/*
 *  Copyright (C) 2000 by Glenn McGrath
 *  Copyright (C) 2001 by Laurence Anderson
 *
 *  Based on previous work by busybox developers and others.
 *
 *  This program 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 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 Library General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <utime.h>
#include <libgen.h>

#include "libbb.h"
#include "gzip.h"

#define CONFIG_FEATURE_TAR_OLDGNU_COMPATABILITY 1
#define CONFIG_FEATURE_TAR_GNU_EXTENSIONS

#ifdef CONFIG_FEATURE_TAR_GNU_EXTENSIONS
static char *longname = NULL;
static char *linkname = NULL;
#endif

off_t archive_offset;

static ssize_t seek_forward(struct gzip_handle *zh, ssize_t len)
{
	ssize_t slen = gzip_seek(zh, len);

	if (slen == len)
		archive_offset += len;

	return slen;
}

/* Extract the data postioned at src_stream to either filesystem, stdout or
 * buffer depending on the value of 'function' which is defined in libbb.h
 *
 * prefix doesnt have to be just a directory, it may prefix the filename as well.
 *
 * e.g. '/var/lib/dpkg/info/dpkg.' will extract all files to the base bath
 * '/var/lib/dpkg/info/' and all files/dirs created in that dir will have
 * 'dpkg.' as their prefix
 *
 * For this reason if prefix does point to a dir then it must end with a
 * trailing '/' or else the last dir will be assumed to be the file prefix
 */
static char *extract_archive(struct gzip_handle *src_stream, FILE * out_stream,
			     const file_header_t * file_entry,
			     const int function, const char *prefix, int *err)
{
	FILE *dst_stream = NULL;
	char *full_name = NULL;
	char *full_link_name = NULL;
	char *buffer = NULL;
	struct utimbuf t;

	*err = 0;

	/* prefix doesnt have to be a proper path it may prepend
	 * the filename as well */
	if (prefix != NULL) {
		/* strip leading '/' in filename to extract as prefix may not be dir */
		/* Cant use concat_path_file here as prefix might not be a directory */
		char *path = file_entry->name;
		if (strncmp("./", path, 2) == 0) {
			path += 2;
			if (strlen(path) == 0)
				/* Do nothing, current dir already exists. */
				return NULL;
		}
		full_name = xmalloc(strlen(prefix) + strlen(path) + 1);
		strcpy(full_name, prefix);
		strcat(full_name, path);
		if (file_entry->link_name) {
			full_link_name =
			    xmalloc(strlen(prefix) +
				    strlen(file_entry->link_name) + 1);
			strcpy(full_link_name, prefix);
			strcat(full_link_name, file_entry->link_name);
		}
	} else {
		full_name = xstrdup(file_entry->name);
		if (file_entry->link_name)
			full_link_name = xstrdup(file_entry->link_name);
	}

	if (function & extract_to_stream) {
		if (S_ISREG(file_entry->mode)) {
			*err =
			    gzip_copy(src_stream, out_stream, file_entry->size);
			archive_offset += file_entry->size;
		}
	} else if (function & extract_one_to_buffer) {
		if (S_ISREG(file_entry->mode)) {
			buffer = (char *)xmalloc(file_entry->size + 1);
			gzip_read(src_stream, buffer, file_entry->size);
			buffer[file_entry->size] = '\0';
			archive_offset += file_entry->size;
			goto cleanup;
		}
	} else if (function & extract_all_to_fs) {
		struct stat oldfile;
		int stat_res;
		stat_res = lstat(full_name, &oldfile);
		if (stat_res == 0) {	/* The file already exists */
			if ((function & extract_unconditional)
			    || (oldfile.st_mtime < file_entry->mtime)) {
				if (!S_ISDIR(oldfile.st_mode)) {
					unlink(full_name);	/* Directories might not be empty etc */
				}
			} else {
				if ((function & extract_quiet) != extract_quiet) {
					*err = -1;
					error_msg
					    ("%s not created: newer or same age file exists",
					     file_entry->name);
				}
				seek_forward(src_stream, file_entry->size);
				goto cleanup;
			}
		}
		if (function & extract_create_leading_dirs) {	/* Create leading directories with default umask */
			char *buf, *parent;
			buf = xstrdup(full_name);
			parent = dirname(buf);
			if (make_directory(parent, -1, FILEUTILS_RECUR) != 0) {
				if ((function & extract_quiet) != extract_quiet) {
					*err = -1;
					error_msg
					    ("couldn't create leading directories");
				}
			}
			free(buf);
		}
		switch (file_entry->mode & S_IFMT) {
		case S_IFREG:
			if (file_entry->link_name) {	/* Found a cpio hard link */
				if (link(full_link_name, full_name) != 0) {
					if ((function & extract_quiet) !=
					    extract_quiet) {
						*err = -1;
						perror_msg
						    ("Cannot link from %s to '%s'",
						     file_entry->name,
						     file_entry->link_name);
					}
				}
			} else {
				if ((dst_stream =
				     wfopen(full_name, "w")) == NULL) {
					*err = -1;
					seek_forward(src_stream,
						     file_entry->size);
					goto cleanup;
				}
				archive_offset += file_entry->size;
				*err =
				    gzip_copy(src_stream, dst_stream,
					      file_entry->size);
				fclose(dst_stream);
			}
			break;
		case S_IFDIR:
			if (stat_res != 0) {
				if (mkdir(full_name, file_entry->mode) < 0) {
					if ((function & extract_quiet) !=
					    extract_quiet) {
						*err = -1;
						perror_msg("Cannot make dir %s",
							   full_name);
					}
				}
			}
			break;
		case S_IFLNK:
			if (symlink(file_entry->link_name, full_name) < 0) {
				if ((function & extract_quiet) != extract_quiet) {
					*err = -1;
					perror_msg
					    ("Cannot create symlink from %s to '%s'",
					     file_entry->name,
					     file_entry->link_name);
				}
				goto cleanup;
			}
			break;
		case S_IFSOCK:
		case S_IFBLK:
		case S_IFCHR:
		case S_IFIFO:
			if (mknod
			    (full_name, file_entry->mode,
			     file_entry->device) == -1) {
				if ((function & extract_quiet) != extract_quiet) {
					*err = -1;
					perror_msg("Cannot create node %s",
						   file_entry->name);
				}
				goto cleanup;
			}
			break;
		default:
			*err = -1;
			perror_msg("Don't know how to handle %s", full_name);

		}

		/* Changing a symlink's properties normally changes the properties of the
		 * file pointed to, so dont try and change the date or mode, lchown does
		 * does the right thing, but isnt available in older versions of libc */
		if (S_ISLNK(file_entry->mode)) {
#if (__GLIBC__ > 2) && (__GLIBC_MINOR__ > 1)
			lchown(full_name, file_entry->uid, file_entry->gid);
#endif
		} else {
			if (function & extract_preserve_date) {
				t.actime = file_entry->mtime;
				t.modtime = file_entry->mtime;
				utime(full_name, &t);
			}
			chown(full_name, file_entry->uid, file_entry->gid);
			chmod(full_name, file_entry->mode);
		}
	} else {
		/* If we arent extracting data we have to skip it,
		 * if data size is 0 then then just do it anyway
		 * (saves testing for it) */
		seek_forward(src_stream, file_entry->size);
	}

	/* extract_list and extract_verbose_list can be used in conjunction
	 * with one of the above four extraction functions, so do this seperately */
	if (function & extract_verbose_list) {
		fprintf(out_stream, "%s %d/%d %8d %s ",
			mode_string(file_entry->mode), file_entry->uid,
			file_entry->gid, (int)file_entry->size,
			time_string(file_entry->mtime));
	}
	if ((function & extract_list) || (function & extract_verbose_list)) {
		/* fputs doesnt add a trailing \n, so use fprintf */
		fprintf(out_stream, "%s\n", file_entry->name);
	}

cleanup:
	free(full_name);
	if (full_link_name)
		free(full_link_name);

	return buffer;
}

static char *unarchive(struct gzip_handle *src_stream, FILE * out_stream,
		       file_header_t * (*get_headers) (struct gzip_handle *),
		       void (*free_headers) (file_header_t *),
		       const int extract_function,
		       const char *prefix, const char **extract_names, int *err)
{
	file_header_t *file_entry;
	int extract_flag;
	int i;
	char *buffer = NULL;

	*err = 0;

	archive_offset = 0;
	while ((file_entry = get_headers(src_stream)) != NULL) {
		extract_flag = TRUE;

		if (extract_names != NULL) {
			int found_flag = FALSE;
			char *p = file_entry->name;

			if (p[0] == '.' && p[1] == '/')
				p += 2;

			for (i = 0; extract_names[i] != 0; i++) {
				if (strcmp(extract_names[i], p) == 0) {
					found_flag = TRUE;
					break;
				}
			}
			if (extract_function & extract_exclude_list) {
				if (found_flag == TRUE) {
					extract_flag = FALSE;
				}
			} else {
				/* If its not found in the include list dont extract it */
				if (found_flag == FALSE) {
					extract_flag = FALSE;
				}
			}
		}

		if (extract_flag == TRUE) {
			buffer = extract_archive(src_stream, out_stream,
						 file_entry, extract_function,
						 prefix, err);
			*err = 0;	/* XXX: ignore extraction errors */
			if (*err) {
				free_headers(file_entry);
				break;
			}
		} else {
			/* seek past the data entry */
			seek_forward(src_stream, file_entry->size);
		}
		free_headers(file_entry);
	}

	return buffer;
}

static file_header_t *get_header_tar(struct gzip_handle *tar_stream)
{
	union {
		unsigned char raw[512];
		struct {
			char name[100];	/*   0-99 */
			char mode[8];	/* 100-107 */
			char uid[8];	/* 108-115 */
			char gid[8];	/* 116-123 */
			char size[12];	/* 124-135 */
			char mtime[12];	/* 136-147 */
			char chksum[8];	/* 148-155 */
			char typeflag;	/* 156-156 */
			char linkname[100];	/* 157-256 */
			char magic[6];	/* 257-262 */
			char version[2];	/* 263-264 */
			char uname[32];	/* 265-296 */
			char gname[32];	/* 297-328 */
			char devmajor[8];	/* 329-336 */
			char devminor[8];	/* 337-344 */
			char prefix[155];	/* 345-499 */
			char padding[12];	/* 500-512 */
		} formated;
	} tar;
	file_header_t *tar_entry = NULL;
	long i;
	long sum = 0;

	if (archive_offset % 512 != 0) {
		seek_forward(tar_stream, 512 - (archive_offset % 512));
	}

	if (gzip_read(tar_stream, tar.raw, 512) != 512) {
		/* Unfortunately its common for tar files to have all sorts of
		 * trailing garbage, fail silently */
//              error_msg("Couldnt read header");
		return (NULL);
	}
	archive_offset += 512;

	/* Check header has valid magic, unfortunately some tar files
	 * have empty (0'ed) tar entries at the end, which will
	 * cause this to fail, so fail silently for now
	 */
	if (strncmp(tar.formated.magic, "ustar", 5) != 0) {
#ifdef CONFIG_FEATURE_TAR_OLDGNU_COMPATABILITY
		if (strncmp(tar.formated.magic, "\0\0\0\0\0", 5) != 0)
#endif
			return (NULL);
	}

	/* Do checksum on headers */
	for (i = 0; i < 148; i++) {
		sum += tar.raw[i];
	}
	sum += ' ' * 8;
	for (i = 156; i < 512; i++) {
		sum += tar.raw[i];
	}
	if (sum != strtol(tar.formated.chksum, NULL, 8)) {
		if (strtol(tar.formated.chksum, NULL, 8) != 0)
			error_msg("Invalid tar header checksum");
		return (NULL);
	}

	/* convert to type'ed variables */
	tar_entry = xcalloc(1, sizeof(file_header_t));

	// tar_entry->name = xstrdup(tar.formated.name);

/*
	parse_mode(tar.formated.mode, &tar_entry->mode);
*/
	tar_entry->mode = 07777 & strtol(tar.formated.mode, NULL, 8);

	tar_entry->uid = strtol(tar.formated.uid, NULL, 8);
	tar_entry->gid = strtol(tar.formated.gid, NULL, 8);
	tar_entry->size = strtol(tar.formated.size, NULL, 8);
	tar_entry->mtime = strtol(tar.formated.mtime, NULL, 8);

	tar_entry->device = (strtol(tar.formated.devmajor, NULL, 8) << 8) +
	    strtol(tar.formated.devminor, NULL, 8);

	/* Fix mode, used by the old format */
	switch (tar.formated.typeflag) {
		/* hard links are detected as regular files with 0 size and a link name */
	case '1':
		tar_entry->mode |= S_IFREG;
		break;
	case 0:
	case '0':

#ifdef CONFIG_FEATURE_TAR_OLDGNU_COMPATABILITY
		if (last_char_is(tar_entry->name, '/')) {
			tar_entry->mode |= S_IFDIR;
		} else
#endif
			tar_entry->mode |= S_IFREG;
		break;
	case '2':
		tar_entry->mode |= S_IFLNK;
		break;
	case '3':
		tar_entry->mode |= S_IFCHR;
		break;
	case '4':
		tar_entry->mode |= S_IFBLK;
		break;
	case '5':
		tar_entry->mode |= S_IFDIR;
		break;
	case '6':
		tar_entry->mode |= S_IFIFO;
		break;
#ifdef CONFIG_FEATURE_TAR_GNU_EXTENSIONS
	case 'L':{
			longname = xmalloc(tar_entry->size + 1);
			if (gzip_read(tar_stream, longname, tar_entry->size) !=
			    tar_entry->size)
				return NULL;
			longname[tar_entry->size] = '\0';
			archive_offset += tar_entry->size;

			return (get_header_tar(tar_stream));
		}
	case 'K':{
			linkname = xmalloc(tar_entry->size + 1);
			if (gzip_read(tar_stream, linkname, tar_entry->size) !=
			    tar_entry->size)
				return NULL;
			linkname[tar_entry->size] = '\0';
			archive_offset += tar_entry->size;

			return (get_header_tar(tar_stream));
		}
	case 'D':
	case 'M':
	case 'N':
	case 'S':
	case 'V':
		perror_msg("Ignoring GNU extension type %c",
			   tar.formated.typeflag);
#endif
	default:
		perror_msg("Unknown typeflag: 0x%x", tar.formated.typeflag);
		break;

	}

#ifdef CONFIG_FEATURE_TAR_GNU_EXTENSIONS
	if (longname) {
		tar_entry->name = longname;
		longname = NULL;
	} else
#endif
	{
		tar_entry->name = xstrndup(tar.formated.name, 100);

		if (tar.formated.prefix[0]) {
			char *temp = tar_entry->name;
			char *prefixTemp = xstrndup(tar.formated.prefix, 155);
			tar_entry->name = concat_path_file(prefixTemp, temp);
			free(temp);
			free(prefixTemp);
		}
	}

	if (linkname) {
		tar_entry->link_name = linkname;
		linkname = NULL;
	} else {
		tar_entry->link_name = *tar.formated.linkname != '\0' ?
		    xstrndup(tar.formated.linkname, 100) : NULL;
	}

	return (tar_entry);
}

static void free_header_tar(file_header_t * tar_entry)
{
	if (tar_entry == NULL)
		return;

	free(tar_entry->name);
	if (tar_entry->link_name)
		free(tar_entry->link_name);

	free(tar_entry);
}

char *deb_extract(const char *package_filename, FILE * out_stream,
		  const int extract_function, const char *prefix,
		  const char *filename, int *err)
{
	FILE *deb_stream = NULL;
	const char **file_list = NULL;
	char *output_buffer = NULL;
	char *ared_file = NULL;
	struct gzip_handle tar_outer = { }, tar_inner = { };
	file_header_t *tar_header;

	*err = 0;

	if (filename != NULL) {
		file_list = xmalloc(sizeof(char *) * 2);
		file_list[0] = filename;
		file_list[1] = NULL;
	}

	if (extract_function & extract_control_tar_gz) {
		ared_file = "control.tar.gz";
	} else if (extract_function & extract_data_tar_gz) {
		ared_file = "data.tar.gz";
	} else {
		opkg_msg(ERROR, "Internal error: extract_function=%x\n",
			 extract_function);
		*err = -1;
		goto cleanup;
	}

	/* open the debian package to be worked on */
	deb_stream = wfopen(package_filename, "r");
	if (deb_stream == NULL) {
		*err = -1;
		goto cleanup;
	}
	/* set the buffer size */
	setvbuf(deb_stream, NULL, _IOFBF, 0x8000);

	tar_outer.file = deb_stream;
	gzip_exec(&tar_outer, NULL);

	/* walk through outer tar file to find ared_file */
	while ((tar_header = get_header_tar(&tar_outer)) != NULL) {
		int name_offset = 0;
		if (strncmp(tar_header->name, "./", 2) == 0)
			name_offset = 2;

		if (strcmp(ared_file, tar_header->name + name_offset) == 0) {
			tar_inner.gzip = &tar_outer;
			gzip_exec(&tar_inner, NULL);

			archive_offset = 0;

			output_buffer = unarchive(&tar_inner,
						  out_stream,
						  get_header_tar,
						  free_header_tar,
						  extract_function,
						  prefix, file_list, err);

			free_header_tar(tar_header);
			gzip_close(&tar_inner);
			break;
		}

		seek_forward(&tar_outer, tar_header->size);
		free_header_tar(tar_header);
	}

cleanup:
	gzip_close(&tar_outer);

	if (file_list)
		free(file_list);

	return output_buffer;
}