This implements archive creation in busybox ar. Long file names
support is to be implemented yet.

function                                             old     new   delta
write_ar_archive                                       -     226    +226
write_ar_header                                        -     218    +218
output_ar_header                                       -      92     +92
copy_data                                              -      58     +58
ar_main                                              191     240     +49
filter_replaceable                                     -      25     +25
.rodata                                            42217   42223      +6
static.msg_unsupported_err                            28       -     -28
------------------------------------------------------------------------------
(add/remove: 6/1 grow/shrink: 2/0 up/down: 674/-28)           Total: 646 bytes

Signed-off-by: Alexander Shishkin <[email protected]>
---
 archival/Config.in                        |    7 ++
 archival/Kbuild                           |    1 +
 archival/ar.c                             |   26 +++++-
 archival/ar.h                             |   27 ++++++
 archival/ar_create.c                      |  133 +++++++++++++++++++++++++++++
 archival/libunarchive/get_header_ar.c     |   11 +--
 archival/libunarchive/unpack_ar_archive.c |    7 +-
 include/unarchive.h                       |    4 +
 8 files changed, 199 insertions(+), 17 deletions(-)
 create mode 100644 archival/ar.h
 create mode 100644 archival/ar_create.c

diff --git a/archival/Config.in b/archival/Config.in
index fb79c7b..9e2e88c 100644
--- a/archival/Config.in
+++ b/archival/Config.in
@@ -62,6 +62,13 @@ config FEATURE_AR_LONG_FILENAMES
          It supports the GNU ar long filename method which moves multiple long
          filenames into a the data section of a new ar entry.
 
+config FEATURE_AR_CREATE
+       bool "Support archive creation"
+       default n
+       depends on AR
+       help
+         This enables archive creation (-c and -r) with busybox ar.
+
 config BUNZIP2
        bool "bunzip2"
        default n
diff --git a/archival/Kbuild b/archival/Kbuild
index 53bd7e2..dab3ab2 100644
--- a/archival/Kbuild
+++ b/archival/Kbuild
@@ -8,6 +8,7 @@ libs-y                          += libunarchive/
 
 lib-y:=
 lib-$(CONFIG_AR)               += ar.o
+lib-$(CONFIG_FEATURE_AR_CREATE)        += ar_create.o
 lib-$(CONFIG_BUNZIP2)          += bbunzip.o
 lib-$(CONFIG_BZIP2)            += bzip2.o bbunzip.o
 lib-$(CONFIG_UNLZMA)           += bbunzip.o
diff --git a/archival/ar.c b/archival/ar.c
index fd7f8e4..a5f3482 100644
--- a/archival/ar.c
+++ b/archival/ar.c
@@ -15,6 +15,12 @@
 
 #include "libbb.h"
 #include "unarchive.h"
+#include "ar.h"
+
+#if !ENABLE_FEATURE_AR_CREATE
+static const char msg_unsupported_err[] ALIGN1 =
+       "archive %s is not supported";
+#endif
 
 static void FAST_FUNC header_verbose_list_ar(const file_header_t *file_header)
 {
@@ -40,16 +46,14 @@ static void FAST_FUNC header_verbose_list_ar(const 
file_header_t *file_header)
 int ar_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int ar_main(int argc UNUSED_PARAM, char **argv)
 {
-       static const char msg_unsupported_err[] ALIGN1 =
-               "archive %s is not supported";
-
        archive_handle_t *archive_handle;
        unsigned opt;
+       bool wr = 0;
 
        archive_handle = init_handle();
 
        /* Prepend '-' to the first argument if required */
-       opt_complementary = "--:p:t:x:-1:p--tx:t--px:x--pt";
+       opt_complementary = "--:p:t:x:-1:p--tx:t--px:x--pt:c:r";
        opt = getopt32(argv, "ptxovcr");
        argv += optind;
 
@@ -68,20 +72,32 @@ int ar_main(int argc UNUSED_PARAM, char **argv)
        if (opt & AR_OPT_VERBOSE) {
                archive_handle->action_header = header_verbose_list_ar;
        }
+#if !ENABLE_FEATURE_AR_CREATE
        if (opt & AR_OPT_CREATE) {
                bb_error_msg_and_die(msg_unsupported_err, "creation");
        }
        if (opt & AR_OPT_INSERT) {
                bb_error_msg_and_die(msg_unsupported_err, "insertion");
        }
+#else
+       archive_handle->ar_name = *argv;
+#endif
 
-       archive_handle->src_fd = xopen(*argv++, O_RDONLY);
+       wr = opt & (AR_OPT_CREATE | AR_OPT_INSERT);
+
+       archive_handle->src_fd = xopen(*argv++,
+                                      wr ? O_RDWR | O_CREAT : O_RDONLY);
 
        while (*argv) {
                archive_handle->filter = filter_accept_list;
                llist_add_to(&archive_handle->accept, *argv++);
        }
 
+#if ENABLE_FEATURE_AR_CREATE
+       if (wr)
+               return write_ar_archive(archive_handle, opt & AR_OPT_INSERT);
+#endif
+
        unpack_ar_archive(archive_handle);
 
        return EXIT_SUCCESS;
diff --git a/archival/ar.h b/archival/ar.h
new file mode 100644
index 0000000..5e8c6f8
--- /dev/null
+++ b/archival/ar.h
@@ -0,0 +1,27 @@
+/*
+ * 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
+
+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
+
+#if ENABLE_FEATURE_AR_CREATE
+int write_ar_archive(archive_handle_t *handle, int append);
+#endif
+
+#endif
diff --git a/archival/ar_create.c b/archival/ar_create.c
new file mode 100644
index 0000000..8076685
--- /dev/null
+++ b/archival/ar_create.c
@@ -0,0 +1,133 @@
+/*
+ * ar archive creation support
+ *
+ * Copyright (C) 2010 Nokia Corporation. All rights reserved.
+ * Written by Alexander Shishkin.
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in the source tree for 
details.
+ */
+
+#include "libbb.h"
+#include "unarchive.h"
+#include "ar.h"
+
+/* filter out entries with same names as specified on the command line */
+static char FAST_FUNC filter_replaceable(archive_handle_t *handle)
+{
+       if (find_list_entry(handle->accept, handle->file_header->name))
+               return EXIT_FAILURE;
+
+       return EXIT_SUCCESS;
+}
+
+static void FAST_FUNC output_ar_header(archive_handle_t *handle)
+{
+       struct file_header_t *fh = handle->file_header;
+
+       if (handle->offset & 1) {
+               xwrite(handle->src_fd, "\n", 1);
+               handle->offset++;
+       }
+
+       dprintf(handle->src_fd, "%-16s%-12lu%-6u%-6u%-8o%-10llu`\n",
+                fh->name, fh->mtime, fh->uid, fh->gid, fh->mode, fh->size);
+
+       handle->offset += AR_HEADER_LEN;
+}
+
+/*
+ * when replacing files in an existing archive, copy from the the
+ * original archive those files that are to be left intact
+ */
+static void FAST_FUNC copy_data(archive_handle_t *handle)
+{
+       archive_handle_t *out_handle = handle->ar_out;
+       struct file_header_t *fh = handle->file_header;
+
+       out_handle->file_header = fh;
+       output_ar_header(out_handle);
+
+       bb_copyfd_exact_size(handle->src_fd, out_handle->src_fd, fh->size);
+       out_handle->offset += fh->size;
+}
+
+static int write_ar_header(archive_handle_t *handle)
+{
+       char *fn = llist_pop(&(handle->accept));
+       char fn_h[FILENAME_MAX];
+       struct stat st;
+       int fd;
+
+       if (!fn)
+               return -1;
+
+       xstat(fn, &st);
+
+       handle->file_header->mtime = st.st_mtime;
+       handle->file_header->uid = st.st_uid;
+       handle->file_header->gid = st.st_gid;
+       handle->file_header->mode = st.st_mode;
+       handle->file_header->size = st.st_size;
+       handle->file_header->name = fn_h;
+
+#if ENABLE_FEATURE_AR_LONG_FILENAMES
+#error nope, not yet
+#else
+       snprintf(fn_h, 17, "%.15s/", bb_basename(fn));
+#endif
+       output_ar_header(handle);
+
+       fd = xopen(fn, O_RDONLY);
+       bb_copyfd_exact_size(fd, handle->src_fd, st.st_size);
+       close(fd);
+       handle->offset += st.st_size;
+
+       return 0;
+}
+
+int write_ar_archive(archive_handle_t *handle, int append)
+{
+       struct stat st;
+       archive_handle_t *out_handle;
+
+       if (fstat(handle->src_fd, &st) < 0)
+               return EXIT_FAILURE;
+
+       /*
+        * if we're appending/replacing stuff in an existing archive,
+        * create a new handle for output, which is a new file created
+        * in place of the old one
+        */
+       if (append && st.st_size) {
+               out_handle = init_handle();
+
+               unlink(handle->ar_name);
+               out_handle->src_fd = xopen(handle->ar_name, O_WRONLY | O_CREAT);
+               out_handle->accept = handle->accept;
+       } else {
+               out_handle = handle;
+       }
+
+       handle->ar_out = out_handle;
+
+       xwrite(out_handle->src_fd, AR_MAGIC "\n", AR_MAGIC_LEN + 1);
+       out_handle->offset += AR_MAGIC_LEN + 1;
+
+       /* skip to the end of the archive if we have to append stuff */
+       if (append && st.st_size) {
+               handle->filter = filter_replaceable;
+               handle->action_data = copy_data;
+               unpack_ar_archive(handle);
+       }
+
+       while (!write_ar_header(out_handle))
+               ;
+
+       close(handle->src_fd);
+
+       if (out_handle->src_fd != handle->src_fd)
+               close(out_handle->src_fd);
+
+       return EXIT_SUCCESS;
+}
+
diff --git a/archival/libunarchive/get_header_ar.c 
b/archival/libunarchive/get_header_ar.c
index 2f38279..31dc3e8 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;
diff --git a/archival/libunarchive/unpack_ar_archive.c 
b/archival/libunarchive/unpack_ar_archive.c
index dc2eec2..db0e616 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;
diff --git a/include/unarchive.h b/include/unarchive.h
index 8bfc92c..39891ff 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)
-- 
1.6.3.3

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