Kernel/vfs/open.c

   1 /*
   2  * AcessMicro VFS
   3  * - Open, Close and ChDir
   4  */
   5 #include <common.h>
   6 #include "vfs.h"
   7 #include "vfs_int.h"
   8 #include "vfs_ext.h"
   9
  10 #define DEBUG   0
  11
  12 #if DEBUG
  13 #else
  14 # undef ENTER
  15 # undef LOG
  16 # undef LEAVE
  17 # define ENTER(...)
  18 # define LOG(...)
  19 # define LEAVE(...)
  20 #endif
  21
  22 // === CONSTANTS ===
  23 #define OPEN_MOUNT_ROOT 1
  24 #define MAX_KERNEL_FILES        128
  25
  26 // === IMPORTS ===
  27 extern tVFS_Node        gVFS_MemRoot;
  28 extern tVFS_Mount       *gRootMount;
  29
  30 // === GLOBALS ===
  31 tVFS_Handle     *gaUserHandles = (void*)MM_PPD_VFS;
  32 tVFS_Handle     *gaKernelHandles = (void*)MM_KERNEL_VFS;
  33
  34 // === CODE ===
  35 /**
  36  * \fn char *VFS_GetAbsPath(char *Path)
  37  * \brief Create an absolute path from a relative one
  38  */
  39 char *VFS_GetAbsPath(char *Path)
  40 {
  41         char    *ret;
  42          int    pathLen = strlen(Path);
  43          int    read, write;
  44          int    pos, slashNum=0, baseLen;
  45         Uint    slashOffsets[256];
  46         char    *cwd = CFGPTR(CFG_VFS_CWD);
  47          int    cwdLen;
  48
  49         ENTER("sPath", Path);
  50
  51         // Memory File
  52         if(Path[0] == '$') {
  53                 ret = malloc(strlen(Path)+1);
  54                 strcpy(ret, Path);
  55                 LEAVE('p', ret);
  56                 return ret;
  57         }
  58
  59         // Check if the path is already absolute
  60         if(Path[0] == '/') {
  61                 ret = malloc(pathLen + 1);
  62                 strcpy(ret, Path);
  63                 baseLen = 1;
  64         } else {
  65                 cwdLen = strlen(cwd);
  66                 // Prepend the current directory
  67                 ret = malloc(cwdLen+pathLen+1);
  68                 strcpy(ret, cwd);
  69                 strcpy(&ret[cwdLen], Path);
  70
  71                 // Pre-fill the slash positions
  72                 pos = 0;
  73                 while( (pos = strpos( &ret[pos+1], '/' )) != -1 )
  74                         slashOffsets[slashNum++] = pos;
  75
  76                 baseLen = cwdLen;
  77         }
  78
  79         // Remove . and ..
  80         read = write = baseLen; // Cwd has already been parsed
  81         for(; read < baseLen+pathLen; read = pos+1)
  82         {
  83                 pos = strpos( &ret[read], '/' );
  84                 // If we are in the last section, force a break at the end of the itteration
  85                 if(pos == -1)   pos = baseLen+pathLen;
  86                 else    pos += read;    // Else, Adjust to absolute
  87
  88                 // Check Length
  89                 if(pos - read <= 2)
  90                 {
  91                         // Current Dir "."
  92                         if(strncmp(&ret[read], ".", pos-read) == 0)     continue;
  93                         // Parent ".."
  94                         if(strncmp(&ret[read], "..", pos-read) == 0)
  95                         {
  96                                 // If there is no higher, silently ignore
  97                                 if(!slashNum)   continue;
  98                                 // Reverse write pointer
  99                                 write = slashOffsets[ slashNum-- ];
 100                                 continue;
 101                         }
 102                 }
 103
 104
 105                 // Only copy if the positions differ
 106                 if(read != write) {
 107                         memcpy( &ret[write], &ret[read], pos-read+1 );
 108                 }
 109                 write = pos+1;
 110                 if(slashNum < 256)
 111                         slashOffsets[ slashNum++ ] = pos;
 112                 else {
 113                         LOG("Path '%s' has too many elements", Path);
 114                         free(ret);
 115                         LEAVE('n');
 116                         return NULL;
 117                 }
 118         }
 119
 120         // `ret` should now be the absolute path
 121         LEAVE('s', ret);
 122         return ret;
 123 }
 124
 125 /**
 126  * \fn char *VFS_ParsePath(char *Path, char **TruePath)
 127  * \brief Parses a path, resolving sysmlinks and applying permissions
 128  */
 129 tVFS_Node *VFS_ParsePath(char *Path, char **TruePath)
 130 {
 131         tVFS_Mount      *mnt;
 132         tVFS_Mount      *longestMount = gRootMount;     // Root is first
 133          int    cmp, retLength = 0;
 134          int    ofs, nextSlash;
 135         tVFS_Node       *curNode, *tmpNode;
 136         char    *tmp;
 137
 138         ENTER("sPath pTruePath", Path, TruePath);
 139
 140         // Memory File
 141         if(Path[0] == '$') {
 142                 if(TruePath) {
 143                         *TruePath = malloc(strlen(Path)+1);
 144                         strcpy(*TruePath, Path);
 145                 }
 146                 curNode = gVFS_MemRoot.FindDir(&gVFS_MemRoot, Path);
 147                 LEAVE('p', curNode);
 148                 return curNode;
 149         }
 150         // For root we always fast return
 151
 152         if(Path[0] == '/' && Path[1] == '\0') {
 153                 if(TruePath) {
 154                         *TruePath = malloc( gRootMount->MountPointLen+1 );
 155                         strcpy(*TruePath, gRootMount->MountPoint);
 156                 }
 157                 LEAVE('p', gRootMount->RootNode);
 158                 return gRootMount->RootNode;
 159         }
 160
 161         // Check if there is anything mounted
 162         if(!gMounts)    return NULL;
 163
 164         // Find Mountpoint
 165         for(mnt = gMounts;
 166                 mnt;
 167                 mnt = mnt->Next)
 168         {
 169                 // Quick Check
 170                 if( Path[mnt->MountPointLen] != '/' && Path[mnt->MountPointLen] != '\0')
 171                         continue;
 172                 // Length Check - If the length is smaller than the longest match sofar
 173                 if(mnt->MountPointLen < longestMount->MountPointLen)    continue;
 174                 // String Compare
 175                 cmp = strcmp(Path, mnt->MountPoint);
 176
 177                 #if OPEN_MOUNT_ROOT
 178                 // Fast Break - Request Mount Root
 179                 if(cmp == 0) {
 180                         if(TruePath) {
 181                                 *TruePath = malloc( mnt->MountPointLen+1 );
 182                                 strcpy(*TruePath, mnt->MountPoint);
 183                         }
 184                         LEAVE('p', mnt->RootNode);
 185                         return mnt->RootNode;
 186                 }
 187                 #endif
 188                 // Not a match, continue
 189                 if(cmp != '/')  continue;
 190                 longestMount = mnt;
 191         }
 192
 193         // Sanity Check
 194         /*if(!longestMount) {
 195                 Log("VFS_GetTruePath - ERROR: No Root Node\n");
 196                 return NULL;
 197         }*/
 198
 199         // Save to shorter variable
 200         mnt = longestMount;
 201
 202         LOG("mnt = {MountPoint:\"%s\"}", mnt->MountPoint);
 203
 204         // Initialise String
 205         if(TruePath)
 206         {
 207                 *TruePath = malloc( mnt->MountPointLen+1 );
 208                 strcpy(*TruePath, mnt->MountPoint);
 209                 retLength = mnt->MountPointLen;
 210         }
 211
 212         curNode = mnt->RootNode;
 213         curNode->ReferenceCount ++;
 214         // Parse Path
 215         ofs = mnt->MountPointLen+1;
 216         for(; (nextSlash = strpos(&Path[ofs], '/')) != -1; Path[nextSlash]='/',ofs = nextSlash + 1)
 217         {
 218                 nextSlash += ofs;
 219                 Path[nextSlash] = '\0';
 220
 221                 // Check for empty string
 222                 if( Path[ofs] == '\0' ) continue;
 223
 224                 // Check permissions on root of filesystem
 225                 if( !VFS_CheckACL(curNode, VFS_PERM_EXECUTE) ) {
 226                         curNode->Close( curNode );
 227                         if(TruePath)    free(*TruePath);
 228                         LEAVE('n');
 229                         return NULL;
 230                 }
 231
 232                 // Check if the node has a FindDir method
 233                 if(!curNode->FindDir) {
 234                         if(curNode->Close)      curNode->Close(curNode);
 235                         if(TruePath)    free(*TruePath);
 236                         Path[nextSlash] = '/';
 237                         LEAVE('n');
 238                         return NULL;
 239                 }
 240                 LOG("FindDir(%p, '%s')", curNode, &Path[ofs]);
 241                 // Get Child Node
 242                 tmpNode = curNode->FindDir(curNode, &Path[ofs]);
 243                 LOG("tmpNode = %p", tmpNode);
 244                 if(curNode->Close)
 245                         curNode->Close(curNode);
 246                 curNode = tmpNode;
 247
 248                 // Error Check
 249                 if(!curNode) {
 250                         LOG("Node '%s' not found in dir '%s'", &Path[ofs], Path);
 251                         if(TruePath)
 252                                 free(*TruePath);
 253                         Path[nextSlash] = '/';
 254                         LEAVE('n');
 255                         return NULL;
 256                 }
 257
 258                 // Handle Symbolic Links
 259                 if(curNode->Flags & VFS_FFLAG_SYMLINK) {
 260                         if(TruePath)
 261                                 free(*TruePath);
 262                         tmp = malloc( curNode->Size + 1 );
 263                         curNode->Read( curNode, 0, curNode->Size, tmp );
 264                         tmp[ curNode->Size ] = '\0';
 265
 266                         // Parse Symlink Path
 267                         curNode = VFS_ParsePath(tmp, TruePath);
 268                         free(tmp);      // Free temp string
 269
 270                         // Error Check
 271                         if(!curNode) {
 272                                 LEAVE('n');
 273                                 return NULL;
 274                         }
 275
 276                         // Set Path Variable
 277                         if(TruePath) {
 278                                 *TruePath = tmp;
 279                                 retLength = strlen(tmp);
 280                         }
 281
 282                         continue;
 283                 }
 284
 285                 // Handle Non-Directories
 286                 if( !(curNode->Flags & VFS_FFLAG_DIRECTORY) )
 287                 {
 288                         Warning("VFS_ParsePath - File in directory context");
 289                         if(TruePath)    free(*TruePath);
 290                         LEAVE('n');
 291                         return NULL;
 292                 }
 293
 294                 // Check if path needs extending
 295                 if(!TruePath)   continue;
 296
 297                 // Increase buffer space
 298                 tmp = realloc( *TruePath, retLength + strlen(&Path[ofs]) + 1 + 1 );
 299                 // Check if allocation succeeded
 300                 if(!tmp) {
 301                         Warning("VFS_ParsePath -  Unable to reallocate true path buffer");
 302                         free(*TruePath);
 303                         if(curNode->Close)      curNode->Close(curNode);
 304                         LEAVE('n');
 305                         return NULL;
 306                 }
 307                 *TruePath = tmp;
 308                 // Append to path
 309                 (*TruePath)[retLength] = '/';
 310                 strcpy(*TruePath+retLength+1, &Path[ofs]);
 311                 // - Extend Path
 312                 retLength += strlen(&Path[ofs])+1;
 313         }
 314
 315         // Get last node
 316         LOG("VFS_ParsePath: FindDir(%p, '%s')", curNode, &Path[ofs]);
 317         tmpNode = curNode->FindDir(curNode, &Path[ofs]);
 318         LOG("tmpNode = %p", tmpNode);
 319         if(curNode->Close)      curNode->Close(curNode);
 320         // Check if file was found
 321         if(!tmpNode) {
 322                 LOG("Node '%s' not found in dir '%s'", &Path[ofs], Path);
 323                 if(TruePath)    free(*TruePath);
 324                 if(curNode->Close)      curNode->Close(curNode);
 325                 LEAVE('n');
 326                 return NULL;
 327         }
 328
 329         if(TruePath)
 330         {
 331                 // Increase buffer space
 332                 tmp = realloc(*TruePath, retLength + strlen(&Path[ofs]) + 1 + 1);
 333                 // Check if allocation succeeded
 334                 if(!tmp) {
 335                         Warning("VFS_ParsePath -  Unable to reallocate true path buffer");
 336                         free(*TruePath);
 337                         if(tmpNode->Close)      tmpNode->Close(curNode);
 338                         LEAVE('n');
 339                         return NULL;
 340                 }
 341                 *TruePath = tmp;
 342                 // Append to path
 343                 (*TruePath)[retLength] = '/';
 344                 strcpy(*TruePath + retLength + 1, &Path[ofs]);
 345                 // - Extend Path
 346                 //retLength += strlen(tmpNode->Name) + 1;
 347         }
 348
 349         LEAVE('p', tmpNode);
 350         return tmpNode;
 351 }
 352
 353 /**
 354  * \fn int VFS_Open(char *Path, Uint Mode)
 355  * \brief Open a file
 356  */
 357 int VFS_Open(char *Path, Uint Mode)
 358 {
 359         tVFS_Node       *node;
 360         char    *absPath;
 361          int    i;
 362
 363         ENTER("sPath xMode", Path, Mode);
 364
 365         // Get absolute path
 366         absPath = VFS_GetAbsPath(Path);
 367         LOG("absPath = \"%s\"", absPath);
 368         // Parse path and get mount point
 369         node = VFS_ParsePath(absPath, NULL);
 370         // Free generated path
 371         free(absPath);
 372
 373         if(!node) {
 374                 LOG("Cannot find node");
 375                 LEAVE('i', -1);
 376                 return -1;
 377         }
 378
 379         // Check for symlinks
 380         if( !(Mode & VFS_OPENFLAG_NOLINK) && (node->Flags & VFS_FFLAG_SYMLINK) )
 381         {
 382                 if( !node->Read ) {
 383                         LOG("No read method on symlink");
 384                         LEAVE('i', -1);
 385                         return -1;
 386                 }
 387                 absPath = malloc(node->Size+1); // Allocate Buffer
 388                 node->Read( node, 0, node->Size, absPath );     // Read Path
 389
 390                 absPath[ node->Size ] = '\0';   // End String
 391                 if(node->Close) node->Close( node );    // Close old node
 392                 node = VFS_ParsePath(absPath, NULL);    // Get new node
 393                 free( absPath );        // Free allocated path
 394         }
 395
 396         if(!node) {
 397                 LEAVE('i', -1);
 398                 return -1;
 399         }
 400
 401         i = 0;
 402         i |= (Mode & VFS_OPENFLAG_EXEC) ? VFS_PERM_EXECUTE : 0;
 403         i |= (Mode & VFS_OPENFLAG_READ) ? VFS_PERM_READ : 0;
 404         i |= (Mode & VFS_OPENFLAG_WRITE) ? VFS_PERM_WRITE : 0;
 405
 406         LOG("i = 0b%b", i);
 407
 408         // Permissions Check
 409         if( !VFS_CheckACL(node, i) ) {
 410                 node->Close( node );
 411                 LEAVE('i', -1);
 412                 return -1;
 413         }
 414
 415         // Check for a user open
 416         if(Mode & VFS_OPENFLAG_USER)
 417         {
 418                 // Allocate Buffer
 419                 if( MM_GetPhysAddr( (Uint)gaUserHandles ) == 0 )
 420                 {
 421                         Uint    addr, size;
 422                         size = CFGINT(CFG_VFS_MAXFILES) * sizeof(tVFS_Handle);
 423                         for(addr = 0; addr < size; addr += 0x1000)
 424                                 MM_Allocate( (Uint)gaUserHandles + addr );
 425                         memset( gaUserHandles, 0, size );
 426                 }
 427                 // Get a handle
 428                 for(i=0;i<CFGINT(CFG_VFS_MAXFILES);i++)
 429                 {
 430                         if(gaUserHandles[i].Node)       continue;
 431                         gaUserHandles[i].Node = node;
 432                         gaUserHandles[i].Position = 0;
 433                         gaUserHandles[i].Mode = Mode;
 434                         LEAVE('i', i);
 435                         return i;
 436                 }
 437         }
 438         else
 439         {
 440                 // Allocate space if not already
 441                 if( MM_GetPhysAddr( (Uint)gaKernelHandles ) == 0 )
 442                 {
 443                         Uint    addr, size;
 444                         size = MAX_KERNEL_FILES * sizeof(tVFS_Handle);
 445                         for(addr = 0; addr < size; addr += 0x1000)
 446                                 MM_Allocate( (Uint)gaKernelHandles + addr );
 447                         memset( gaKernelHandles, 0, size );
 448                 }
 449                 // Get a handle
 450                 for(i=0;i<MAX_KERNEL_FILES;i++)
 451                 {
 452                         if(gaKernelHandles[i].Node)     continue;
 453                         gaKernelHandles[i].Node = node;
 454                         gaKernelHandles[i].Position = 0;
 455                         gaKernelHandles[i].Mode = Mode;
 456                         LEAVE('x', i|VFS_KERNEL_FLAG);
 457                         return i|VFS_KERNEL_FLAG;
 458                 }
 459         }
 460
 461         LEAVE('i', -1);
 462         return -1;
 463 }
 464
 465 /**
 466  * \fn void VFS_Close(int FD)
 467  * \brief Closes an open file handle
 468  */
 469 void VFS_Close(int FD)
 470 {
 471         tVFS_Handle     *h;
 472
 473         // Get handle
 474         h = VFS_GetHandle(FD);
 475         if(h == NULL) {
 476                 Warning("Invalid file handle passed to VFS_Close, 0x%x\n", FD);
 477                 return;
 478         }
 479
 480         if(h->Node->Close)
 481                 h->Node->Close( h->Node );
 482
 483         h->Node = NULL;
 484 }
 485
 486 /**
 487  * \fn tVFS_Handle *VFS_GetHandle(int FD)
 488  * \brief Gets a pointer to the handle information structure
 489  */
 490 tVFS_Handle *VFS_GetHandle(int FD)
 491 {
 492         if(FD < 0)      return NULL;
 493
 494         if(FD & VFS_KERNEL_FLAG) {
 495                 FD &= (VFS_KERNEL_FLAG - 1);
 496                 if(FD >= MAX_KERNEL_FILES)      return NULL;
 497                 return &gaKernelHandles[ FD ];
 498         } else {
 499                 if(FD >= CFGINT(CFG_VFS_MAXFILES))      return NULL;
 500                 return &gaUserHandles[ FD ];
 501         }
 502 }