/* vi: set sw=4 ts=4: */
/*
 * Mini ar implementation for busybox
 *
 * Copyright (C) 2000 by Glenn McGrath
 *
 * Based in part on BusyBox tar, Debian dpkg-deb and GNU ar.
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 *
 * Archive creation support:
 * Copyright (C) 2010 Nokia Corporation. All rights reserved.
 * Written by Alexander Shishkin.
 *
 * There is no single standard to adhere to so ar may not portable
 * between different systems
 * http://www.unix-systems.org/single_unix_specification_v2/xcu/ar.html
 */

//config:config AR
//config:       bool "ar"
//config:       default n  # needs to be improved to be able to replace binutils ar
//config:       help
//config:         ar is an archival utility program used to create, modify, and
//config:         extract contents from archives. An archive is a single file holding
//config:         a collection of other files in a structure that makes it possible to
//config:         retrieve the original individual files (called archive members).
//config:         The original files' contents, mode (permissions), timestamp, owner,
//config:         and group are preserved in the archive, and can be restored on
//config:         extraction.
//config:
//config:         The stored filename is limited to 15 characters. (for more information
//config:         see long filename support).
//config:         ar has 60 bytes of overheads for every stored file.
//config:
//config:         This implementation of ar can extract archives, it cannot create or
//config:         modify them.
//config:         On an x86 system, the ar applet adds about 1K.
//config:
//config:         Unless you have a specific application which requires ar, you should
//config:         probably say N here.
//config:
//config:config FEATURE_AR_LONG_FILENAMES
//config:       bool "Support for long filenames (not needed for debs)"
//config:       default y
//config:       depends on AR
//config:       help
//config:         By default the ar format can only store the first 15 characters
//config:         of the filename, this option removes that limitation.
//config:         It supports the GNU ar long filename method which moves multiple long
//config:         filenames into a the data section of a new ar entry.
//config:
//config:config FEATURE_AR_CREATE
//config:       bool "Support archive creation"
//config:       default y
//config:       depends on AR
//config:       help
//config:         This enables archive creation (-c and -r) with busybox ar.

//applet:IF_AR(APPLET(ar, BB_DIR_USR_BIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_AR) += ar.o

//usage:#define ar_trivial_usage
//usage:       "[-o] [-v] [-p] [-t] [-x] ARCHIVE FILES"
//usage:#define ar_full_usage "\n\n"
//usage:       "Extract or list FILES from an ar archive\n"
//usage:     "\n        -o      Preserve original dates"
//usage:     "\n        -p      Extract to stdout"
//usage:     "\n        -t      List"
//usage:     "\n        -x      Extract"
//usage:     "\n        -v      Verbose"

#include "libbb.h"
#include "bb_archive.h"
#include "ar.h"

#if ENABLE_FEATURE_AR_CREATE
/* 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 output_ar_header(archive_handle_t *handle)
{
        /* GNU ar 2.19.51.0.14 creates malformed archives
         * if input files are >10G. It also truncates files >4GB
         * (uses "size mod 4G"). We abort in this case:
         * We could add support for up to 10G files, but this is unlikely to be useful.
         * Note that unpacking side limits all fields to "unsigned int" data type,
         * and treats "all ones" as an error indicator. Thus max we allow here is UINT_MAX-1.
         */
        enum {
                /* for 2nd field: mtime */
                MAX11CHARS = UINT_MAX > 0xffffffff ? (unsigned)99999999999 : UINT_MAX-1,
                /* for last field: filesize */
                MAX10CHARS = UINT_MAX > 0xffffffff ? (unsigned)9999999999 : UINT_MAX-1,
        };

        struct file_header_t *fh = handle->file_header;

        if (handle->offset & 1) {
                xwrite(handle->src_fd, "\n", 1);
                handle->offset++;
        }

        /* Careful! The widths should be exact. Fields must be separated */
        if (sizeof(off_t) > 4 && fh->size > (off_t)MAX10CHARS) {
                bb_error_msg_and_die("'%s' is bigger than ar can handle", fh->name);
        }
        fdprintf(handle->src_fd, "%-16.16s%-12lu%-6u%-6u%-8o%-10"OFF_FMT"u`\n",
                        fh->name,
                        (sizeof(time_t) > 4 && fh->mtime > MAX11CHARS) ? (long)0 : (long)fh->mtime,
                        fh->uid > 99999 ? 0 : (int)fh->uid,
                        fh->gid > 99999 ? 0 : (int)fh->gid,
                        (int)fh->mode & 07777777,
                        fh->size
        );

        handle->offset += AR_HEADER_LEN;
}

/*
 * when replacing files in an existing archive, copy from 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;
        char fn_h[17]; /* 15 + "/" + NUL */
        struct stat st;
        int fd;

        fn = llist_pop(&handle->accept);
        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;
//TODO: if ENABLE_FEATURE_AR_LONG_FILENAMES...
        sprintf(fn_h, "%.15s/", bb_basename(fn));

        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;
}

static int write_ar_archive(archive_handle_t *handle)
{
        struct stat st;
        archive_handle_t *out_handle;

        xfstat(handle->src_fd, &st, handle->ar__name);

        /* if archive exists, create a new handle for output.
         * we create it in place of the old one.
         */
        if (st.st_size != 0) {
                out_handle = init_handle();
                xunlink(handle->ar__name);
                out_handle->src_fd = xopen(handle->ar__name, O_WRONLY | O_CREAT | O_TRUNC);
                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 (st.st_size != 0) {
                handle->filter = filter_replaceable;
                handle->action_data = copy_data;
                unpack_ar_archive(handle);
        }

        while (write_ar_header(out_handle) == 0)
                continue;

        /* optional, since we exit right after we return */
        if (ENABLE_FEATURE_CLEAN_UP) {
                close(handle->src_fd);
                if (out_handle->src_fd != handle->src_fd)
                        close(out_handle->src_fd);
        }

        return EXIT_SUCCESS;
}
#endif /* FEATURE_AR_CREATE */

static void FAST_FUNC header_verbose_list_ar(const file_header_t *file_header)
{
        const char *mode = bb_mode_string(file_header->mode);
        char *mtime;

        mtime = ctime(&file_header->mtime);
        mtime[16] = ' ';
        memmove(&mtime[17], &mtime[20], 4);
        mtime[21] = '\0';
        printf("%s %u/%u%7"OFF_FMT"u %s %s\n", &mode[1],
                        (int)file_header->uid, (int)file_header->gid,
                        file_header->size,
                        &mtime[4], file_header->name
        );
}

#define AR_OPT_VERBOSE          (1 << 0)
#define AR_OPT_PRESERVE_DATE    (1 << 1)
/* "ar r" implies create, but warns about it. c suppresses warning.
 * bbox accepts but ignores it: */
#define AR_OPT_CREATE           (1 << 2)

#define AR_CMD_PRINT            (1 << 3)
#define FIRST_CMD               AR_CMD_PRINT
#define AR_CMD_LIST             (1 << 4)
#define AR_CMD_EXTRACT          (1 << 5)
#define AR_CMD_INSERT           (1 << 6)

int ar_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int ar_main(int argc UNUSED_PARAM, char **argv)
{
        archive_handle_t *archive_handle;
        unsigned opt, t;

        archive_handle = init_handle();

        /* --: prepend '-' to the first argument if required */
        /* -1: at least one param is reqd */
        /* one of p,t,x[,r] is required */
        opt_complementary = "--:-1:p:t:x"IF_FEATURE_AR_CREATE(":r");
        opt = getopt32(argv, "voc""ptx"IF_FEATURE_AR_CREATE("r"));
        argv += optind;

        t = opt / FIRST_CMD;
        if (t & (t-1)) /* more than one of p,t,x[,r] are specified */
                bb_show_usage();

        if (opt & AR_CMD_PRINT) {
                archive_handle->action_data = data_extract_to_stdout;
        }
        if (opt & AR_CMD_LIST) {
                archive_handle->action_header = header_list;
        }
        if (opt & AR_CMD_EXTRACT) {
                archive_handle->action_data = data_extract_all;
        }
        if (opt & AR_OPT_PRESERVE_DATE) {
                archive_handle->ah_flags |= ARCHIVE_RESTORE_DATE;
        }
        if (opt & AR_OPT_VERBOSE) {
                archive_handle->action_header = header_verbose_list_ar;
        }
#if ENABLE_FEATURE_AR_CREATE
        archive_handle->ar__name = *argv;
#endif
        archive_handle->src_fd = xopen(*argv++,
                        (opt & AR_CMD_INSERT)
                                ? O_RDWR | O_CREAT
                                : O_RDONLY
        );

        if (*argv)
                archive_handle->filter = filter_accept_list;
        while (*argv) {
                llist_add_to_end(&archive_handle->accept, *argv++);
        }

#if ENABLE_FEATURE_AR_CREATE
        if (opt & AR_CMD_INSERT)
                return write_ar_archive(archive_handle);
#endif

        unpack_ar_archive(archive_handle);

        return EXIT_SUCCESS;
}