/*
 * Copyright 2013 The Chromium OS Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>

#include "futility.h"

#define MYNAME "futility"
#define MYNAME_S MYNAME "_s"

/* File to use for logging, if present */
#define LOGFILE "/tmp/futility.log"

/* Normally logging will only happen if the logfile already exists. Uncomment
 * this to force log file creation (and thus logging) always. */
/* #define FORCE_LOGGING_ON */

/******************************************************************************/

static const char *const usage = "\n\
Usage: " MYNAME " PROGRAM|COMMAND [args...]\n\
\n\
This is the unified firmware utility, which will eventually replace\n\
most of the distinct verified boot tools formerly produced by the\n\
vboot_reference package.\n\
\n\
When symlinked under the name of one of those previous tools, should\n\
fully implement the original behavior. It can also be invoked directly\n\
as " MYNAME ", followed by the original name as the first argument.\n\
\n\
In either case it will append some usage information to " LOGFILE "\n\
(iff that file exists), to help improve coverage and correctness.\n\
\n";

static int do_help(int argc, char *argv[])
{
	const struct futil_cmd_t *const *cmd;
	int i;

	fputs(usage, stdout);

	printf("The following commands are built-in:\n\n");

	for (cmd = futil_cmds; *cmd; cmd++)
		printf("  %-20s %s\n", (*cmd)->name, (*cmd)->shorthelp);
	printf("\n");

	if (argc) {
		printf("FYI, you added these args that I'm ignoring:\n");
		for (i = 0; i < argc; i++)
			printf("argv[%d] = %s\n", i, argv[i]);
	}

	return 0;
}

DECLARE_FUTIL_COMMAND(help, do_help,
		      "Show a bit of help (you're looking at it)");

/*
 * These are built-in functions that we'd like to abandon completely someday.
 * TODO: If no one complains, get rid of them.
 */
static const char *const dep_cmds[] = {
	"dev_sign_file",
};

static const char *const dep_usage = "\n\
The program \"%s\" is deprecated and may go away soon.\n\
\n\
If you feel this is in error, please open a bug at\n\
\n\
  http://dev.chromium.org/for-testers/bug-reporting-guidelines\n\
\n\
In the meantime, you may continue to use the program by invoking it as\n\
\n\
  " MYNAME " %s [...]\n\
\n";

static void deprecated(const char *depname)
{
	fprintf(stderr, dep_usage, depname, depname);
	exit(1);
}

/******************************************************************************/
/* Logging stuff */

static int log_fd = -1;

/* Write the string and a newline. Silently give up on errors */
static void log_str(char *str)
{
	int len, done, n;

	if (log_fd < 0)
		return;

	if (!str)
		str = "(NULL)";

	len = strlen(str);
	if (len == 0) {
		str = "(EMPTY)";
		len = strlen(str);
	}

	for (done = 0; done < len; done += n) {
		n = write(log_fd, str + done, len - done);
		if (n < 0)
			return;
	}

	if (write(log_fd, "\n", 1) < 0)
		return;
}

static void log_close(void)
{
	struct flock lock;

	if (log_fd >= 0) {
		memset(&lock, 0, sizeof(lock));
		lock.l_type = F_UNLCK;
		lock.l_whence = SEEK_SET;
		if (fcntl(log_fd, F_SETLKW, &lock))
			perror("Unable to unlock log file");

		close(log_fd);
		log_fd = -1;
	}
}

static void log_open(void)
{
	struct flock lock;
	int ret;

#ifdef FORCE_LOGGING_ON
	log_fd = open(LOGFILE, O_WRONLY | O_APPEND | O_CREAT, 0666);
#else
	log_fd = open(LOGFILE, O_WRONLY | O_APPEND);
#endif
	if (log_fd < 0) {

		if (errno != EACCES)
			return;

		/* Permission problems should improve shortly ... */
		sleep(1);
		log_fd = open(LOGFILE, O_WRONLY | O_APPEND | O_CREAT, 0666);
		if (log_fd < 0)	/* Nope, they didn't */
			return;
	}

	/* Let anyone have a turn */
	fchmod(log_fd, 0666);

	/* But only one at a time */
	memset(&lock, 0, sizeof(lock));
	lock.l_type = F_WRLCK;
	lock.l_whence = SEEK_END;

	ret = fcntl(log_fd, F_SETLKW, &lock);	/* this blocks */
	if (ret < 0)
		log_close();
}

#define CALLER_PREFIX "CALLER:"
static void log_args(int argc, char *argv[])
{
	int i;
	ssize_t r;
	pid_t parent;
	char buf[80];
	char str_caller[PATH_MAX + sizeof(CALLER_PREFIX)] = CALLER_PREFIX;
	char *truename = str_caller + sizeof(CALLER_PREFIX) - 1;
	/* Note: truename starts on the \0 from CALLER_PREFIX, so we can write
	 * PATH_MAX chars into truename and still append a \0 at the end. */

	log_open();

	/* delimiter */
	log_str("##### HEY #####");

	/* Can we tell who called us? */
	parent = getppid();
	snprintf(buf, sizeof(buf), "/proc/%d/exe", parent);
	r = readlink(buf, truename, PATH_MAX);
	if (r >= 0) {
		truename[r] = '\0';
		log_str(str_caller);
	}

	/* Now log the stuff about ourselves */
	for (i = 0; i < argc; i++)
		log_str(argv[i]);

	log_close();
}

/******************************************************************************/
/* Here we go */

int main(int argc, char *argv[], char *envp[])
{
	char *fullname, *progname;
	char truename[PATH_MAX];
	char buf[80];
	pid_t myproc;
	ssize_t r;
	const struct futil_cmd_t *const *cmd;
	int i;
	int via_symlink = 0;

	log_args(argc, argv);

	/* How were we invoked? */
	fullname = strdup(argv[0]);
	progname = strrchr(argv[0], '/');
	if (progname)
		progname++;
	else
		progname = argv[0];

	/* Invoked directly by name */
	if (0 == strcmp(progname, MYNAME) || 0 == strcmp(progname, MYNAME_S)) {
		if (argc < 2) {	/* must have an argument */
			do_help(0, 0);
			exit(1);
		}

		/* We can just pass the rest along, then */
		argc--;
		argv++;

		/* So now what function do we want to invoke? */
		progname = strrchr(argv[0], '/');
		if (progname)
			progname++;
		else
			progname = argv[0];
	} else {		/* Invoked by symlink */
		via_symlink = 1;
		/* Block any deprecated functions. */
		for (i = 0; i < ARRAY_SIZE(dep_cmds); i++)
			if (0 == strcmp(dep_cmds[i], progname))
				deprecated(progname);
	}

	/* See if it's asking for something we know how to do ourselves */
	for (cmd = futil_cmds; *cmd; cmd++)
		if (0 == strcmp((*cmd)->name, progname))
			return (*cmd)->handler(argc, argv);

	/* Nope */
	if (!via_symlink) {
		do_help(0, 0);
		exit(1);
	}

	/* Complain about bogus symlink */

	myproc = getpid();
	snprintf(buf, sizeof(buf), "/proc/%d/exe", myproc);
	r = readlink(buf, truename, PATH_MAX - 1);
	if (r < 0) {
		fprintf(stderr, "%s is lost: %s => %s: %s\n", MYNAME, argv[0],
			buf, strerror(errno));
		exit(1);
	}
	truename[r] = '\0';

	fprintf(stderr, "\n\
The program\n\n  %s\n\nis a symlink to\n\n  %s\n\
\n\
However, " MYNAME " doesn't know how to implement that function.\n\
\n\
This is probably an error in your installation. If the problem persists\n\
after a fresh checkout/build/install, please open a bug at\n\
\n\
  http://dev.chromium.org/for-testers/bug-reporting-guidelines\n\
\n", fullname, truename);
	return 1;
}