/* vi: set sw=4 ts=4: */
/*
 * Mini unzip implementation for busybox
 *
 * Copyright (C) 2004 by Ed Clark
 *
 * Loosely based on original busybox unzip applet by Laurence Anderson.
 * All options and features should work in this version.
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
/* For reference see
 * http://www.pkware.com/company/standards/appnote/
 * http://www.info-zip.org/pub/infozip/doc/appnote-iz-latest.zip
 *
 * TODO
 * Zip64 + other methods
 */
//config:config UNZIP
//config:       bool "unzip (24 kb)"
//config:       default y
//config:       help
//config:       unzip will list or extract files from a ZIP archive,
//config:       commonly found on DOS/WIN systems. The default behavior
//config:       (with no options) is to extract the archive into the
//config:       current directory.
//config:
//config:config FEATURE_UNZIP_CDF
//config:       bool "Read and use Central Directory data"
//config:       default y
//config:       depends on UNZIP
//config:       help
//config:       If you know that you only need to deal with simple
//config:       ZIP files without deleted/updated files, SFX archives etc,
//config:       you can reduce code size by unselecting this option.
//config:       To support less trivial ZIPs, say Y.
//config:
//config:config FEATURE_UNZIP_BZIP2
//config:       bool "Support compression method 12 (bzip2)"
//config:       default y
//config:       depends on FEATURE_UNZIP_CDF && DESKTOP
// FEATURE_UNZIP_CDF is needed, otherwise we can't find start of next file
// DESKTOP is needed to get back uncompressed length
//config:
//config:config FEATURE_UNZIP_LZMA
//config:       bool "Support compression method 14 (lzma)"
//config:       default y
//config:       depends on FEATURE_UNZIP_CDF && DESKTOP
//config:
//config:config FEATURE_UNZIP_XZ
//config:       bool "Support compression method 95 (xz)"
//config:       default y
//config:       depends on FEATURE_UNZIP_CDF && DESKTOP

//applet:IF_UNZIP(APPLET(unzip, BB_DIR_USR_BIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_UNZIP) += unzip.o

//usage:#define unzip_trivial_usage
//usage:       "[-lnojpq] FILE[.zip] [FILE]... [-x FILE...] [-d DIR]"
//usage:#define unzip_full_usage "\n\n"
//usage:       "Extract FILEs from ZIP archive\n"
//usage:     "\n        -l      List contents (with -q for short form)"
//usage:     "\n        -n      Never overwrite files (default: ask)"
//usage:     "\n        -o      Overwrite"
//usage:     "\n        -j      Do not restore paths"
//usage:     "\n        -p      Print to stdout"
//usage:     "\n        -q      Quiet"
//usage:     "\n        -x FILE Exclude FILEs"
//usage:     "\n        -d DIR  Extract into DIR"

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

#if 0
# define dbg(...) bb_error_msg(__VA_ARGS__)
#else
# define dbg(...) ((void)0)
#endif

enum {
#if BB_BIG_ENDIAN
        ZIP_FILEHEADER_MAGIC = 0x504b0304,
        ZIP_CDF_MAGIC        = 0x504b0102, /* CDF item */
        ZIP_CDE_MAGIC        = 0x504b0506, /* End of CDF */
        ZIP_DD_MAGIC         = 0x504b0708,
#else
        ZIP_FILEHEADER_MAGIC = 0x04034b50,
        ZIP_CDF_MAGIC        = 0x02014b50,
        ZIP_CDE_MAGIC        = 0x06054b50,
        ZIP_DD_MAGIC         = 0x08074b50,
#endif
};

#define ZIP_HEADER_LEN 26

typedef union {
        uint8_t raw[ZIP_HEADER_LEN];
        struct {
                uint16_t version;               /* 0-1 */
                uint16_t zip_flags;             /* 2-3 */
                uint16_t method;                /* 4-5 */
                uint16_t modtime;               /* 6-7 */
                uint16_t moddate;               /* 8-9 */
                uint32_t crc32 PACKED;          /* 10-13 */
                uint32_t cmpsize PACKED;        /* 14-17 */
                uint32_t ucmpsize PACKED;       /* 18-21 */
                uint16_t filename_len;          /* 22-23 */
                uint16_t extra_len;             /* 24-25 */
                /* filename follows (not NUL terminated) */
                /* extra field follows */
                /* data follows */
        } fmt PACKED;
} zip_header_t; /* PACKED - gcc 4.2.1 doesn't like it (spews warning) */

#define FIX_ENDIANNESS_ZIP(zip) \
do { if (BB_BIG_ENDIAN) { \
        (zip).fmt.method        = SWAP_LE16((zip).fmt.method      ); \
        (zip).fmt.crc32         = SWAP_LE32((zip).fmt.crc32       ); \
        (zip).fmt.cmpsize       = SWAP_LE32((zip).fmt.cmpsize     ); \
        (zip).fmt.ucmpsize      = SWAP_LE32((zip).fmt.ucmpsize    ); \
        (zip).fmt.filename_len  = SWAP_LE16((zip).fmt.filename_len); \
        (zip).fmt.extra_len     = SWAP_LE16((zip).fmt.extra_len   ); \
}} while (0)

#define CDF_HEADER_LEN 42

typedef union {
        uint8_t raw[CDF_HEADER_LEN];
        struct {
                /* uint32_t signature; 50 4b 01 02 */
                uint16_t version_made_by;       /* 0-1 */
                uint16_t version_needed;        /* 2-3 */
                uint16_t cdf_flags;             /* 4-5 */
                uint16_t method;                /* 6-7 */
                uint16_t modtime;               /* 8-9 */
                uint16_t moddate;               /* 10-11 */
                uint32_t crc32;                 /* 12-15 */
                uint32_t cmpsize;               /* 16-19 */
                uint32_t ucmpsize;              /* 20-23 */
                uint16_t filename_len;          /* 24-25 */
                uint16_t extra_len;             /* 26-27 */
                uint16_t file_comment_length;   /* 28-29 */
                uint16_t disk_number_start;     /* 30-31 */
                uint16_t internal_attributes;   /* 32-33 */
                uint32_t external_attributes PACKED; /* 34-37 */
                uint32_t relative_offset_of_local_header PACKED; /* 38-41 */
                /* filename follows (not NUL terminated) */
                /* extra field follows */
                /* file comment follows */
        } fmt PACKED;
} cdf_header_t;

#define FIX_ENDIANNESS_CDF(cdf) \
do { if (BB_BIG_ENDIAN) { \
        (cdf).fmt.version_made_by = SWAP_LE16((cdf).fmt.version_made_by); \
        (cdf).fmt.version_needed = SWAP_LE16((cdf).fmt.version_needed); \
        (cdf).fmt.method        = SWAP_LE16((cdf).fmt.method      ); \
        (cdf).fmt.modtime       = SWAP_LE16((cdf).fmt.modtime     ); \
        (cdf).fmt.moddate       = SWAP_LE16((cdf).fmt.moddate     ); \
        (cdf).fmt.crc32         = SWAP_LE32((cdf).fmt.crc32       ); \
        (cdf).fmt.cmpsize       = SWAP_LE32((cdf).fmt.cmpsize     ); \
        (cdf).fmt.ucmpsize      = SWAP_LE32((cdf).fmt.ucmpsize    ); \
        (cdf).fmt.filename_len  = SWAP_LE16((cdf).fmt.filename_len); \
        (cdf).fmt.extra_len     = SWAP_LE16((cdf).fmt.extra_len   ); \
        (cdf).fmt.file_comment_length = SWAP_LE16((cdf).fmt.file_comment_length); \
        (cdf).fmt.external_attributes = SWAP_LE32((cdf).fmt.external_attributes); \
}} while (0)

#define CDE_LEN 16

typedef union {
        uint8_t raw[CDE_LEN];
        struct {
                /* uint32_t signature; 50 4b 05 06 */
                uint16_t this_disk_no;
                uint16_t disk_with_cdf_no;
                uint16_t cdf_entries_on_this_disk;
                uint16_t cdf_entries_total;
                uint32_t cdf_size;
                uint32_t cdf_offset;
                /* uint16_t archive_comment_length; */
                /* archive comment follows */
        } fmt PACKED;
} cde_t;

#define FIX_ENDIANNESS_CDE(cde) \
do { if (BB_BIG_ENDIAN) { \
        (cde).fmt.cdf_offset = SWAP_LE32((cde).fmt.cdf_offset); \
}} while (0)

struct BUG {
        /* Check the offset of the last element, not the length.  This leniency
         * allows for poor packing, whereby the overall struct may be too long,
         * even though the elements are all in the right place.
         */
        char BUG_zip_header_must_be_26_bytes[
                offsetof(zip_header_t, fmt.extra_len) + 2
                        == ZIP_HEADER_LEN ? 1 : -1];
        char BUG_cdf_header_must_be_42_bytes[
                offsetof(cdf_header_t, fmt.relative_offset_of_local_header) + 4
                        == CDF_HEADER_LEN ? 1 : -1];
        char BUG_cde_must_be_16_bytes[
                sizeof(cde_t) == CDE_LEN ? 1 : -1];
};


enum { zip_fd = 3 };


/* This value means that we failed to find CDF */
#define BAD_CDF_OFFSET ((uint32_t)0xffffffff)

#if !ENABLE_FEATURE_UNZIP_CDF

# define find_cdf_offset() BAD_CDF_OFFSET

#else
/* Seen in the wild:
 * Self-extracting PRO2K3XP_32.exe contains 19078464 byte zip archive,
 * where CDE was nearly 48 kbytes before EOF.
 * (Surprisingly, it also apparently has *another* CDE structure
 * closer to the end, with bogus cdf_offset).
 * To make extraction work, bumped PEEK_FROM_END from 16k to 64k.
 */
#define PEEK_FROM_END (64*1024)
/* NB: does not preserve file position! */
static uint32_t find_cdf_offset(void)
{
        cde_t cde;
        unsigned char *buf;
        unsigned char *p;
        off_t end;
        uint32_t found;

        end = lseek(zip_fd, 0, SEEK_END);
        if (end == (off_t) -1)
                return BAD_CDF_OFFSET;

        end -= PEEK_FROM_END;
        if (end < 0)
                end = 0;

        dbg("Looking for cdf_offset starting from 0x%"OFF_FMT"x", end);
        xlseek(zip_fd, end, SEEK_SET);
        buf = xzalloc(PEEK_FROM_END);
        full_read(zip_fd, buf, PEEK_FROM_END);

        found = BAD_CDF_OFFSET;
        p = buf;
        while (p <= buf + PEEK_FROM_END - CDE_LEN - 4) {
                if (*p != 'P') {
                        p++;
                        continue;
                }
                if (*++p != 'K')
                        continue;
                if (*++p != 5)
                        continue;
                if (*++p != 6)
                        continue;
                /* we found CDE! */
                memcpy(cde.raw, p + 1, CDE_LEN);
                FIX_ENDIANNESS_CDE(cde);
                /*
                 * I've seen .ZIP files with seemingly valid CDEs
                 * where cdf_offset points past EOF - ??
                 * This check ignores such CDEs:
                 */
                if (cde.fmt.cdf_offset < end + (p - buf)) {
                        found = cde.fmt.cdf_offset;
                        dbg("Possible cdf_offset:0x%x at 0x%"OFF_FMT"x",
                                (unsigned)found, end + (p-3 - buf));
                        dbg("  cdf_offset+cdf_size:0x%x",
                                (unsigned)(found + SWAP_LE32(cde.fmt.cdf_size)));
                        /*
                         * We do not "break" here because only the last CDE is valid.
                         * I've seen a .zip archive which contained a .zip file,
                         * uncompressed, and taking the first CDE was using
                         * the CDE inside that file!
                         */
                }
        }
        free(buf);
        dbg("Found cdf_offset:0x%x", (unsigned)found);
        return found;
};

static uint32_t read_next_cdf(uint32_t cdf_offset, cdf_header_t *cdf)
{
        uint32_t magic;

        if (cdf_offset == BAD_CDF_OFFSET)
                return cdf_offset;

        dbg("Reading CDF at 0x%x", (unsigned)cdf_offset);
        xlseek(zip_fd, cdf_offset, SEEK_SET);
        xread(zip_fd, &magic, 4);
        /* Central Directory End? Assume CDF has ended.
         * (more correct method is to use cde.cdf_entries_total counter)
         */
        if (magic == ZIP_CDE_MAGIC) {
                dbg("got ZIP_CDE_MAGIC");
                return 0; /* EOF */
        }
        xread(zip_fd, cdf->raw, CDF_HEADER_LEN);

        FIX_ENDIANNESS_CDF(*cdf);
        dbg("  filename_len:%u extra_len:%u file_comment_length:%u",
                (unsigned)cdf->fmt.filename_len,
                (unsigned)cdf->fmt.extra_len,
                (unsigned)cdf->fmt.file_comment_length
        );
        cdf_offset += 4 + CDF_HEADER_LEN
                + cdf->fmt.filename_len
                + cdf->fmt.extra_len
                + cdf->fmt.file_comment_length;

        return cdf_offset;
};
#endif

static void die_if_bad_fnamesize(unsigned sz)
{
        if (sz > 0xfff) /* more than 4k?! no funny business please */
                bb_error_msg_and_die("bad archive");
}

static void unzip_skip(off_t skip)
{
        if (skip != 0)
                if (lseek(zip_fd, skip, SEEK_CUR) == (off_t)-1)
                        bb_copyfd_exact_size(zip_fd, -1, skip);
}

static void unzip_create_leading_dirs(const char *fn)
{
        /* Create all leading directories */
        char *name = xstrdup(fn);

        /* mode of -1: set mode according to umask */
        if (bb_make_directory(dirname(name), -1, FILEUTILS_RECUR)) {
                xfunc_die(); /* bb_make_directory is noisy */
        }
        free(name);
}

#if ENABLE_FEATURE_UNZIP_CDF
static void unzip_extract_symlink(llist_t **symlink_placeholders,
                zip_header_t *zip,
                const char *dst_fn)
{
        char *target;

        die_if_bad_fnamesize(zip->fmt.ucmpsize);

        if (zip->fmt.method == 0) {
                /* Method 0 - stored (not compressed) */
                target = xzalloc(zip->fmt.ucmpsize + 1);
                xread(zip_fd, target, zip->fmt.ucmpsize);
        } else {
#if 1
                bb_error_msg_and_die("compressed symlink is not supported");
#else
                transformer_state_t xstate;
                init_transformer_state(&xstate);
                xstate.mem_output_size_max = zip->fmt.ucmpsize;
                /* ...unpack... */
                if (!xstate.mem_output_buf)
                        WTF();
                target = xstate.mem_output_buf;
                target = xrealloc(target, xstate.mem_output_size + 1);
                target[xstate.mem_output_size] = '\0';
#endif
        }
        create_or_remember_link(symlink_placeholders,
                        target,
                        dst_fn,
                        0);
        free(target);
}
#endif

static void unzip_extract(zip_header_t *zip, int dst_fd)
{
        transformer_state_t xstate;

        if (zip->fmt.method == 0) {
                /* Method 0 - stored (not compressed) */
                off_t size = zip->fmt.ucmpsize;
                if (size)
                        bb_copyfd_exact_size(zip_fd, dst_fd, size);
                return;
        }

        init_transformer_state(&xstate);
        xstate.bytes_in = zip->fmt.cmpsize;
        xstate.src_fd = zip_fd;
        xstate.dst_fd = dst_fd;
        if (zip->fmt.method == 8) {
                /* Method 8 - inflate */
                if (inflate_unzip(&xstate) < 0)
                        bb_error_msg_and_die("inflate error");
                /* Validate decompression - crc */
                if (zip->fmt.crc32 != (xstate.crc32 ^ 0xffffffffL)) {
                        bb_error_msg_and_die("crc error");
                }
        }
#if ENABLE_FEATURE_UNZIP_BZIP2
        else if (zip->fmt.method == 12) {
                /* Tested. Unpacker reads too much, but we use CDF
                 * and will seek to the correct beginning of next file.
                 */
                xstate.bytes_out = unpack_bz2_stream(&xstate);
                if (xstate.bytes_out < 0)
                        bb_error_msg_and_die("inflate error");
        }
#endif
#if ENABLE_FEATURE_UNZIP_LZMA
        else if (zip->fmt.method == 14) {
                /* Not tested yet */
                xstate.bytes_out = unpack_lzma_stream(&xstate);
                if (xstate.bytes_out < 0)
                        bb_error_msg_and_die("inflate error");
        }
#endif
#if ENABLE_FEATURE_UNZIP_XZ
        else if (zip->fmt.method == 95) {
                /* Not tested yet */
                xstate.bytes_out = unpack_xz_stream(&xstate);
                if (xstate.bytes_out < 0)
                        bb_error_msg_and_die("inflate error");
        }
#endif
        else {
                bb_error_msg_and_die("unsupported method %u", zip->fmt.method);
        }

        /* Validate decompression - size */
        if (zip->fmt.ucmpsize != xstate.bytes_out) {
                /* Don't die. Who knows, maybe len calculation
                 * was botched somewhere. After all, crc matched! */
                bb_error_msg("bad length");
        }
}

static void my_fgets80(char *buf80)
{
        fflush_all();
        if (!fgets(buf80, 80, stdin)) {
                bb_perror_msg_and_die("can't read standard input");
        }
}

static int get_lstat_mode(const char *dst_fn)
{
        struct stat stat_buf;
        if (lstat(dst_fn, &stat_buf) == -1) {
                if (errno != ENOENT) {
                        bb_perror_msg_and_die("can't stat '%s'", dst_fn);
                }
                /* File does not exist */
                return -1;
        }
        return stat_buf.st_mode;
}

int unzip_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int unzip_main(int argc, char **argv)
{
        enum {
                OPT_l = (1 << 0),
                OPT_x = (1 << 1),
                OPT_j = (1 << 2),
        };
        unsigned opts;
        smallint quiet = 0;
        IF_NOT_FEATURE_UNZIP_CDF(const) smallint verbose = 0;
        enum { O_PROMPT, O_NEVER, O_ALWAYS };
        smallint overwrite = O_PROMPT;
        uint32_t cdf_offset;
        unsigned long total_usize;
        unsigned long total_size;
        unsigned total_entries;
        int dst_fd = -1;
        char *src_fn = NULL;
        char *dst_fn = NULL;
        llist_t *zaccept = NULL;
        llist_t *zreject = NULL;
        char *base_dir = NULL;
#if ENABLE_FEATURE_UNZIP_CDF
        llist_t *symlink_placeholders = NULL;
#endif
        int i;
        char key_buf[80]; /* must match size used by my_fgets80 */

/* -q, -l and -v: UnZip 5.52 of 28 February 2005, by Info-ZIP:
 *
 * # /usr/bin/unzip -qq -v decompress_unlzma.i.zip
 *   204372  Defl:N    35278  83%  09-06-09 14:23  0d056252  decompress_unlzma.i
 * # /usr/bin/unzip -q -v decompress_unlzma.i.zip
 *  Length   Method    Size  Ratio   Date   Time   CRC-32    Name
 * --------  ------  ------- -----   ----   ----   ------    ----
 *   204372  Defl:N    35278  83%  09-06-09 14:23  0d056252  decompress_unlzma.i
 * --------          -------  ---                            -------
 *   204372            35278  83%                            1 file
 * # /usr/bin/unzip -v decompress_unlzma.i.zip
 * Archive:  decompress_unlzma.i.zip
 *  Length   Method    Size  Ratio   Date   Time   CRC-32    Name
 * --------  ------  ------- -----   ----   ----   ------    ----
 *   204372  Defl:N    35278  83%  09-06-09 14:23  0d056252  decompress_unlzma.i
 * --------          -------  ---                            -------
 *   204372            35278  83%                            1 file
 * # unzip -v decompress_unlzma.i.zip
 * Archive:  decompress_unlzma.i.zip
 *   Length     Date   Time    Name
 *  --------    ----   ----    ----
 *    204372  09-06-09 14:23   decompress_unlzma.i
 *  --------                   -------
 *    204372                   1 files
 * # /usr/bin/unzip -l -qq decompress_unlzma.i.zip
 *    204372  09-06-09 14:23   decompress_unlzma.i
 * # /usr/bin/unzip -l -q decompress_unlzma.i.zip
 *   Length     Date   Time    Name
 *  --------    ----   ----    ----
 *    204372  09-06-09 14:23   decompress_unlzma.i
 *  --------                   -------
 *    204372                   1 file
 * # /usr/bin/unzip -l decompress_unlzma.i.zip
 * Archive:  decompress_unlzma.i.zip
 *   Length     Date   Time    Name
 *  --------    ----   ----    ----
 *    204372  09-06-09 14:23   decompress_unlzma.i
 *  --------                   -------
 *    204372                   1 file
 */

        opts = 0;
        /* '-' makes getopt return 1 for non-options */
        while ((i = getopt(argc, argv, "-d:lnopqxjv")) != -1) {
                switch (i) {
                case 'd':  /* Extract to base directory */
                        base_dir = optarg;
                        break;

                case 'l': /* List */
                        opts |= OPT_l;
                        break;

                case 'n': /* Never overwrite existing files */
                        overwrite = O_NEVER;
                        break;

                case 'o': /* Always overwrite existing files */
                        overwrite = O_ALWAYS;
                        break;

                case 'p': /* Extract files to stdout and fall through to set verbosity */
                        dst_fd = STDOUT_FILENO;

                case 'q': /* Be quiet */
                        quiet++;
                        break;

                case 'v': /* Verbose list */
                        IF_FEATURE_UNZIP_CDF(verbose++;)
                        opts |= OPT_l;
                        break;

                case 'x':
                        opts |= OPT_x;
                        break;

                case 'j':
                        opts |= OPT_j;
                        break;

                case 1:
                        if (!src_fn) {
                                /* The zip file */
                                /* +5: space for ".zip" and NUL */
                                src_fn = xmalloc(strlen(optarg) + 5);
                                strcpy(src_fn, optarg);
                        } else if (!(opts & OPT_x)) {
                                /* Include files */
                                llist_add_to(&zaccept, optarg);
                        } else {
                                /* Exclude files */
                                llist_add_to(&zreject, optarg);
                        }
                        break;

                default:
                        bb_show_usage();
                }
        }

#ifndef __GLIBC__
        /*
         * This code is needed for non-GNU getopt
         * which doesn't understand "-" in option string.
         * The -x option won't work properly in this case:
         * "unzip a.zip q -x w e" will be interpreted as
         * "unzip a.zip q w e -x" = "unzip a.zip q w e"
         */
        argv += optind;
        if (argv[0]) {
                /* +5: space for ".zip" and NUL */
                src_fn = xmalloc(strlen(argv[0]) + 5);
                strcpy(src_fn, argv[0]);
                while (*++argv)
                        llist_add_to(&zaccept, *argv);
        }
#endif

        if (!src_fn) {
                bb_show_usage();
        }

        /* Open input file */
        if (LONE_DASH(src_fn)) {
                xdup2(STDIN_FILENO, zip_fd);
                /* Cannot use prompt mode since zip data is arriving on STDIN */
                if (overwrite == O_PROMPT)
                        overwrite = O_NEVER;
        } else {
                static const char extn[][5] ALIGN1 = { ".zip", ".ZIP" };
                char *ext = src_fn + strlen(src_fn);
                int src_fd;

                i = 0;
                for (;;) {
                        src_fd = open(src_fn, O_RDONLY);
                        if (src_fd >= 0)
                                break;
                        if (++i > 2) {
                                *ext = '\0';
                                bb_error_msg_and_die("can't open %s[.zip]", src_fn);
                        }
                        strcpy(ext, extn[i - 1]);
                }
                xmove_fd(src_fd, zip_fd);
        }

        /* Change dir if necessary */
        if (base_dir)
                xchdir(base_dir);

        if (quiet <= 1) { /* not -qq */
                if (quiet == 0)
                        printf("Archive:  %s\n", src_fn);
                if (opts & OPT_l) {
                        puts(verbose ?
                                " Length   Method    Size  Cmpr    Date    Time   CRC-32   Name\n"
                                "--------  ------  ------- ---- ---------- ----- --------  ----"
                                :
                                "  Length      Date    Time    Name\n"
                                "---------  ---------- -----   ----"
                                );
                }
        }

/* Example of an archive with one 0-byte long file named 'z'
 * created by Zip 2.31 on Unix:
 * 0000 [50 4b]03 04 0a 00 00 00 00 00 42 1a b8 3c 00 00 |PK........B..<..|
 *       sig........ vneed flags compr mtime mdate crc32>
 * 0010  00 00 00 00 00 00 00 00 00 00 01 00 15 00 7a 55 |..............zU|
 *      >..... csize...... usize...... fnlen exlen fn ex>
 * 0020  54 09 00 03 cc d3 f9 4b cc d3 f9 4b 55 78 04 00 |T......K...KUx..|
 *      >tra_field......................................
 * 0030  00 00 00 00[50 4b]01 02 17 03 0a 00 00 00 00 00 |....PK..........|
 *       ........... sig........ vmade vneed flags compr
 * 0040  42 1a b8 3c 00 00 00 00 00 00 00 00 00 00 00 00 |B..<............|
 *       mtime mdate crc32...... csize...... usize......
 * 0050  01 00 0d 00 00 00 00 00 00 00 00 00 a4 81 00 00 |................|
 *       fnlen exlen clen. dnum. iattr eattr...... relofs> (eattr = rw-r--r--)
 * 0060  00 00 7a 55 54 05 00 03 cc d3 f9 4b 55 78 00 00 |..zUT......KUx..|
 *      >..... fn extra_field...........................
 * 0070 [50 4b]05 06 00 00 00 00 01 00 01 00 3c 00 00 00 |PK..........<...|
 * 0080  34 00 00 00 00 00                               |4.....|
 */
        total_usize = 0;
        total_size = 0;
        total_entries = 0;
        cdf_offset = find_cdf_offset(); /* try to seek to the end, find CDE and CDF start */
        while (1) {
                zip_header_t zip;
                mode_t dir_mode = 0777;
#if ENABLE_FEATURE_UNZIP_CDF
                mode_t file_mode = 0666;
#endif

                if (!ENABLE_FEATURE_UNZIP_CDF || cdf_offset == BAD_CDF_OFFSET) {
                        /* Normally happens when input is unseekable.
                         *
                         * Valid ZIP file has Central Directory at the end
                         * with central directory file headers (CDFs).
                         * After it, there is a Central Directory End structure.
                         * CDFs identify what files are in the ZIP and where
                         * they are located. This allows ZIP readers to load
                         * the list of files without reading the entire ZIP archive.
                         * ZIP files may be appended to, only files specified in
                         * the CD are valid. Scanning for local file headers is
                         * not a correct algorithm.
                         *
                         * We try to do the above, and resort to "linear" reading
                         * of ZIP file only if seek failed or CDE wasn't found.
                         */
                        uint32_t magic;

                        /* Check magic number */
                        xread(zip_fd, &magic, 4);
                        /* CDF item? Assume there are no more files, exit */
                        if (magic == ZIP_CDF_MAGIC) {
                                dbg("got ZIP_CDF_MAGIC");
                                break;
                        }
                        /* Data descriptor? It was a streaming file, go on */
                        if (magic == ZIP_DD_MAGIC) {
                                dbg("got ZIP_DD_MAGIC");
                                /* skip over duplicate crc32, cmpsize and ucmpsize */
                                unzip_skip(3 * 4);
                                continue;
                        }
                        if (magic != ZIP_FILEHEADER_MAGIC)
                                bb_error_msg_and_die("invalid zip magic %08X", (int)magic);
                        dbg("got ZIP_FILEHEADER_MAGIC");

                        xread(zip_fd, zip.raw, ZIP_HEADER_LEN);
                        FIX_ENDIANNESS_ZIP(zip);
                        if (zip.fmt.zip_flags & SWAP_LE16(0x0008)) {
                                bb_error_msg_and_die("zip flag %s is not supported",
                                        "8 (streaming)");
                        }
                }
#if ENABLE_FEATURE_UNZIP_CDF
                else {
                        /* cdf_offset is valid (and we know the file is seekable) */
                        cdf_header_t cdf;
                        cdf_offset = read_next_cdf(cdf_offset, &cdf);
                        if (cdf_offset == 0) /* EOF? */
                                break;
# if 1
                        xlseek(zip_fd,
                                SWAP_LE32(cdf.fmt.relative_offset_of_local_header) + 4,
                                SEEK_SET);
                        xread(zip_fd, zip.raw, ZIP_HEADER_LEN);
                        FIX_ENDIANNESS_ZIP(zip);
                        if (zip.fmt.zip_flags & SWAP_LE16(0x0008)) {
                                /* 0x0008 - streaming. [u]cmpsize can be reliably gotten
                                 * only from Central Directory.
                                 */
                                zip.fmt.crc32    = cdf.fmt.crc32;
                                zip.fmt.cmpsize  = cdf.fmt.cmpsize;
                                zip.fmt.ucmpsize = cdf.fmt.ucmpsize;
                        }
// Seen in some zipfiles: central directory 9 byte extra field contains
// a subfield with ID 0x5455 and 5 data bytes, which is a Unix-style UTC mtime.
// Local header version:
//  u16 0x5455 ("UT")
//  u16 size (1 + 4 * n)
//  u8  flags: bit 0:mtime is present, bit 1:atime is present, bit 2:ctime is present
//  u32 mtime
//  u32 atime
//  u32 ctime
// Central header version:
//  u16 0x5455 ("UT")
//  u16 size (5 (or 1?))
//  u8  flags: bit 0:mtime is present, bit 1:atime is present, bit 2:ctime is present
//  u32 mtime (CDF does not store atime/ctime)
# else
                        /* CDF has the same data as local header, no need to read the latter...
                         * ...not really. An archive was seen with cdf.extra_len == 6 but
                         * zip.extra_len == 0.
                         */
                        memcpy(&zip.fmt.version,
                                &cdf.fmt.version_needed, ZIP_HEADER_LEN);
                        xlseek(zip_fd,
                                SWAP_LE32(cdf.fmt.relative_offset_of_local_header) + 4 + ZIP_HEADER_LEN,
                                SEEK_SET);
# endif
                        if ((cdf.fmt.version_made_by >> 8) == 3) {
                                /* This archive is created on Unix */
                                dir_mode = file_mode = (cdf.fmt.external_attributes >> 16);
                        }
                }
#endif

                if (zip.fmt.zip_flags & SWAP_LE16(0x0001)) {
                        /* 0x0001 - encrypted */
                        bb_error_msg_and_die("zip flag %s is not supported",
                                        "1 (encryption)");
                }
                dbg("File cmpsize:0x%x extra_len:0x%x ucmpsize:0x%x",
                        (unsigned)zip.fmt.cmpsize,
                        (unsigned)zip.fmt.extra_len,
                        (unsigned)zip.fmt.ucmpsize
                );

                /* Read filename */
                free(dst_fn);
                die_if_bad_fnamesize(zip.fmt.filename_len);
                dst_fn = xzalloc(zip.fmt.filename_len + 1);
                xread(zip_fd, dst_fn, zip.fmt.filename_len);
                /* Skip extra header bytes */
                unzip_skip(zip.fmt.extra_len);

                /* Guard against "/abspath", "/../" and similar attacks */
                overlapping_strcpy(dst_fn, strip_unsafe_prefix(dst_fn));

                /* Filter zip entries */
                if (find_list_entry(zreject, dst_fn)
                 || (zaccept && !find_list_entry(zaccept, dst_fn))
                ) { /* Skip entry */
                        goto skip_cmpsize;
                }

                if (opts & OPT_l) {
                        /* List entry */
                        char dtbuf[sizeof("mm-dd-yyyy hh:mm")];
                        sprintf(dtbuf, "%02u-%02u-%04u %02u:%02u",
                                (zip.fmt.moddate >> 5) & 0xf,  // mm: 0x01e0
                                (zip.fmt.moddate)      & 0x1f, // dd: 0x001f
                                (zip.fmt.moddate >> 9) + 1980, // yy: 0xfe00
                                (zip.fmt.modtime >> 11),       // hh: 0xf800
                                (zip.fmt.modtime >> 5) & 0x3f  // mm: 0x07e0
                                // seconds/2 not shown, encoded in -- 0x001f
                        );
                        if (!verbose) {
                                //      "  Length      Date    Time    Name\n"
                                //      "---------  ---------- -----   ----"
                                printf(       "%9u  " "%s   "         "%s\n",
                                        (unsigned)zip.fmt.ucmpsize,
                                        dtbuf,
                                        dst_fn);
                        } else {
                                char method6[7];
                                unsigned long percents;

                                sprintf(method6, "%6u", zip.fmt.method);
                                if (zip.fmt.method == 0) {
                                        strcpy(method6, "Stored");
                                }
                                if (zip.fmt.method == 8) {
                                        strcpy(method6, "Defl:N");
                                        /* normal, maximum, fast, superfast */
                                        IF_DESKTOP(method6[5] = "NXFS"[(zip.fmt.zip_flags >> 1) & 3];)
                                }
                                percents = zip.fmt.ucmpsize - zip.fmt.cmpsize;
                                if ((int32_t)percents < 0)
                                        percents = 0; /* happens if ucmpsize < cmpsize */
                                percents = percents * 100;
                                if (zip.fmt.ucmpsize)
                                        percents /= zip.fmt.ucmpsize;
                                //      " Length   Method    Size  Cmpr    Date    Time   CRC-32   Name\n"
                                //      "--------  ------  ------- ---- ---------- ----- --------  ----"
                                printf(      "%8u  %s"        "%9u%4u%% " "%s "         "%08x  "  "%s\n",
                                        (unsigned)zip.fmt.ucmpsize,
                                        method6,
                                        (unsigned)zip.fmt.cmpsize,
                                        (unsigned)percents,
                                        dtbuf,
                                        zip.fmt.crc32,
                                        dst_fn);
                                total_size += zip.fmt.cmpsize;
                        }
                        total_usize += zip.fmt.ucmpsize;
                        goto skip_cmpsize;
                }

                if (dst_fd == STDOUT_FILENO) {
                        /* Extracting to STDOUT */
                        goto do_extract;
                }

                /* Strip paths (after -l: unzip -lj a.zip lists full names) */
                if (opts & OPT_j)
                        overlapping_strcpy(dst_fn, bb_basename(dst_fn));
                /* Did this strip everything ("DIR/" case)? Then skip */
                if (!dst_fn[0])
                        goto skip_cmpsize;

                if (last_char_is(dst_fn, '/')) {
                        int mode;

                        /* Extract directory */
                        mode = get_lstat_mode(dst_fn);
                        if (mode == -1) { /* ENOENT */
                                if (!quiet) {
                                        printf("   creating: %s\n", dst_fn);
                                }
                                unzip_create_leading_dirs(dst_fn);
                                if (bb_make_directory(dst_fn, dir_mode, FILEUTILS_IGNORE_CHMOD_ERR)) {
                                        xfunc_die();
                                }
                        } else {
                                if (!S_ISDIR(mode)) {
                                        bb_error_msg_and_die("'%s' exists but is not a %s",
                                                dst_fn, "directory");
                                }
                        }
                        goto skip_cmpsize;
                }
 check_file:
                /* Does target file already exist? */
                {
                        int mode = get_lstat_mode(dst_fn);
                        if (mode == -1) {
                                /* ENOENT: does not exist */
                                goto do_open_and_extract;
                        }
                        if (overwrite == O_NEVER) {
                                goto skip_cmpsize;
                        }
                        if (!S_ISREG(mode)) {
 fishy:
                                bb_error_msg_and_die("'%s' exists but is not a %s",
                                        dst_fn, "regular file");
                        }
                        if (overwrite == O_ALWAYS) {
                                goto do_open_and_extract;
                        }
                        printf("replace %s? [y]es, [n]o, [A]ll, [N]one, [r]ename: ", dst_fn);
                        my_fgets80(key_buf);
                        /* User input could take a long time. Is it still a regular file? */
                        mode = get_lstat_mode(dst_fn);
                        if (!S_ISREG(mode))
                                goto fishy;
                }

                /* Extract (or skip) it */
                switch (key_buf[0]) {
                case 'A':
                        overwrite = O_ALWAYS;
                case 'y': /* Open file and fall into unzip */
 do_open_and_extract:
                        unzip_create_leading_dirs(dst_fn);
#if ENABLE_FEATURE_UNZIP_CDF
                        dst_fd = -1;
                        if (!S_ISLNK(file_mode)) {
                                dst_fd = xopen3(dst_fn,
                                        O_WRONLY | O_CREAT | O_TRUNC | O_NOFOLLOW,
                                        file_mode);
                        }
#else
                        /* O_NOFOLLOW defends against symlink attacks */
                        dst_fd = xopen(dst_fn, O_WRONLY | O_CREAT | O_TRUNC | O_NOFOLLOW);
#endif
 do_extract:
                        if (!quiet) {
                                printf(/* zip.fmt.method == 0
                                        ? " extracting: %s\n"
                                        : */ "  inflating: %s\n", dst_fn);
                        }
#if ENABLE_FEATURE_UNZIP_CDF
                        if (S_ISLNK(file_mode)) {
                                if (dst_fd != STDOUT_FILENO) /* not -p? */
                                        unzip_extract_symlink(&symlink_placeholders, &zip, dst_fn);
                        } else
#endif
                        {
                                unzip_extract(&zip, dst_fd);
                                if (dst_fd != STDOUT_FILENO) {
                                        /* closing STDOUT is potentially bad for future business */
                                        close(dst_fd);
                                }
                        }
                        break;

                case 'N':
                        overwrite = O_NEVER;
                case 'n': /* Skip entry data */
 skip_cmpsize:
                        unzip_skip(zip.fmt.cmpsize);
                        break;

                case 'r':
                        /* Prompt for new name */
                        printf("new name: ");
                        my_fgets80(key_buf);
                        free(dst_fn);
                        dst_fn = xstrdup(key_buf);
                        chomp(dst_fn);
                        goto check_file;

                default:
                        printf("error: invalid response [%c]\n", (char)key_buf[0]);
                        goto check_file;
                }

                total_entries++;
        }

#if ENABLE_FEATURE_UNZIP_CDF
        create_links_from_list(symlink_placeholders);
#endif

        if ((opts & OPT_l) && quiet <= 1) {
                if (!verbose) {
                        //      "  Length      Date    Time    Name\n"
                        //      "---------  ---------- -----   ----"

                        printf( " --------%21s"               "-------\n"
                                     "%9lu%21s"               "%u files\n",
                                "",
                                total_usize, "", total_entries);
                } else {
                        unsigned long percents = total_usize - total_size;
                        if ((long)percents < 0)
                                percents = 0; /* happens if usize < size */
                        percents = percents * 100;
                        if (total_usize)
                                percents /= total_usize;
                        //      " Length   Method    Size  Cmpr    Date    Time   CRC-32   Name\n"
                        //      "--------  ------  ------- ---- ---------- ----- --------  ----"
                        printf( "--------          ------- ----%28s"                      "----\n"
                                "%8lu"              "%17lu%4u%%%28s"                      "%u files\n",
                                "",
                                total_usize, total_size, (unsigned)percents, "",
                                total_entries);
                }
        }

        return 0;
}