1 | /* vi: set sw=4 ts=4: */
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2 | /* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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3 | *
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4 | * FIXME:
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5 | * In privileged mode if uname and gname map to a uid and gid then use the
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6 | * mapped value instead of the uid/gid values in tar header
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7 | *
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8 | * References:
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9 | * GNU tar and star man pages,
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10 | * Opengroup's ustar interchange format,
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11 | * http://www.opengroup.org/onlinepubs/007904975/utilities/pax.html
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12 | */
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13 |
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14 | #include "libbb.h"
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15 | #include "unarchive.h"
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16 |
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17 | #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
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18 | static char *longname;
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19 | static char *linkname;
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20 | #else
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21 | enum {
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22 | longname = 0,
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23 | linkname = 0,
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24 | };
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25 | #endif
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26 |
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27 | /* NB: _DESTROYS_ str[len] character! */
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28 | static unsigned long long getOctal(char *str, int len)
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29 | {
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30 | unsigned long long v;
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31 | /* Actually, tar header allows leading spaces also.
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32 | * Oh well, we will be liberal and skip this...
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33 | * The only downside probably is that we allow "-123" too :)
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34 | if (*str < '0' || *str > '7')
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35 | bb_error_msg_and_die("corrupted octal value in tar header");
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36 | */
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37 | str[len] = '\0';
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38 | v = strtoull(str, &str, 8);
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39 | if (*str && (!ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY || *str != ' '))
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40 | bb_error_msg_and_die("corrupted octal value in tar header");
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41 | return v;
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42 | }
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43 | #define GET_OCTAL(a) getOctal((a), sizeof(a))
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44 |
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45 | void BUG_tar_header_size(void);
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46 | char get_header_tar(archive_handle_t *archive_handle)
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47 | {
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48 | static smallint end;
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49 |
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50 | file_header_t *file_header = archive_handle->file_header;
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51 | struct {
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52 | /* ustar header, Posix 1003.1 */
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53 | char name[100]; /* 0-99 */
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54 | char mode[8]; /* 100-107 */
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55 | char uid[8]; /* 108-115 */
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56 | char gid[8]; /* 116-123 */
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57 | char size[12]; /* 124-135 */
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58 | char mtime[12]; /* 136-147 */
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59 | char chksum[8]; /* 148-155 */
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60 | char typeflag; /* 156-156 */
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61 | char linkname[100]; /* 157-256 */
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62 | char magic[6]; /* 257-262 */
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63 | char version[2]; /* 263-264 */
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64 | char uname[32]; /* 265-296 */
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65 | char gname[32]; /* 297-328 */
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66 | char devmajor[8]; /* 329-336 */
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67 | char devminor[8]; /* 337-344 */
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68 | char prefix[155]; /* 345-499 */
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69 | char padding[12]; /* 500-512 */
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70 | } tar;
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71 | char *cp;
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72 | int i, sum_u, sum;
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73 | #if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
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74 | int sum_s;
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75 | #endif
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76 | int parse_names;
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77 |
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78 | if (sizeof(tar) != 512)
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79 | BUG_tar_header_size();
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80 |
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81 | #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
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82 | again:
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83 | #endif
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84 | /* Align header */
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85 | data_align(archive_handle, 512);
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86 |
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87 | again_after_align:
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88 |
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89 | xread(archive_handle->src_fd, &tar, 512);
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90 | archive_handle->offset += 512;
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91 |
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92 | /* If there is no filename its an empty header */
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93 | if (tar.name[0] == 0) {
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94 | if (end) {
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95 | /* This is the second consecutive empty header! End of archive!
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96 | * Read until the end to empty the pipe from gz or bz2
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97 | */
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98 | while (full_read(archive_handle->src_fd, &tar, 512) == 512)
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99 | /* repeat */;
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100 | return EXIT_FAILURE;
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101 | }
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102 | end = 1;
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103 | return EXIT_SUCCESS;
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104 | }
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105 | end = 0;
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106 |
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107 | /* Check header has valid magic, "ustar" is for the proper tar
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108 | * 0's are for the old tar format
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109 | */
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110 | if (strncmp(tar.magic, "ustar", 5) != 0) {
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111 | #if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
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112 | if (memcmp(tar.magic, "\0\0\0\0", 5) != 0)
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113 | #endif
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114 | bb_error_msg_and_die("invalid tar magic");
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115 | }
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116 |
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117 | /* Do checksum on headers.
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118 | * POSIX says that checksum is done on unsigned bytes, but
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119 | * Sun and HP-UX gets it wrong... more details in
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120 | * GNU tar source. */
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121 | #if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
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122 | sum_s = ' ' * sizeof(tar.chksum);
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123 | #endif
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124 | sum_u = ' ' * sizeof(tar.chksum);
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125 | for (i = 0; i < 148; i++) {
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126 | sum_u += ((unsigned char*)&tar)[i];
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127 | #if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
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128 | sum_s += ((signed char*)&tar)[i];
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129 | #endif
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130 | }
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131 | for (i = 156; i < 512; i++) {
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132 | sum_u += ((unsigned char*)&tar)[i];
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133 | #if ENABLE_FEATURE_TAR_OLDSUN_COMPATIBILITY
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134 | sum_s += ((signed char*)&tar)[i];
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135 | #endif
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136 | }
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137 | #if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
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138 | sum = strtoul(tar.chksum, &cp, 8);
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139 | if ((*cp && *cp != ' ')
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140 | || (sum_u != sum USE_FEATURE_TAR_OLDSUN_COMPATIBILITY(&& sum_s != sum))
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141 | ) {
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142 | bb_error_msg_and_die("invalid tar header checksum");
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143 | }
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144 | #else
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145 | /* This field does not need special treatment (getOctal) */
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146 | sum = xstrtoul(tar.chksum, 8);
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147 | if (sum_u != sum USE_FEATURE_TAR_OLDSUN_COMPATIBILITY(&& sum_s != sum)) {
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148 | bb_error_msg_and_die("invalid tar header checksum");
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149 | }
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150 | #endif
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151 |
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152 | /* 0 is reserved for high perf file, treat as normal file */
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153 | if (!tar.typeflag) tar.typeflag = '0';
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154 | parse_names = (tar.typeflag >= '0' && tar.typeflag <= '7');
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155 |
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156 | /* getOctal trashes subsequent field, therefore we call it
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157 | * on fields in reverse order */
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158 | if (tar.devmajor[0]) {
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159 | unsigned minor = GET_OCTAL(tar.devminor);
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160 | unsigned major = GET_OCTAL(tar.devmajor);
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161 | file_header->device = makedev(major, minor);
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162 | }
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163 | file_header->link_target = NULL;
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164 | if (!linkname && parse_names && tar.linkname[0]) {
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165 | /* we trash magic[0] here, it's ok */
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166 | tar.linkname[sizeof(tar.linkname)] = '\0';
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167 | file_header->link_target = xstrdup(tar.linkname);
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168 | /* FIXME: what if we have non-link object with link_target? */
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169 | /* Will link_target be free()ed? */
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170 | }
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171 | file_header->mtime = GET_OCTAL(tar.mtime);
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172 | file_header->size = GET_OCTAL(tar.size);
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173 | file_header->gid = GET_OCTAL(tar.gid);
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174 | file_header->uid = GET_OCTAL(tar.uid);
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175 | /* Set bits 0-11 of the files mode */
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176 | file_header->mode = 07777 & GET_OCTAL(tar.mode);
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177 |
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178 | file_header->name = NULL;
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179 | if (!longname && parse_names) {
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180 | /* we trash mode[0] here, it's ok */
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181 | tar.name[sizeof(tar.name)] = '\0';
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182 | if (tar.prefix[0]) {
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183 | /* and padding[0] */
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184 | tar.prefix[sizeof(tar.prefix)] = '\0';
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185 | file_header->name = concat_path_file(tar.prefix, tar.name);
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186 | } else
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187 | file_header->name = xstrdup(tar.name);
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188 | }
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189 |
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190 | /* Set bits 12-15 of the files mode */
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191 | /* (typeflag was not trashed because chksum does not use getOctal) */
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192 | switch (tar.typeflag) {
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193 | /* busybox identifies hard links as being regular files with 0 size and a link name */
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194 | case '1':
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195 | file_header->mode |= S_IFREG;
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196 | break;
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197 | case '7':
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198 | /* case 0: */
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199 | case '0':
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200 | #if ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
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201 | if (last_char_is(file_header->name, '/')) {
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202 | file_header->mode |= S_IFDIR;
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203 | } else
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204 | #endif
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205 | file_header->mode |= S_IFREG;
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206 | break;
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207 | case '2':
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208 | file_header->mode |= S_IFLNK;
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209 | break;
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210 | case '3':
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211 | file_header->mode |= S_IFCHR;
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212 | break;
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213 | case '4':
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214 | file_header->mode |= S_IFBLK;
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215 | break;
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216 | case '5':
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217 | file_header->mode |= S_IFDIR;
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218 | break;
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219 | case '6':
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220 | file_header->mode |= S_IFIFO;
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221 | break;
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222 | #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
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223 | case 'L':
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224 | /* free: paranoia: tar with several consecutive longnames */
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225 | free(longname);
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226 | /* For paranoia reasons we allocate extra NUL char */
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227 | longname = xzalloc(file_header->size + 1);
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228 | /* We read ASCIZ string, including NUL */
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229 | xread(archive_handle->src_fd, longname, file_header->size);
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230 | archive_handle->offset += file_header->size;
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231 | /* return get_header_tar(archive_handle); */
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232 | /* gcc 4.1.1 didn't optimize it into jump */
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233 | /* so we will do it ourself, this also saves stack */
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234 | goto again;
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235 | case 'K':
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236 | free(linkname);
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237 | linkname = xzalloc(file_header->size + 1);
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238 | xread(archive_handle->src_fd, linkname, file_header->size);
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239 | archive_handle->offset += file_header->size;
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240 | /* return get_header_tar(archive_handle); */
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241 | goto again;
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242 | case 'D': /* GNU dump dir */
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243 | case 'M': /* Continuation of multi volume archive */
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244 | case 'N': /* Old GNU for names > 100 characters */
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245 | case 'S': /* Sparse file */
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246 | case 'V': /* Volume header */
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247 | #endif
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248 | case 'g': /* pax global header */
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249 | case 'x': { /* pax extended header */
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250 | off_t sz;
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251 | bb_error_msg("warning: skipping header '%c'", tar.typeflag);
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252 | sz = (file_header->size + 511) & ~(off_t)511;
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253 | archive_handle->offset += sz;
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254 | sz >>= 9; /* sz /= 512 but w/o contortions for signed div */
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255 | while (sz--)
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256 | xread(archive_handle->src_fd, &tar, 512);
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257 | /* return get_header_tar(archive_handle); */
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258 | goto again_after_align;
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259 | }
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260 | default:
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261 | bb_error_msg_and_die("unknown typeflag: 0x%x", tar.typeflag);
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262 | }
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263 |
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264 | #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
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265 | if (longname) {
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266 | file_header->name = longname;
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267 | longname = NULL;
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268 | }
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269 | if (linkname) {
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270 | file_header->link_target = linkname;
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271 | linkname = NULL;
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272 | }
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273 | #endif
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274 | if (!strncmp(file_header->name, "/../"+1, 3)
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275 | || strstr(file_header->name, "/../")
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276 | ) {
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277 | bb_error_msg_and_die("name with '..' encountered: '%s'",
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278 | file_header->name);
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279 | }
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280 |
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281 | /* Strip trailing '/' in directories */
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282 | /* Must be done after mode is set as '/' is used to check if it's a directory */
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283 | cp = last_char_is(file_header->name, '/');
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284 |
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285 | if (archive_handle->filter(archive_handle) == EXIT_SUCCESS) {
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286 | archive_handle->action_header(archive_handle->file_header);
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287 | /* Note that we kill the '/' only after action_header() */
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288 | /* (like GNU tar 1.15.1: verbose mode outputs "dir/dir/") */
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289 | if (cp) *cp = '\0';
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290 | archive_handle->flags |= ARCHIVE_EXTRACT_QUIET;
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291 | archive_handle->action_data(archive_handle);
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292 | llist_add_to(&(archive_handle->passed), file_header->name);
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293 | } else {
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294 | data_skip(archive_handle);
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295 | free(file_header->name);
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296 | }
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297 | archive_handle->offset += file_header->size;
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298 |
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299 | free(file_header->link_target);
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300 | /* Do not free(file_header->name)! */
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301 |
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302 | return EXIT_SUCCESS;
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303 | }
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