archival/libunarchive/get_header_tar.c

   1 /* vi: set sw=4 ts=4: */
   2 /* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   3  *
   4  *  FIXME:
   5  *    In privileged mode if uname and gname map to a uid and gid then use the
   6  *    mapped value instead of the uid/gid values in tar header
   7  *
   8  *  References:
   9  *    GNU tar and star man pages,
  10  *    Opengroup's ustar interchange format,
  11  *      http://www.opengroup.org/onlinepubs/007904975/utilities/pax.html
  12  */
  13
  14 #include <stdio.h>
  15 #include <stdlib.h>
  16 #include <string.h>
  17 #include <sys/sysmacros.h>      /* For makedev */
  18 #include "unarchive.h"
  19 #include "libbb.h"
  20
  21 #ifdef CONFIG_FEATURE_TAR_GNU_EXTENSIONS
  22 static char *longname = NULL;
  23 static char *linkname = NULL;
  24 #endif
  25
  26 char get_header_tar(archive_handle_t *archive_handle)
  27 {
  28         file_header_t *file_header = archive_handle->file_header;
  29         union {
  30                 /* ustar header, Posix 1003.1 */
  31                 unsigned char raw[512];
  32                 struct {
  33                         char name[100]; /*   0-99 */
  34                         char mode[8];   /* 100-107 */
  35                         char uid[8];    /* 108-115 */
  36                         char gid[8];    /* 116-123 */
  37                         char size[12];  /* 124-135 */
  38                         char mtime[12]; /* 136-147 */
  39                         char chksum[8]; /* 148-155 */
  40                         char typeflag;  /* 156-156 */
  41                         char linkname[100];     /* 157-256 */
  42                         char magic[6];  /* 257-262 */
  43                         char version[2];        /* 263-264 */
  44                         char uname[32]; /* 265-296 */
  45                         char gname[32]; /* 297-328 */
  46                         char devmajor[8];       /* 329-336 */
  47                         char devminor[8];       /* 337-344 */
  48                         char prefix[155];       /* 345-499 */
  49                         char padding[12];       /* 500-512 */
  50                 } formated;
  51         } tar;
  52         long sum = 0;
  53         long i;
  54         static int end = 0;
  55
  56         /* Align header */
  57         data_align(archive_handle, 512);
  58
  59         xread(archive_handle->src_fd, tar.raw, 512);
  60         archive_handle->offset += 512;
  61
  62         /* If there is no filename its an empty header */
  63         if (tar.formated.name[0] == 0) {
  64                 if (end) {
  65                         /* This is the second consecutive empty header! End of archive!
  66                          * Read until the end to empty the pipe from gz or bz2
  67                          */
  68                         while (full_read(archive_handle->src_fd, tar.raw, 512) == 512);
  69                         return(EXIT_FAILURE);
  70                 }
  71                 end = 1;
  72                 return(EXIT_SUCCESS);
  73         }
  74         end = 0;
  75
  76         /* Check header has valid magic, "ustar" is for the proper tar
  77          * 0's are for the old tar format
  78          */
  79         if (strncmp(tar.formated.magic, "ustar", 5) != 0) {
  80 #ifdef CONFIG_FEATURE_TAR_OLDGNU_COMPATIBILITY
  81                 if (strncmp(tar.formated.magic, "\0\0\0\0\0", 5) != 0)
  82 #endif
  83                         bb_error_msg_and_die("Invalid tar magic");
  84         }
  85         /* Do checksum on headers */
  86         for (i =  0; i < 148 ; i++) {
  87                 sum += tar.raw[i];
  88         }
  89         sum += ' ' * 8;
  90         for (i =  156; i < 512 ; i++) {
  91                 sum += tar.raw[i];
  92         }
  93         if (sum != strtol(tar.formated.chksum, NULL, 8)) {
  94                 bb_error_msg("Invalid tar header checksum");
  95                 return(EXIT_FAILURE);
  96         }
  97
  98 #ifdef CONFIG_FEATURE_TAR_GNU_EXTENSIONS
  99         if (longname) {
 100                 file_header->name = longname;
 101                 longname = NULL;
 102         }
 103         else if (linkname) {
 104                 file_header->name = linkname;
 105                 linkname = NULL;
 106         } else
 107 #endif
 108         {
 109                 file_header->name = bb_xstrndup(tar.formated.name,100);
 110
 111                 if (tar.formated.prefix[0]) {
 112                         char *temp = file_header->name;
 113                         file_header->name = concat_path_file(tar.formated.prefix, temp);
 114                         free(temp);
 115                 }
 116         }
 117
 118         file_header->uid = strtol(tar.formated.uid, NULL, 8);
 119         file_header->gid = strtol(tar.formated.gid, NULL, 8);
 120         file_header->size = strtol(tar.formated.size, NULL, 8);
 121         file_header->mtime = strtol(tar.formated.mtime, NULL, 8);
 122         file_header->link_name = (tar.formated.linkname[0] != '\0') ?
 123             bb_xstrdup(tar.formated.linkname) : NULL;
 124         file_header->device = makedev(strtol(tar.formated.devmajor, NULL, 8),
 125                 strtol(tar.formated.devminor, NULL, 8));
 126
 127         /* Set bits 0-11 of the files mode */
 128         file_header->mode = 07777 & strtol(tar.formated.mode, NULL, 8);
 129
 130         /* Set bits 12-15 of the files mode */
 131         switch (tar.formated.typeflag) {
 132         /* busybox identifies hard links as being regular files with 0 size and a link name */
 133         case '1':
 134                 file_header->mode |= S_IFREG;
 135                 break;
 136         case '7':
 137                 /* Reserved for high performance files, treat as normal file */
 138         case 0:
 139         case '0':
 140 #ifdef CONFIG_FEATURE_TAR_OLDGNU_COMPATIBILITY
 141                 if (last_char_is(file_header->name, '/')) {
 142                         file_header->mode |= S_IFDIR;
 143                 } else
 144 #endif
 145                         file_header->mode |= S_IFREG;
 146                 break;
 147         case '2':
 148                 file_header->mode |= S_IFLNK;
 149                 break;
 150         case '3':
 151                 file_header->mode |= S_IFCHR;
 152                 break;
 153         case '4':
 154                 file_header->mode |= S_IFBLK;
 155                 break;
 156         case '5':
 157                 file_header->mode |= S_IFDIR;
 158                 break;
 159         case '6':
 160                 file_header->mode |= S_IFIFO;
 161                 break;
 162 #ifdef CONFIG_FEATURE_TAR_GNU_EXTENSIONS
 163         case 'L': {
 164                         longname = xzalloc(file_header->size + 1);
 165                         xread(archive_handle->src_fd, longname, file_header->size);
 166                         archive_handle->offset += file_header->size;
 167
 168                         return(get_header_tar(archive_handle));
 169                 }
 170         case 'K': {
 171                         linkname = xzalloc(file_header->size + 1);
 172                         xread(archive_handle->src_fd, linkname, file_header->size);
 173                         archive_handle->offset += file_header->size;
 174
 175                         file_header->name = linkname;
 176                         return(get_header_tar(archive_handle));
 177                 }
 178         case 'D':       /* GNU dump dir */
 179         case 'M':       /* Continuation of multi volume archive*/
 180         case 'N':       /* Old GNU for names > 100 characters */
 181         case 'S':       /* Sparse file */
 182         case 'V':       /* Volume header */
 183 #endif
 184         case 'g':       /* pax global header */
 185         case 'x':       /* pax extended header */
 186                 bb_error_msg("Ignoring extension type %c", tar.formated.typeflag);
 187                 break;
 188         default:
 189                 bb_error_msg("Unknown typeflag: 0x%x", tar.formated.typeflag);
 190         }
 191         {       /* Strip trailing '/' in directories */
 192                 /* Must be done after mode is set as '/' is used to check if its a directory */
 193                 char *tmp = last_char_is(file_header->name, '/');
 194                 if (tmp) {
 195                         *tmp = '\0';
 196                 }
 197         }
 198
 199         if (archive_handle->filter(archive_handle) == EXIT_SUCCESS) {
 200                 archive_handle->action_header(archive_handle->file_header);
 201                 archive_handle->flags |= ARCHIVE_EXTRACT_QUIET;
 202                 archive_handle->action_data(archive_handle);
 203                 llist_add_to(&(archive_handle->passed), file_header->name);
 204         } else {
 205                 data_skip(archive_handle);
 206         }
 207         archive_handle->offset += file_header->size;
 208
 209         free(file_header->link_name);
 210
 211         return(EXIT_SUCCESS);
 212 }