archival/libunarchive/get_header_tar.c

   1 /* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   2  *
   3  *  FIXME:
   4  *    In privileged mode if uname and gname map to a uid and gid then use the
   5  *    mapped value instead of the uid/gid values in tar header
   6  *
   7  *  References:
   8  *    GNU tar and star man pages,
   9  *    Opengroup's ustar interchange format,
  10  *      http://www.opengroup.org/onlinepubs/007904975/utilities/pax.html
  11  */
  12
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <string.h>
  16 #include <sys/sysmacros.h>      /* For makedev */
  17 #include "unarchive.h"
  18 #include "libbb.h"
  19
  20 #ifdef CONFIG_FEATURE_TAR_GNU_EXTENSIONS
  21 static char *longname = NULL;
  22 static char *linkname = NULL;
  23 #endif
  24
  25 char get_header_tar(archive_handle_t *archive_handle)
  26 {
  27         file_header_t *file_header = archive_handle->file_header;
  28         union {
  29                 /* ustar header, Posix 1003.1 */
  30                 unsigned char raw[512];
  31                 struct {
  32                         char name[100]; /*   0-99 */
  33                         char mode[8];   /* 100-107 */
  34                         char uid[8];    /* 108-115 */
  35                         char gid[8];    /* 116-123 */
  36                         char size[12];  /* 124-135 */
  37                         char mtime[12]; /* 136-147 */
  38                         char chksum[8]; /* 148-155 */
  39                         char typeflag;  /* 156-156 */
  40                         char linkname[100];     /* 157-256 */
  41                         char magic[6];  /* 257-262 */
  42                         char version[2];        /* 263-264 */
  43                         char uname[32]; /* 265-296 */
  44                         char gname[32]; /* 297-328 */
  45                         char devmajor[8];       /* 329-336 */
  46                         char devminor[8];       /* 337-344 */
  47                         char prefix[155];       /* 345-499 */
  48                         char padding[12];       /* 500-512 */
  49                 } formated;
  50         } tar;
  51         long sum = 0;
  52         long i;
  53         static int end = 0;
  54
  55         /* Align header */
  56         data_align(archive_handle, 512);
  57
  58         if (bb_full_read(archive_handle->src_fd, tar.raw, 512) != 512) {
  59                 /* Assume end of file */
  60                 bb_error_msg_and_die("Short header");
  61                 //return(EXIT_FAILURE);
  62         }
  63         archive_handle->offset += 512;
  64
  65         /* If there is no filename its an empty header */
  66         if (tar.formated.name[0] == 0) {
  67                 if (end) {
  68                         /* This is the second consecutive empty header! End of archive!
  69                          * Read until the end to empty the pipe from gz or bz2
  70                          */
  71                         while (bb_full_read(archive_handle->src_fd, tar.raw, 512) == 512);
  72                         return(EXIT_FAILURE);
  73                 }
  74                 end = 1;
  75                 return(EXIT_SUCCESS);
  76         }
  77         end = 0;
  78
  79         /* Check header has valid magic, "ustar" is for the proper tar
  80          * 0's are for the old tar format
  81          */
  82         if (strncmp(tar.formated.magic, "ustar", 5) != 0) {
  83 #ifdef CONFIG_FEATURE_TAR_OLDGNU_COMPATIBILITY
  84                 if (strncmp(tar.formated.magic, "\0\0\0\0\0", 5) != 0)
  85 #endif
  86                         bb_error_msg_and_die("Invalid tar magic");
  87         }
  88         /* Do checksum on headers */
  89         for (i =  0; i < 148 ; i++) {
  90                 sum += tar.raw[i];
  91         }
  92         sum += ' ' * 8;
  93         for (i =  156; i < 512 ; i++) {
  94                 sum += tar.raw[i];
  95         }
  96         if (sum != strtol(tar.formated.chksum, NULL, 8)) {
  97                 bb_error_msg("Invalid tar header checksum");
  98                 return(EXIT_FAILURE);
  99         }
 100
 101 #ifdef CONFIG_FEATURE_TAR_GNU_EXTENSIONS
 102         if (longname) {
 103                 file_header->name = longname;
 104                 longname = NULL;
 105         }
 106         else if (linkname) {
 107                 file_header->name = linkname;
 108                 linkname = NULL;
 109         } else
 110 #endif
 111         {
 112                 file_header->name = bb_xstrndup(tar.formated.name,100);
 113
 114                 if (tar.formated.prefix[0]) {
 115                         char *temp = file_header->name;
 116                         file_header->name = concat_path_file(tar.formated.prefix, temp);
 117                         free(temp);
 118                 }
 119         }
 120
 121         file_header->uid = strtol(tar.formated.uid, NULL, 8);
 122         file_header->gid = strtol(tar.formated.gid, NULL, 8);
 123         file_header->size = strtol(tar.formated.size, NULL, 8);
 124         file_header->mtime = strtol(tar.formated.mtime, NULL, 8);
 125         file_header->link_name = (tar.formated.linkname[0] != '\0') ?
 126             bb_xstrdup(tar.formated.linkname) : NULL;
 127         file_header->device = makedev(strtol(tar.formated.devmajor, NULL, 8),
 128                 strtol(tar.formated.devminor, NULL, 8));
 129
 130         /* Set bits 0-11 of the files mode */
 131         file_header->mode = 07777 & strtol(tar.formated.mode, NULL, 8);
 132
 133         /* Set bits 12-15 of the files mode */
 134         switch (tar.formated.typeflag) {
 135         /* busybox identifies hard links as being regular files with 0 size and a link name */
 136         case '1':
 137                 file_header->mode |= S_IFREG;
 138                 break;
 139         case 'x':
 140         case 'g':
 141                 bb_error_msg_and_die("pax is not tar");
 142                 break;
 143         case '7':
 144                 /* Reserved for high performance files, treat as normal file */
 145         case 0:
 146         case '0':
 147 #ifdef CONFIG_FEATURE_TAR_OLDGNU_COMPATIBILITY
 148                 if (last_char_is(file_header->name, '/')) {
 149                         file_header->mode |= S_IFDIR;
 150                 } else
 151 #endif
 152                         file_header->mode |= S_IFREG;
 153                 break;
 154         case '2':
 155                 file_header->mode |= S_IFLNK;
 156                 break;
 157         case '3':
 158                 file_header->mode |= S_IFCHR;
 159                 break;
 160         case '4':
 161                 file_header->mode |= S_IFBLK;
 162                 break;
 163         case '5':
 164                 file_header->mode |= S_IFDIR;
 165                 break;
 166         case '6':
 167                 file_header->mode |= S_IFIFO;
 168                 break;
 169 #ifdef CONFIG_FEATURE_TAR_GNU_EXTENSIONS
 170         case 'L': {
 171                         longname = xmalloc(file_header->size + 1);
 172                         archive_xread_all(archive_handle, longname, file_header->size);
 173                         longname[file_header->size] = '\0';
 174                         archive_handle->offset += file_header->size;
 175
 176                         return(get_header_tar(archive_handle));
 177                 }
 178         case 'K': {
 179                         linkname = xmalloc(file_header->size + 1);
 180                         archive_xread_all(archive_handle, linkname, file_header->size);
 181                         linkname[file_header->size] = '\0';
 182                         archive_handle->offset += file_header->size;
 183
 184                         file_header->name = linkname;
 185                         return(get_header_tar(archive_handle));
 186                 }
 187         case 'D':       /* GNU dump dir */
 188         case 'M':       /* Continuation of multi volume archive*/
 189         case 'N':       /* Old GNU for names > 100 characters */
 190         case 'S':       /* Sparse file */
 191         case 'V':       /* Volume header */
 192                 bb_error_msg("Ignoring GNU extension type %c", tar.formated.typeflag);
 193 #endif
 194         default:
 195                 bb_error_msg("Unknown typeflag: 0x%x", tar.formated.typeflag);
 196         }
 197         {       /* Strip trailing '/' in directories */
 198                 /* Must be done after mode is set as '/' is used to check if its a directory */
 199                 char *tmp = last_char_is(file_header->name, '/');
 200                 if (tmp) {
 201                         *tmp = '\0';
 202                 }
 203         }
 204
 205         if (archive_handle->filter(archive_handle) == EXIT_SUCCESS) {
 206                 archive_handle->action_header(archive_handle->file_header);
 207                 archive_handle->flags |= ARCHIVE_EXTRACT_QUIET;
 208                 archive_handle->action_data(archive_handle);
 209                 archive_handle->passed = llist_add_to(archive_handle->passed, file_header->name);
 210         } else {
 211                 data_skip(archive_handle);
 212         }
 213         archive_handle->offset += file_header->size;
 214
 215         free(file_header->link_name);
 216
 217         return(EXIT_SUCCESS);
 218 }