ar: add archive creation support

function                                             old     new   delta
ar_main                                              184     542    +358
output_ar_header                                       -     166    +166
copy_data                                              -      54     +54
filter_replaceable                                     -      19     +19
get_header_ar                                        409     414      +5
header_verbose_list_ar                                85      88      +3
static.msg_unsupported_err                            28       -     -28
------------------------------------------------------------------------------
(add/remove: 3/1 grow/shrink: 3/0 up/down: 605/-28)           Total: 577 bytes

Signed-off-by: Alexander Shishkin <virtuoso@slind.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 7 insertions, 13 deletions

diff --git a/archival/libunarchive/get_header_ar.c b/archival/libunarchive/get_header_ar.c
index 2f38279cc..dbc5ec004 100644
--- a/archival/libunarchive/get_header_ar.c
+++ b/archival/libunarchive/get_header_ar.c
@@ -6,6 +6,7 @@
 
 #include "libbb.h"
 #include "unarchive.h"
+#include "ar.h"
 
 static unsigned read_num(const char *str, int base)
 {
@@ -23,15 +24,7 @@ char FAST_FUNC get_header_ar(archive_handle_t *archive_handle)
         unsigned size;
         union {
                 char raw[60];
-                struct {
-                        char name[16];
-                        char date[12];
-                        char uid[6];
-                        char gid[6];
-                        char mode[8];
-                        char size[10];
-                        char magic[2];
-                } formatted;
+                struct ar_header formatted;
         } ar;
 #if ENABLE_FEATURE_AR_LONG_FILENAMES
         static char *ar_long_names;
@@ -55,13 +48,13 @@ char FAST_FUNC get_header_ar(archive_handle_t *archive_handle)
         }
         archive_handle->offset += 60;
 
-        /* align the headers based on the header magic */
         if (ar.formatted.magic[0] != '`' || ar.formatted.magic[1] != '\n')
                 bb_error_msg_and_die("invalid ar header");
 
         /* FIXME: more thorough routine would be in order here
          * (we have something like that in tar)
          * but for now we are lax. */
+        ar.formatted.magic[0] = '\0'; /* else 4G-2 file will have size="4294967294`\n..." */
         typed->size = size = read_num(ar.formatted.size, 10);
 
         /* special filenames have '/' as the first character */
diff --git a/archival/libunarchive/unpack_ar_archive.c b/archival/libunarchive/unpack_ar_archive.c
index dc2eec223..300d10e48 100644
--- a/archival/libunarchive/unpack_ar_archive.c
+++ b/archival/libunarchive/unpack_ar_archive.c
@@ -5,16 +5,17 @@
 
 #include "libbb.h"
 #include "unarchive.h"
+#include "ar.h"
 
 void FAST_FUNC unpack_ar_archive(archive_handle_t *ar_archive)
 {
         char magic[7];
 
-        xread(ar_archive->src_fd, magic, 7);
-        if (strncmp(magic, "!<arch>", 7) != 0) {
+        xread(ar_archive->src_fd, magic, AR_MAGIC_LEN);
+        if (strncmp(magic, AR_MAGIC, AR_MAGIC_LEN) != 0) {
                 bb_error_msg_and_die("invalid ar magic");
         }
-        ar_archive->offset += 7;
+        ar_archive->offset += AR_MAGIC_LEN;
 
         while (get_header_ar(ar_archive) == EXIT_SUCCESS)
                 continue;