contrib/chg/chg.c

tests: add more tests of copy tracing with removed and re-added files

We had a test where the destination of a copy was removed and then
added back. This patch adds similar cases where the break in history
instead happens to the source file. There are three versions of this:

 1. The break happens before the rename.

 2. The break happens on a branch parallel to the rename (where copy
    tracing is done via the merge base)

 3. The source is added on each side of the merge base. The break in
    history is thus in the form of a deletion when going backwards to
    the merge base and the re-add happens on the other branch.

I've also added calls to `hg graft` in these cases to show the
breakage in issue 6163.

Another factor in these cases is matching nodeid (checked in
copies._tracefile()). I've made two copies each of the cases to show
the impact of that. One of these is the same as a test in
test-rename-merge1.t, so I also deleted that test from there.

Some of these tests currently fail, where "fail" is based on my
current thinking of how things should work. I had initially thought
that we should be more strict about not tracing copies across commits
where the file did not exist, but issue 6163 made me reconsider.

The only test case here that behaved differently in 4.9 is the
exact case reported in issue 6163.

Differential Revision: https://phab.mercurial-scm.org/D6599

/*
 * A fast client for Mercurial command server
 *
 * 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 <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

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);
}

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->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;

	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 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,
	};
	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;
	}
	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[], const char *envp[])
{
	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;
		}
	}

	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), hgc_peerpgid(hgc));
	atexit(waitpager);
	int exitcode = hgc_runcommand(hgc, argv + 1, argc - 1);
	restoresignalhandler();
	hgc_close(hgc);
	freecmdserveropts(&opts);

	return exitcode;
}