config: use the writefile() utility to create the sample hgrc
This function uses a context manager.
/*
* 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 <dirent.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 "procutil.h"
#include "util.h"
#ifndef PATH_MAX
#define PATH_MAX 4096
#endif
extern char **environ;
struct cmdserveropts {
char sockname[PATH_MAX];
char initsockname[PATH_MAX];
char redirectsockname[PATH_MAX];
size_t argsize;
const char **args;
};
static void initcmdserveropts(struct cmdserveropts *opts)
{
memset(opts, 0, sizeof(struct cmdserveropts));
}
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)
abortmsgerrno("cannot create sockdir %s", sockdir);
struct stat st;
r = lstat(sockdir, &st);
if (r < 0)
abortmsgerrno("cannot stat %s", sockdir);
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);
}
/*
* Check if a socket directory exists and is only owned by the current user.
* Return 1 if so, 0 if not. This is used to check if XDG_RUNTIME_DIR can be
* used or not. According to the specification [1], XDG_RUNTIME_DIR should be
* ignored if the directory is not owned by the user with mode 0700.
* [1]: https://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
*/
static int checkruntimedir(const char *sockdir)
{
struct stat st;
int r = lstat(sockdir, &st);
if (r < 0) /* ex. does not exist */
return 0;
if (!S_ISDIR(st.st_mode)) /* ex. is a file, not a directory */
return 0;
return st.st_uid == geteuid() && (st.st_mode & 0777) == 0700;
}
static void getdefaultsockdir(char sockdir[], size_t size)
{
/* by default, put socket file in secure directory
* (${XDG_RUNTIME_DIR}/chg, or /${TMPDIR:-tmp}/chg$UID)
* (permission of socket file may be ignored on some Unices) */
const char *runtimedir = getenv("XDG_RUNTIME_DIR");
int r;
if (runtimedir && checkruntimedir(runtimedir)) {
r = snprintf(sockdir, size, "%s/chg", runtimedir);
} else {
const char *tmpdir = getenv("TMPDIR");
if (!tmpdir)
tmpdir = "/tmp";
r = snprintf(sockdir, size, "%s/chg%d", tmpdir, geteuid());
}
if (r < 0 || (size_t)r >= size)
abortmsg("too long TMPDIR (r = %d)", r);
}
static void setcmdserveropts(struct cmdserveropts *opts)
{
int r;
char sockdir[PATH_MAX];
const char *envsockname = getenv("CHGSOCKNAME");
if (!envsockname) {
getdefaultsockdir(sockdir, sizeof(sockdir));
preparesockdir(sockdir);
}
const char *basename = (envsockname) ? envsockname : sockdir;
const char *sockfmt = (envsockname) ? "%s" : "%s/server";
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->initsockname, sizeof(opts->initsockname), "%s.%u",
opts->sockname, (unsigned)getpid());
if (r < 0 || (size_t)r >= sizeof(opts->initsockname))
abortmsg("too long TMPDIR or CHGSOCKNAME (r = %d)", r);
}
/* If the current program is, say, /a/b/c/chg, returns /a/b/c/hg. */
static char *getrelhgcmd(void)
{
ssize_t n;
char *res, *slash;
int maxsize = 4096;
res = malloc(maxsize);
if (res == NULL)
goto cleanup;
n = readlink("/proc/self/exe", res, maxsize);
if (n < 0 || n >= maxsize)
goto cleanup;
res[n] = '\0';
slash = strrchr(res, '/');
if (slash == NULL)
goto cleanup;
/* 4 is strlen("/hg") + nul byte */
if (slash + 4 >= res + maxsize)
goto cleanup;
memcpy(slash, "/hg", 4);
return res;
cleanup:
free(res);
return NULL;
}
static const char *gethgcmd(void)
{
static const char *hgcmd = NULL;
#ifdef HGPATHREL
int tryrelhgcmd = 1;
#else
int tryrelhgcmd = 0;
#endif
if (!hgcmd) {
hgcmd = getenv("CHGHG");
if (!hgcmd || hgcmd[0] == '\0')
hgcmd = getenv("HG");
if (tryrelhgcmd && (!hgcmd || hgcmd[0] == '\0'))
hgcmd = getrelhgcmd();
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", "--no-profile", "--cmdserver",
"chgunix", "--address", opts->initsockname, "--daemon-postexec",
"chdir:/",
};
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));
if (opts->args) {
size_t size = sizeof(char *) * opts->argsize;
memcpy(argv + baseargvsize, opts->args, size);
}
argv[argsize - 1] = NULL;
const char *lc_ctype_env = getenv("LC_CTYPE");
if (lc_ctype_env == NULL) {
if (putenv("CHG_CLEAR_LC_CTYPE=") != 0)
abortmsgerrno("failed to putenv CHG_CLEAR_LC_CTYPE");
} else {
if (setenv("CHGORIG_LC_CTYPE", lc_ctype_env, 1) != 0) {
abortmsgerrno("failed to setenv CHGORIG_LC_CTYPE");
}
}
/* close any open files to avoid hanging locks */
DIR *dp = opendir("/proc/self/fd");
if (dp != NULL) {
debugmsg("closing files based on /proc contents");
struct dirent *de;
while ((de = readdir(dp))) {
errno = 0;
char *end;
long fd_value = strtol(de->d_name, &end, 10);
if (end == de->d_name) {
/* unable to convert to int (. or ..) */
continue;
}
if (errno == ERANGE) {
debugmsg("tried to parse %s, but range error "
"occurred",
de->d_name);
continue;
}
if (fd_value > STDERR_FILENO && fd_value != dirfd(dp)) {
debugmsg("closing fd %ld", fd_value);
int res = close(fd_value);
if (res) {
debugmsg("tried to close fd %ld: %d "
"(errno: %d)",
fd_value, res, errno);
}
}
}
closedir(dp);
}
if (putenv("CHGINTERNALMARK=") != 0)
abortmsgerrno("failed to putenv");
if (execvp(hgcmd, (char **)argv) < 0)
abortmsgerrno("failed to exec cmdserver");
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;
debugmsg("try connect to %s repeatedly", opts->initsockname);
unsigned int timeoutsec = 60; /* default: 60 seconds */
const char *timeoutenv = getenv("CHGTIMEOUT");
if (timeoutenv)
sscanf(timeoutenv, "%u", &timeoutsec);
for (unsigned int i = 0; !timeoutsec || i < timeoutsec * 100; i++) {
hgclient_t *hgc = hgc_open(opts->initsockname);
if (hgc) {
debugmsg("rename %s to %s", opts->initsockname,
opts->sockname);
int r = rename(opts->initsockname, opts->sockname);
if (r != 0)
abortmsgerrno("cannot rename");
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->initsockname);
return NULL;
cleanup:
if (WIFEXITED(pst)) {
if (WEXITSTATUS(pst) == 0)
abortmsg("could not connect to cmdserver "
"(exited with status 0)");
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 while waiting for 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;
debugmsg("try connect to %s", sockname);
hgclient_t *hgc = hgc_open(sockname);
if (hgc)
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->initsockname);
pid_t pid = fork();
if (pid < 0)
abortmsg("failed to fork cmdserver process");
if (pid == 0) {
execcmdserver(opts);
} else {
hgc = retryconnectcmdserver(opts, pid);
}
return hgc;
}
static void killcmdserver(const struct cmdserveropts *opts)
{
/* resolve config hash */
char *resolvedpath = realpath(opts->sockname, NULL);
if (resolvedpath) {
unlink(resolvedpath);
free(resolvedpath);
}
}
/* 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 and the environment is unsupported or not.
*
* If any of the stdio file descriptors are not present (rare, but some tools
* might spawn new processes without stdio instead of redirecting them to the
* null device), then mark it as not supported because attachio won't work
* correctly.
*
* The command list is not designed to cover all cases. But it's fast, and does
* not depend on the server.
*/
static int isunsupported(int argc, const char *argv[])
{
enum {
SERVE = 1,
DAEMON = 2,
SERVEDAEMON = SERVE | DAEMON,
};
unsigned int state = 0;
int i;
/* use fcntl to test missing stdio fds */
if (fcntl(STDIN_FILENO, F_GETFD) == -1 ||
fcntl(STDOUT_FILENO, F_GETFD) == -1 ||
fcntl(STDERR_FILENO, F_GETFD) == -1) {
debugmsg("stdio fds are missing");
return 1;
}
for (i = 0; i < argc; ++i) {
if (strcmp(argv[i], "--") == 0)
break;
/*
* there can be false positives but no false negative
* we cannot assume `serve` will always be first argument
* because global options can be passed before the command name
*/
if (strcmp("serve", argv[i]) == 0)
state |= SERVE;
else if (strcmp("-d", argv[i]) == 0 ||
strcmp("--daemon", argv[i]) == 0)
state |= DAEMON;
}
return (state & SERVEDAEMON) == SERVEDAEMON;
}
static void execoriginalhg(const char *argv[])
{
debugmsg("execute original hg");
if (execvp(gethgcmd(), (char **)argv) < 0)
abortmsgerrno("failed to exec original hg");
}
int main(int argc, const char *argv[])
{
if (getenv("CHGDEBUG"))
enabledebugmsg();
if (!getenv("HGPLAIN") && isatty(fileno(stderr)))
enablecolor();
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;
}
}
/* Set $CHGHG to the path of the hg executable we intend to use. This
* is a no-op if $CHGHG was expliclty specified, but otherwise this
* ensures that we will spawn a new command server if we connect to an
* existing one running from a different executable. This should only
* only be needed when chg is built with HGPATHREL since otherwise the
* hg executable used when CHGHG is absent should be deterministic.
* */
if (setenv("CHGHG", gethgcmd(), 1) != 0)
abortmsgerrno("failed to setenv");
hgclient_t *hgc;
size_t retry = 0;
while (1) {
hgc = connectcmdserver(&opts);
if (!hgc)
abortmsg("cannot open hg client");
/* Use `environ(7)` instead of the optional `envp` argument to
* `main` because `envp` does not update when the environment
* changes, but `environ` does. */
hgc_setenv(hgc, (const char *const *)environ);
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), hgc_peerpgid(hgc));
atexit(waitpager);
int exitcode = hgc_runcommand(hgc, argv + 1, argc - 1);
restoresignalhandler();
hgc_close(hgc);
freecmdserveropts(&opts);
return exitcode;
}