/*

  *  Copyright (C) 2007-2008 Sourcefire, Inc.
  *
  *  Authors: Nigel Horne

  *
  *  This program is free software; you can redistribute it and/or modify

  *  it under the terms of the GNU General Public License version 2 as
  *  published by the Free Software Foundation.

  *
  *  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 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., 51 Franklin Street, Fifth Floor, Boston,
  *  MA 02110-1301, USA.

  */

 static	char	const	rcsid[] = "$Id: untar.c,v 1.35 2007/02/12 20:46:09 njh Exp $";

 
 #if HAVE_CONFIG_H
 #include "clamav-config.h"
 #endif

 
 #include <stdio.h>
 #include <errno.h>
 #include <string.h>

 #ifdef	HAVE_UNISTD_H

 #include <unistd.h>

 #endif

 #include <sys/stat.h>

 #include <fcntl.h>

 #ifdef	HAVE_SYS_PARAM_H

 #include <sys/param.h>	/* for NAME_MAX */

 #endif

 
 #include "clamav.h"
 #include "others.h"

 #include "untar.h"

 #include "mbox.h"
 #include "blob.h"

 #include "scanners.h"

 
 #define BLOCKSIZE 512
 

 #ifndef	O_BINARY
 #define	O_BINARY	0
 #endif
 

 static int
 octal(const char *str)

 {

 	int ret;

 	if(sscanf(str, "%o", (unsigned int *)&ret) != 1)
 		return -1;

 	return ret;
 }
 
 int

 cli_untar(const char *dir, int desc, unsigned int posix, cli_ctx *ctx)

 {

 	int size = 0, ret, fout=-1;

 	int in_block = 0;

 	unsigned int files = 0;

 	char fullname[NAME_MAX + 1];

 	cli_dbgmsg("In untar(%s, %d)\n", dir, desc);

 
 	for(;;) {
 		char block[BLOCKSIZE];

 		const int nread = cli_readn(desc, block, (unsigned int)sizeof(block));

 
 		if(!in_block && nread == 0)
 			break;
 

 		if(nread < 0) {

 			if(fout>=0)
 				close(fout);

 			cli_errmsg("cli_untar: block read error\n");

 			return CL_EREAD;

 		}
 
 		if(!in_block) {
 			char type;

 			int directory, skipEntry = 0;

 			char magic[7], name[101], osize[13];
 

 			if(fout>=0) {
 				lseek(fout, 0, SEEK_SET);
 				ret = cli_magic_scandesc(fout, ctx);
 				close(fout);

 				if (!ctx->engine->keeptmp)

 					if (cli_unlink(fullname)) return CL_EUNLINK;

 				if (ret==CL_VIRUS)
 					return CL_VIRUS;
 				fout = -1;

 			}

 			if(block[0] == '\0')	/* We're done */

 				break;

 			if((ret=cli_checklimits("cli_untar", ctx, 0, 0, 0))!=CL_CLEAN)
 				return ret;

 			/* Notice assumption that BLOCKSIZE > 262 */

 			if(posix) {
 				strncpy(magic, block+257, 5);
 				magic[5] = '\0';
 				if(strcmp(magic, "ustar") != 0) {

 					cli_dbgmsg("cli_untar: Incorrect magic string '%s' in tar header\n", magic);

 					return CL_EFORMAT;
 				}

 			}
 
 			type = block[156];
 
 			switch(type) {

 				default:

 					cli_dbgmsg("cli_untar: unknown type flag %c\n", type);

 				case '0':	/* plain file */
 				case '\0':	/* plain file */
 				case '7':	/* contiguous file */

 				case 'M':	/* continuation of a file from another volume; might as well scan it. */

 					files++;

 					directory = 0;
 					break;

 				case '1':	/* Link to already archived file */

 				case '5':	/* directory */
 				case '2':	/* sym link */
 				case '3':	/* char device */
 				case '4':	/* block device */
 				case '6':	/* fifo special */

 				case 'V':	/* Volume header */

 					directory = 1;
 					break;

 				case 'K':
 				case 'L':
 					/* GNU extension - ././@LongLink
 					 * Discard the blocks with the extended filename,
 					 * the last header will contain parts of it anyway
 					 */

 				case 'N': 	/* Old GNU format way of storing long filenames. */
 				case 'A':	/* Solaris ACL */
 				case 'E':	/* Solaris Extended attribute s*/
 				case 'I':	/* Inode only */
 				case 'g':	/* Global extended header */
 				case 'x': 	/* Extended attributes */
 				case 'X':	/* Extended attributes (POSIX) */

 					directory = 0;
 					skipEntry = 1;
 					break;

 			}
 

 			if(directory) {
 				in_block = 0;

 				continue;

 			}

 			strncpy(osize, block+124, 12);
 			osize[12] = '\0';
 			size = octal(osize);
 			if(size < 0) {

 				cli_dbgmsg("cli_untar: Invalid size in tar header\n");

 				skipEntry++;

 			} else {
 				cli_dbgmsg("cli_untar: size = %d\n", size);
 				if((ret=cli_checklimits("cli_untar", ctx, size, 0, 0))!=CL_CLEAN)
 					skipEntry++;

 			}

 
 			if(skipEntry) {
 				const int nskip = (size % BLOCKSIZE || !size) ? size + BLOCKSIZE - (size % BLOCKSIZE) : size;

 				
 				if(nskip < 0) {
 					cli_dbgmsg("cli_untar: got nagative skip size, giving up\n");
 					return CL_CLEAN;
 				}

 				cli_dbgmsg("cli_untar: skipping entry\n");

 				lseek(desc, nskip, SEEK_CUR);
 				continue;
 			}
 

 			strncpy(name, block, 100);
 			name[100] = '\0';

 			snprintf(fullname, sizeof(fullname)-1, "%s/tar%02u", dir, files);
 			fullname[sizeof(fullname)-1] = '\0';
 			fout = open(fullname, O_RDWR|O_CREAT|O_EXCL|O_TRUNC|O_BINARY, 0600);

 			if(fout < 0) {

 				char err[128];
 				cli_errmsg("cli_untar: Can't create temporary file %s: %s\n", fullname, cli_strerror(errno, err, sizeof(err)));

 				return CL_ETMPFILE;
 			}

 			cli_dbgmsg("cli_untar: extracting to %s\n", fullname);

 
 			in_block = 1;

 		} else { /* write or continue writing file contents */
 			const int nbytes = size>512? 512:size;

 			const int nwritten = (int)write(fout, block, (size_t)nbytes);

 
 			if(nwritten != nbytes) {

 				cli_errmsg("cli_untar: only wrote %d bytes to file %s (out of disc space?)\n",

 					nwritten, fullname);

 				close(fout);

 				return CL_EWRITE;

 			}
 			size -= nbytes;
 		}

 		if (size == 0)
 			in_block = 0;

         }	

 	if(fout>=0) {
 		lseek(fout, 0, SEEK_SET);
 		ret = cli_magic_scandesc(fout, ctx);
 		close(fout);

 		if (!ctx->engine->keeptmp)

 			if (cli_unlink(fullname)) return CL_EUNLINK;

 		if (ret==CL_VIRUS)
 			return CL_VIRUS;
 	}
 	return CL_CLEAN;

 }