archival/libunarchive/get_header_tar.c - codeaurora/busybox - Gitiles

 /* vi: set sw=4 ts=4: */
 /* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  *
  *  FIXME:
  *    In privileged mode if uname and gname map to a uid and gid then use the
  *    mapped value instead of the uid/gid values in tar header
  *
  *  References:
  *    GNU tar and star man pages,
  *    Opengroup's ustar interchange format,
  *	http://www.opengroup.org/onlinepubs/007904975/utilities/pax.html
  */

 #include "libbb.h"
 #include "unarchive.h"

 #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
 static char *longname;
 static char *linkname;
 #else
 enum {
 	longname = 0,
 	linkname = 0,
 };
 #endif

 /* NB: _DESTROYS_ str[len] character! */
 static unsigned long long getOctal(char *str, int len)
 {
 	unsigned long long v;
 	/* Actually, tar header allows leading spaces also.
 	 * Oh well, we will be liberal and skip this...
 	 * The only downside probably is that we allow "-123" too :)
 	if (*str < '0' || *str > '7')
 		bb_error_msg_and_die("corrupted octal value in tar header");
 	*/
 	str[len] = '\0';
 	v = strtoull(str, &str, 8);
 	if (*str)
 		bb_error_msg_and_die("corrupted octal value in tar header");
 	return v;
 }
 #define GET_OCTAL(a) getOctal((a), sizeof(a))

 void BUG_tar_header_size(void);
 char get_header_tar(archive_handle_t *archive_handle)
 {
 	static int end;

 	file_header_t *file_header = archive_handle->file_header;
 	struct {
 		/* ustar header, Posix 1003.1 */
 		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 */
 	} tar;
 	char *cp;
 	int i, sum_u, sum_s, sum;
 	int parse_names;

 	if (sizeof(tar) != 512)
 		BUG_tar_header_size();

 #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
  again:
 #endif
 	/* Align header */
 	data_align(archive_handle, 512);

  again_after_align:

 	xread(archive_handle->src_fd, &tar, 512);
 	archive_handle->offset += 512;

 	/* If there is no filename its an empty header */
 	if (tar.name[0] == 0) {
 		if (end) {
 			/* This is the second consecutive empty header! End of archive!
 			 * Read until the end to empty the pipe from gz or bz2
 			 */
 			while (full_read(archive_handle->src_fd, &tar, 512) == 512)
 				/* repeat */;
 			return EXIT_FAILURE;
 		}
 		end = 1;
 		return EXIT_SUCCESS;
 	}
 	end = 0;

 	/* Check header has valid magic, "ustar" is for the proper tar
 	 * 0's are for the old tar format
 	 */
 	if (strncmp(tar.magic, "ustar", 5) != 0) {
 #if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
 		if (memcmp(tar.magic, "\0\0\0\0", 5) != 0)
 #endif
 			bb_error_msg_and_die("invalid tar magic");
 	}

 	/* Do checksum on headers.
 	 * POSIX says that checksum is done on unsigned bytes, but
 	 * Sun and HP-UX gets it wrong... more details in
 	 * GNU tar source. */
 	sum_s = sum_u = ' ' * sizeof(tar.chksum);
 	for (i = 0; i < 148 ; i++) {
 		sum_u += ((unsigned char*)&tar)[i];
 		sum_s += ((signed char*)&tar)[i];
 	}
 	for (i = 156; i < 512 ; i++) {
 		sum_u += ((unsigned char*)&tar)[i];
 		sum_s += ((signed char*)&tar)[i];
 	}
 	/* This field does not need special treatment (getOctal) */
 	sum = xstrtoul(tar.chksum, 8);
 	if (sum_u != sum && sum_s != sum) {
 		bb_error_msg_and_die("invalid tar header checksum");
 	}

 	/* 0 is reserved for high perf file, treat as normal file */
 	if (!tar.typeflag) tar.typeflag = '0';
 	parse_names = (tar.typeflag >= '0' && tar.typeflag <= '7');

 	/* getOctal trashes subsequent field, therefore we call it
 	 * on fields in reverse order */
 	if (tar.devmajor[0]) {
 		unsigned minor = GET_OCTAL(tar.devminor);
 		unsigned major = GET_OCTAL(tar.devmajor);
 		file_header->device = makedev(major, minor);
 	}
 	file_header->link_target = NULL;
 	if (!linkname && parse_names && tar.linkname[0]) {
 		/* we trash magic[0] here, it's ok */
 		tar.linkname[sizeof(tar.linkname)] = '\0';
 		file_header->link_target = xstrdup(tar.linkname);
 		/* FIXME: what if we have non-link object with link_target? */
 		/* Will link_target be free()ed? */
 	}
 	file_header->mtime = GET_OCTAL(tar.mtime);
 	file_header->size = GET_OCTAL(tar.size);
 	file_header->gid = GET_OCTAL(tar.gid);
 	file_header->uid = GET_OCTAL(tar.uid);
 	/* Set bits 0-11 of the files mode */
 	file_header->mode = 07777 & GET_OCTAL(tar.mode);

 	file_header->name = NULL;
 	if (!longname && parse_names) {
 		/* we trash mode[0] here, it's ok */
 		tar.name[sizeof(tar.name)] = '\0';
 		if (tar.prefix[0]) {
 			/* and padding[0] */
 			tar.prefix[sizeof(tar.prefix)] = '\0';
 			file_header->name = concat_path_file(tar.prefix, tar.name);
 		} else
 			file_header->name = xstrdup(tar.name);
 	}

 	/* Set bits 12-15 of the files mode */
 	/* (typeflag was not trashed because chksum does not use getOctal) */
 	switch (tar.typeflag) {
 	/* busybox identifies hard links as being regular files with 0 size and a link name */
 	case '1':
 		file_header->mode |= S_IFREG;
 		break;
 	case '7':
 	/* case 0: */
 	case '0':
 #if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
 		if (last_char_is(file_header->name, '/')) {
 			file_header->mode |= S_IFDIR;
 		} else
 #endif
 		file_header->mode |= S_IFREG;
 		break;
 	case '2':
 		file_header->mode |= S_IFLNK;
 		break;
 	case '3':
 		file_header->mode |= S_IFCHR;
 		break;
 	case '4':
 		file_header->mode |= S_IFBLK;
 		break;
 	case '5':
 		file_header->mode |= S_IFDIR;
 		break;
 	case '6':
 		file_header->mode |= S_IFIFO;
 		break;
 #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
 	case 'L':
 		/* free: paranoia: tar with several consecutive longnames */
 		free(longname);
 		/* For paranoia reasons we allocate extra NUL char */
 		longname = xzalloc(file_header->size + 1);
 		/* We read ASCIZ string, including NUL */
 		xread(archive_handle->src_fd, longname, file_header->size);
 		archive_handle->offset += file_header->size;
 		/* return get_header_tar(archive_handle); */
 		/* gcc 4.1.1 didn't optimize it into jump */
 		/* so we will do it ourself, this also saves stack */
 		goto again;
 	case 'K':
 		free(linkname);
 		linkname = xzalloc(file_header->size + 1);
 		xread(archive_handle->src_fd, linkname, file_header->size);
 		archive_handle->offset += file_header->size;
 		/* return get_header_tar(archive_handle); */
 		goto again;
 	case 'D':	/* GNU dump dir */
 	case 'M':	/* Continuation of multi volume archive */
 	case 'N':	/* Old GNU for names > 100 characters */
 	case 'S':	/* Sparse file */
 	case 'V':	/* Volume header */
 #endif
 	case 'g':	/* pax global header */
 	case 'x': {	/* pax extended header */
 		off_t sz;
 		bb_error_msg("warning: skipping header '%c'", tar.typeflag);
 		sz = (file_header->size + 511) & ~(off_t)511;
 		archive_handle->offset += sz;
 		sz >>= 9; /* sz /= 512 but w/o contortions for signed div */
 		while (sz--)
 			xread(archive_handle->src_fd, &tar, 512);
 		/* return get_header_tar(archive_handle); */
 		goto again_after_align;
 	}
 	default:
 		bb_error_msg_and_die("unknown typeflag: 0x%x", tar.typeflag);
 	}

 #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
 	if (longname) {
 		file_header->name = longname;
 		longname = NULL;
 	}
 	if (linkname) {
 		file_header->link_target = linkname;
 		linkname = NULL;
 	}
 #endif
 	if (!strncmp(file_header->name, "/../"+1, 3)
 	 || strstr(file_header->name, "/../")
 	) {
 		bb_error_msg_and_die("name with '..' encountered: '%s'",
 				file_header->name);
 	}

 	/* Strip trailing '/' in directories */
 	/* Must be done after mode is set as '/' is used to check if it's a directory */
 	cp = last_char_is(file_header->name, '/');

 	if (archive_handle->filter(archive_handle) == EXIT_SUCCESS) {
 		archive_handle->action_header(archive_handle->file_header);
 		/* Note that we kill the '/' only after action_header() */
 		/* (like GNU tar 1.15.1: verbose mode outputs "dir/dir/") */
 		if (cp) *cp = '\0';
 		archive_handle->flags |= ARCHIVE_EXTRACT_QUIET;
 		archive_handle->action_data(archive_handle);
 		llist_add_to(&(archive_handle->passed), file_header->name);
 	} else {
 		data_skip(archive_handle);
 		free(file_header->name);
 	}
 	archive_handle->offset += file_header->size;

 	free(file_header->link_target);
 	/* Do not free(file_header->name)! */

 	return EXIT_SUCCESS;
 }
	/* vi: set sw=4 ts=4: */
	/* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
	*
	* FIXME:
	* In privileged mode if uname and gname map to a uid and gid then use the
	* mapped value instead of the uid/gid values in tar header
	*
	* References:
	* GNU tar and star man pages,
	* Opengroup's ustar interchange format,
	* http://www.opengroup.org/onlinepubs/007904975/utilities/pax.html
	*/

	#include "libbb.h"
	#include "unarchive.h"

	#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
	static char *longname;
	static char *linkname;
	#else
	enum {
	longname = 0,
	linkname = 0,
	};
	#endif

	/* NB: _DESTROYS_ str[len] character! */
	static unsigned long long getOctal(char *str, int len)
	{
	unsigned long long v;
	/* Actually, tar header allows leading spaces also.
	* Oh well, we will be liberal and skip this...
	* The only downside probably is that we allow "-123" too :)
	if (str < '0' \|\| str > '7')
	bb_error_msg_and_die("corrupted octal value in tar header");
	*/
	str[len] = '\0';
	v = strtoull(str, &str, 8);
	if (*str)
	bb_error_msg_and_die("corrupted octal value in tar header");
	return v;
	}
	#define GET_OCTAL(a) getOctal((a), sizeof(a))

	void BUG_tar_header_size(void);
	char get_header_tar(archive_handle_t *archive_handle)
	{
	static int end;

	file_header_t *file_header = archive_handle->file_header;
	struct {
	/* ustar header, Posix 1003.1 */
	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 */
	} tar;
	char *cp;
	int i, sum_u, sum_s, sum;
	int parse_names;

	if (sizeof(tar) != 512)
	BUG_tar_header_size();

	#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
	again:
	#endif
	/* Align header */
	data_align(archive_handle, 512);

	again_after_align:

	xread(archive_handle->src_fd, &tar, 512);
	archive_handle->offset += 512;

	/* If there is no filename its an empty header */
	if (tar.name[0] == 0) {
	if (end) {
	/* This is the second consecutive empty header! End of archive!
	* Read until the end to empty the pipe from gz or bz2
	*/
	while (full_read(archive_handle->src_fd, &tar, 512) == 512)
	/* repeat */;
	return EXIT_FAILURE;
	}
	end = 1;
	return EXIT_SUCCESS;
	}
	end = 0;

	/* Check header has valid magic, "ustar" is for the proper tar
	* 0's are for the old tar format
	*/
	if (strncmp(tar.magic, "ustar", 5) != 0) {
	#if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
	if (memcmp(tar.magic, "\0\0\0\0", 5) != 0)
	#endif
	bb_error_msg_and_die("invalid tar magic");
	}

	/* Do checksum on headers.
	* POSIX says that checksum is done on unsigned bytes, but
	* Sun and HP-UX gets it wrong... more details in
	* GNU tar source. */
	sum_s = sum_u = ' ' * sizeof(tar.chksum);
	for (i = 0; i < 148 ; i++) {
	sum_u += ((unsigned char*)&tar)[i];
	sum_s += ((signed char*)&tar)[i];
	}
	for (i = 156; i < 512 ; i++) {
	sum_u += ((unsigned char*)&tar)[i];
	sum_s += ((signed char*)&tar)[i];
	}
	/* This field does not need special treatment (getOctal) */
	sum = xstrtoul(tar.chksum, 8);
	if (sum_u != sum && sum_s != sum) {
	bb_error_msg_and_die("invalid tar header checksum");
	}

	/* 0 is reserved for high perf file, treat as normal file */
	if (!tar.typeflag) tar.typeflag = '0';
	parse_names = (tar.typeflag >= '0' && tar.typeflag <= '7');

	/* getOctal trashes subsequent field, therefore we call it
	* on fields in reverse order */
	if (tar.devmajor[0]) {
	unsigned minor = GET_OCTAL(tar.devminor);
	unsigned major = GET_OCTAL(tar.devmajor);
	file_header->device = makedev(major, minor);
	}
	file_header->link_target = NULL;
	if (!linkname && parse_names && tar.linkname[0]) {
	/* we trash magic[0] here, it's ok */
	tar.linkname[sizeof(tar.linkname)] = '\0';
	file_header->link_target = xstrdup(tar.linkname);
	/* FIXME: what if we have non-link object with link_target? */
	/* Will link_target be free()ed? */
	}
	file_header->mtime = GET_OCTAL(tar.mtime);
	file_header->size = GET_OCTAL(tar.size);
	file_header->gid = GET_OCTAL(tar.gid);
	file_header->uid = GET_OCTAL(tar.uid);
	/* Set bits 0-11 of the files mode */
	file_header->mode = 07777 & GET_OCTAL(tar.mode);

	file_header->name = NULL;
	if (!longname && parse_names) {
	/* we trash mode[0] here, it's ok */
	tar.name[sizeof(tar.name)] = '\0';
	if (tar.prefix[0]) {
	/* and padding[0] */
	tar.prefix[sizeof(tar.prefix)] = '\0';
	file_header->name = concat_path_file(tar.prefix, tar.name);
	} else
	file_header->name = xstrdup(tar.name);
	}

	/* Set bits 12-15 of the files mode */
	/* (typeflag was not trashed because chksum does not use getOctal) */
	switch (tar.typeflag) {
	/* busybox identifies hard links as being regular files with 0 size and a link name */
	case '1':
	file_header->mode \|= S_IFREG;
	break;
	case '7':
	/* case 0: */
	case '0':
	#if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
	if (last_char_is(file_header->name, '/')) {
	file_header->mode \|= S_IFDIR;
	} else
	#endif
	file_header->mode \|= S_IFREG;
	break;
	case '2':
	file_header->mode \|= S_IFLNK;
	break;
	case '3':
	file_header->mode \|= S_IFCHR;
	break;
	case '4':
	file_header->mode \|= S_IFBLK;
	break;
	case '5':
	file_header->mode \|= S_IFDIR;
	break;
	case '6':
	file_header->mode \|= S_IFIFO;
	break;
	#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
	case 'L':
	/* free: paranoia: tar with several consecutive longnames */
	free(longname);
	/* For paranoia reasons we allocate extra NUL char */
	longname = xzalloc(file_header->size + 1);
	/* We read ASCIZ string, including NUL */
	xread(archive_handle->src_fd, longname, file_header->size);
	archive_handle->offset += file_header->size;
	/* return get_header_tar(archive_handle); */
	/* gcc 4.1.1 didn't optimize it into jump */
	/* so we will do it ourself, this also saves stack */
	goto again;
	case 'K':
	free(linkname);
	linkname = xzalloc(file_header->size + 1);
	xread(archive_handle->src_fd, linkname, file_header->size);
	archive_handle->offset += file_header->size;
	/* return get_header_tar(archive_handle); */
	goto again;
	case 'D': /* GNU dump dir */
	case 'M': /* Continuation of multi volume archive */
	case 'N': /* Old GNU for names > 100 characters */
	case 'S': /* Sparse file */
	case 'V': /* Volume header */
	#endif
	case 'g': /* pax global header */
	case 'x': { /* pax extended header */
	off_t sz;
	bb_error_msg("warning: skipping header '%c'", tar.typeflag);
	sz = (file_header->size + 511) & ~(off_t)511;
	archive_handle->offset += sz;
	sz >>= 9; /* sz /= 512 but w/o contortions for signed div */
	while (sz--)
	xread(archive_handle->src_fd, &tar, 512);
	/* return get_header_tar(archive_handle); */
	goto again_after_align;
	}
	default:
	bb_error_msg_and_die("unknown typeflag: 0x%x", tar.typeflag);
	}

	#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
	if (longname) {
	file_header->name = longname;
	longname = NULL;
	}
	if (linkname) {
	file_header->link_target = linkname;
	linkname = NULL;
	}
	#endif
	if (!strncmp(file_header->name, "/../"+1, 3)
	\|\| strstr(file_header->name, "/../")
	) {
	bb_error_msg_and_die("name with '..' encountered: '%s'",
	file_header->name);
	}

	/* Strip trailing '/' in directories */
	/* Must be done after mode is set as '/' is used to check if it's a directory */
	cp = last_char_is(file_header->name, '/');

	if (archive_handle->filter(archive_handle) == EXIT_SUCCESS) {
	archive_handle->action_header(archive_handle->file_header);
	/* Note that we kill the '/' only after action_header() */
	/* (like GNU tar 1.15.1: verbose mode outputs "dir/dir/") */
	if (cp) *cp = '\0';
	archive_handle->flags \|= ARCHIVE_EXTRACT_QUIET;
	archive_handle->action_data(archive_handle);
	llist_add_to(&(archive_handle->passed), file_header->name);
	} else {
	data_skip(archive_handle);
	free(file_header->name);
	}
	archive_handle->offset += file_header->size;

	free(file_header->link_target);
	/* Do not free(file_header->name)! */

	return EXIT_SUCCESS;
	}