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, 30 insertions, 0 deletions

diff --git a/include/ar.h b/include/ar.h
new file mode 100644
index 000000000..26678895a
--- /dev/null
+++ b/include/ar.h
@@ -0,0 +1,26 @@
+/*
+ * busybox ar archive data structures
+ * Licensed under the GPL v2 or later, see the file LICENSE in this source tree.
+ */
+#ifndef AR_H
+#define AR_H
+
+PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
+
+struct ar_header {
+        char name[16];
+        char date[12];
+        char uid[6];
+        char gid[6];
+        char mode[8];
+        char size[10];
+        char magic[2];
+};
+
+#define AR_HEADER_LEN sizeof(struct ar_header)
+#define AR_MAGIC      "!<arch>"
+#define AR_MAGIC_LEN  7
+
+POP_SAVED_FUNCTION_VISIBILITY
+
+#endif
diff --git a/include/unarchive.h b/include/unarchive.h
index 8bfc92cbe..92ebd6565 100644
--- a/include/unarchive.h
+++ b/include/unarchive.h
@@ -73,6 +73,10 @@ typedef struct archive_handle_t {
         /* Contains the handle to a sub archive */
         struct archive_handle_t *dpkg__sub_archive;
 #endif
+#if ENABLE_FEATURE_AR_CREATE
+        const char *ar__name;
+        struct archive_handle_t *ar__out;
+#endif
 } archive_handle_t;
 /* bits in ah_flags */
 #define ARCHIVE_RESTORE_DATE        (1 << 0)