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     i = close (fdout);
 108     fdout = -1;
 109     if (i == -1)
 110     {
 111         fdout = -1;
 112         goto fail;
 113     }
 114
 115     if (mc_stat (filename_vpath, &mystat) != -1)
 116         mc_chmod (tmp_vpath, mystat.st_mode);
 117
 118     return tmp_vpath;
 119
 120   fail:
 121     vfs_path_free (tmp_vpath);
 122     if (fdout != -1)
 123         close (fdout);
 124     if (fdin != -1)
 125         mc_close (fdin);
 126     return NULL;
 127 }
 128
 129 /* --------------------------------------------------------------------------------------------- */
 130
 131 static int
 132 mc_def_ungetlocalcopy (const vfs_path_t * filename_vpath,
 133                        const vfs_path_t * local_vpath, gboolean has_changed)
 134 {
 135     int fdin = -1, fdout = -1;
 136     const char *local;
 137
 138     local = vfs_path_get_last_path_str (local_vpath);
 139
 140     if (has_changed)
 141     {
 142         char buffer[BUF_1K * 8];
 143         ssize_t i;
 144
 145         if (vfs_path_get_last_path_vfs (filename_vpath)->write == NULL)
 146             goto failed;
 147
 148         fdin = open (local, O_RDONLY);
 149         if (fdin == -1)
 150             goto failed;
 151         fdout = mc_open (filename_vpath, O_WRONLY | O_TRUNC);
 152         if (fdout == -1)
 153             goto failed;
 154         while ((i = read (fdin, buffer, sizeof (buffer))) > 0)
 155             if (mc_write (fdout, buffer, (size_t) i) != i)
 156                 goto failed;
 157         if (i == -1)
 158             goto failed;
 159
 160         if (close (fdin) == -1)
 161         {
 162             fdin = -1;
 163             goto failed;
 164         }
 165         fdin = -1;
 166         if (mc_close (fdout) == -1)
 167         {
 168             fdout = -1;
 169             goto failed;
 170         }
 171     }
 172     unlink (local);
 173     return 0;
 174
 175   failed:
 176     message (D_ERROR, _("Changes to file lost"), "%s", vfs_path_get_last_path_str (filename_vpath));
 177     if (fdout != -1)
 178         mc_close (fdout);
 179     if (fdin != -1)
 180         close (fdin);
 181     unlink (local);
 182     return -1;
 183 }
 184
 185 /* --------------------------------------------------------------------------------------------- */
 186 /*** public functions ****************************************************************************/
 187 /* --------------------------------------------------------------------------------------------- */
 188
 189 int
 190 mc_open (const vfs_path_t * vpath, int flags, ...)
 191 {
 192     int mode = 0, result = -1;
 193     const vfs_path_element_t *path_element;
 194
 195     if (vpath == NULL)
 196         return -1;
 197
 198     /* Get the mode flag */
 199     if (flags & O_CREAT)
 200     {
 201         va_list ap;
 202         va_start (ap, flags);
 203         mode = va_arg (ap, int);
 204         va_end (ap);
 205     }
 206
 207     path_element = vfs_path_get_by_index (vpath, -1);
 208     if (vfs_path_element_valid (path_element) && path_element->class->open != NULL)
 209     {
 210         void *info;
 211         /* open must be supported */
 212         info = path_element->class->open (vpath, flags, mode);
 213         if (info == NULL)
 214             errno = vfs_ferrno (path_element->class);
 215         else
 216             result = vfs_new_handle (path_element->class, info);
 217     }
 218     else
 219         errno = -EOPNOTSUPP;
 220
 221     return result;
 222 }
 223
 224 /* --------------------------------------------------------------------------------------------- */
 225
 226 /* *INDENT-OFF* */
 227
 228 #define MC_NAMEOP(name, inarg, callarg) \
 229 int mc_##name inarg \
 230 { \
 231     int result; \
 232     const vfs_path_element_t *path_element; \
 233 \
 234     if (vpath == NULL) \
 235         return -1; \
 236 \
 237     path_element = vfs_path_get_by_index (vpath, -1); \
 238     if (!vfs_path_element_valid (path_element)) \
 239     { \
 240         return -1; \
 241     } \
 242 \
 243     result = path_element->class->name != NULL ? path_element->class->name callarg : -1; \
 244     if (result == -1) \
 245         errno = path_element->class->name != NULL ? vfs_ferrno (path_element->class) : E_NOTSUPP; \
 246     return result; \
 247 }
 248
 249 MC_NAMEOP (chmod, (const vfs_path_t *vpath, mode_t mode), (vpath, mode))
 250 MC_NAMEOP (chown, (const vfs_path_t *vpath, uid_t owner, gid_t group), (vpath, owner, group))
 251 MC_NAMEOP (utime, (const vfs_path_t *vpath, struct utimbuf * times), (vpath, times))
 252 MC_NAMEOP (readlink, (const vfs_path_t *vpath, char *buf, size_t bufsiz), (vpath, buf, bufsiz))
 253 MC_NAMEOP (unlink, (const vfs_path_t *vpath), (vpath))
 254 MC_NAMEOP (mkdir, (const vfs_path_t *vpath, mode_t mode), (vpath, mode))
 255 MC_NAMEOP (rmdir, (const vfs_path_t *vpath), (vpath))
 256 MC_NAMEOP (mknod, (const vfs_path_t *vpath, mode_t mode, dev_t dev), (vpath, mode, dev))
 257
 258 /* *INDENT-ON* */
 259
 260 /* --------------------------------------------------------------------------------------------- */
 261
 262 int
 263 mc_symlink (const vfs_path_t * vpath1, const vfs_path_t * vpath2)
 264 {
 265     int result = -1;
 266
 267     if (vpath1 == NULL)
 268         return -1;
 269
 270     if (vpath1 != NULL)
 271     {
 272         const vfs_path_element_t *path_element;
 273
 274         path_element = vfs_path_get_by_index (vpath2, -1);
 275         if (vfs_path_element_valid (path_element))
 276         {
 277             result =
 278                 path_element->class->symlink != NULL ?
 279                 path_element->class->symlink (vpath1, vpath2) : -1;
 280
 281             if (result == -1)
 282                 errno =
 283                     path_element->class->symlink != NULL ?
 284                     vfs_ferrno (path_element->class) : E_NOTSUPP;
 285         }
 286     }
 287     return result;
 288 }
 289
 290 /* --------------------------------------------------------------------------------------------- */
 291
 292 /* *INDENT-OFF* */
 293
 294 #define MC_HANDLEOP(name, inarg, callarg) \
 295 ssize_t mc_##name inarg \
 296 { \
 297     struct vfs_class *vfs; \
 298     int result; \
 299     if (handle == -1) \
 300         return -1; \
 301     vfs = vfs_class_find_by_handle (handle); \
 302     if (vfs == NULL) \
 303         return -1; \
 304     result = vfs->name != NULL ? vfs->name callarg : -1; \
 305     if (result == -1) \
 306         errno = vfs->name != NULL ? vfs_ferrno (vfs) : E_NOTSUPP; \
 307     return result; \
 308 }
 309
 310 MC_HANDLEOP (read, (int handle, void *buffer, size_t count), (vfs_class_data_find_by_handle (handle), buffer, count))
 311 MC_HANDLEOP (write, (int handle, const void *buf, size_t nbyte), (vfs_class_data_find_by_handle (handle), buf, nbyte))
 312
 313 /* --------------------------------------------------------------------------------------------- */
 314
 315 #define MC_RENAMEOP(name) \
 316 int mc_##name (const vfs_path_t *vpath1, const vfs_path_t *vpath2) \
 317 { \
 318     int result; \
 319     const vfs_path_element_t *path_element1; \
 320     const vfs_path_element_t *path_element2; \
 321 \
 322     if (vpath1 == NULL || vpath2 == NULL) \
 323         return -1; \
 324 \
 325     path_element1 = vfs_path_get_by_index (vpath1, - 1); \
 326     path_element2 = vfs_path_get_by_index (vpath2, - 1); \
 327 \
 328     if (!vfs_path_element_valid (path_element1) || !vfs_path_element_valid (path_element2) || \
 329         path_element1->class != path_element2->class) \
 330     { \
 331         errno = EXDEV; \
 332         return -1; \
 333     }\
 334 \
 335     result = path_element1->class->name != NULL \
 336         ? path_element1->class->name (vpath1, vpath2) \
 337         : -1; \
 338     if (result == -1) \
 339         errno = path_element1->class->name != NULL ? vfs_ferrno (path_element1->class) : E_NOTSUPP; \
 340     return result; \
 341 }
 342
 343 MC_RENAMEOP (link)
 344 MC_RENAMEOP (rename)
 345
 346 /* *INDENT-ON* */
 347
 348 /* --------------------------------------------------------------------------------------------- */
 349
 350 int
 351 mc_ctl (int handle, int ctlop, void *arg)
 352 {
 353     struct vfs_class *vfs = vfs_class_find_by_handle (handle);
 354
 355     if (vfs == NULL)
 356         return 0;
 357
 358     return vfs->ctl ? (*vfs->ctl) (vfs_class_data_find_by_handle (handle), ctlop, arg) : 0;
 359 }
 360
 361 /* --------------------------------------------------------------------------------------------- */
 362
 363 int
 364 mc_setctl (const vfs_path_t * vpath, int ctlop, void *arg)
 365 {
 366     int result = -1;
 367     const vfs_path_element_t *path_element;
 368
 369     if (vpath == NULL)
 370         vfs_die ("You don't want to pass NULL to mc_setctl.");
 371
 372     path_element = vfs_path_get_by_index (vpath, -1);
 373     if (vfs_path_element_valid (path_element))
 374         result =
 375             path_element->class->setctl != NULL ? path_element->class->setctl (vpath,
 376                                                                                ctlop, arg) : 0;
 377
 378     return result;
 379 }
 380
 381 /* --------------------------------------------------------------------------------------------- */
 382
 383 int
 384 mc_close (int handle)
 385 {
 386     struct vfs_class *vfs;
 387     int result;
 388
 389     if (handle == -1 || !vfs_class_data_find_by_handle (handle))
 390         return -1;
 391
 392     vfs = vfs_class_find_by_handle (handle);
 393     if (vfs == NULL)
 394         return -1;
 395
 396     if (handle < 3)
 397         return close (handle);
 398
 399     if (!vfs->close)
 400         vfs_die ("VFS must support close.\n");
 401     result = (*vfs->close) (vfs_class_data_find_by_handle (handle));
 402     vfs_free_handle (handle);
 403     if (result == -1)
 404         errno = vfs_ferrno (vfs);
 405
 406     return result;
 407 }
 408
 409 /* --------------------------------------------------------------------------------------------- */
 410
 411 DIR *
 412 mc_opendir (const vfs_path_t * vpath)
 413 {
 414     int handle, *handlep;
 415     void *info;
 416     vfs_path_element_t *path_element;
 417
 418     if (vpath == NULL)
 419         return NULL;
 420
 421     path_element = (vfs_path_element_t *) vfs_path_get_by_index (vpath, -1);
 422
 423     if (!vfs_path_element_valid (path_element))
 424     {
 425         errno = E_NOTSUPP;
 426         return NULL;
 427     }
 428
 429     info = path_element->class->opendir ? (*path_element->class->opendir) (vpath) : NULL;
 430
 431     if (info == NULL)
 432     {
 433         errno = path_element->class->opendir ? vfs_ferrno (path_element->class) : E_NOTSUPP;
 434         return NULL;
 435     }
 436
 437     path_element->dir.info = info;
 438
 439 #ifdef HAVE_CHARSET
 440     path_element->dir.converter = (path_element->encoding != NULL) ?
 441         str_crt_conv_from (path_element->encoding) : str_cnv_from_term;
 442     if (path_element->dir.converter == INVALID_CONV)
 443         path_element->dir.converter = str_cnv_from_term;
 444 #endif
 445
 446     handle = vfs_new_handle (path_element->class, vfs_path_element_clone (path_element));
 447
 448     handlep = g_new (int, 1);
 449     *handlep = handle;
 450     return (DIR *) handlep;
 451 }
 452
 453 /* --------------------------------------------------------------------------------------------- */
 454
 455 struct dirent *
 456 mc_readdir (DIR * dirp)
 457 {
 458     int handle;
 459     struct vfs_class *vfs;
 460     struct dirent *entry = NULL;
 461     vfs_path_element_t *vfs_path_element;
 462 #ifdef HAVE_CHARSET
 463     estr_t state;
 464 #endif
 465
 466     if (!mc_readdir_result)
 467     {
 468         /* We can't just allocate struct dirent as (see man dirent.h)
 469          * struct dirent has VERY nonnaive semantics of allocating
 470          * d_name in it. Moreover, linux's glibc-2.9 allocates dirents _less_,
 471          * than 'sizeof (struct dirent)' making full bitwise (sizeof dirent) copy
 472          * heap corrupter. So, allocate longliving dirent with at least
 473          * (MAXNAMLEN + 1) for d_name in it.
 474          * Strictly saying resulting dirent is unusable as we don't adjust internal
 475          * structures, holding dirent size. But we don't use it in libc infrastructure.
 476          * TODO: to make simpler homemade dirent-alike structure.
 477          */
 478         mc_readdir_result = (struct dirent *) g_malloc (sizeof (struct dirent) + MAXNAMLEN + 1);
 479     }
 480
 481     if (!dirp)
 482     {
 483         errno = EFAULT;
 484         return NULL;
 485     }
 486     handle = *(int *) dirp;
 487
 488     vfs = vfs_class_find_by_handle (handle);
 489     if (vfs == NULL)
 490         return NULL;
 491
 492     vfs_path_element = vfs_class_data_find_by_handle (handle);
 493     if (vfs->readdir)
 494     {
 495         entry = (*vfs->readdir) (vfs_path_element->dir.info);
 496         if (entry == NULL)
 497             return NULL;
 498
 499         g_string_set_size (vfs_str_buffer, 0);
 500 #ifdef HAVE_CHARSET
 501         state =
 502             str_vfs_convert_from (vfs_path_element->dir.converter, entry->d_name, vfs_str_buffer);
 503 #else
 504         g_string_assign (vfs_str_buffer, entry->d_name);
 505 #endif
 506         mc_readdir_result->d_ino = entry->d_ino;
 507         g_strlcpy (mc_readdir_result->d_name, vfs_str_buffer->str, MAXNAMLEN + 1);
 508     }
 509     if (entry == NULL)
 510         errno = vfs->readdir ? vfs_ferrno (vfs) : E_NOTSUPP;
 511     return (entry != NULL) ? mc_readdir_result : NULL;
 512 }
 513
 514 /* --------------------------------------------------------------------------------------------- */
 515
 516 int
 517 mc_closedir (DIR * dirp)
 518 {
 519     int handle = *(int *) dirp;
 520     struct vfs_class *vfs;
 521     int result = -1;
 522
 523     vfs = vfs_class_find_by_handle (handle);
 524     if (vfs != NULL)
 525     {
 526         vfs_path_element_t *vfs_path_element;
 527         vfs_path_element = vfs_class_data_find_by_handle (handle);
 528
 529 #ifdef HAVE_CHARSET
 530         if (vfs_path_element->dir.converter != str_cnv_from_term)
 531         {
 532             str_close_conv (vfs_path_element->dir.converter);
 533             vfs_path_element->dir.converter = INVALID_CONV;
 534         }
 535 #endif
 536
 537         result = vfs->closedir ? (*vfs->closedir) (vfs_path_element->dir.info) : -1;
 538         vfs_free_handle (handle);
 539         vfs_path_element_free (vfs_path_element);
 540     }
 541     g_free (dirp);
 542     return result;
 543 }
 544
 545 /* --------------------------------------------------------------------------------------------- */
 546
 547 int
 548 mc_stat (const vfs_path_t * vpath, struct stat *buf)
 549 {
 550     int result = -1;
 551     const vfs_path_element_t *path_element;
 552
 553     if (vpath == NULL)
 554         return -1;
 555
 556     path_element = vfs_path_get_by_index (vpath, -1);
 557
 558     if (vfs_path_element_valid (path_element))
 559     {
 560         result = path_element->class->stat ? (*path_element->class->stat) (vpath, buf) : -1;
 561         if (result == -1)
 562             errno = path_element->class->name ? vfs_ferrno (path_element->class) : E_NOTSUPP;
 563     }
 564
 565     return result;
 566 }
 567
 568 /* --------------------------------------------------------------------------------------------- */
 569
 570 int
 571 mc_lstat (const vfs_path_t * vpath, struct stat *buf)
 572 {
 573     int result = -1;
 574     const vfs_path_element_t *path_element;
 575
 576     if (vpath == NULL)
 577         return -1;
 578
 579     path_element = vfs_path_get_by_index (vpath, -1);
 580
 581     if (vfs_path_element_valid (path_element))
 582     {
 583         result = path_element->class->lstat ? (*path_element->class->lstat) (vpath, buf) : -1;
 584         if (result == -1)
 585             errno = path_element->class->name ? vfs_ferrno (path_element->class) : E_NOTSUPP;
 586     }
 587
 588     return result;
 589 }
 590
 591 /* --------------------------------------------------------------------------------------------- */
 592
 593 int
 594 mc_fstat (int handle, struct stat *buf)
 595 {
 596     struct vfs_class *vfs;
 597     int result;
 598
 599     if (handle == -1)
 600         return -1;
 601
 602     vfs = vfs_class_find_by_handle (handle);
 603     if (vfs == NULL)
 604         return -1;
 605
 606     result = vfs->fstat ? (*vfs->fstat) (vfs_class_data_find_by_handle (handle), buf) : -1;
 607     if (result == -1)
 608         errno = vfs->name ? vfs_ferrno (vfs) : E_NOTSUPP;
 609     return result;
 610 }
 611
 612 /* --------------------------------------------------------------------------------------------- */
 613
 614 vfs_path_t *
 615 mc_getlocalcopy (const vfs_path_t * pathname_vpath)
 616 {
 617     vfs_path_t *result = NULL;
 618     const vfs_path_element_t *path_element;
 619
 620     if (pathname_vpath == NULL)
 621         return NULL;
 622
 623     path_element = vfs_path_get_by_index (pathname_vpath, -1);
 624
 625     if (vfs_path_element_valid (path_element))
 626     {
 627         result = path_element->class->getlocalcopy != NULL ?
 628             path_element->class->getlocalcopy (pathname_vpath) :
 629             mc_def_getlocalcopy (pathname_vpath);
 630         if (result == NULL)
 631             errno = vfs_ferrno (path_element->class);
 632     }
 633     return result;
 634 }
 635
 636 /* --------------------------------------------------------------------------------------------- */
 637
 638 int
 639 mc_ungetlocalcopy (const vfs_path_t * pathname_vpath, const vfs_path_t * local_vpath,
 640                    gboolean has_changed)
 641 {
 642     int return_value = -1;
 643     const vfs_path_element_t *path_element;
 644
 645     if (pathname_vpath == NULL)
 646         return -1;
 647
 648     path_element = vfs_path_get_by_index (pathname_vpath, -1);
 649
 650     if (vfs_path_element_valid (path_element))
 651         return_value = path_element->class->ungetlocalcopy != NULL ?
 652             path_element->class->ungetlocalcopy (pathname_vpath, local_vpath, has_changed) :
 653             mc_def_ungetlocalcopy (pathname_vpath, local_vpath, has_changed);
 654
 655     return return_value;
 656 }
 657
 658 /* --------------------------------------------------------------------------------------------- */
 659 /**
 660  * VFS chdir.
 661  *
 662  * @param vpath VFS-path
 663  *
 664  * @return 0 on success, -1 on failure.
 665  */
 666
 667 int
 668 mc_chdir (const vfs_path_t * vpath)
 669 {
 670     struct vfs_class *old_vfs;
 671     vfsid old_vfsid;
 672     int result;
 673     const vfs_path_element_t *path_element;
 674     vfs_path_t *cd_vpath;
 675
 676     if (vpath == NULL)
 677         return -1;
 678
 679     if (vpath->relative)
 680         cd_vpath = vfs_path_to_absolute (vpath);
 681     else
 682         cd_vpath = vfs_path_clone (vpath);
 683
 684     path_element = vfs_path_get_by_index (cd_vpath, -1);
 685
 686     if (!vfs_path_element_valid (path_element) || path_element->class->chdir == NULL)
 687     {
 688         goto error_end;
 689     }
 690
 691     result = (*path_element->class->chdir) (cd_vpath);
 692
 693     if (result == -1)
 694     {
 695         errno = vfs_ferrno (path_element->class);
 696         goto error_end;
 697     }
 698
 699     old_vfsid = vfs_getid (vfs_get_raw_current_dir ());
 700     old_vfs = current_vfs;
 701
 702     /* Actually change directory */
 703     vfs_set_raw_current_dir (cd_vpath);
 704
 705     current_vfs = path_element->class;
 706
 707     /* This function uses the new current_dir implicitly */
 708     vfs_stamp_create (old_vfs, old_vfsid);
 709
 710     /* Sometimes we assume no trailing slash on cwd */
 711     path_element = vfs_path_get_by_index (vfs_get_raw_current_dir (), -1);
 712     if (vfs_path_element_valid (path_element))
 713     {
 714         struct vfs_s_super *super;
 715
 716         if (*path_element->path != '\0')
 717         {
 718             char *p;
 719
 720             p = strchr (path_element->path, 0) - 1;
 721             if (*p == PATH_SEP && p > path_element->path)
 722                 *p = '\0';
 723         }
 724
 725         super = vfs_get_super_by_vpath (vpath);
 726         if (super != NULL)
 727         {
 728             g_free (super->path_element->path);
 729             super->path_element->path = g_strdup (path_element->path);
 730         }
 731     }
 732
 733     return 0;
 734
 735   error_end:
 736     vfs_path_free (cd_vpath);
 737     return -1;
 738 }
 739
 740 /* --------------------------------------------------------------------------------------------- */
 741
 742 off_t
 743 mc_lseek (int fd, off_t offset, int whence)
 744 {
 745     struct vfs_class *vfs;
 746     off_t result;
 747
 748     if (fd == -1)
 749         return -1;
 750
 751     vfs = vfs_class_find_by_handle (fd);
 752     if (vfs == NULL)
 753         return -1;
 754
 755     result = vfs->lseek ? (*vfs->lseek) (vfs_class_data_find_by_handle (fd), offset, whence) : -1;
 756     if (result == -1)
 757         errno = vfs->lseek ? vfs_ferrno (vfs) : E_NOTSUPP;
 758     return result;
 759 }
 760
 761 /* --------------------------------------------------------------------------------------------- */
 762 /* Following code heavily borrows from libiberty, mkstemps.c */
 763 /*
 764  * Arguments:
 765  * pname (output) - pointer to the name of the temp file (needs g_free).
 766  *                  NULL if the function fails.
 767  * prefix - part of the filename before the random part.
 768  *          Prepend $TMPDIR or /tmp if there are no path separators.
 769  * suffix - if not NULL, part of the filename after the random part.
 770  *
 771  * Result:
 772  * handle of the open file or -1 if couldn't open any.
 773  */
 774
 775 int
 776 mc_mkstemps (vfs_path_t ** pname_vpath, const char *prefix, const char *suffix)
 777 {
 778     static const char letters[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
 779     static unsigned long value;
 780     struct timeval tv;
 781     char *tmpbase;
 782     char *tmpname;
 783     char *XXXXXX;
 784     char *ret_path;
 785     int count;
 786
 787     if (strchr (prefix, PATH_SEP) == NULL)
 788     {
 789         /* Add prefix first to find the position of XXXXXX */
 790         tmpbase = g_build_filename (mc_tmpdir (), prefix, NULL);
 791     }
 792     else
 793     {
 794         tmpbase = g_strdup (prefix);
 795     }
 796
 797     tmpname = g_strconcat (tmpbase, "XXXXXX", suffix, (char *) NULL);
 798     ret_path = tmpname;
 799     XXXXXX = &tmpname[strlen (tmpbase)];
 800     g_free (tmpbase);
 801
 802     /* Get some more or less random data.  */
 803     gettimeofday (&tv, NULL);
 804     value += (tv.tv_usec << 16) ^ tv.tv_sec ^ getpid ();
 805
 806     for (count = 0; count < TMP_MAX; ++count)
 807     {
 808         unsigned long v = value;
 809         int fd;
 810
 811         /* Fill in the random bits.  */
 812         XXXXXX[0] = letters[v % 62];
 813         v /= 62;
 814         XXXXXX[1] = letters[v % 62];
 815         v /= 62;
 816         XXXXXX[2] = letters[v % 62];
 817         v /= 62;
 818         XXXXXX[3] = letters[v % 62];
 819         v /= 62;
 820         XXXXXX[4] = letters[v % 62];
 821         v /= 62;
 822         XXXXXX[5] = letters[v % 62];
 823
 824         fd = open (tmpname, O_RDWR | O_CREAT | O_TRUNC | O_EXCL, S_IRUSR | S_IWUSR);
 825         if (fd >= 0)
 826         {
 827             /* Successfully created.  */
 828             *pname_vpath = vfs_path_from_str (ret_path);
 829             g_free (ret_path);
 830             return fd;
 831         }
 832
 833         /* This is a random value.  It is only necessary that the next
 834            TMP_MAX values generated by adding 7777 to VALUE are different
 835            with (module 2^32).  */
 836         value += 7777;
 837     }
 838
 839     /* Unsuccessful. Free the filename. */
 840     g_free (ret_path);
 841     *pname_vpath = NULL;
 842
 843     return -1;
 844 }
 845
 846 /* --------------------------------------------------------------------------------------------- */
 847 /**
 848  * Return the directory where mc should keep its temporary files.
 849  * This directory is (in Bourne shell terms) "${TMPDIR=/tmp}/mc-$USER"
 850  * When called the first time, the directory is created if needed.
 851  * The first call should be done early, since we are using fprintf()
 852  * and not message() to report possible problems.
 853  */
 854
 855 const char *
 856 mc_tmpdir (void)
 857 {
 858     static char buffer[64];
 859     static const char *tmpdir = NULL;
 860     const char *sys_tmp;
 861     struct passwd *pwd;
 862     struct stat st;
 863     const char *error = NULL;
 864
 865     /* Check if already correctly initialized */
 866     if (tmpdir && lstat (tmpdir, &st) == 0 && S_ISDIR (st.st_mode) &&
 867         st.st_uid == getuid () && (st.st_mode & 0777) == 0700)
 868         return tmpdir;
 869
 870     sys_tmp = getenv ("TMPDIR");
 871     if (!sys_tmp || sys_tmp[0] != '/')
 872     {
 873         sys_tmp = TMPDIR_DEFAULT;
 874     }
 875
 876     pwd = getpwuid (getuid ());
 877
 878     if (pwd)
 879         g_snprintf (buffer, sizeof (buffer), "%s/mc-%s", sys_tmp, pwd->pw_name);
 880     else
 881         g_snprintf (buffer, sizeof (buffer), "%s/mc-%lu", sys_tmp, (unsigned long) getuid ());
 882
 883     canonicalize_pathname (buffer);
 884
 885     if (lstat (buffer, &st) == 0)
 886     {
 887         /* Sanity check for existing directory */
 888         if (!S_ISDIR (st.st_mode))
 889             error = _("%s is not a directory\n");
 890         else if (st.st_uid != getuid ())
 891             error = _("Directory %s is not owned by you\n");
 892         else if (((st.st_mode & 0777) != 0700) && (chmod (buffer, 0700) != 0))
 893             error = _("Cannot set correct permissions for directory %s\n");
 894     }
 895     else
 896     {
 897         /* Need to create directory */
 898         if (mkdir (buffer, S_IRWXU) != 0)
 899         {
 900             fprintf (stderr,
 901                      _("Cannot create temporary directory %s: %s\n"),
 902                      buffer, unix_error_string (errno));
 903             error = "";
 904         }
 905     }
 906
 907     if (error != NULL)
 908     {
 909         int test_fd;
 910         char *fallback_prefix;
 911         gboolean fallback_ok = FALSE;
 912         vfs_path_t *test_vpath;
 913
 914         if (*error)
 915             fprintf (stderr, error, buffer);
 916
 917         /* Test if sys_tmp is suitable for temporary files */
 918         fallback_prefix = g_strdup_printf ("%s/mctest", sys_tmp);
 919         test_fd = mc_mkstemps (&test_vpath, fallback_prefix, NULL);
 920         g_free (fallback_prefix);
 921         if (test_fd != -1)
 922         {
 923             char *test_fn;
 924
 925             test_fn = vfs_path_to_str (test_vpath);
 926             close (test_fd);
 927             test_fd = open (test_fn, O_RDONLY);
 928             g_free (test_fn);
 929             if (test_fd != -1)
 930             {
 931                 close (test_fd);
 932                 unlink (test_fn);
 933                 fallback_ok = TRUE;
 934             }
 935         }
 936
 937         if (fallback_ok)
 938         {
 939             fprintf (stderr, _("Temporary files will be created in %s\n"), sys_tmp);
 940             g_snprintf (buffer, sizeof (buffer), "%s", sys_tmp);
 941             error = NULL;
 942         }
 943         else
 944         {
 945             fprintf (stderr, _("Temporary files will not be created\n"));
 946             g_snprintf (buffer, sizeof (buffer), "%s", "/dev/null/");
 947         }
 948
 949         vfs_path_free (test_vpath);
 950         fprintf (stderr, "%s\n", _("Press any key to continue..."));
 951         getc (stdin);
 952     }
 953
 954     tmpdir = buffer;
 955
 956     if (!error)
 957         g_setenv ("MC_TMPDIR", tmpdir, TRUE);
 958
 959     return tmpdir;
 960 }
 961
 962 /* --------------------------------------------------------------------------------------------- */