LXR busybox/archival/libarchive/get_header

   1/* vi: set sw=4 ts=4: */
   2/* Copyright 2001 Glenn McGrath.
   3 *
   4 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   5 */
   6
   7#include "libbb.h"
   8#include "bb_archive.h"
   9#include "ar.h"
  10
  11/* WARNING: Clobbers str[len], so fields must be read in reverse order! */
  12static unsigned read_num(char *str, int base, int len)
  13{
  14        int err;
  15
  16        /* ar fields are fixed length text strings (padded with spaces).
  17         * Ensure bb_strtou doesn't read past the field in case the full
  18         * width is used. */
  19        str[len] = 0;
  20
  21        /* This code works because
  22         * on misformatted numbers bb_strtou returns all-ones */
  23        err = bb_strtou(str, NULL, base);
  24        if (err == -1)
  25                bb_error_msg_and_die("invalid ar header");
  26        return err;
  27}
  28
  29char FAST_FUNC get_header_ar(archive_handle_t *archive_handle)
  30{
  31        file_header_t *typed = archive_handle->file_header;
  32        unsigned size;
  33        union {
  34                char raw[60];
  35                struct ar_header formatted;
  36        } ar;
  37#if ENABLE_FEATURE_AR_LONG_FILENAMES
  38        static char *ar_long_names;
  39        static unsigned ar_long_name_size;
  40#endif
  41
  42        /* dont use xread as we want to handle the error ourself */
  43        if (read(archive_handle->src_fd, ar.raw, 60) != 60) {
  44                /* End Of File */
  45                return EXIT_FAILURE;
  46        }
  47
  48        /* ar header starts on an even byte (2 byte aligned)
  49         * '\n' is used for padding
  50         */
  51        if (ar.raw[0] == '\n') {
  52                /* fix up the header, we started reading 1 byte too early */
  53                memmove(ar.raw, &ar.raw[1], 59);
  54                ar.raw[59] = xread_char(archive_handle->src_fd);
  55                archive_handle->offset++;
  56        }
  57        archive_handle->offset += 60;
  58
  59        if (ar.formatted.magic[0] != '`' || ar.formatted.magic[1] != '\n')
  60                bb_error_msg_and_die("invalid ar header");
  61
  62        /*
  63         * Note that the fields MUST be read in reverse order as
  64         * read_num() clobbers the next byte after the field!
  65         * Order is: name, date, uid, gid, mode, size, magic.
  66         */
  67        typed->size = size = read_num(ar.formatted.size, 10,
  68                                      sizeof(ar.formatted.size));
  69
  70        /* special filenames have '/' as the first character */
  71        if (ar.formatted.name[0] == '/') {
  72                if (ar.formatted.name[1] == ' ') {
  73                        /* This is the index of symbols in the file for compilers */
  74                        data_skip(archive_handle);
  75                        archive_handle->offset += size;
  76                        return get_header_ar(archive_handle); /* Return next header */
  77                }
  78#if ENABLE_FEATURE_AR_LONG_FILENAMES
  79                if (ar.formatted.name[1] == '/') {
  80                        /* If the second char is a '/' then this entries data section
  81                         * stores long filename for multiple entries, they are stored
  82                         * in static variable long_names for use in future entries
  83                         */
  84                        ar_long_name_size = size;
  85                        free(ar_long_names);
  86                        ar_long_names = xmalloc(size);
  87                        xread(archive_handle->src_fd, ar_long_names, size);
  88                        archive_handle->offset += size;
  89                        /* Return next header */
  90                        return get_header_ar(archive_handle);
  91                }
  92#else
  93                bb_error_msg_and_die("long filenames not supported");
  94#endif
  95        }
  96        /* Only size is always present, the rest may be missing in
  97         * long filename pseudo file. Thus we decode the rest
  98         * after dealing with long filename pseudo file.
  99         */
 100        typed->mode = read_num(ar.formatted.mode, 8, sizeof(ar.formatted.mode));
 101        typed->gid = read_num(ar.formatted.gid, 10, sizeof(ar.formatted.gid));
 102        typed->uid = read_num(ar.formatted.uid, 10, sizeof(ar.formatted.uid));
 103        typed->mtime = read_num(ar.formatted.date, 10, sizeof(ar.formatted.date));
 104
 105#if ENABLE_FEATURE_AR_LONG_FILENAMES
 106        if (ar.formatted.name[0] == '/') {
 107                unsigned long_offset;
 108
 109                /* The number after the '/' indicates the offset in the ar data section
 110                 * (saved in ar_long_names) that conatains the real filename */
 111                long_offset = read_num(&ar.formatted.name[1], 10,
 112                                       sizeof(ar.formatted.name) - 1);
 113                if (long_offset >= ar_long_name_size) {
 114                        bb_error_msg_and_die("can't resolve long filename");
 115                }
 116                typed->name = xstrdup(ar_long_names + long_offset);
 117        } else
 118#endif
 119        {
 120                /* short filenames */
 121                typed->name = xstrndup(ar.formatted.name, 16);
 122        }
 123
 124        typed->name[strcspn(typed->name, " /")] = '\0';
 125
 126        if (archive_handle->filter(archive_handle) == EXIT_SUCCESS) {
 127                archive_handle->action_header(typed);
 128#if ENABLE_DPKG || ENABLE_DPKG_DEB
 129                if (archive_handle->dpkg__sub_archive) {
 130                        while (archive_handle->dpkg__action_data_subarchive(archive_handle->dpkg__sub_archive) == EXIT_SUCCESS)
 131                                continue;
 132                } else
 133#endif
 134                        archive_handle->action_data(archive_handle);
 135        } else {
 136                data_skip(archive_handle);
 137        }
 138
 139        archive_handle->offset += typed->size;
 140        /* Set the file pointer to the correct spot, we may have been reading a compressed file */
 141        lseek(archive_handle->src_fd, archive_handle->offset, SEEK_SET);
 142
 143        return EXIT_SUCCESS;
 144}
 145