*: refactor handling of archived files. "tar f file.tar.lzma" now works too.

function                                             old     new   delta
unpack_Z_stream                                        -    1229   +1229
open_zipped                                            -     176    +176
unpack_bz2_stream_prime                                -      60     +60
tar_main                                             642     677     +35
find_main                                            406     418     +12
sv_main                                             1222    1233     +11
decode_format_string                                 829     837      +8
cmp_main                                             641     649      +8
popstring                                            134     140      +6
filter_accept_list_reassign                          120     125      +5
parse_and_put_prompt                                 800     804      +4
passwd_main                                         1053    1049      -4
make_new_name_gunzip                                 119     114      -5
rpm_main                                            1688    1670     -18
prepare                                              302     283     -19
xmalloc_open_zipped_read_close                       135      61     -74
uncompress                                          1229       -   -1229
------------------------------------------------------------------------------
(add/remove: 3/1 grow/shrink: 8/5 up/down: 1554/-1349)        Total: 205 bytes

12 files changed, 145 insertions, 193 deletions

diff --git a/archival/Config.in b/archival/Config.in
index b26be6486..d6332a2b2 100644
--- a/archival/Config.in
+++ b/archival/Config.in
@@ -5,6 +5,30 @@
 
 menu "Archival Utilities"
 
+config FEATURE_SEAMLESS_LZMA
+	bool "Make tar, rpm, man, modprobe etc understand .lzma data"
+	default n
+	help
+	  Make tar, rpm, man, modprobe etc understand .lzma data.
+
+config FEATURE_SEAMLESS_BZ2
+	bool "Make tar, rpm, man, modprobe etc understand .bz2 data"
+	default n
+	help
+	  Make tar, rpm, man, modprobe etc understand .bz2 data.
+
+config FEATURE_SEAMLESS_GZ
+	bool "Make tar, rpm, man, modprobe etc understand .gz data"
+	default n
+	help
+	  Make tar, rpm, man, modprobe etc understand .gz data.
+
+config FEATURE_SEAMLESS_Z
+	bool "Make tar and gunzip understand .Z data"
+	default n
+	help
+	  Make tar and gunzip understand .Z data.
+
 config AR
 	bool "ar"
 	default n
@@ -126,15 +150,6 @@ config GUNZIP
 	  You can use the `-t' option to test the integrity of
 	  an archive, without decompressing it.
 
-config FEATURE_GUNZIP_UNCOMPRESS
-	bool "Uncompress support"
-	default n
-	depends on GUNZIP
-	help
-	  Enable if you want gunzip to have the ability to decompress
-	  archives created by the program compress (not much
-	  used anymore).
-
 config GZIP
 	bool "gzip"
 	default n
@@ -154,13 +169,6 @@ config RPM
 	help
 	  Mini RPM applet - queries and extracts RPM packages.
 
-config FEATURE_RPM_BZ2
-	bool "Enable handling of rpms with bzip2-compressed data inside"
-	default n
-	depends on RPM
-	help
-	  Enable handling of rpms with bzip2-compressed data inside.
-
 config TAR
 	bool "tar"
 	default n
@@ -179,42 +187,10 @@ config FEATURE_TAR_CREATE
 	  If you enable this option you'll be able to create
 	  tar archives using the `-c' option.
 
-config FEATURE_TAR_GZIP
-	bool "Enable -z option"
-	default y
-	depends on TAR
-	help
-	  If you enable this option tar will be able to call gzip,
-	  when creating or extracting tar gziped archives.
-
-config FEATURE_TAR_BZIP2
-	bool "Enable -j option to handle .tar.bz2 files"
-	default n
-	depends on TAR
-	help
-	  If you enable this option you'll be able to extract
-	  archives compressed with bzip2.
-
-config FEATURE_TAR_LZMA
-	bool "Enable -a option to handle .tar.lzma files"
-	default n
-	depends on TAR
-	help
-	  If you enable this option you'll be able to extract
-	  archives compressed with lzma.
-
-config FEATURE_TAR_COMPRESS
-	bool "Enable -Z option"
-	default n
-	depends on TAR
-	help
-	  If you enable this option tar will be able to call uncompress,
-	  when extracting .tar.Z archives.
-
 config FEATURE_TAR_AUTODETECT
-	bool "Autodetect gz/bz2 compresses tarballs"
+	bool "Autodetect gz/bz2 compressed tarballs"
 	default n
-	depends on FEATURE_TAR_GZIP || FEATURE_TAR_BZIP2
+	depends on FEATURE_SEAMLESS_Z || FEATURE_SEAMLESS_GZ || FEATURE_SEAMLESS_BZ2 || FEATURE_SEAMLESS_LZMA
 	help
 	  With this option tar can automatically detect gzip/bzip2 compressed
 	  tarballs. Currently it works only on files (not pipes etc).
@@ -312,42 +288,4 @@ config UNZIP
 	  current directory. Use the `-d' option to extract to a
 	  directory of your choice.
 
-comment "Common options for cpio and tar"
-	depends on CPIO || TAR
-
-comment "Common options for dpkg and dpkg_deb"
-	depends on DPKG || DPKG_DEB
-
-config FEATURE_DEB_TAR_GZ
-	bool "gzip debian packages (normal)"
-	default y if DPKG || DPKG_DEB
-	depends on DPKG || DPKG_DEB
-	help
-	  This is the default compression method inside the debian ar file.
-
-	  If you want compatibility with standard .deb's you should say yes
-	  here.
-
-config FEATURE_DEB_TAR_BZ2
-	bool "bzip2 debian packages"
-	default n
-	depends on DPKG || DPKG_DEB
-	help
-	  This allows dpkg and dpkg-deb to extract deb's that are compressed
-	  internally with bzip2 instead of gzip.
-
-	  You only want this if you are creating your own custom debian
-	  packages that use an internal control.tar.bz2 or data.tar.bz2.
-
-config FEATURE_DEB_TAR_LZMA
-	bool "lzma debian packages"
-	default n
-	depends on DPKG || DPKG_DEB
-	help
-	  This allows dpkg and dpkg-deb to extract deb's that are compressed
-	  internally with lzma instead of gzip.
-
-	  You only want this if you are creating your own custom debian
-	  packages that use an internal control.tar.lzma or data.tar.lzma.
-
 endmenu
diff --git a/archival/bbunzip.c b/archival/bbunzip.c
index 65bb8b7f4..c7962058e 100644
--- a/archival/bbunzip.c
+++ b/archival/bbunzip.c
@@ -161,7 +161,7 @@ char* make_new_name_bunzip2(char *filename)
 static
 USE_DESKTOP(long long) int unpack_bunzip2(void)
 {
-	return unpack_bz2_stream(STDIN_FILENO, STDOUT_FILENO);
+	return unpack_bz2_stream_prime(STDIN_FILENO, STDOUT_FILENO);
 }
 
 int bunzip2_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
@@ -218,8 +218,8 @@ char* make_new_name_gunzip(char *filename)
 
 	extension++;
 	if (strcmp(extension, "tgz" + 1) == 0
-#if ENABLE_FEATURE_GUNZIP_UNCOMPRESS
-	 || strcmp(extension, "Z") == 0
+#if ENABLE_FEATURE_SEAMLESS_Z
+	 || (extension[0] == 'Z' && extension[1] == '\0')
 #endif
 	) {
 		extension[-1] = '\0';
@@ -244,8 +244,8 @@ USE_DESKTOP(long long) int unpack_gunzip(void)
 		unsigned char magic2;
 
 		magic2 = xread_char(STDIN_FILENO);
-		if (ENABLE_FEATURE_GUNZIP_UNCOMPRESS && magic2 == 0x9d) {
-			status = uncompress(STDIN_FILENO, STDOUT_FILENO);
+		if (ENABLE_FEATURE_SEAMLESS_Z && magic2 == 0x9d) {
+			status = unpack_Z_stream(STDIN_FILENO, STDOUT_FILENO);
 		} else if (magic2 == 0x8b) {
 			status = unpack_gz_stream(STDIN_FILENO, STDOUT_FILENO);
 		} else {
@@ -351,7 +351,7 @@ USE_DESKTOP(long long) int unpack_uncompress(void)
 	if ((xread_char(STDIN_FILENO) != 0x1f) || (xread_char(STDIN_FILENO) != 0x9d)) {
 		bb_error_msg("invalid magic");
 	} else {
-		status = uncompress(STDIN_FILENO, STDOUT_FILENO);
+		status = unpack_Z_stream(STDIN_FILENO, STDOUT_FILENO);
 	}
 	return status;
 }
diff --git a/archival/dpkg.c b/archival/dpkg.c
index 54e963233..f31a7f017 100644
--- a/archival/dpkg.c
+++ b/archival/dpkg.c
@@ -1438,10 +1438,10 @@ static void init_archive_deb_control(archive_handle_t *ar_handle)
 	tar_handle->src_fd = ar_handle->src_fd;
 
 	/* We don't care about data.tar.* or debian-binary, just control.tar.* */
-#if ENABLE_FEATURE_DEB_TAR_GZ
+#if ENABLE_FEATURE_SEAMLESS_GZ
 	llist_add_to(&(ar_handle->accept), (char*)"control.tar.gz");
 #endif
-#if ENABLE_FEATURE_DEB_TAR_BZ2
+#if ENABLE_FEATURE_SEAMLESS_BZ2
 	llist_add_to(&(ar_handle->accept), (char*)"control.tar.bz2");
 #endif
 
@@ -1458,10 +1458,10 @@ static void init_archive_deb_data(archive_handle_t *ar_handle)
 	tar_handle->src_fd = ar_handle->src_fd;
 
 	/* We don't care about control.tar.* or debian-binary, just data.tar.* */
-#if ENABLE_FEATURE_DEB_TAR_GZ
+#if ENABLE_FEATURE_SEAMLESS_GZ
 	llist_add_to(&(ar_handle->accept), (char*)"data.tar.gz");
 #endif
-#if ENABLE_FEATURE_DEB_TAR_BZ2
+#if ENABLE_FEATURE_SEAMLESS_BZ2
 	llist_add_to(&(ar_handle->accept), (char*)"data.tar.bz2");
 #endif
 
diff --git a/archival/dpkg_deb.c b/archival/dpkg_deb.c
index 9e6340fd3..f94c90c55 100644
--- a/archival/dpkg_deb.c
+++ b/archival/dpkg_deb.c
@@ -31,12 +31,12 @@ int dpkg_deb_main(int argc, char **argv)
 	ar_archive->sub_archive = tar_archive;
 	ar_archive->filter = filter_accept_list_reassign;
 
-#if ENABLE_FEATURE_DEB_TAR_GZ
+#if ENABLE_FEATURE_SEAMLESS_GZ
 	llist_add_to(&(ar_archive->accept), (char*)"data.tar.gz");
 	llist_add_to(&control_tar_llist, (char*)"control.tar.gz");
 #endif
 
-#if ENABLE_FEATURE_DEB_TAR_BZ2
+#if ENABLE_FEATURE_SEAMLESS_BZ2
 	llist_add_to(&(ar_archive->accept), (char*)"data.tar.bz2");
 	llist_add_to(&control_tar_llist, (char*)"control.tar.bz2");
 #endif
diff --git a/archival/libunarchive/Kbuild b/archival/libunarchive/Kbuild
index 468a7e82a..364f9174c 100644
--- a/archival/libunarchive/Kbuild
+++ b/archival/libunarchive/Kbuild
@@ -32,36 +32,20 @@ DPKG_FILES:= \
 	get_header_tar.o \
 	filter_accept_list_reassign.o
 
-lib-$(CONFIG_RPM)                       += open_transformer.o
-lib-$(CONFIG_FEATURE_TAR_BZIP2)         += open_transformer.o
-lib-$(CONFIG_FEATURE_TAR_LZMA)          += open_transformer.o
-lib-$(CONFIG_FEATURE_TAR_GZIP)          += open_transformer.o
-lib-$(CONFIG_FEATURE_TAR_COMPRESS)      += open_transformer.o
-lib-$(CONFIG_FEATURE_DEB_TAR_GZ)        += open_transformer.o
-lib-$(CONFIG_FEATURE_DEB_TAR_BZ2)       += open_transformer.o
-lib-$(CONFIG_FEATURE_DEB_TAR_LZMA)      += open_transformer.o
-
-lib-$(CONFIG_FEATURE_MODPROBE_SMALL_ZIPPED) += open_transformer.o decompress_unzip.o decompress_bunzip2.o
-
 lib-$(CONFIG_AR)                        += get_header_ar.o unpack_ar_archive.o
 lib-$(CONFIG_BUNZIP2)                   += decompress_bunzip2.o
 lib-$(CONFIG_UNLZMA)                    += decompress_unlzma.o
 lib-$(CONFIG_CPIO)                      += get_header_cpio.o
 lib-$(CONFIG_DPKG)                      += $(DPKG_FILES)
 lib-$(CONFIG_DPKG_DEB)                  += $(DPKG_FILES)
-lib-$(CONFIG_FEATURE_DEB_TAR_GZ)        += decompress_unzip.o get_header_tar_gz.o
-lib-$(CONFIG_FEATURE_DEB_TAR_BZ2)       += decompress_bunzip2.o get_header_tar_bz2.o
-lib-$(CONFIG_FEATURE_DEB_TAR_LZMA)      += decompress_unlzma.o get_header_tar_lzma.o
 lib-$(CONFIG_GUNZIP)                    += decompress_unzip.o
-lib-$(CONFIG_FEATURE_GUNZIP_UNCOMPRESS) += decompress_uncompress.o
 lib-$(CONFIG_RPM2CPIO)                  += decompress_unzip.o get_header_cpio.o
-lib-$(CONFIG_RPM)                       += decompress_unzip.o get_header_cpio.o
-lib-$(CONFIG_FEATURE_RPM_BZ2)           += decompress_bunzip2.o
+lib-$(CONFIG_RPM)                       += open_transformer.o decompress_unzip.o get_header_cpio.o
 lib-$(CONFIG_TAR)                       += get_header_tar.o
-lib-$(CONFIG_FEATURE_TAR_BZIP2)         += decompress_bunzip2.o get_header_tar_bz2.o
-lib-$(CONFIG_FEATURE_TAR_LZMA)          += decompress_unlzma.o get_header_tar_lzma.o
-lib-$(CONFIG_FEATURE_TAR_GZIP)          += decompress_unzip.o get_header_tar_gz.o
-lib-$(CONFIG_FEATURE_TAR_COMPRESS)      += decompress_uncompress.o
 lib-$(CONFIG_UNCOMPRESS)                += decompress_uncompress.o
 lib-$(CONFIG_UNZIP)                     += decompress_unzip.o
+lib-$(CONFIG_FEATURE_SEAMLESS_Z)        += open_transformer.o decompress_uncompress.o
+lib-$(CONFIG_FEATURE_SEAMLESS_GZ)       += open_transformer.o decompress_unzip.o get_header_tar_gz.o
+lib-$(CONFIG_FEATURE_SEAMLESS_BZ2)      += open_transformer.o decompress_bunzip2.o get_header_tar_bz2.o
+lib-$(CONFIG_FEATURE_SEAMLESS_LZMA)     += open_transformer.o decompress_unlzma.o get_header_tar_lzma.o
 lib-$(CONFIG_FEATURE_COMPRESS_USAGE)    += decompress_bunzip2.o
diff --git a/archival/libunarchive/decompress_bunzip2.c b/archival/libunarchive/decompress_bunzip2.c
index 654dc28a9..b53720f23 100644
--- a/archival/libunarchive/decompress_bunzip2.c
+++ b/archival/libunarchive/decompress_bunzip2.c
@@ -590,7 +590,8 @@ int FAST_FUNC start_bunzip(bunzip_data **bdp, int in_fd, const unsigned char *in
 	bunzip_data *bd;
 	unsigned i;
 	enum {
-		BZh0 = ('B' << 24) + ('Z' << 16) + ('h' << 8) + '0'
+		BZh0 = ('B' << 24) + ('Z' << 16) + ('h' << 8) + '0',
+		h0 = ('h' << 8) + '0',
 	};
 
 	/* Figure out how much data to allocate */
@@ -617,12 +618,18 @@ int FAST_FUNC start_bunzip(bunzip_data **bdp, int in_fd, const unsigned char *in
 	if (i) return i;
 
 	/* Ensure that file starts with "BZh['1'-'9']." */
-	i = get_bits(bd, 32);
-	if ((unsigned)(i - BZh0 - 1) >= 9) return RETVAL_NOT_BZIP_DATA;
+	/* Update: now caller verifies 1st two bytes, makes .gz/.bz2
+	 * integration easier */
+	/* was: */
+	/* i = get_bits(bd, 32); */
+	/* if ((unsigned)(i - BZh0 - 1) >= 9) return RETVAL_NOT_BZIP_DATA; */
+	i = get_bits(bd, 16);
+	if ((unsigned)(i - h0 - 1) >= 9) return RETVAL_NOT_BZIP_DATA;
 
 	/* Fourth byte (ascii '1'-'9') indicates block size in units of 100k of
 	   uncompressed data.  Allocate intermediate buffer for block. */
-	bd->dbufSize = 100000 * (i - BZh0);
+	/* bd->dbufSize = 100000 * (i - BZh0); */
+	bd->dbufSize = 100000 * (i - h0);
 
 	/* Cannot use xmalloc - may leak bd in NOFORK case! */
 	bd->dbuf = malloc_or_warn(bd->dbufSize * sizeof(int));
@@ -682,6 +689,17 @@ unpack_bz2_stream(int src_fd, int dst_fd)
 	return i ? i : USE_DESKTOP(total_written) + 0;
 }
 
+USE_DESKTOP(long long) int FAST_FUNC
+unpack_bz2_stream_prime(int src_fd, int dst_fd)
+{
+	unsigned char magic[2];
+	xread(src_fd, magic, 2);
+	if (magic[0] != 'B' || magic[1] != 'Z') {
+		bb_error_msg_and_die("invalid magic");
+	}
+	return unpack_bz2_stream(src_fd, dst_fd);
+}
+
 #ifdef TESTING
 
 static char *const bunzip_errors[] = {
@@ -693,9 +711,10 @@ static char *const bunzip_errors[] = {
 /* Dumb little test thing, decompress stdin to stdout */
 int main(int argc, char **argv)
 {
-	int i = unpack_bz2_stream(0, 1);
+	int i;
 	char c;
 
+	int i = unpack_bz2_stream_prime(0, 1);
 	if (i < 0)
 		fprintf(stderr, "%s\n", bunzip_errors[-i]);
 	else if (read(STDIN_FILENO, &c, 1))
diff --git a/archival/libunarchive/decompress_uncompress.c b/archival/libunarchive/decompress_uncompress.c
index 161570040..fe1491e71 100644
--- a/archival/libunarchive/decompress_uncompress.c
+++ b/archival/libunarchive/decompress_uncompress.c
@@ -1,6 +1,4 @@
 /* vi: set sw=4 ts=4: */
-#include "libbb.h"
-
 /* uncompress for busybox -- (c) 2002 Robert Griebl
  *
  * based on the original compress42.c source
@@ -26,6 +24,10 @@
  *
  */
 
+#include "libbb.h"
+#include "unarchive.h"
+
+
 /* Default input buffer size */
 #define	IBUFSIZ	2048
 
@@ -71,7 +73,7 @@
  */
 
 USE_DESKTOP(long long) int FAST_FUNC
-uncompress(int fd_in, int fd_out)
+unpack_Z_stream(int fd_in, int fd_out)
 {
 	USE_DESKTOP(long long total_written = 0;)
 	USE_DESKTOP(long long) int retval = -1;
diff --git a/archival/libunarchive/filter_accept_list_reassign.c b/archival/libunarchive/filter_accept_list_reassign.c
index 4dbc2d13e..f1de4e803 100644
--- a/archival/libunarchive/filter_accept_list_reassign.c
+++ b/archival/libunarchive/filter_accept_list_reassign.c
@@ -23,22 +23,25 @@ char FAST_FUNC filter_accept_list_reassign(archive_handle_t *archive_handle)
 
 		/* Find extension */
 		name_ptr = strrchr(archive_handle->file_header->name, '.');
+		if (!name_ptr)
+			return EXIT_FAILURE;
+		name_ptr++;
 
 		/* Modify the subarchive handler based on the extension */
-		if (ENABLE_FEATURE_DEB_TAR_GZ
-		 && strcmp(name_ptr, ".gz") == 0
+		if (ENABLE_FEATURE_SEAMLESS_GZ
+		 && strcmp(name_ptr, "gz") == 0
 		) {
 			archive_handle->action_data_subarchive = get_header_tar_gz;
 			return EXIT_SUCCESS;
 		}
-		if (ENABLE_FEATURE_DEB_TAR_BZ2
-		 && strcmp(name_ptr, ".bz2") == 0
+		if (ENABLE_FEATURE_SEAMLESS_BZ2
+		 && strcmp(name_ptr, "bz2") == 0
 		) {
 			archive_handle->action_data_subarchive = get_header_tar_bz2;
 			return EXIT_SUCCESS;
 		}
-		if (ENABLE_FEATURE_DEB_TAR_LZMA
-		 && strcmp(name_ptr, ".lzma") == 0
+		if (ENABLE_FEATURE_SEAMLESS_LZMA
+		 && strcmp(name_ptr, "lzma") == 0
 		) {
 			archive_handle->action_data_subarchive = get_header_tar_lzma;
 			return EXIT_SUCCESS;
diff --git a/archival/libunarchive/get_header_tar.c b/archival/libunarchive/get_header_tar.c
index 5310f3f7c..bf0f92b25 100644
--- a/archival/libunarchive/get_header_tar.c
+++ b/archival/libunarchive/get_header_tar.c
@@ -148,12 +148,12 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
 		 * we can switch to get_header_tar_gz/bz2/lzma().
 		 * Needs seekable fd. I wish recv(MSG_PEEK) works
 		 * on any fd... */
-#if ENABLE_FEATURE_TAR_GZIP
+#if ENABLE_FEATURE_SEAMLESS_GZ
 		if (tar.name[0] == 0x1f && tar.name[1] == (char)0x8b) { /* gzip */
 			get_header_ptr = get_header_tar_gz;
 		} else
 #endif
-#if ENABLE_FEATURE_TAR_BZIP2
+#if ENABLE_FEATURE_SEAMLESS_BZ2
 		if (tar.name[0] == 'B' && tar.name[1] == 'Z'
 		 && tar.name[2] == 'h' && isdigit(tar.name[3])
 		) { /* bzip2 */
diff --git a/archival/libunarchive/get_header_tar_bz2.c b/archival/libunarchive/get_header_tar_bz2.c
index 035c10bfb..615bbba4a 100644
--- a/archival/libunarchive/get_header_tar_bz2.c
+++ b/archival/libunarchive/get_header_tar_bz2.c
@@ -11,7 +11,7 @@ char FAST_FUNC get_header_tar_bz2(archive_handle_t *archive_handle)
 	/* Can't lseek over pipes */
 	archive_handle->seek = seek_by_read;
 
-	open_transformer(archive_handle->src_fd, unpack_bz2_stream, "bunzip2");
+	open_transformer(archive_handle->src_fd, unpack_bz2_stream_prime, "bunzip2");
 	archive_handle->offset = 0;
 	while (get_header_tar(archive_handle) == EXIT_SUCCESS)
 		continue;
diff --git a/archival/rpm.c b/archival/rpm.c
index e6dd3d853..e1f3c8930 100644
--- a/archival/rpm.c
+++ b/archival/rpm.c
@@ -206,27 +206,27 @@ static void extract_cpio_gz(int fd)
 	archive_handle->src_fd = fd;
 	/*archive_handle->offset = 0; - init_handle() did it */
 
+// TODO: open_zipped does the same
+
 	xread(archive_handle->src_fd, &magic, 2);
 #if BB_MMU
 	xformer = unpack_gz_stream;
 #else
 	xformer_prog = "gunzip";
 #endif
-	if ((magic[0] != 0x1f) || (magic[1] != 0x8b)) {
-		if (ENABLE_FEATURE_RPM_BZ2
-		 && (magic[0] == 0x42) && (magic[1] == 0x5a)) {
+	if (magic[0] != 0x1f || magic[1] != 0x8b) {
+		if (!ENABLE_FEATURE_SEAMLESS_BZ2
+		 || magic[0] != 'B' || magic[1] != 'Z'
+		) {
+			bb_error_msg_and_die("no gzip"
+				USE_FEATURE_SEAMLESS_BZ2("/bzip2")
+				" magic");
+		}
 #if BB_MMU
-			xformer = unpack_bz2_stream;
+		xformer = unpack_bz2_stream;
 #else
-			xformer_prog = "bunzip2";
+		xformer_prog = "bunzip2";
 #endif
-	/* We can do better, need modifying unpack_bz2_stream to not require
-	 * first 2 bytes. Not very hard to do... I mean, TODO :) */
-			xlseek(archive_handle->src_fd, -2, SEEK_CUR);
-		} else
-			bb_error_msg_and_die("no gzip"
-				USE_FEATURE_RPM_BZ2("/bzip")
-				" magic");
 	} else {
 #if !BB_MMU
 		/* NOMMU version of open_transformer execs an external unzipper that should
diff --git a/archival/tar.c b/archival/tar.c
index b2481b843..45701c985 100644
--- a/archival/tar.c
+++ b/archival/tar.c
@@ -36,7 +36,7 @@
 #define block_buf bb_common_bufsiz1
 
 
-#if !ENABLE_FEATURE_TAR_GZIP && !ENABLE_FEATURE_TAR_BZIP2
+#if !ENABLE_FEATURE_SEAMLESS_GZ && !ENABLE_FEATURE_SEAMLESS_BZ2
 /* Do not pass gzip flag to writeTarFile() */
 #define writeTarFile(tar_fd, verboseFlag, dereferenceFlag, include, exclude, gzip) \
 	writeTarFile(tar_fd, verboseFlag, dereferenceFlag, include, exclude)
@@ -503,19 +503,19 @@ static int FAST_FUNC writeFileToTarball(const char *fileName, struct stat *statb
 	return TRUE;
 }
 
-#if ENABLE_FEATURE_TAR_GZIP || ENABLE_FEATURE_TAR_BZIP2
-#if !(ENABLE_FEATURE_TAR_GZIP && ENABLE_FEATURE_TAR_BZIP2)
+#if ENABLE_FEATURE_SEAMLESS_GZ || ENABLE_FEATURE_SEAMLESS_BZ2
+#if !(ENABLE_FEATURE_SEAMLESS_GZ && ENABLE_FEATURE_SEAMLESS_BZ2)
 #define vfork_compressor(tar_fd, gzip) vfork_compressor(tar_fd)
 #endif
 /* Don't inline: vfork scares gcc and pessimizes code */
 static void NOINLINE vfork_compressor(int tar_fd, int gzip)
 {
 	pid_t gzipPid;
-#if ENABLE_FEATURE_TAR_GZIP && ENABLE_FEATURE_TAR_BZIP2
+#if ENABLE_FEATURE_SEAMLESS_GZ && ENABLE_FEATURE_SEAMLESS_BZ2
 	const char *zip_exec = (gzip == 1) ? "gzip" : "bzip2";
-#elif ENABLE_FEATURE_TAR_GZIP
+#elif ENABLE_FEATURE_SEAMLESS_GZ
 	const char *zip_exec = "gzip";
-#else /* only ENABLE_FEATURE_TAR_BZIP2 */
+#else /* only ENABLE_FEATURE_SEAMLESS_BZ2 */
 	const char *zip_exec = "bzip2";
 #endif
 	// On Linux, vfork never unpauses parent early, although standard
@@ -579,7 +579,7 @@ static void NOINLINE vfork_compressor(int tar_fd, int gzip)
 		bb_perror_msg_and_die("cannot exec %s", zip_exec);
 	}
 }
-#endif /* ENABLE_FEATURE_TAR_GZIP || ENABLE_FEATURE_TAR_BZIP2 */
+#endif /* ENABLE_FEATURE_SEAMLESS_GZ || ENABLE_FEATURE_SEAMLESS_BZ2 */
 
 
 /* gcc 4.2.1 inlines it, making code bigger */
@@ -601,7 +601,7 @@ static NOINLINE int writeTarFile(int tar_fd, int verboseFlag,
 	if (fstat(tbInfo.tarFd, &tbInfo.statBuf) < 0)
 		bb_perror_msg_and_die("cannot stat tar file");
 
-#if ENABLE_FEATURE_TAR_GZIP || ENABLE_FEATURE_TAR_BZIP2
+#if ENABLE_FEATURE_SEAMLESS_GZ || ENABLE_FEATURE_SEAMLESS_BZ2
 	if (gzip)
 		vfork_compressor(tbInfo.tarFd, gzip);
 #endif
@@ -637,7 +637,7 @@ static NOINLINE int writeTarFile(int tar_fd, int verboseFlag,
 	if (errorFlag)
 		bb_error_msg("error exit delayed from previous errors");
 
-#if ENABLE_FEATURE_TAR_GZIP || ENABLE_FEATURE_TAR_BZIP2
+#if ENABLE_FEATURE_SEAMLESS_GZ || ENABLE_FEATURE_SEAMLESS_BZ2
 	if (gzip) {
 		int status;
 		if (safe_waitpid(-1, &status, 0) == -1)
@@ -679,7 +679,7 @@ static llist_t *append_file_list_to_list(llist_t *list)
 #define append_file_list_to_list(x) 0
 #endif
 
-#if ENABLE_FEATURE_TAR_COMPRESS
+#if ENABLE_FEATURE_SEAMLESS_Z
 static char FAST_FUNC get_header_tar_Z(archive_handle_t *archive_handle)
 {
 	/* Can't lseek over pipes */
@@ -692,7 +692,7 @@ static char FAST_FUNC get_header_tar_Z(archive_handle_t *archive_handle)
 		bb_error_msg_and_die("invalid magic");
 	}
 
-	open_transformer(archive_handle->src_fd, uncompress, "uncompress");
+	open_transformer(archive_handle->src_fd, unpack_Z_stream, "uncompress");
 	archive_handle->offset = 0;
 	while (get_header_tar(archive_handle) == EXIT_SUCCESS)
 		continue;
@@ -729,14 +729,14 @@ static void handle_SIGCHLD(int status)
 
 enum {
 	OPTBIT_KEEP_OLD = 7,
-	USE_FEATURE_TAR_CREATE(  OPTBIT_CREATE      ,)
-	USE_FEATURE_TAR_CREATE(  OPTBIT_DEREFERENCE ,)
-	USE_FEATURE_TAR_BZIP2(   OPTBIT_BZIP2       ,)
-	USE_FEATURE_TAR_LZMA(    OPTBIT_LZMA        ,)
-	USE_FEATURE_TAR_FROM(    OPTBIT_INCLUDE_FROM,)
-	USE_FEATURE_TAR_FROM(    OPTBIT_EXCLUDE_FROM,)
-	USE_FEATURE_TAR_GZIP(    OPTBIT_GZIP        ,)
-	USE_FEATURE_TAR_COMPRESS(OPTBIT_COMPRESS    ,)
+	USE_FEATURE_TAR_CREATE(   OPTBIT_CREATE      ,)
+	USE_FEATURE_TAR_CREATE(   OPTBIT_DEREFERENCE ,)
+	USE_FEATURE_SEAMLESS_BZ2( OPTBIT_BZIP2       ,)
+	USE_FEATURE_SEAMLESS_LZMA(OPTBIT_LZMA        ,)
+	USE_FEATURE_TAR_FROM(     OPTBIT_INCLUDE_FROM,)
+	USE_FEATURE_TAR_FROM(     OPTBIT_EXCLUDE_FROM,)
+	USE_FEATURE_SEAMLESS_GZ(  OPTBIT_GZIP        ,)
+	USE_FEATURE_SEAMLESS_Z(   OPTBIT_COMPRESS    ,)
 	OPTBIT_NOPRESERVE_OWN,
 	OPTBIT_NOPRESERVE_PERM,
 	OPT_TEST         = 1 << 0, // t
@@ -747,14 +747,14 @@ enum {
 	OPT_P            = 1 << 5, // p
 	OPT_VERBOSE      = 1 << 6, // v
 	OPT_KEEP_OLD     = 1 << 7, // k
-	OPT_CREATE       = USE_FEATURE_TAR_CREATE(  (1<<OPTBIT_CREATE      )) + 0, // c
-	OPT_DEREFERENCE  = USE_FEATURE_TAR_CREATE(  (1<<OPTBIT_DEREFERENCE )) + 0, // h
-	OPT_BZIP2        = USE_FEATURE_TAR_BZIP2(   (1<<OPTBIT_BZIP2       )) + 0, // j
-	OPT_LZMA         = USE_FEATURE_TAR_LZMA(    (1<<OPTBIT_LZMA        )) + 0, // a
-	OPT_INCLUDE_FROM = USE_FEATURE_TAR_FROM(    (1<<OPTBIT_INCLUDE_FROM)) + 0, // T
-	OPT_EXCLUDE_FROM = USE_FEATURE_TAR_FROM(    (1<<OPTBIT_EXCLUDE_FROM)) + 0, // X
-	OPT_GZIP         = USE_FEATURE_TAR_GZIP(    (1<<OPTBIT_GZIP        )) + 0, // z
-	OPT_COMPRESS     = USE_FEATURE_TAR_COMPRESS((1<<OPTBIT_COMPRESS    )) + 0, // Z
+	OPT_CREATE       = USE_FEATURE_TAR_CREATE(   (1 << OPTBIT_CREATE      )) + 0, // c
+	OPT_DEREFERENCE  = USE_FEATURE_TAR_CREATE(   (1 << OPTBIT_DEREFERENCE )) + 0, // h
+	OPT_BZIP2        = USE_FEATURE_SEAMLESS_BZ2( (1 << OPTBIT_BZIP2       )) + 0, // j
+	OPT_LZMA         = USE_FEATURE_SEAMLESS_LZMA((1 << OPTBIT_LZMA        )) + 0, // a
+	OPT_INCLUDE_FROM = USE_FEATURE_TAR_FROM(     (1 << OPTBIT_INCLUDE_FROM)) + 0, // T
+	OPT_EXCLUDE_FROM = USE_FEATURE_TAR_FROM(     (1 << OPTBIT_EXCLUDE_FROM)) + 0, // X
+	OPT_GZIP         = USE_FEATURE_SEAMLESS_GZ(  (1 << OPTBIT_GZIP        )) + 0, // z
+	OPT_COMPRESS     = USE_FEATURE_SEAMLESS_Z(   (1 << OPTBIT_COMPRESS    )) + 0, // Z
 	OPT_NOPRESERVE_OWN  = 1 << OPTBIT_NOPRESERVE_OWN , // no-same-owner
 	OPT_NOPRESERVE_PERM = 1 << OPTBIT_NOPRESERVE_PERM, // no-same-permissions
 };
@@ -772,20 +772,20 @@ static const char tar_longopts[] ALIGN1 =
 	"create\0"              No_argument       "c"
 	"dereference\0"         No_argument       "h"
 # endif
-# if ENABLE_FEATURE_TAR_BZIP2
+# if ENABLE_FEATURE_SEAMLESS_BZ2
 	"bzip2\0"               No_argument       "j"
 # endif
-# if ENABLE_FEATURE_TAR_LZMA
+# if ENABLE_FEATURE_SEAMLESS_LZMA
 	"lzma\0"                No_argument       "a"
 # endif
 # if ENABLE_FEATURE_TAR_FROM
 	"files-from\0"          Required_argument "T"
 	"exclude-from\0"        Required_argument "X"
 # endif
-# if ENABLE_FEATURE_TAR_GZIP
+# if ENABLE_FEATURE_SEAMLESS_GZ
 	"gzip\0"                No_argument       "z"
 # endif
-# if ENABLE_FEATURE_TAR_COMPRESS
+# if ENABLE_FEATURE_SEAMLESS_Z
 	"compress\0"            No_argument       "Z"
 # endif
 	"no-same-owner\0"       No_argument       "\xfd"
@@ -834,12 +834,12 @@ int tar_main(int argc UNUSED_PARAM, char **argv)
 #endif
 	opt = getopt32(argv,
 		"txC:f:Opvk"
-		USE_FEATURE_TAR_CREATE(  "ch"  )
-		USE_FEATURE_TAR_BZIP2(   "j"   )
-		USE_FEATURE_TAR_LZMA(    "a"   )
-		USE_FEATURE_TAR_FROM(    "T:X:")
-		USE_FEATURE_TAR_GZIP(    "z"   )
-		USE_FEATURE_TAR_COMPRESS("Z"   )
+		USE_FEATURE_TAR_CREATE(   "ch"  )
+		USE_FEATURE_SEAMLESS_BZ2( "j"   )
+		USE_FEATURE_SEAMLESS_LZMA("a"   )
+		USE_FEATURE_TAR_FROM(     "T:X:")
+		USE_FEATURE_SEAMLESS_GZ(  "z"   )
+		USE_FEATURE_SEAMLESS_Z(   "Z"   )
 		, &base_dir // -C dir
 		, &tar_filename // -f filename
 		USE_FEATURE_TAR_FROM(, &(tar_handle->accept)) // T
@@ -922,8 +922,7 @@ int tar_main(int argc UNUSED_PARAM, char **argv)
 
 			tar_stream = stdout;
 			/* Mimicking GNU tar 1.15.1: */
-			flags = O_WRONLY|O_CREAT|O_TRUNC;
-		/* was doing unlink; open(O_WRONLY|O_CREAT|O_EXCL); why? */
+			flags = O_WRONLY | O_CREAT | O_TRUNC;
 		} else {
 			tar_stream = stdin;
 			flags = O_RDONLY;
@@ -933,7 +932,14 @@ int tar_main(int argc UNUSED_PARAM, char **argv)
 			tar_handle->src_fd = fileno(tar_stream);
 			tar_handle->seek = seek_by_read;
 		} else {
-			tar_handle->src_fd = xopen(tar_filename, flags);
+			if (ENABLE_FEATURE_TAR_AUTODETECT && flags == O_RDONLY) {
+				get_header_ptr = get_header_tar;
+				tar_handle->src_fd = open_zipped(tar_filename);
+				if (tar_handle->src_fd < 0)
+					bb_perror_msg_and_die("can't open '%s'", tar_filename);
+			} else {
+				tar_handle->src_fd = xopen(tar_filename, flags);
+			}
 		}
 	}
 
@@ -947,11 +953,11 @@ int tar_main(int argc UNUSED_PARAM, char **argv)
 
 	/* create an archive */
 	if (opt & OPT_CREATE) {
-#if ENABLE_FEATURE_TAR_GZIP || ENABLE_FEATURE_TAR_BZIP2
+#if ENABLE_FEATURE_SEAMLESS_GZ || ENABLE_FEATURE_SEAMLESS_BZ2
 		int zipMode = 0;
-		if (ENABLE_FEATURE_TAR_GZIP && (opt & OPT_GZIP))
+		if (ENABLE_FEATURE_SEAMLESS_GZ && (opt & OPT_GZIP))
 			zipMode = 1;
-		if (ENABLE_FEATURE_TAR_BZIP2 && (opt & OPT_BZIP2))
+		if (ENABLE_FEATURE_SEAMLESS_BZ2 && (opt & OPT_BZIP2))
 			zipMode = 2;
 #endif
 		/* NB: writeTarFile() closes tar_handle->src_fd */