diff --git a/archival/cpio.c b/archival/cpio.c
index 067d6e88d..b21ba6e79 100644
--- a/archival/cpio.c
+++ b/archival/cpio.c
@@ -412,14 +412,14 @@ int cpio_main(int argc UNUSED_PARAM, char **argv)
 	}
 
 	/* see get_header_cpio */
-	archive_handle->ah_priv[2] = (void*) ~(ptrdiff_t)0;
+	archive_handle->cpio__blocks = (off_t)-1;
 	while (get_header_cpio(archive_handle) == EXIT_SUCCESS)
 		continue;
 
-	if (archive_handle->ah_priv[2] != (void*) ~(ptrdiff_t)0
+	if (archive_handle->cpio__blocks != (off_t)-1
 	 && !(opt & CPIO_OPT_QUIET)
 	)
-		printf("%lu blocks\n", (unsigned long)(ptrdiff_t)(archive_handle->ah_priv[2]));
+		printf("%"OFF_FMT"u blocks\n", archive_handle->cpio__blocks);
 
 	return EXIT_SUCCESS;
 }
diff --git a/archival/dpkg.c b/archival/dpkg.c
index 2e24541bf..616bce977 100644
--- a/archival/dpkg.c
+++ b/archival/dpkg.c
@@ -1446,7 +1446,7 @@ static void init_archive_deb_control(archive_handle_t *ar_handle)
 #endif
 
 	/* Assign the tar handle as a subarchive of the ar handle */
-	ar_handle->sub_archive = tar_handle;
+	ar_handle->dpkg__sub_archive = tar_handle;
 }
 
 static void init_archive_deb_data(archive_handle_t *ar_handle)
@@ -1466,27 +1466,27 @@ static void init_archive_deb_data(archive_handle_t *ar_handle)
 #endif
 
 	/* Assign the tar handle as a subarchive of the ar handle */
-	ar_handle->sub_archive = tar_handle;
+	ar_handle->dpkg__sub_archive = tar_handle;
 }
 
 static void FAST_FUNC data_extract_to_buffer(archive_handle_t *archive_handle)
 {
 	unsigned size = archive_handle->file_header->size;
 
-	archive_handle->ah_buffer = xzalloc(size + 1);
-	xread(archive_handle->src_fd, archive_handle->ah_buffer, size);
+	archive_handle->dpkg__buffer = xzalloc(size + 1);
+	xread(archive_handle->src_fd, archive_handle->dpkg__buffer, size);
 }
 
 static char *deb_extract_control_file_to_buffer(archive_handle_t *ar_handle, llist_t *myaccept)
 {
-	ar_handle->sub_archive->action_data = data_extract_to_buffer;
-	ar_handle->sub_archive->accept = myaccept;
-	ar_handle->sub_archive->filter = filter_accept_list;
+	ar_handle->dpkg__sub_archive->action_data = data_extract_to_buffer;
+	ar_handle->dpkg__sub_archive->accept = myaccept;
+	ar_handle->dpkg__sub_archive->filter = filter_accept_list;
 
 	unpack_ar_archive(ar_handle);
 	close(ar_handle->src_fd);
 
-	return ar_handle->sub_archive->ah_buffer;
+	return ar_handle->dpkg__sub_archive->dpkg__buffer;
 }
 
 static void FAST_FUNC data_extract_all_prefix(archive_handle_t *archive_handle)
@@ -1495,7 +1495,7 @@ static void FAST_FUNC data_extract_all_prefix(archive_handle_t *archive_handle)
 
 	name_ptr += strspn(name_ptr, "./");
 	if (name_ptr[0] != '\0') {
-		archive_handle->file_header->name = xasprintf("%s%s", archive_handle->ah_buffer, name_ptr);
+		archive_handle->file_header->name = xasprintf("%s%s", archive_handle->dpkg__buffer, name_ptr);
 		data_extract_all(archive_handle);
 	}
 }
@@ -1535,11 +1535,11 @@ static void unpack_package(deb_file_t *deb_file)
 		llist_add_to(&accept_list, c);
 		i++;
 	}
-	archive_handle->sub_archive->accept = accept_list;
-	archive_handle->sub_archive->filter = filter_accept_list;
-	archive_handle->sub_archive->action_data = data_extract_all_prefix;
-	archive_handle->sub_archive->ah_buffer = info_prefix;
-	archive_handle->sub_archive->ah_flags |= ARCHIVE_UNLINK_OLD;
+	archive_handle->dpkg__sub_archive->accept = accept_list;
+	archive_handle->dpkg__sub_archive->filter = filter_accept_list;
+	archive_handle->dpkg__sub_archive->action_data = data_extract_all_prefix;
+	archive_handle->dpkg__sub_archive->dpkg__buffer = info_prefix;
+	archive_handle->dpkg__sub_archive->ah_flags |= ARCHIVE_UNLINK_OLD;
 	unpack_ar_archive(archive_handle);
 
 	/* Run the preinst prior to extracting */
@@ -1548,19 +1548,19 @@ static void unpack_package(deb_file_t *deb_file)
 	/* Extract data.tar.gz to the root directory */
 	archive_handle = init_archive_deb_ar(deb_file->filename);
 	init_archive_deb_data(archive_handle);
-	archive_handle->sub_archive->action_data = data_extract_all_prefix;
-	archive_handle->sub_archive->ah_buffer = (char*)"/"; /* huh? */
-	archive_handle->sub_archive->ah_flags |= ARCHIVE_UNLINK_OLD;
+	archive_handle->dpkg__sub_archive->action_data = data_extract_all_prefix;
+	archive_handle->dpkg__sub_archive->dpkg__buffer = (char*)"/"; /* huh? */
+	archive_handle->dpkg__sub_archive->ah_flags |= ARCHIVE_UNLINK_OLD;
 	unpack_ar_archive(archive_handle);
 
 	/* Create the list file */
 	list_filename = xasprintf("/var/lib/dpkg/info/%s.%s", package_name, "list");
 	out_stream = xfopen_for_write(list_filename);
-	while (archive_handle->sub_archive->passed) {
+	while (archive_handle->dpkg__sub_archive->passed) {
 		/* the leading . has been stripped by data_extract_all_prefix already */
-		fputs(archive_handle->sub_archive->passed->data, out_stream);
+		fputs(archive_handle->dpkg__sub_archive->passed->data, out_stream);
 		fputc('\n', out_stream);
-		archive_handle->sub_archive->passed = archive_handle->sub_archive->passed->link;
+		archive_handle->dpkg__sub_archive->passed = archive_handle->dpkg__sub_archive->passed->link;
 	}
 	fclose(out_stream);
 
diff --git a/archival/dpkg_deb.c b/archival/dpkg_deb.c
index f94c90c55..cfbd78420 100644
--- a/archival/dpkg_deb.c
+++ b/archival/dpkg_deb.c
@@ -28,7 +28,7 @@ int dpkg_deb_main(int argc, char **argv)
 
 	/* Setup an ar archive handle that refers to the gzip sub archive */
 	ar_archive = init_handle();
-	ar_archive->sub_archive = tar_archive;
+	ar_archive->dpkg__sub_archive = tar_archive;
 	ar_archive->filter = filter_accept_list_reassign;
 
 #if ENABLE_FEATURE_SEAMLESS_GZ
diff --git a/archival/libunarchive/data_extract_all.c b/archival/libunarchive/data_extract_all.c
index 874d37d94..58b05335b 100644
--- a/archival/libunarchive/data_extract_all.c
+++ b/archival/libunarchive/data_extract_all.c
@@ -127,13 +127,13 @@ void FAST_FUNC data_extract_all(archive_handle_t *archive_handle)
 			uid_t uid = file_header->uid;
 			gid_t gid = file_header->gid;
 
-			if (file_header->uname) {
+			if (file_header->tar__uname) {
 //TODO: cache last name/id pair?
-				struct passwd *pwd = getpwnam(file_header->uname);
+				struct passwd *pwd = getpwnam(file_header->tar__uname);
 				if (pwd) uid = pwd->pw_uid;
 			}
-			if (file_header->gname) {
-				struct group *grp = getgrnam(file_header->gname);
+			if (file_header->tar__gname) {
+				struct group *grp = getgrnam(file_header->tar__gname);
 				if (grp) gid = grp->gr_gid;
 			}
 			/* GNU tar 1.15.1 uses chown, not lchown */
diff --git a/archival/libunarchive/filter_accept_list_reassign.c b/archival/libunarchive/filter_accept_list_reassign.c
index f1de4e803..060a2c72b 100644
--- a/archival/libunarchive/filter_accept_list_reassign.c
+++ b/archival/libunarchive/filter_accept_list_reassign.c
@@ -31,19 +31,19 @@ char FAST_FUNC filter_accept_list_reassign(archive_handle_t *archive_handle)
 		if (ENABLE_FEATURE_SEAMLESS_GZ
 		 && strcmp(name_ptr, "gz") == 0
 		) {
-			archive_handle->action_data_subarchive = get_header_tar_gz;
+			archive_handle->dpkg__action_data_subarchive = get_header_tar_gz;
 			return EXIT_SUCCESS;
 		}
 		if (ENABLE_FEATURE_SEAMLESS_BZ2
 		 && strcmp(name_ptr, "bz2") == 0
 		) {
-			archive_handle->action_data_subarchive = get_header_tar_bz2;
+			archive_handle->dpkg__action_data_subarchive = get_header_tar_bz2;
 			return EXIT_SUCCESS;
 		}
 		if (ENABLE_FEATURE_SEAMLESS_LZMA
 		 && strcmp(name_ptr, "lzma") == 0
 		) {
-			archive_handle->action_data_subarchive = get_header_tar_lzma;
+			archive_handle->dpkg__action_data_subarchive = get_header_tar_lzma;
 			return EXIT_SUCCESS;
 		}
 	}
diff --git a/archival/libunarchive/get_header_ar.c b/archival/libunarchive/get_header_ar.c
index e6d712d8d..2f38279cc 100644
--- a/archival/libunarchive/get_header_ar.c
+++ b/archival/libunarchive/get_header_ar.c
@@ -122,8 +122,8 @@ char FAST_FUNC get_header_ar(archive_handle_t *archive_handle)
 	if (archive_handle->filter(archive_handle) == EXIT_SUCCESS) {
 		archive_handle->action_header(typed);
 #if ENABLE_DPKG || ENABLE_DPKG_DEB
-		if (archive_handle->sub_archive) {
-			while (archive_handle->action_data_subarchive(archive_handle->sub_archive) == EXIT_SUCCESS)
+		if (archive_handle->dpkg__sub_archive) {
+			while (archive_handle->dpkg__action_data_subarchive(archive_handle->dpkg__sub_archive) == EXIT_SUCCESS)
 				continue;
 		} else
 #endif
diff --git a/archival/libunarchive/get_header_cpio.c b/archival/libunarchive/get_header_cpio.c
index 52854dff9..ddc49f70e 100644
--- a/archival/libunarchive/get_header_cpio.c
+++ b/archival/libunarchive/get_header_cpio.c
@@ -25,15 +25,6 @@ char FAST_FUNC get_header_cpio(archive_handle_t *archive_handle)
 	int major, minor, nlink, mode, inode;
 	unsigned size, uid, gid, mtime;
 
-#define hardlinks_to_create (*(hardlinks_t **)(&archive_handle->ah_priv[0]))
-#define created_hardlinks   (*(hardlinks_t **)(&archive_handle->ah_priv[1]))
-#define block_count         (archive_handle->ah_priv[2])
-//	if (!archive_handle->ah_priv_inited) {
-//		archive_handle->ah_priv_inited = 1;
-//		hardlinks_to_create = NULL;
-//		created_hardlinks = NULL;
-//	}
-
 	/* There can be padding before archive header */
 	data_align(archive_handle, 4);
 
@@ -86,7 +77,7 @@ char FAST_FUNC get_header_cpio(archive_handle_t *archive_handle)
 
 	if (strcmp(file_header->name, "TRAILER!!!") == 0) {
 		/* Always round up. ">> 9" divides by 512 */
-		block_count = (void*)(ptrdiff_t) ((archive_handle->offset + 511) >> 9);
+		archive_handle->cpio__blocks = (uoff_t)(archive_handle->offset + 511) >> 9;
 		goto create_hardlinks;
 	}
 
@@ -112,13 +103,13 @@ char FAST_FUNC get_header_cpio(archive_handle_t *archive_handle)
 		strcpy(new->name, file_header->name);
 		/* Put file on a linked list for later */
 		if (size == 0) {
-			new->next = hardlinks_to_create;
-			hardlinks_to_create = new;
+			new->next = archive_handle->cpio__hardlinks_to_create;
+			archive_handle->cpio__hardlinks_to_create = new;
 			return EXIT_SUCCESS; /* Skip this one */
 			/* TODO: this breaks cpio -t (it does not show hardlinks) */
 		}
-		new->next = created_hardlinks;
-		created_hardlinks = new;
+		new->next = archive_handle->cpio__created_hardlinks;
+		archive_handle->cpio__created_hardlinks = new;
 	}
 	file_header->device = makedev(major, minor);
 
@@ -142,11 +133,11 @@ char FAST_FUNC get_header_cpio(archive_handle_t *archive_handle)
 	free(file_header->link_target);
 	free(file_header->name);
 
-	while (hardlinks_to_create) {
+	while (archive_handle->cpio__hardlinks_to_create) {
 		hardlinks_t *cur;
-		hardlinks_t *make_me = hardlinks_to_create;
+		hardlinks_t *make_me = archive_handle->cpio__hardlinks_to_create;
 
-		hardlinks_to_create = make_me->next;
+		archive_handle->cpio__hardlinks_to_create = make_me->next;
 
 		memset(file_header, 0, sizeof(*file_header));
 		file_header->mtime = make_me->mtime;
@@ -158,7 +149,7 @@ char FAST_FUNC get_header_cpio(archive_handle_t *archive_handle)
 		/*file_header->link_target = NULL;*/
 
 		/* Try to find a file we are hardlinked to */
-		cur = created_hardlinks;
+		cur = archive_handle->cpio__created_hardlinks;
 		while (cur) {
 			/* TODO: must match maj/min too! */
 			if (cur->inode == make_me->inode) {
@@ -176,14 +167,14 @@ char FAST_FUNC get_header_cpio(archive_handle_t *archive_handle)
 		if (archive_handle->filter(archive_handle) == EXIT_SUCCESS)
 			archive_handle->action_data(archive_handle);
 		/* Move to the list of created hardlinked files */
-		make_me->next = created_hardlinks;
-		created_hardlinks = make_me;
+		make_me->next = archive_handle->cpio__created_hardlinks;
+		archive_handle->cpio__created_hardlinks = make_me;
  next_link: ;
 	}
 
-	while (created_hardlinks) {
-		hardlinks_t *p = created_hardlinks;
-		created_hardlinks = p->next;
+	while (archive_handle->cpio__created_hardlinks) {
+		hardlinks_t *p = archive_handle->cpio__created_hardlinks;
+		archive_handle->cpio__created_hardlinks = p->next;
 		free(p);
 	}
 
diff --git a/archival/libunarchive/get_header_tar.c b/archival/libunarchive/get_header_tar.c
index 1f799277b..982404d14 100644
--- a/archival/libunarchive/get_header_tar.c
+++ b/archival/libunarchive/get_header_tar.c
@@ -135,20 +135,13 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
 	int parse_names;
 
 	/* Our "private data" */
-#define p_end (*(smallint *)(&archive_handle->ah_priv[0]))
 #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
-#define p_longname (*(char* *)(&archive_handle->ah_priv[1]))
-#define p_linkname (*(char* *)(&archive_handle->ah_priv[2]))
+# define p_longname (archive_handle->tar__longname)
+# define p_linkname (archive_handle->tar__linkname)
 #else
-#define p_longname 0
-#define p_linkname 0
+# define p_longname 0
+# define p_linkname 0
 #endif
-//	if (!archive_handle->ah_priv_inited) {
-//		archive_handle->ah_priv_inited = 1;
-//		p_end = 0;
-//		IF_FEATURE_TAR_GNU_EXTENSIONS(p_longname = NULL;)
-//		IF_FEATURE_TAR_GNU_EXTENSIONS(p_linkname = NULL;)
-//	}
 
 	if (sizeof(tar) != 512)
 		BUG_tar_header_size();
@@ -190,7 +183,7 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
 
 	/* If there is no filename its an empty header */
 	if (tar.name[0] == 0 && tar.prefix[0] == 0) {
-		if (p_end) {
+		if (archive_handle->tar__end) {
 			/* Second consecutive empty header - end of archive.
 			 * Read until the end to empty the pipe from gz or bz2
 			 */
@@ -198,10 +191,10 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
 				continue;
 			return EXIT_FAILURE;
 		}
-		p_end = 1;
+		archive_handle->tar__end = 1;
 		return EXIT_SUCCESS;
 	}
-	p_end = 0;
+	archive_handle->tar__end = 0;
 
 	/* Check header has valid magic, "ustar" is for the proper tar,
 	 * five NULs are for the old tar format  */
@@ -301,8 +294,8 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
 		/* Will link_target be free()ed? */
 	}
 #if ENABLE_FEATURE_TAR_UNAME_GNAME
-	file_header->uname = tar.uname[0] ? xstrndup(tar.uname, sizeof(tar.uname)) : NULL;
-	file_header->gname = tar.gname[0] ? xstrndup(tar.gname, sizeof(tar.gname)) : NULL;
+	file_header->tar__uname = tar.uname[0] ? xstrndup(tar.uname, sizeof(tar.uname)) : NULL;
+	file_header->tar__gname = tar.gname[0] ? xstrndup(tar.gname, sizeof(tar.gname)) : NULL;
 #endif
 	/* mtime: rudimentally handle GNU tar's "base256 encoding"
 	 * People report tarballs with NEGATIVE unix times encoded that way */
@@ -449,8 +442,8 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
 	free(file_header->link_target);
 	/* Do not free(file_header->name)! (why?) */
 #if ENABLE_FEATURE_TAR_UNAME_GNAME
-	free(file_header->uname);
-	free(file_header->gname);
+	free(file_header->tar__uname);
+	free(file_header->tar__gname);
 #endif
 	return EXIT_SUCCESS;
 }
diff --git a/archival/libunarchive/header_verbose_list.c b/archival/libunarchive/header_verbose_list.c
index 102cd9e11..da21a15af 100644
--- a/archival/libunarchive/header_verbose_list.c
+++ b/archival/libunarchive/header_verbose_list.c
@@ -16,12 +16,12 @@ void FAST_FUNC header_verbose_list(const file_header_t *file_header)
 	char *user;
 	char *group;
 
-	user = file_header->uname;
+	user = file_header->tar__uname;
 	if (user == NULL) {
 		sprintf(uid, "%u", (unsigned)file_header->uid);
 		user = uid;
 	}
-	group = file_header->gname;
+	group = file_header->tar__gname;
 	if (group == NULL) {
 		/*sprintf(gid, "%u", (unsigned)file_header->gid);*/
 		group = utoa(file_header->gid);
diff --git a/include/unarchive.h b/include/unarchive.h
index 68e83f01c..e3afb8af9 100644
--- a/include/unarchive.h
+++ b/include/unarchive.h
@@ -8,8 +8,8 @@ typedef struct file_header_t {
 	char *name;
 	char *link_target;
 #if ENABLE_FEATURE_TAR_UNAME_GNAME
-	char *uname;
-	char *gname;
+	char *tar__uname;
+	char *tar__gname;
 #endif
 	off_t size;
 	uid_t uid;
@@ -19,16 +19,25 @@ typedef struct file_header_t {
 	dev_t device;
 } file_header_t;
 
+struct hardlinks_t;
+
 typedef struct archive_handle_t {
+	/* Flags. 1st since it is most used member */
+	unsigned ah_flags;
+
+	/* The raw stream as read from disk or stdin */
+	int src_fd;
+
 	/* Define if the header and data component should be processed */
 	char FAST_FUNC (*filter)(struct archive_handle_t *);
+	/* List of files that have been accepted */
 	llist_t *accept;
 	/* List of files that have been rejected */
 	llist_t *reject;
 	/* List of files that have successfully been worked on */
 	llist_t *passed;
 
-	/* Contains the processed header entry */
+	/* Currently processed file's header */
 	file_header_t *file_header;
 
 	/* Process the header component, e.g. tar -t */
@@ -37,33 +46,33 @@ typedef struct archive_handle_t {
 	/* Process the data component, e.g. extract to filesystem */
 	void FAST_FUNC (*action_data)(struct archive_handle_t *);
 
-#if ENABLE_DPKG || ENABLE_DPKG_DEB
-	/* "subarchive" is used only by dpkg[-deb] applets */
-	/* How to process any sub archive, e.g. get_header_tar_gz */
-	char FAST_FUNC (*action_data_subarchive)(struct archive_handle_t *);
-	/* Contains the handle to a sub archive */
-	struct archive_handle_t *sub_archive;
-#endif
-
-	/* The raw stream as read from disk or stdin */
-	int src_fd;
-
-	/* Count the number of bytes processed */
-	off_t offset;
-
 	/* Function that skips data */
 	void FAST_FUNC (*seek)(int fd, off_t amount);
 
+	/* Count processed bytes */
+	off_t offset;
+
+	/* Archiver specific. Can make it a union if it ever gets big */
+#if ENABLE_TAR
+	smallint tar__end;
+# if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
+	char* tar__longname;
+	char* tar__linkname;
+# endif
+#endif
+#if ENABLE_CPIO
+	uoff_t cpio__blocks;
+	struct hardlinks_t *cpio__hardlinks_to_create;
+	struct hardlinks_t *cpio__created_hardlinks;
+#endif
+#if ENABLE_DPKG || ENABLE_DPKG_DEB
 	/* Temporary storage */
-	char *ah_buffer;
-
-	/* Flags and misc. stuff */
-	unsigned ah_flags;
-
-	/* "Private" storage for archivers */
-//	unsigned char ah_priv_inited;
-	void *ah_priv[8];
-
+	char *dpkg__buffer;
+	/* How to process any sub archive, e.g. get_header_tar_gz */
+	char FAST_FUNC (*dpkg__action_data_subarchive)(struct archive_handle_t *);
+	/* Contains the handle to a sub archive */
+	struct archive_handle_t *dpkg__sub_archive;
+#endif
 } archive_handle_t;
 /* bits in ah_flags */
 #define ARCHIVE_RESTORE_DATE        (1 << 0)