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222 volume VI os16 Script e sorgenti del kernel 223 740078 | // 740079 | return ((zno_t) -1); 740080 | } 740081 | } 740082 | // 740083 | // The zone is there: return it. 740084 | // 740085 | return (inode->direct[fzone]); 740086 | } 740087 | if (fzone < 7 + indirect_zones) 740088 | { 740089 | // 740090 | // 7 sb); 740107 | if (allocated_zone == 0) 740108 | { 740109 | // 740110 | // Cannot allocate the zone for the indirection table: 740111 | // this is an error and the ‘errno’ value is produced 740112 | // by ‘zone_alloc()’. 740113 | // 740114 | return ((zno_t) -1); 740115 | } 740116 | // 740117 | // The zone for the indirection table is allocated: 740118 | // clear the zone and save. 740119 | // 740120 | memset (buffer, 0, SB_MAX_ZONE_SIZE); 740121 | status = zone_write (inode->sb, allocated_zone, buffer); 740122 | if (status < 0) 740123 | { 740124 | // 740125 | // Cannot overwrite the zone. The variable ‘errno’ is 740126 | // set by ‘zone_write()’. 740127 | // 740128 | return ((zno_t) -1); 740129 | } 740130 | // 740131 | // The indirection table zone is allocated and cleared: 740132 | // save the inode. 740133 | // 740134 | inode->indirect1 = allocated_zone; 740135 | inode->changed = 1; 740136 | status = inode_save (inode); 740137 | if (status != 0) 740138 | { 740139 | // 740140 | // Cannot save the inode. This is an error and the value 740141 | // for ‘errno’ is produced by ‘inode_save()’. 740142 | // 740143 | return ((zno_t) -1); 740144 | } 740145 | } 740146 | // 740147 | // An indirect table is present inside the file system: 740148 | // load it. 740149 | // 740150 | status = zone_read (inode->sb, inode->indirect1, zone_table); 740151 | if (status != 0) 740152 | { 740153 | // 740154 | // Cannot load the indirect table. This is an error and the 740155 | // value for ‘errno’ is assigned by function ‘zone_read()’. 740156 | // 740157 | return ((zno_t) -1); 740158 | } 740159 | // 740160 | // The indirect table was read. Calculate the index inside 740161 | // the table, for the requested zone. 740162 | // 740163 | i0 = (fzone - 7); 740164 | // 740165 | // Check if the zone is to be allocated. 740166 | // 740167 | if (zone_table[i0] == 0) 740168 | { 740169 | // 740170 | // There is not such zone, but it is not an error. 740171 | // 740172 | if (!write) 740173 | { 740174 | return ((zno_t) 0); 740175 | } 740176 | // 740177 | // The zone must be allocated. 740178 | // 740179 | allocated_zone = zone_alloc (inode->sb); 740180 | if (allocated_zone == 0) 740181 | { 740182 | // 740183 | // There is no space for the zone allocation. The 740184 | // variable ‘errno’ is already updated by 740185 | // ‘zone_alloc()’. 740186 | // 740187 | return ((zno_t) -1); 740188 | } 740189 | // 740190 | // The zone is allocated: clear the zone and save. 740191 | // 740192 | memset (buffer, 0, SB_MAX_ZONE_SIZE); 740193 | status = zone_write (inode->sb, allocated_zone, buffer); 740194 | if (status < 0) 740195 | { 740196 | // 740197 | // Cannot overwrite the zone. The variable ‘errno’ is 740198 | // set by ‘zone_write()’. 740199 | // 740200 | return ((zno_t) -1); 740201 | } 740202 | // 740203 | // The zone is allocated and cleared: update the indirect 740204 | // zone table an save it. The inode is not modified, 740205 | // because the indirect table is outside. 740206 | // 740207 | zone_table[i0] = allocated_zone; 740208 | status = zone_write (inode->sb, inode->indirect1, zone_table); 740209 | if (status != 0) 740210 | { 740211 | // 740212 | // Cannot save the zone. The variable ‘errno’ is already 740213 | // set by ‘zone_write()’. 740214 | // 740215 | return ((zno_t) -1); 740216 | } 740217 | } 740218 | // 740219 | // The zone is allocated. 740220 | // 740221 | return (zone_table[i0]); 740222 | } 740223 | else 740224 | { 740225 | // 740226 | // (7 + indirect_zones) indirect2 == 0) 740232 | { 740233 | // 740234 | // There is not such zone, but it is not an error. 740235 | // 740236 | if (!write) 740237 | { 740238 | return ((zno_t) 0); 740239 | } 740240 | // 740241 | // The first level of second indirection must be 740242 | // initialized. 740243 | // 740244 | allocated_zone = zone_alloc (inode->sb); 740245 | if (allocated_zone == 0) 740246 | { 740247 | // 740248 | // Cannot allocate the zone. The variable ‘errno’ is 740249 | // set by ‘zone_alloc()’. 740250 | // 740251 | return ((zno_t) -1); 740252 | } 740253 | // 740254 | // The zone for the indirection table is allocated: 740255 | // clear the zone and save. 740256 | // 740257 | memset (buffer, 0, SB_MAX_ZONE_SIZE); 740258 | status = zone_write (inode->sb, allocated_zone, buffer); 740259 | if (status < 0) 740260 | { 740261 | // 740262 | // Cannot overwrite the zone. The variable ‘errno’ is 740263 | // set by ‘zone_write()’. 740264 | // 740265 | return ((zno_t) -1); 740266 | } 740267 | // 740268 | // The zone for the indirection table is allocated and 740269 | // cleared: save the inode. 740270 | // 740271 | inode->indirect2 = allocated_zone; 740272 | inode->changed = 1; 740273 | status = inode_save (inode); 740274 | if (status != 0) 740275 | { 740276 | // 740277 | // Cannot save the inode. The variable ‘errno’ is 740278 | // set by ‘inode_save()’. 740279 | // 740280 | return ((zno_t) -1); 740281 | } 740282 | } 740283 | // 740284 | // The first level of second indirection is present: 740285 | // Read the second indirect table. 740286 | // 740287 | status = zone_read (inode->sb, inode->indirect2, zone_table); 740288 | if (status != 0) 740289 | { 740290 | // 740291 | // Cannot read the second indirect table. The variable 740292 | // ‘errno’ is set by ‘zone_read()’. 740293 | // 740294 | return ((zno_t) -1); 740295 | } 740296 | // 740297 | // The first double indirect table was read: calculate 740298 | // indexes inside first and second level of table. 740299 | // 740300 | fzone -= 7; 740301 | fzone -= indirect_zones; 740302 | i1 = fzone / indirect_zones; 740303 | i2 = fzone % indirect_zones; 740304 | // 740305 | // Verify to have a second level. 740306 | // 740307 | if (zone_table[i1] == 0) 740308 | { 740309 | //
224 volume VI os16 Script e sorgenti del kernel 225 740310 | // There is not such zone, but it is not an error. 740311 | // 740312 | if (!write) 740313 | { 740314 | return ((zno_t) 0); 740315 | } 740316 | // 740317 | // The second level must be initialized. 740318 | // 740319 | allocated_zone = zone_alloc (inode->sb); 740320 | if (allocated_zone == 0) 740321 | { 740322 | // 740323 | // Cannot allocate the zone. The variable ‘errno’ is set 740324 | // by ‘zone_alloc()’. 740325 | // 740326 | return ((zno_t) -1); 740327 | } 740328 | // 740329 | // The zone for the indirection table is allocated: 740330 | // clear the zone and save. 740331 | // 740332 | memset (buffer, 0, SB_MAX_ZONE_SIZE); 740333 | status = zone_write (inode->sb, allocated_zone, buffer); 740334 | if (status < 0) 740335 | { 740336 | // 740337 | // Cannot overwrite the zone. The variable ‘errno’ is 740338 | // set by ‘zone_write()’. 740339 | // 740340 | return ((zno_t) -1); 740341 | } 740342 | // 740343 | // Update the first level index and save it. 740344 | // 740345 | zone_table[i1] = allocated_zone; 740346 | status = zone_write (inode->sb, inode->indirect2, zone_table); 740347 | if (status != 0) 740348 | { 740349 | // 740350 | // Cannot write the zone. The variable ‘errno’ is set 740351 | // by ‘zone_write()’. 740352 | // 740353 | return ((zno_t) -1); 740354 | } 740355 | } 740356 | // 740357 | // The second level can be read, overwriting the array 740358 | // ‘zone_table[]’. The zone number for the second level 740359 | // indirection table is saved inside ‘zone_second’, before 740360 | // overwriting the array. 740361 | // 740362 | zone_second = zone_table[i1]; 740363 | status = zone_read (inode->sb, zone_second, zone_table); 740364 | if (status != 0) 740365 | { 740366 | // 740367 | // Cannot read the second level indirect table. The variable 740368 | // ‘errno’ is set by ‘zone_read()’. 740369 | // 740370 | return ((zno_t) -1); 740371 | } 740372 | // 740373 | // The second level was read and ‘zone_table[]’ is now 740374 | // such second one: check if the zone is to be allocated. 740375 | // 740376 | if (zone_table[i2] == 0) 740377 | { 740378 | // 740379 | // There is not such zone, but it is not an error. 740380 | // 740381 | if (!write) 740382 | { 740383 | return ((zno_t) 0); 740384 | } 740385 | // 740386 | // Must be allocated. 740387 | // 740388 | allocated_zone = zone_alloc (inode->sb); 740389 | if (allocated_zone == 0) 740390 | { 740391 | // 740392 | // Cannot allocate the zone. The variable ‘errno’ is set 740393 | // by ‘zone_alloc()’. 740394 | // 740395 | return ((zno_t) -1); 740396 | } 740397 | // 740398 | // The zone is allocated: clear the zone and save. 740399 | // 740400 | memset (buffer, 0, SB_MAX_ZONE_SIZE); 740401 | status = zone_write (inode->sb, allocated_zone, buffer); 740402 | if (status < 0) 740403 | { 740404 | // 740405 | // Cannot overwrite the zone. The variable ‘errno’ is 740406 | // set by ‘zone_write()’. 740407 | // 740408 | return ((zno_t) -1); 740409 | } 740410 | // 740411 | // The zone was allocated and cleared: update the indirect 740412 | // zone table an save it. The inode is not modified, because 740413 | // the indirect table is outside. 740414 | // 740415 | zone_table[i2] = allocated_zone; 740416 | status = zone_write (inode->sb, zone_second, zone_table); 740417 | if (status != 0) 740418 | { 740419 | // 740420 | // Cannot write the zone. The variable ‘errno’ is set 740421 | // by ‘zone_write()’. 740422 | // 740423 | return ((zno_t) -1); 740424 | } 740425 | } 740426 | // 740427 | // The zone is there: return the zone number. 740428 | // 740429 | return (zone_table[i2]); 740430 | } 740431 |} 104.4.32 kernel/fs/path_chdir.c Si veda la sezione 103.3.30. 750001 |#include 750002 |#include 750003 |#include 750004 |//---------------------------------------------------------------------- 750005 |int 750006 |path_chdir (pid_t pid, const char *path) 750007 |{ 750008 | proc_t *ps; 750009 | inode_t *inode_directory; 750010 | int status; 750011 | char path_directory[PATH_MAX]; 750012 | // 750013 | // Get process. 750014 | // 750015 | ps = proc_reference (pid); 750016 | // 750017 | // The full directory path is needed. 750018 | // 750019 | status = path_full (path, ps->path_cwd, path_directory); 750020 | if (status < 0) 750021 | { 750022 | return (-1); 750023 | } 750024 | // 750025 | // Try to load the new directory inode. 750026 | // 750027 | inode_directory = path_inode (pid, path_directory); 750028 | if (inode_directory == NULL) 750029 | { 750030 | // 750031 | // Cannot access the directory: it does not exists or 750032 | // permissions are not sufficient. Variable ‘errno’ is set by 750033 | // function ‘inode_directory()’. 750034 | // 750035 | errset (errno); 750036 | return (-1); 750037 | } 750038 | // 750039 | // Inode loaded: release the old directory and set the new one. 750040 | // 750041 | inode_put (ps->inode_cwd); 750042 | // 750043 | ps->inode_cwd = inode_directory; 750044 | strncpy (ps->path_cwd, path_directory, PATH_MAX); 750045 | // 750046 | // Return. 750047 | // 750048 | return (0); 750049 |} 104.4.33 kernel/fs/path_chmod.c Si veda la sezione 103.3.31. 760001 |#include 760002 |#include 760003 |#include 760004 |//---------------------------------------------------------------------- 760005 |int 760006 |path_chmod (pid_t pid, const char *path, mode_t mode) 760007 |{ 760008 | proc_t *ps; 760009 | inode_t *inode; 760010 | // 760011 | // Get process. 760012 | // 760013 | ps = proc_reference (pid); 760014 | // 760015 | // Try to load the file inode. 760016 | // 760017 | inode = path_inode (pid, path); 760018 | if (inode == NULL) 760019 | { 760020 | // 760021 | // Cannot access the file: it does not exists or permissions are 760022 | // not sufficient. Variable ‘errno’ is set by function 760023 | // ‘inode_directory()’. 760024 | // 760025 | return (-1); 760026 | } 760027 | // 760028 | // Verify to be root or to be the owner. 760029 | // 760030 | if (ps->euid != 0 && ps->euid != inode->uid) 760031 | { 760032 | errset (EACCES); // Permission denied. 760033 | return (-1); 760034 | } 760035 | // 760036 | // Update the mode: the file type is kept and the 760037 | // rest is taken form the parameter ‘mode’. 760038 | // 760039 | inode->mode = (S_IFMT & inode->mode) | (~S_IFMT & mode); 760040 | // 760041 | // Save and release the inode. 760042 | // 760043 | inode->changed = 1; 760044 | inode_save (inode); 760045 | inode_put (inode); 760046 | // 760047 | // Return. 760048 | // 760049 | return (0); 760050 |} « «
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