON;
else if (strcmp("--time", argv[i]) == 0)
state |= TIME;
}
return (state & TIME) == TIME ||
(state & SERVEDAEMON) == SERVEDAEMON;
}
static void execoriginalhg(const char *argv[])
{
debugmsg("execute original hg");
if (execvp(gethgcmd(), (char **)argv) < 0)
abortmsg("failed to exec original hg (errno = %d)", errno);
}
int main(int argc, const char *argv[], const char *envp[])
{
if (getenv("CHGDEBUG"))
enabledebugmsg();
if (getenv("CHGINTERNALMARK"))
abortmsg("chg started by chg detected.\n"
"Please make sure ${HG:-hg} is not a symlink or "
"wrapper to chg. Alternatively, set $CHGHG to the "
"path of real hg.");
if (isunsupported(argc - 1, argv + 1))
execoriginalhg(argv);
struct cmdserveropts opts;
initcmdserveropts(&opts);
setcmdserveropts(&opts);
setcmdserverargs(&opts, argc, argv);
if (argc == 2) {
if (strcmp(argv[1], "--kill-chg-daemon") == 0) {
killcmdserver(&opts);
return 0;
}
}
hgclient_t *hgc;
size_t retry = 0;
while (1) {
hgc = connectcmdserver(&opts);
if (!hgc)
abortmsg("cannot open hg client");
hgc_setenv(hgc, envp);
const char **insts = hgc_validate(hgc, argv + 1, argc - 1);
int needreconnect = runinstructions(&opts, insts);
free(insts);
if (!needreconnect)
break;
hgc_close(hgc);
if (++retry > 10)
abortmsg("too many redirections.\n"
"Please make sure %s is not a wrapper which "
"changes sensitive environment variables "
"before executing hg. If you have to use a "
"wrapper, wrap chg instead of hg.",
gethgcmd());
}
setupsignalhandler(hgc_peerpid(hgc));
setuppager(hgc, argv + 1, argc - 1);
int exitcode = hgc_runcommand(hgc, argv + 1, argc - 1);
hgc_close(hgc);
freecmdserveropts(&opts);
return exitcode;
}