tar,unzip: postpone creation of symlinks with "suspicious" targets

This mostly reverts commit bc9bbeb2b81001e8731cd2ae501c8fccc8d87cc7
"libarchive: do not extract unsafe symlinks unless $EXTRACT_UNSAFE_SYMLINKS=1"

Users report that it is somewhat too restrictive. See
https://bugs.busybox.net/show_bug.cgi?id=8411

In particular, this interferes with unpacking of busybox-based
filesystems with links like "sbin/applet" -> "../bin/busybox".

The change is made smaller by deleting ARCHIVE_EXTRACT_QUIET flag -
it is unused since 2010, and removing conditionals on it
allows commonalizing some error message codes.

function                                             old     new   delta
create_or_remember_symlink                             -      94     +94
create_symlinks_from_list                              -      64     +64
tar_main                                            1002    1006      +4
unzip_main                                          2732    2724      -8
data_extract_all                                     984     891     -93
unsafe_symlink_target                                147       -    -147
------------------------------------------------------------------------------
(add/remove: 2/1 grow/shrink: 1/2 up/down: 162/-248)          Total: -86 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 14 insertions, 9 deletions

diff --git a/include/bb_archive.h b/include/bb_archive.h
index 8ed20d70e..a5c61e95b 100644
--- a/include/bb_archive.h
+++ b/include/bb_archive.h
@@ -64,6 +64,9 @@ typedef struct archive_handle_t {
         /* Currently processed file's header */
         file_header_t *file_header;
 
+        /* List of symlink placeholders */
+        llist_t *symlink_placeholders;
+
         /* Process the header component, e.g. tar -t */
         void FAST_FUNC (*action_header)(const file_header_t *);
 
@@ -119,15 +122,14 @@ typedef struct archive_handle_t {
 #define ARCHIVE_RESTORE_DATE        (1 << 0)
 #define ARCHIVE_CREATE_LEADING_DIRS (1 << 1)
 #define ARCHIVE_UNLINK_OLD          (1 << 2)
-#define ARCHIVE_EXTRACT_QUIET       (1 << 3)
-#define ARCHIVE_EXTRACT_NEWER       (1 << 4)
-#define ARCHIVE_DONT_RESTORE_OWNER  (1 << 5)
-#define ARCHIVE_DONT_RESTORE_PERM   (1 << 6)
-#define ARCHIVE_NUMERIC_OWNER       (1 << 7)
-#define ARCHIVE_O_TRUNC             (1 << 8)
-#define ARCHIVE_REMEMBER_NAMES      (1 << 9)
+#define ARCHIVE_EXTRACT_NEWER       (1 << 3)
+#define ARCHIVE_DONT_RESTORE_OWNER  (1 << 4)
+#define ARCHIVE_DONT_RESTORE_PERM   (1 << 5)
+#define ARCHIVE_NUMERIC_OWNER       (1 << 6)
+#define ARCHIVE_O_TRUNC             (1 << 7)
+#define ARCHIVE_REMEMBER_NAMES      (1 << 8)
 #if ENABLE_RPM
-#define ARCHIVE_REPLACE_VIA_RENAME  (1 << 10)
+#define ARCHIVE_REPLACE_VIA_RENAME  (1 << 9)
 #endif
 
 
@@ -197,7 +199,10 @@ void seek_by_jump(int fd, off_t amount) FAST_FUNC;
 void seek_by_read(int fd, off_t amount) FAST_FUNC;
 
 const char *strip_unsafe_prefix(const char *str) FAST_FUNC;
-int unsafe_symlink_target(const char *target) FAST_FUNC;
+void create_or_remember_symlink(llist_t **symlink_placeholders,
+                const char *target,
+                const char *linkname) FAST_FUNC;
+void create_symlinks_from_list(llist_t *list) FAST_FUNC;
 
 void data_align(archive_handle_t *archive_handle, unsigned boundary) FAST_FUNC;
 const llist_t *find_list_entry(const llist_t *list, const char *filename) FAST_FUNC;