/*
 * Copyright (C) 2023  Patrick McDermott
 *
 * This file is part of opkg-opk.
 *
 * opkg-opk is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * opkg-opk is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with opkg-opk.  If not, see <https://www.gnu.org/licenses/>.
 */

#include "config.h"

#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
#include "defs.h"
#include "error.h"
#include "mode.h"

#ifdef ENABLE_NLS
#include <locale.h>
#include <libintl.h>
#define _(msgid) gettext(msgid)
#else
#define _(msgid) (msgid)
#endif

#ifdef HAVE_GETOPT_LONG
#include <getopt.h>
#endif

static const char *_OPTSTRING = "m:";
#ifdef HAVE_GETOPT_LONG
static const struct option _LONGOPTS[] = {
	{
		.name    = "mode",
		.has_arg = 1,
		.flag    = NULL,
		.val     = 'm',
	},
};
#endif

static const unsigned int _TIMEOUT = 10U;

static int
_get_work_area(int argc, char *argv[], char **work_area)
{
	char **exec_argv;
	int    arg;

	*work_area = getenv("OPK_WORK_AREA");
	if (*work_area == NULL || *work_area[0] == '\0') {
		opkg_opk_error(_("OPK_WORK_AREA environment variable not set"));
		opkg_opk_error(_("Possibly building package dependent on "
					"opkg-opk with opkbuild too old to use "
					"it"));
		opkg_opk_error(_("Executing system mknod instead"));
		exec_argv = calloc(argc + 1, sizeof(*exec_argv));
		if (exec_argv == NULL) {
			opkg_opk_error(_("Failed to allocate memory"));
			return OPKG_OPK_ERROR;
		}
		exec_argv[0] = malloc(strlen(MKNOD) + 1);
		if (exec_argv[0] == NULL) {
			opkg_opk_error(_("Failed to allocate memory"));
			free(exec_argv);
			return OPKG_OPK_ERROR;
		}
		strcpy(exec_argv[0], MKNOD);
		for (arg = 1; arg < argc; ++arg) {
			exec_argv[arg] = argv[arg];
		}
		exec_argv[argc] = NULL;
		execve(MKNOD, exec_argv, NULL);  /* Shouldn't return */
		opkg_opk_error(_("Failed to execute system mknod"));
		free(exec_argv[0]);
		free(exec_argv);
		return OPKG_OPK_ERROR;
	}
	return OPKG_OPK_OK;
}

static int
_strtol_or_err(const char *str, long int *l)
{
	char *end;

	*l = strtol(str, &end, 10);
	if (*end != '\0') {
		opkg_opk_error(_("Invalid number \"%s\""), str);
		return OPKG_OPK_ERROR;
	}
	return OPKG_OPK_OK;
}

int
main(int argc, char *argv[])
{
	char          *work_area;
	mode_t         mode;
	int            opt;
	char          *name;
	char           type;
	long int       major;
	long int       minor;
	size_t         work_area_len;
	size_t         specials_file_name_len;
	char          *specials_file_name;
	char          *specials_lock_name;
	int            fd;
	unsigned int   timeout;
	int            specials_fd;
	FILE          *specials_file;
	struct stat    stat_buf;

#ifdef ENABLE_NLS
	bindtextdomain(GETTEXT_PACKAGE, LOCALEDIR);
#ifdef HAVE_BIND_TEXTDOMAIN_CODESET
	bind_textdomain_codeset(PACKAGE, "UTF-8");
#endif
	textdomain(PACKAGE);
	setlocale(LC_ALL, "");
#endif

	opkg_opk_set_program_name(argv[0]);

	if (_get_work_area(argc, argv, &work_area) != OPKG_OPK_OK) {
		return EXIT_FAILURE;
	}

	mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
#ifdef HAVE_GETOPT_LONG
	while ((opt = getopt_long(argc, argv, _OPTSTRING, _LONGOPTS, NULL))
			!= -1) {
#else
	while ((opt = getopt(argc, argv, _OPTSTRING)) != -1) {
#endif
		switch(opt) {
			case 'm':
				mode = umask(0);
				umask(mode);
				mode = 0666 ^ mode;
				if (opkg_opk_helper_mode_parse(mode, optarg,
							&mode) != OPKG_OPK_OK) {
					opkg_opk_error(_("Invalid mode \"%s\""),
							optarg);
					return EXIT_FAILURE;
				}
				break;
			default:
				opkg_opk_error(_("Warning: Unknown option: "
							"\"%c\""), optopt);
		}
	}
	argc -= optind;
	argv += optind;

	if (argc < 2) {
		opkg_opk_error(_("Wrong number of operands"));
		return EXIT_FAILURE;
	}
	name = argv[0];
	switch (argv[1][0]) {
		case 'c':
		case 'u':
			type = 'c';
			break;
		case 'b':
			type = 'b';
			break;
		case 'p':
			if (argc != 2) {
				opkg_opk_error(_("Wrong number of operands"));
				return EXIT_FAILURE;
			}
			if (mkfifo(name, mode) != 0) {
				opkg_opk_errno(_("Failed to create link "
							"\"%s\""), name);
				return EXIT_FAILURE;
			}
			return EXIT_SUCCESS;
		default:
			opkg_opk_error(_("Invalid node type \"%c\""),
					argv[1][0]);
			return EXIT_FAILURE;
	}

	if (argc != 4) {
		opkg_opk_error(_("Wrong number of operands"));
		return EXIT_FAILURE;
	}
	if (_strtol_or_err(argv[2], &major) != OPKG_OPK_OK ||
			_strtol_or_err(argv[3], &minor) != OPKG_OPK_OK) {
		return EXIT_FAILURE;
	}

	/* Find path of file relative to binary package data directory within
	 * build work area. */
	work_area_len = strlen(work_area);
	if (work_area[work_area_len - 1] == '/') {
		--work_area_len;
	}
	if (strncmp(name, work_area, work_area_len) != 0 ||
			name[work_area_len] != '/') {
		opkg_opk_error(_("Node \"%s\" not within work area \"%s\""),
				name, work_area);
		return EXIT_FAILURE;
	}
	do {
		++work_area_len;
		if (name[work_area_len] == '\0') {
			opkg_opk_error(_("Node \"%s\" not within a binary "
						"package data directory"),
					name);
			return EXIT_FAILURE;
		}
	} while (name[work_area_len] != '/');

	specials_file_name_len = strlen(work_area) + strlen("/specials") + 1;
	specials_file_name = malloc(specials_file_name_len * 2 + 1);
	if (specials_file_name == NULL) {
		opkg_opk_error(_("Failed to allocate memory"));
		return EXIT_FAILURE;
	}
	specials_lock_name = specials_file_name + specials_file_name_len ;
	sprintf(specials_file_name, "%s/specials",  work_area);
	sprintf(specials_lock_name, "%s/specials~", work_area);

	/* Create the named node.  This should be done before appending to the
	 * specials file, in case a file by the specified name already exists.
	 */
	fd = open(name, O_CREAT | O_EXCL, mode);
	if (fd < 0 || close(fd) < 0) {
		opkg_opk_errno(_("Failed to create node"));
		goto err0;
	}

	/* Acquire lock ("specials~"). */
	for (timeout = _TIMEOUT; timeout > 0; --timeout) {
		specials_fd = open(specials_lock_name,
				O_CREAT | O_EXCL | O_WRONLY, 0644);
		if (specials_fd >= 0) {
			goto opened;
		}
	}
	opkg_opk_errno(_("Failed to lock specials file"));
	goto err1;

 opened:
	close(specials_fd);

	specials_file = fopen(specials_file_name, "a");
	if (specials_file == NULL) {
		opkg_opk_errno(_("Failed to open specials file stream"));
		goto err2;
	}

	/* If "specials" is empty, write header. */
	if (fstat(fileno(specials_file), &stat_buf) != 0) {
		opkg_opk_errno(_("Failed to stat specials file"));
		goto err3;
	}
	if (stat_buf.st_size == 0) {
		if (fputs("version=1\n", specials_file) < 0 ||
				fputs("type     major     minor  name\n",
					specials_file) < 0) {
			opkg_opk_errno(_("Failed to write specials file"));
			goto err3;
		}
	}

	if (fprintf(specials_file, "%c     %8ld  %8ld  %s\n",
				type, major, minor, name + work_area_len) < 0) {
		opkg_opk_errno(_("Failed to write specials file"));
		goto err3;
	}

	fclose(specials_file);
	unlink(specials_lock_name);
	free(specials_file_name);

	return EXIT_SUCCESS;

 err3:
	fclose(specials_file);
 err2:
	unlink(specials_lock_name);
 err1:
	unlink(name);
 err0:
	free(specials_file_name);
	return EXIT_FAILURE;
}