lib/vfs/interface.c

   1 /*
   2    Virtual File System: interface functions
   3
   4    Copyright (C) 2011
   5    The Free Software Foundation, Inc.
   6
   7    Written by:
   8    Slava Zanko <slavazanko@gmail.com>, 2011
   9
  10    This file is part of the Midnight Commander.
  11
  12    The Midnight Commander is free software: you can redistribute it
  13    and/or modify it under the terms of the GNU General Public License as
  14    published by the Free Software Foundation, either version 3 of the License,
  15    or (at your option) any later version.
  16
  17    The Midnight Commander is distributed in the hope that it will be useful,
  18    but WITHOUT ANY WARRANTY; without even the implied warranty of
  19    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20    GNU General Public License for more details.
  21
  22    You should have received a copy of the GNU General Public License
  23    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  24  */
  25
  26 /**
  27  * \file
  28  * \brief Source: Virtual File System: path handlers
  29  * \author Slava Zanko
  30  * \date 2011
  31  */
  32
  33
  34 #include <config.h>
  35
  36 #include <stdio.h>
  37 #include <stdlib.h>             /* For atol() */
  38 #include <stdarg.h>
  39 #include <string.h>
  40 #include <errno.h>
  41 #include <sys/types.h>
  42 #include <signal.h>
  43 #include <ctype.h>              /* is_digit() */
  44 #include <fcntl.h>
  45 #include <sys/stat.h>
  46 #include <unistd.h>
  47 #include <dirent.h>
  48 #include <pwd.h>
  49 #include <grp.h>
  50
  51 #include "lib/global.h"
  52
  53 #include "lib/widget.h"         /* message() */
  54 #include "lib/strutil.h"        /* str_crt_conv_from() */
  55 #include "lib/util.h"
  56
  57 #include "vfs.h"
  58 #include "utilvfs.h"
  59 #include "path.h"
  60 #include "gc.h"
  61 #include "xdirentry.h"
  62
  63 extern GString *vfs_str_buffer;
  64 extern struct vfs_class *current_vfs;
  65
  66 /*** global variables ****************************************************************************/
  67
  68 struct dirent *mc_readdir_result = NULL;
  69
  70 /*** file scope macro definitions ****************************************************************/
  71
  72 /*** file scope type declarations ****************************************************************/
  73
  74 /*** file scope variables ************************************************************************/
  75
  76 /*** file scope functions ************************************************************************/
  77 /* --------------------------------------------------------------------------------------------- */
  78
  79 static vfs_path_t *
  80 mc_def_getlocalcopy (const vfs_path_t * filename_vpath)
  81 {
  82     vfs_path_t *tmp_vpath = NULL;
  83     int fdin = -1, fdout = -1;
  84     ssize_t i;
  85     char buffer[BUF_1K * 8];
  86     struct stat mystat;
  87
  88     fdin = mc_open (filename_vpath, O_RDONLY | O_LINEAR);
  89     if (fdin == -1)
  90         goto fail;
  91
  92     fdout = vfs_mkstemps (&tmp_vpath, "vfs", vfs_path_get_last_path_str (filename_vpath));
  93     if (fdout == -1)
  94         goto fail;
  95
  96     while ((i = mc_read (fdin, buffer, sizeof (buffer))) > 0)
  97     {
  98         if (write (fdout, buffer, i) != i)
  99             goto fail;
 100     }
 101     if (i == -1)
 102         goto fail;
 103     i = mc_close (fdin);
 104     fdin = -1;
 105     if (i == -1)
 106         goto fail;
 107
 108     i = close (fdout);
 109     fdout = -1;
 110     if (i == -1)
 111         goto fail;
 112
 113     if (mc_stat (filename_vpath, &mystat) != -1)
 114         mc_chmod (tmp_vpath, mystat.st_mode);
 115
 116     return tmp_vpath;
 117
 118   fail:
 119     vfs_path_free (tmp_vpath);
 120     if (fdout != -1)
 121         close (fdout);
 122     if (fdin != -1)
 123         mc_close (fdin);
 124     return NULL;
 125 }
 126
 127 /* --------------------------------------------------------------------------------------------- */
 128
 129 static int
 130 mc_def_ungetlocalcopy (const vfs_path_t * filename_vpath,
 131                        const vfs_path_t * local_vpath, gboolean has_changed)
 132 {
 133     int fdin = -1, fdout = -1;
 134     const char *local;
 135
 136     local = vfs_path_get_last_path_str (local_vpath);
 137
 138     if (has_changed)
 139     {
 140         char buffer[BUF_1K * 8];
 141         ssize_t i;
 142
 143         if (vfs_path_get_last_path_vfs (filename_vpath)->write == NULL)
 144             goto failed;
 145
 146         fdin = open (local, O_RDONLY);
 147         if (fdin == -1)
 148             goto failed;
 149         fdout = mc_open (filename_vpath, O_WRONLY | O_TRUNC);
 150         if (fdout == -1)
 151             goto failed;
 152         while ((i = read (fdin, buffer, sizeof (buffer))) > 0)
 153             if (mc_write (fdout, buffer, (size_t) i) != i)
 154                 goto failed;
 155         if (i == -1)
 156             goto failed;
 157
 158         if (close (fdin) == -1)
 159         {
 160             fdin = -1;
 161             goto failed;
 162         }
 163         fdin = -1;
 164         if (mc_close (fdout) == -1)
 165         {
 166             fdout = -1;
 167             goto failed;
 168         }
 169     }
 170     unlink (local);
 171     return 0;
 172
 173   failed:
 174     message (D_ERROR, _("Changes to file lost"), "%s", vfs_path_get_last_path_str (filename_vpath));
 175     if (fdout != -1)
 176         mc_close (fdout);
 177     if (fdin != -1)
 178         close (fdin);
 179     unlink (local);
 180     return -1;
 181 }
 182
 183 /* --------------------------------------------------------------------------------------------- */
 184 /*** public functions ****************************************************************************/
 185 /* --------------------------------------------------------------------------------------------- */
 186
 187 int
 188 mc_open (const vfs_path_t * vpath, int flags, ...)
 189 {
 190     int mode = 0, result = -1;
 191     const vfs_path_element_t *path_element;
 192
 193     if (vpath == NULL)
 194         return -1;
 195
 196     /* Get the mode flag */
 197     if (flags & O_CREAT)
 198     {
 199         va_list ap;
 200         va_start (ap, flags);
 201         mode = va_arg (ap, int);
 202         va_end (ap);
 203     }
 204
 205     path_element = vfs_path_get_by_index (vpath, -1);
 206     if (vfs_path_element_valid (path_element) && path_element->class->open != NULL)
 207     {
 208         void *info;
 209         /* open must be supported */
 210         info = path_element->class->open (vpath, flags, mode);
 211         if (info == NULL)
 212             errno = vfs_ferrno (path_element->class);
 213         else
 214             result = vfs_new_handle (path_element->class, info);
 215     }
 216     else
 217         errno = -EOPNOTSUPP;
 218
 219     return result;
 220 }
 221
 222 /* --------------------------------------------------------------------------------------------- */
 223
 224 /* *INDENT-OFF* */
 225
 226 #define MC_NAMEOP(name, inarg, callarg) \
 227 int mc_##name inarg \
 228 { \
 229     int result; \
 230     const vfs_path_element_t *path_element; \
 231 \
 232     if (vpath == NULL) \
 233         return -1; \
 234 \
 235     path_element = vfs_path_get_by_index (vpath, -1); \
 236     if (!vfs_path_element_valid (path_element)) \
 237     { \
 238         return -1; \
 239     } \
 240 \
 241     result = path_element->class->name != NULL ? path_element->class->name callarg : -1; \
 242     if (result == -1) \
 243         errno = path_element->class->name != NULL ? vfs_ferrno (path_element->class) : E_NOTSUPP; \
 244     return result; \
 245 }
 246
 247 MC_NAMEOP (chmod, (const vfs_path_t *vpath, mode_t mode), (vpath, mode))
 248 MC_NAMEOP (chown, (const vfs_path_t *vpath, uid_t owner, gid_t group), (vpath, owner, group))
 249 MC_NAMEOP (utime, (const vfs_path_t *vpath, struct utimbuf * times), (vpath, times))
 250 MC_NAMEOP (readlink, (const vfs_path_t *vpath, char *buf, size_t bufsiz), (vpath, buf, bufsiz))
 251 MC_NAMEOP (unlink, (const vfs_path_t *vpath), (vpath))
 252 MC_NAMEOP (mkdir, (const vfs_path_t *vpath, mode_t mode), (vpath, mode))
 253 MC_NAMEOP (rmdir, (const vfs_path_t *vpath), (vpath))
 254 MC_NAMEOP (mknod, (const vfs_path_t *vpath, mode_t mode, dev_t dev), (vpath, mode, dev))
 255
 256 /* *INDENT-ON* */
 257
 258 /* --------------------------------------------------------------------------------------------- */
 259
 260 int
 261 mc_symlink (const vfs_path_t * vpath1, const vfs_path_t * vpath2)
 262 {
 263     int result = -1;
 264
 265     if (vpath1 == NULL)
 266         return -1;
 267
 268     if (vpath1 != NULL)
 269     {
 270         const vfs_path_element_t *path_element;
 271
 272         path_element = vfs_path_get_by_index (vpath2, -1);
 273         if (vfs_path_element_valid (path_element))
 274         {
 275             result =
 276                 path_element->class->symlink != NULL ?
 277                 path_element->class->symlink (vpath1, vpath2) : -1;
 278
 279             if (result == -1)
 280                 errno =
 281                     path_element->class->symlink != NULL ?
 282                     vfs_ferrno (path_element->class) : E_NOTSUPP;
 283         }
 284     }
 285     return result;
 286 }
 287
 288 /* --------------------------------------------------------------------------------------------- */
 289
 290 /* *INDENT-OFF* */
 291
 292 #define MC_HANDLEOP(name, inarg, callarg) \
 293 ssize_t mc_##name inarg \
 294 { \
 295     struct vfs_class *vfs; \
 296     int result; \
 297     if (handle == -1) \
 298         return -1; \
 299     vfs = vfs_class_find_by_handle (handle); \
 300     if (vfs == NULL) \
 301         return -1; \
 302     result = vfs->name != NULL ? vfs->name callarg : -1; \
 303     if (result == -1) \
 304         errno = vfs->name != NULL ? vfs_ferrno (vfs) : E_NOTSUPP; \
 305     return result; \
 306 }
 307
 308 MC_HANDLEOP (read, (int handle, void *buffer, size_t count), (vfs_class_data_find_by_handle (handle), buffer, count))
 309 MC_HANDLEOP (write, (int handle, const void *buf, size_t nbyte), (vfs_class_data_find_by_handle (handle), buf, nbyte))
 310
 311 /* --------------------------------------------------------------------------------------------- */
 312
 313 #define MC_RENAMEOP(name) \
 314 int mc_##name (const vfs_path_t *vpath1, const vfs_path_t *vpath2) \
 315 { \
 316     int result; \
 317     const vfs_path_element_t *path_element1; \
 318     const vfs_path_element_t *path_element2; \
 319 \
 320     if (vpath1 == NULL || vpath2 == NULL) \
 321         return -1; \
 322 \
 323     path_element1 = vfs_path_get_by_index (vpath1, (-1)); \
 324     path_element2 = vfs_path_get_by_index (vpath2, (-1)); \
 325 \
 326     if (!vfs_path_element_valid (path_element1) || !vfs_path_element_valid (path_element2) || \
 327         path_element1->class != path_element2->class) \
 328     { \
 329         errno = EXDEV; \
 330         return -1; \
 331     }\
 332 \
 333     result = path_element1->class->name != NULL \
 334         ? path_element1->class->name (vpath1, vpath2) \
 335         : -1; \
 336     if (result == -1) \
 337         errno = path_element1->class->name != NULL ? vfs_ferrno (path_element1->class) : E_NOTSUPP; \
 338     return result; \
 339 }
 340
 341 MC_RENAMEOP (link)
 342 MC_RENAMEOP (rename)
 343
 344 /* *INDENT-ON* */
 345
 346 /* --------------------------------------------------------------------------------------------- */
 347
 348 int
 349 mc_ctl (int handle, int ctlop, void *arg)
 350 {
 351     struct vfs_class *vfs = vfs_class_find_by_handle (handle);
 352
 353     if (vfs == NULL)
 354         return 0;
 355
 356     return vfs->ctl ? (*vfs->ctl) (vfs_class_data_find_by_handle (handle), ctlop, arg) : 0;
 357 }
 358
 359 /* --------------------------------------------------------------------------------------------- */
 360
 361 int
 362 mc_setctl (const vfs_path_t * vpath, int ctlop, void *arg)
 363 {
 364     int result = -1;
 365     const vfs_path_element_t *path_element;
 366
 367     if (vpath == NULL)
 368         vfs_die ("You don't want to pass NULL to mc_setctl.");
 369
 370     path_element = vfs_path_get_by_index (vpath, -1);
 371     if (vfs_path_element_valid (path_element))
 372         result =
 373             path_element->class->setctl != NULL ? path_element->class->setctl (vpath,
 374                                                                                ctlop, arg) : 0;
 375
 376     return result;
 377 }
 378
 379 /* --------------------------------------------------------------------------------------------- */
 380
 381 int
 382 mc_close (int handle)
 383 {
 384     struct vfs_class *vfs;
 385     int result;
 386
 387     if (handle == -1 || !vfs_class_data_find_by_handle (handle))
 388         return -1;
 389
 390     vfs = vfs_class_find_by_handle (handle);
 391     if (vfs == NULL)
 392         return -1;
 393
 394     if (handle < 3)
 395         return close (handle);
 396
 397     if (!vfs->close)
 398         vfs_die ("VFS must support close.\n");
 399     result = (*vfs->close) (vfs_class_data_find_by_handle (handle));
 400     vfs_free_handle (handle);
 401     if (result == -1)
 402         errno = vfs_ferrno (vfs);
 403
 404     return result;
 405 }
 406
 407 /* --------------------------------------------------------------------------------------------- */
 408
 409 DIR *
 410 mc_opendir (const vfs_path_t * vpath)
 411 {
 412     int handle, *handlep;
 413     void *info;
 414     vfs_path_element_t *path_element;
 415
 416     if (vpath == NULL)
 417         return NULL;
 418
 419     path_element = (vfs_path_element_t *) vfs_path_get_by_index (vpath, -1);
 420
 421     if (!vfs_path_element_valid (path_element))
 422     {
 423         errno = E_NOTSUPP;
 424         return NULL;
 425     }
 426
 427     info = path_element->class->opendir ? (*path_element->class->opendir) (vpath) : NULL;
 428
 429     if (info == NULL)
 430     {
 431         errno = path_element->class->opendir ? vfs_ferrno (path_element->class) : E_NOTSUPP;
 432         return NULL;
 433     }
 434
 435     path_element->dir.info = info;
 436
 437 #ifdef HAVE_CHARSET
 438     path_element->dir.converter = (path_element->encoding != NULL) ?
 439         str_crt_conv_from (path_element->encoding) : str_cnv_from_term;
 440     if (path_element->dir.converter == INVALID_CONV)
 441         path_element->dir.converter = str_cnv_from_term;
 442 #endif
 443
 444     handle = vfs_new_handle (path_element->class, vfs_path_element_clone (path_element));
 445
 446     handlep = g_new (int, 1);
 447     *handlep = handle;
 448     return (DIR *) handlep;
 449 }
 450
 451 /* --------------------------------------------------------------------------------------------- */
 452
 453 struct dirent *
 454 mc_readdir (DIR * dirp)
 455 {
 456     int handle;
 457     struct vfs_class *vfs;
 458     struct dirent *entry = NULL;
 459     vfs_path_element_t *vfs_path_element;
 460
 461     if (!mc_readdir_result)
 462     {
 463         /* We can't just allocate struct dirent as (see man dirent.h)
 464          * struct dirent has VERY nonnaive semantics of allocating
 465          * d_name in it. Moreover, linux's glibc-2.9 allocates dirents _less_,
 466          * than 'sizeof (struct dirent)' making full bitwise (sizeof dirent) copy
 467          * heap corrupter. So, allocate longliving dirent with at least
 468          * (MAXNAMLEN + 1) for d_name in it.
 469          * Strictly saying resulting dirent is unusable as we don't adjust internal
 470          * structures, holding dirent size. But we don't use it in libc infrastructure.
 471          * TODO: to make simpler homemade dirent-alike structure.
 472          */
 473         mc_readdir_result = (struct dirent *) g_malloc (sizeof (struct dirent) + MAXNAMLEN + 1);
 474     }
 475
 476     if (!dirp)
 477     {
 478         errno = EFAULT;
 479         return NULL;
 480     }
 481     handle = *(int *) dirp;
 482
 483     vfs = vfs_class_find_by_handle (handle);
 484     if (vfs == NULL)
 485         return NULL;
 486
 487     vfs_path_element = vfs_class_data_find_by_handle (handle);
 488     if (vfs->readdir)
 489     {
 490         entry = (*vfs->readdir) (vfs_path_element->dir.info);
 491         if (entry == NULL)
 492             return NULL;
 493
 494         g_string_set_size (vfs_str_buffer, 0);
 495 #ifdef HAVE_CHARSET
 496         str_vfs_convert_from (vfs_path_element->dir.converter, entry->d_name, vfs_str_buffer);
 497 #else
 498         g_string_assign (vfs_str_buffer, entry->d_name);
 499 #endif
 500         mc_readdir_result->d_ino = entry->d_ino;
 501         g_strlcpy (mc_readdir_result->d_name, vfs_str_buffer->str, MAXNAMLEN + 1);
 502     }
 503     if (entry == NULL)
 504         errno = vfs->readdir ? vfs_ferrno (vfs) : E_NOTSUPP;
 505     return (entry != NULL) ? mc_readdir_result : NULL;
 506 }
 507
 508 /* --------------------------------------------------------------------------------------------- */
 509
 510 int
 511 mc_closedir (DIR * dirp)
 512 {
 513     int handle = *(int *) dirp;
 514     struct vfs_class *vfs;
 515     int result = -1;
 516
 517     vfs = vfs_class_find_by_handle (handle);
 518     if (vfs != NULL)
 519     {
 520         vfs_path_element_t *vfs_path_element;
 521         vfs_path_element = vfs_class_data_find_by_handle (handle);
 522
 523 #ifdef HAVE_CHARSET
 524         if (vfs_path_element->dir.converter != str_cnv_from_term)
 525         {
 526             str_close_conv (vfs_path_element->dir.converter);
 527             vfs_path_element->dir.converter = INVALID_CONV;
 528         }
 529 #endif
 530
 531         result = vfs->closedir ? (*vfs->closedir) (vfs_path_element->dir.info) : -1;
 532         vfs_free_handle (handle);
 533         vfs_path_element_free (vfs_path_element);
 534     }
 535     g_free (dirp);
 536     return result;
 537 }
 538
 539 /* --------------------------------------------------------------------------------------------- */
 540
 541 int
 542 mc_stat (const vfs_path_t * vpath, struct stat *buf)
 543 {
 544     int result = -1;
 545     const vfs_path_element_t *path_element;
 546
 547     if (vpath == NULL)
 548         return -1;
 549
 550     path_element = vfs_path_get_by_index (vpath, -1);
 551
 552     if (vfs_path_element_valid (path_element))
 553     {
 554         result = path_element->class->stat ? (*path_element->class->stat) (vpath, buf) : -1;
 555         if (result == -1)
 556             errno = path_element->class->name ? vfs_ferrno (path_element->class) : E_NOTSUPP;
 557     }
 558
 559     return result;
 560 }
 561
 562 /* --------------------------------------------------------------------------------------------- */
 563
 564 int
 565 mc_lstat (const vfs_path_t * vpath, struct stat *buf)
 566 {
 567     int result = -1;
 568     const vfs_path_element_t *path_element;
 569
 570     if (vpath == NULL)
 571         return -1;
 572
 573     path_element = vfs_path_get_by_index (vpath, -1);
 574
 575     if (vfs_path_element_valid (path_element))
 576     {
 577         result = path_element->class->lstat ? (*path_element->class->lstat) (vpath, buf) : -1;
 578         if (result == -1)
 579             errno = path_element->class->name ? vfs_ferrno (path_element->class) : E_NOTSUPP;
 580     }
 581
 582     return result;
 583 }
 584
 585 /* --------------------------------------------------------------------------------------------- */
 586
 587 int
 588 mc_fstat (int handle, struct stat *buf)
 589 {
 590     struct vfs_class *vfs;
 591     int result;
 592
 593     if (handle == -1)
 594         return -1;
 595
 596     vfs = vfs_class_find_by_handle (handle);
 597     if (vfs == NULL)
 598         return -1;
 599
 600     result = vfs->fstat ? (*vfs->fstat) (vfs_class_data_find_by_handle (handle), buf) : -1;
 601     if (result == -1)
 602         errno = vfs->name ? vfs_ferrno (vfs) : E_NOTSUPP;
 603     return result;
 604 }
 605
 606 /* --------------------------------------------------------------------------------------------- */
 607
 608 vfs_path_t *
 609 mc_getlocalcopy (const vfs_path_t * pathname_vpath)
 610 {
 611     vfs_path_t *result = NULL;
 612     const vfs_path_element_t *path_element;
 613
 614     if (pathname_vpath == NULL)
 615         return NULL;
 616
 617     path_element = vfs_path_get_by_index (pathname_vpath, -1);
 618
 619     if (vfs_path_element_valid (path_element))
 620     {
 621         result = path_element->class->getlocalcopy != NULL ?
 622             path_element->class->getlocalcopy (pathname_vpath) :
 623             mc_def_getlocalcopy (pathname_vpath);
 624         if (result == NULL)
 625             errno = vfs_ferrno (path_element->class);
 626     }
 627     return result;
 628 }
 629
 630 /* --------------------------------------------------------------------------------------------- */
 631
 632 int
 633 mc_ungetlocalcopy (const vfs_path_t * pathname_vpath, const vfs_path_t * local_vpath,
 634                    gboolean has_changed)
 635 {
 636     int return_value = -1;
 637     const vfs_path_element_t *path_element;
 638
 639     if (pathname_vpath == NULL)
 640         return -1;
 641
 642     path_element = vfs_path_get_by_index (pathname_vpath, -1);
 643
 644     if (vfs_path_element_valid (path_element))
 645         return_value = path_element->class->ungetlocalcopy != NULL ?
 646             path_element->class->ungetlocalcopy (pathname_vpath, local_vpath, has_changed) :
 647             mc_def_ungetlocalcopy (pathname_vpath, local_vpath, has_changed);
 648
 649     return return_value;
 650 }
 651
 652 /* --------------------------------------------------------------------------------------------- */
 653 /**
 654  * VFS chdir.
 655  *
 656  * @param vpath VFS-path
 657  *
 658  * @return 0 on success, -1 on failure.
 659  */
 660
 661 int
 662 mc_chdir (const vfs_path_t * vpath)
 663 {
 664     struct vfs_class *old_vfs;
 665     vfsid old_vfsid;
 666     int result;
 667     const vfs_path_element_t *path_element;
 668     vfs_path_t *cd_vpath;
 669
 670     if (vpath == NULL)
 671         return -1;
 672
 673     if (vpath->relative)
 674         cd_vpath = vfs_path_to_absolute (vpath);
 675     else
 676         cd_vpath = vfs_path_clone (vpath);
 677
 678     path_element = vfs_path_get_by_index (cd_vpath, -1);
 679
 680     if (!vfs_path_element_valid (path_element) || path_element->class->chdir == NULL)
 681     {
 682         goto error_end;
 683     }
 684
 685     result = (*path_element->class->chdir) (cd_vpath);
 686
 687     if (result == -1)
 688     {
 689         errno = vfs_ferrno (path_element->class);
 690         goto error_end;
 691     }
 692
 693     old_vfsid = vfs_getid (vfs_get_raw_current_dir ());
 694     old_vfs = current_vfs;
 695
 696     /* Actually change directory */
 697     vfs_set_raw_current_dir (cd_vpath);
 698
 699     current_vfs = path_element->class;
 700
 701     /* This function uses the new current_dir implicitly */
 702     vfs_stamp_create (old_vfs, old_vfsid);
 703
 704     /* Sometimes we assume no trailing slash on cwd */
 705     path_element = vfs_path_get_by_index (vfs_get_raw_current_dir (), -1);
 706     if (vfs_path_element_valid (path_element))
 707     {
 708         if (*path_element->path != '\0')
 709         {
 710             char *p;
 711
 712             p = strchr (path_element->path, 0) - 1;
 713             if (*p == PATH_SEP && p > path_element->path)
 714                 *p = '\0';
 715         }
 716
 717 #ifdef ENABLE_VFS_NET
 718         {
 719             struct vfs_s_super *super;
 720
 721             super = vfs_get_super_by_vpath (vpath);
 722             if (super != NULL && super->path_element != NULL)
 723             {
 724                 g_free (super->path_element->path);
 725                 super->path_element->path = g_strdup (path_element->path);
 726             }
 727         }
 728 #endif /* ENABLE_VFS_NET */
 729     }
 730
 731     return 0;
 732
 733   error_end:
 734     vfs_path_free (cd_vpath);
 735     return -1;
 736 }
 737
 738 /* --------------------------------------------------------------------------------------------- */
 739
 740 off_t
 741 mc_lseek (int fd, off_t offset, int whence)
 742 {
 743     struct vfs_class *vfs;
 744     off_t result;
 745
 746     if (fd == -1)
 747         return -1;
 748
 749     vfs = vfs_class_find_by_handle (fd);
 750     if (vfs == NULL)
 751         return -1;
 752
 753     result = vfs->lseek ? (*vfs->lseek) (vfs_class_data_find_by_handle (fd), offset, whence) : -1;
 754     if (result == -1)
 755         errno = vfs->lseek ? vfs_ferrno (vfs) : E_NOTSUPP;
 756     return result;
 757 }
 758
 759 /* --------------------------------------------------------------------------------------------- */
 760 /* Following code heavily borrows from libiberty, mkstemps.c */
 761 /*
 762  * Arguments:
 763  * pname (output) - pointer to the name of the temp file (needs g_free).
 764  *                  NULL if the function fails.
 765  * prefix - part of the filename before the random part.
 766  *          Prepend $TMPDIR or /tmp if there are no path separators.
 767  * suffix - if not NULL, part of the filename after the random part.
 768  *
 769  * Result:
 770  * handle of the open file or -1 if couldn't open any.
 771  */
 772
 773 int
 774 mc_mkstemps (vfs_path_t ** pname_vpath, const char *prefix, const char *suffix)
 775 {
 776     char *p1, *p2;
 777     int fd;
 778
 779     if (strchr (prefix, PATH_SEP) != NULL)
 780         p1 = g_strdup (prefix);
 781     else
 782     {
 783         /* Add prefix first to find the position of XXXXXX */
 784         p1 = g_build_filename (mc_tmpdir (), prefix, (char *) NULL);
 785     }
 786
 787     p2 = g_strconcat (p1, "XXXXXX", suffix, (char *) NULL);
 788     g_free (p1);
 789
 790     fd = g_mkstemp (p2);
 791     if (fd >= 0)
 792         *pname_vpath = vfs_path_from_str (p2);
 793     else
 794     {
 795         *pname_vpath = NULL;
 796         fd = -1;
 797     }
 798
 799     g_free (p2);
 800
 801     return fd;
 802 }
 803
 804 /* --------------------------------------------------------------------------------------------- */
 805 /**
 806  * Return the directory where mc should keep its temporary files.
 807  * This directory is (in Bourne shell terms) "${TMPDIR=/tmp}/mc-$USER"
 808  * When called the first time, the directory is created if needed.
 809  * The first call should be done early, since we are using fprintf()
 810  * and not message() to report possible problems.
 811  */
 812
 813 const char *
 814 mc_tmpdir (void)
 815 {
 816     static char buffer[64];
 817     static const char *tmpdir = NULL;
 818     const char *sys_tmp;
 819     struct passwd *pwd;
 820     struct stat st;
 821     const char *error = NULL;
 822
 823     /* Check if already correctly initialized */
 824     if (tmpdir && lstat (tmpdir, &st) == 0 && S_ISDIR (st.st_mode) &&
 825         st.st_uid == getuid () && (st.st_mode & 0777) == 0700)
 826         return tmpdir;
 827
 828     sys_tmp = getenv ("TMPDIR");
 829     if (!sys_tmp || sys_tmp[0] != '/')
 830     {
 831         sys_tmp = TMPDIR_DEFAULT;
 832     }
 833
 834     pwd = getpwuid (getuid ());
 835
 836     if (pwd)
 837         g_snprintf (buffer, sizeof (buffer), "%s/mc-%s", sys_tmp, pwd->pw_name);
 838     else
 839         g_snprintf (buffer, sizeof (buffer), "%s/mc-%lu", sys_tmp, (unsigned long) getuid ());
 840
 841     canonicalize_pathname (buffer);
 842
 843     if (lstat (buffer, &st) == 0)
 844     {
 845         /* Sanity check for existing directory */
 846         if (!S_ISDIR (st.st_mode))
 847             error = _("%s is not a directory\n");
 848         else if (st.st_uid != getuid ())
 849             error = _("Directory %s is not owned by you\n");
 850         else if (((st.st_mode & 0777) != 0700) && (chmod (buffer, 0700) != 0))
 851             error = _("Cannot set correct permissions for directory %s\n");
 852     }
 853     else
 854     {
 855         /* Need to create directory */
 856         if (mkdir (buffer, S_IRWXU) != 0)
 857         {
 858             fprintf (stderr,
 859                      _("Cannot create temporary directory %s: %s\n"),
 860                      buffer, unix_error_string (errno));
 861             error = "";
 862         }
 863     }
 864
 865     if (error != NULL)
 866     {
 867         int test_fd;
 868         char *fallback_prefix;
 869         gboolean fallback_ok = FALSE;
 870         vfs_path_t *test_vpath;
 871
 872         if (*error)
 873             fprintf (stderr, error, buffer);
 874
 875         /* Test if sys_tmp is suitable for temporary files */
 876         fallback_prefix = g_strdup_printf ("%s/mctest", sys_tmp);
 877         test_fd = mc_mkstemps (&test_vpath, fallback_prefix, NULL);
 878         g_free (fallback_prefix);
 879         if (test_fd != -1)
 880         {
 881             char *test_fn;
 882
 883             test_fn = vfs_path_to_str (test_vpath);
 884             close (test_fd);
 885             test_fd = open (test_fn, O_RDONLY);
 886             g_free (test_fn);
 887             if (test_fd != -1)
 888             {
 889                 close (test_fd);
 890                 unlink (test_fn);
 891                 fallback_ok = TRUE;
 892             }
 893         }
 894
 895         if (fallback_ok)
 896         {
 897             fprintf (stderr, _("Temporary files will be created in %s\n"), sys_tmp);
 898             g_snprintf (buffer, sizeof (buffer), "%s", sys_tmp);
 899             error = NULL;
 900         }
 901         else
 902         {
 903             fprintf (stderr, _("Temporary files will not be created\n"));
 904             g_snprintf (buffer, sizeof (buffer), "%s", "/dev/null/");
 905         }
 906
 907         vfs_path_free (test_vpath);
 908         fprintf (stderr, "%s\n", _("Press any key to continue..."));
 909         getc (stdin);
 910     }
 911
 912     tmpdir = buffer;
 913
 914     if (!error)
 915         g_setenv ("MC_TMPDIR", tmpdir, TRUE);
 916
 917     return tmpdir;
 918 }
 919
 920 /* --------------------------------------------------------------------------------------------- */