#define _GNU_SOURCE
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <poll.h>
#include <signal.h>
#include <stdarg.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

enum
{
	Failtimeout = 4000,
};

typedef struct Test Test;
struct Test
{
	pid_t child;
	int errfd;
	char root[256];
	char runtime[320];
	char config[320];
	char ibus[384];
	char bus[448];
	char home[320];
	char socket[384];
	char badmap[320];
	char err[4096];
	size_t nerr;
};

static int
fail(char *fmt, ...)
{
	va_list ap;

	fprintf(stderr, "daemon_failure_test: ");
	va_start(ap, fmt);
	vfprintf(stderr, fmt, ap);
	va_end(ap);
	fputc('\n', stderr);
	return 0;
}

static int64_t
nowms(void)
{
	struct timespec ts;

	if(clock_gettime(CLOCK_MONOTONIC, &ts) < 0)
		return -1;
	return (int64_t)ts.tv_sec * 1000 + ts.tv_nsec / 1000000;
}

static int
leftms(int64_t deadline)
{
	int64_t n;

	n = nowms();
	if(n < 0)
		return -1;
	n = deadline - n;
	if(n <= 0)
		return 0;
	return n > INT_MAX ? INT_MAX : n;
}

static int
makedir(char *path)
{
	if(mkdir(path, 0700) == 0)
		return 1;
	return fail("mkdir %s: %s", path, strerror(errno));
}

static void
readerrors(Test *t)
{
	ssize_t n;

	while(t->errfd >= 0 && t->nerr + 1 < sizeof t->err){
		n = read(t->errfd, t->err + t->nerr,
			sizeof t->err - t->nerr - 1);
		if(n > 0){
			t->nerr += n;
			continue;
		}
		if(n < 0 && errno == EINTR)
			continue;
		break;
	}
	t->err[t->nerr] = '\0';
}

static int
setup(Test *t)
{
	memset(t, 0, sizeof *t);
	t->child = -1;
	t->errfd = -1;
	snprintf(t->root, sizeof t->root, "/tmp/strans-failure.XXXXXX");
	if(mkdtemp(t->root) == NULL){
		t->root[0] = '\0';
		return fail("mkdtemp: %s", strerror(errno));
	}
	if(snprintf(t->runtime, sizeof t->runtime, "%s/runtime", t->root)
	   >= (int)sizeof t->runtime ||
	   snprintf(t->config, sizeof t->config, "%s/config", t->root)
	   >= (int)sizeof t->config ||
	   snprintf(t->ibus, sizeof t->ibus, "%s/ibus", t->config)
	   >= (int)sizeof t->ibus ||
	   snprintf(t->bus, sizeof t->bus, "%s/bus", t->ibus)
	   >= (int)sizeof t->bus ||
	   snprintf(t->home, sizeof t->home, "%s/home", t->root)
	   >= (int)sizeof t->home ||
	   snprintf(t->socket, sizeof t->socket, "%s/strans.sock", t->runtime)
	   >= (int)sizeof t->socket ||
	   snprintf(t->badmap, sizeof t->badmap, "%s/missing-map", t->root)
	   >= (int)sizeof t->badmap)
		return fail("temporary path is too long");
	return makedir(t->runtime) && makedir(t->config) && makedir(t->ibus) &&
		makedir(t->bus) && makedir(t->home);
}

static int
startchild(Test *t, char *program)
{
	int errpipe[2], fd;
	long maxfd;
	pid_t pid;

	if(pipe2(errpipe, O_CLOEXEC|O_NONBLOCK) < 0)
		return fail("pipe2: %s", strerror(errno));
	pid = fork();
	if(pid < 0){
		close(errpipe[0]);
		close(errpipe[1]);
		return fail("fork: %s", strerror(errno));
	}
	if(pid == 0){
		close(errpipe[0]);
		if(dup2(errpipe[1], STDERR_FILENO) < 0)
			_exit(126);
		close(errpipe[1]);
		if(close_range(3, UINT_MAX, 0) < 0){
			maxfd = sysconf(_SC_OPEN_MAX);
			if(maxfd < 0)
				maxfd = 1024;
			for(fd = 3; fd < maxfd; fd++)
				close(fd);
		}
		if(setenv("XDG_RUNTIME_DIR", t->runtime, 1) < 0 ||
		   setenv("XDG_CONFIG_HOME", t->config, 1) < 0 ||
		   setenv("HOME", t->home, 1) < 0 || unsetenv("DISPLAY") < 0 ||
		   unsetenv("DBUS_SESSION_BUS_ADDRESS") < 0 ||
		   unsetenv("IBUS_ADDRESS") < 0 ||
		   unsetenv("IBUS_ADDRESS_FILE") < 0)
			_exit(126);
		execl(program, program, t->badmap, (char*)0);
		dprintf(STDERR_FILENO, "exec %s: %s\n", program, strerror(errno));
		_exit(127);
	}
	close(errpipe[1]);
	t->child = pid;
	t->errfd = errpipe[0];
	return 1;
}

static int
waitfailed(Test *t)
{
	struct pollfd pfd;
	int n, status;
	int64_t deadline;

	deadline = nowms();
	if(deadline < 0)
		return fail("read monotonic clock: %s", strerror(errno));
	deadline += Failtimeout;
	for(;;){
		n = waitpid(t->child, &status, WNOHANG);
		if(n == t->child){
			t->child = -1;
			readerrors(t);
			break;
		}
		if(n < 0 && errno == EINTR)
			continue;
		if(n < 0){
			if(errno == ECHILD)
				t->child = -1;
			return fail("waitpid: %s", strerror(errno));
		}
		n = leftms(deadline);
		if(n < 0)
			return fail("read monotonic clock: %s", strerror(errno));
		if(n == 0)
			return fail("daemon did not exit after map initialization failure");
		pfd.fd = t->errfd;
		pfd.events = POLLIN|POLLHUP;
		pfd.revents = 0;
		n = poll(&pfd, 1, n);
		if(n < 0 && errno == EINTR)
			continue;
		if(n < 0)
			return fail("poll daemon: %s", strerror(errno));
		if(n > 0)
			readerrors(t);
	}
	if(!WIFEXITED(status) || WEXITSTATUS(status) == 0)
		return fail("daemon map failure had wait status %#x", status);
	if(strstr(t->err, "can't open") == NULL || strstr(t->err, t->badmap) == NULL)
		return fail("daemon did not report the missing map directory");
	return 1;
}

static int
emptydir(char *path)
{
	DIR *dir;
	struct dirent *de;
	int empty;

	dir = opendir(path);
	if(dir == NULL)
		return fail("open %s: %s", path, strerror(errno));
	empty = 1;
	errno = 0;
	while((de = readdir(dir)) != NULL)
		if(strcmp(de->d_name, ".") != 0 && strcmp(de->d_name, "..") != 0){
			fail("unexpected endpoint %s/%s", path, de->d_name);
			empty = 0;
		}
	if(errno != 0){
		fail("read %s: %s", path, strerror(errno));
		empty = 0;
	}
	if(closedir(dir) < 0){
		fail("close %s: %s", path, strerror(errno));
		empty = 0;
	}
	return empty;
}

static int
checkendpoints(Test *t)
{
	struct stat st;

	if(lstat(t->socket, &st) == 0)
		return fail("IPC endpoint exists after failed startup: %s", t->socket);
	if(errno != ENOENT)
		return fail("lstat IPC endpoint: %s", strerror(errno));
	return emptydir(t->runtime) && emptydir(t->bus);
}

static int
cleanup(Test *t)
{
	int n, ok, status;

	ok = 1;
	if(t->child > 0){
		kill(t->child, SIGKILL);
		do
			n = waitpid(t->child, &status, 0);
		while(n < 0 && errno == EINTR);
		if(n != t->child)
			ok = fail("reap child: %s", strerror(errno));
		t->child = -1;
	}
	readerrors(t);
	if(t->errfd >= 0 && close(t->errfd) < 0)
		ok = fail("close stderr: %s", strerror(errno));
	if(t->socket[0] != '\0' && unlink(t->socket) < 0 && errno != ENOENT)
		ok = fail("remove socket: %s", strerror(errno));
	if(t->bus[0] != '\0' && rmdir(t->bus) < 0 && errno != ENOENT)
		ok = fail("remove bus directory: %s", strerror(errno));
	if(t->ibus[0] != '\0' && rmdir(t->ibus) < 0 && errno != ENOENT)
		ok = fail("remove IBus directory: %s", strerror(errno));
	if(t->config[0] != '\0' && rmdir(t->config) < 0 && errno != ENOENT)
		ok = fail("remove config directory: %s", strerror(errno));
	if(t->runtime[0] != '\0' && rmdir(t->runtime) < 0 && errno != ENOENT)
		ok = fail("remove runtime directory: %s", strerror(errno));
	if(t->home[0] != '\0' && rmdir(t->home) < 0 && errno != ENOENT)
		ok = fail("remove home directory: %s", strerror(errno));
	if(t->root[0] != '\0' && rmdir(t->root) < 0 && errno != ENOENT)
		ok = fail("remove root directory: %s", strerror(errno));
	return ok;
}

int
main(int argc, char **argv)
{
	Test test;
	int ok;

	if(argc != 2){
		fprintf(stderr, "usage: daemon_failure_test strans\n");
		return 2;
	}
	ok = setup(&test);
	if(ok)
		ok = startchild(&test, argv[1]);
	if(ok)
		ok = waitfailed(&test) && checkendpoints(&test);
	if(!cleanup(&test))
		ok = 0;
	if(!ok){
		if(test.nerr != 0)
			fprintf(stderr, "daemon_failure_test: daemon stderr:\n%s", test.err);
		return 1;
	}
	printf("failed daemon startup leaves no endpoints: ok\n");
	return 0;
}