glib/gfileutils.c

   1 /* gfileutils.c - File utility functions
   2  *
   3  *  Copyright 2000 Red Hat, Inc.
   4  *
   5  * GLib is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU Lesser General Public License as
   7  * published by the Free Software Foundation; either version 2 of the
   8  * License, or (at your option) any later version.
   9  *
  10  * GLib is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with GLib; see the file COPYING.LIB.  If not,
  17  * write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18  *   Boston, MA 02111-1307, USA.
  19  */
  20
  21 #include "config.h"
  22
  23 #include "galias.h"
  24 #include "glib.h"
  25
  26 #include <sys/stat.h>
  27 #ifdef HAVE_UNISTD_H
  28 #include <unistd.h>
  29 #endif
  30 #include <stdio.h>
  31 #include <stdlib.h>
  32 #include <stdarg.h>
  33 #include <string.h>
  34 #include <errno.h>
  35 #include <sys/types.h>
  36 #include <sys/stat.h>
  37 #include <fcntl.h>
  38 #include <stdlib.h>
  39
  40 #ifdef G_OS_WIN32
  41 #include <io.h>
  42 #ifndef F_OK
  43 #define F_OK 0
  44 #define W_OK 2
  45 #define R_OK 4
  46 #endif /* !F_OK */
  47
  48 #ifndef S_ISREG
  49 #define S_ISREG(mode) ((mode)&_S_IFREG)
  50 #endif
  51
  52 #ifndef S_ISDIR
  53 #define S_ISDIR(mode) ((mode)&_S_IFDIR)
  54 #endif
  55
  56 #endif /* G_OS_WIN32 */
  57
  58 #ifndef S_ISLNK
  59 #define S_ISLNK(x) 0
  60 #endif
  61
  62 #ifndef O_BINARY
  63 #define O_BINARY 0
  64 #endif
  65
  66 #include "gstdio.h"
  67 #include "glibintl.h"
  68
  69 /**
  70  * g_file_test:
  71  * @filename: a filename to test
  72  * @test: bitfield of #GFileTest flags
  73  *
  74  * Returns %TRUE if any of the tests in the bitfield @test are
  75  * %TRUE. For example, <literal>(G_FILE_TEST_EXISTS |
  76  * G_FILE_TEST_IS_DIR)</literal> will return %TRUE if the file exists;
  77  * the check whether it's a directory doesn't matter since the existence
  78  * test is %TRUE. With the current set of available tests, there's no point
  79  * passing in more than one test at a time.
  80  *
  81  * Apart from %G_FILE_TEST_IS_SYMLINK all tests follow symbolic links,
  82  * so for a symbolic link to a regular file g_file_test() will return
  83  * %TRUE for both %G_FILE_TEST_IS_SYMLINK and %G_FILE_TEST_IS_REGULAR.
  84  *
  85  * Note, that for a dangling symbolic link g_file_test() will return
  86  * %TRUE for %G_FILE_TEST_IS_SYMLINK and %FALSE for all other flags.
  87  *
  88  * You should never use g_file_test() to test whether it is safe
  89  * to perform an operaton, because there is always the possibility
  90  * of the condition changing before you actually perform the operation.
  91  * For example, you might think you could use %G_FILE_TEST_IS_SYMLINK
  92  * to know whether it is is safe to write to a file without being
  93  * tricked into writing into a different location. It doesn't work!
  94  *
  95  * <informalexample><programlisting>
  96  * /&ast; DON'T DO THIS &ast;/
  97  *  if (!g_file_test (filename, G_FILE_TEST_IS_SYMLINK)) {
  98  *    fd = g_open (filename, O_WRONLY);
  99  *    /&ast; write to fd &ast;/
 100  *  }
 101  * </programlisting></informalexample>
 102  *
 103  * Another thing to note is that %G_FILE_TEST_EXISTS and
 104  * %G_FILE_TEST_IS_EXECUTABLE are implemented using the access()
 105  * system call. This usually doesn't matter, but if your program
 106  * is setuid or setgid it means that these tests will give you
 107  * the answer for the real user ID and group ID , rather than the
 108  * effective user ID and group ID.
 109  *
 110  * Return value: whether a test was %TRUE
 111  **/
 112 gboolean
 113 g_file_test (const gchar *filename,
 114              GFileTest    test)
 115 {
 116 #ifdef G_OS_WIN32
 117   if (G_WIN32_HAVE_WIDECHAR_API ())
 118     {
 119       wchar_t *wfilename = g_utf8_to_utf16 (filename, -1, NULL, NULL, NULL);
 120
 121       if (wfilename == NULL)
 122         return FALSE;
 123
 124       if ((test & G_FILE_TEST_EXISTS) && (_waccess (wfilename, F_OK) == 0))
 125         {
 126           g_free (wfilename);
 127           return TRUE;
 128         }
 129
 130       if (test & (G_FILE_TEST_IS_REGULAR |
 131                   G_FILE_TEST_IS_DIR |
 132                   G_FILE_TEST_IS_EXECUTABLE))
 133         {
 134           struct _stat s;
 135
 136           if (_wstat (wfilename, &s) == 0)
 137             {
 138               if ((test & G_FILE_TEST_IS_REGULAR) && S_ISREG (s.st_mode))
 139                 {
 140                   g_free (wfilename);
 141                   return TRUE;
 142                 }
 143
 144               if ((test & G_FILE_TEST_IS_DIR) && S_ISDIR (s.st_mode))
 145                 {
 146                   g_free (wfilename);
 147                   return TRUE;
 148                 }
 149
 150               if ((test & G_FILE_TEST_IS_EXECUTABLE) &&
 151                   (s.st_mode & _S_IEXEC))
 152                 {
 153                   g_free (wfilename);
 154                   return TRUE;
 155                 }
 156             }
 157         }
 158
 159       g_free (wfilename);
 160
 161       return FALSE;
 162     }
 163   else
 164     {
 165       gchar *cp_filename = g_locale_from_utf8 (filename, -1, NULL, NULL, NULL);
 166
 167       if (cp_filename == NULL)
 168         return FALSE;
 169
 170       if ((test & G_FILE_TEST_EXISTS) && (access (cp_filename, F_OK) == 0))
 171         {
 172           g_free (cp_filename);
 173           return TRUE;
 174         }
 175
 176       if (test & (G_FILE_TEST_IS_REGULAR |
 177                   G_FILE_TEST_IS_DIR |
 178                   G_FILE_TEST_IS_EXECUTABLE))
 179         {
 180           struct stat s;
 181
 182           if (stat (cp_filename, &s) == 0)
 183             {
 184               if ((test & G_FILE_TEST_IS_REGULAR) && S_ISREG (s.st_mode))
 185                 {
 186                   g_free (cp_filename);
 187                   return TRUE;
 188                 }
 189
 190               if ((test & G_FILE_TEST_IS_DIR) && S_ISDIR (s.st_mode))
 191                 {
 192                   g_free (cp_filename);
 193                   return TRUE;
 194                 }
 195
 196               if ((test & G_FILE_TEST_IS_EXECUTABLE) &&
 197                   (s.st_mode & _S_IEXEC))
 198                 {
 199                   g_free (cp_filename);
 200                   return TRUE;
 201                 }
 202             }
 203         }
 204
 205       g_free (cp_filename);
 206
 207       return FALSE;
 208     }
 209 #else
 210   if ((test & G_FILE_TEST_EXISTS) && (access (filename, F_OK) == 0))
 211     return TRUE;
 212
 213   if ((test & G_FILE_TEST_IS_EXECUTABLE) && (access (filename, X_OK) == 0))
 214     {
 215       if (getuid () != 0)
 216         return TRUE;
 217
 218       /* For root, on some POSIX systems, access (filename, X_OK)
 219        * will succeed even if no executable bits are set on the
 220        * file. We fall through to a stat test to avoid that.
 221        */
 222     }
 223   else
 224     test &= ~G_FILE_TEST_IS_EXECUTABLE;
 225
 226   if (test & G_FILE_TEST_IS_SYMLINK)
 227     {
 228       struct stat s;
 229
 230       if ((lstat (filename, &s) == 0) && S_ISLNK (s.st_mode))
 231         return TRUE;
 232     }
 233
 234   if (test & (G_FILE_TEST_IS_REGULAR |
 235               G_FILE_TEST_IS_DIR |
 236               G_FILE_TEST_IS_EXECUTABLE))
 237     {
 238       struct stat s;
 239
 240       if (stat (filename, &s) == 0)
 241         {
 242           if ((test & G_FILE_TEST_IS_REGULAR) && S_ISREG (s.st_mode))
 243             return TRUE;
 244
 245           if ((test & G_FILE_TEST_IS_DIR) && S_ISDIR (s.st_mode))
 246             return TRUE;
 247
 248           /* The extra test for root when access (file, X_OK) succeeds.
 249            */
 250           if ((test & G_FILE_TEST_IS_EXECUTABLE) &&
 251               ((s.st_mode & S_IXOTH) ||
 252                (s.st_mode & S_IXUSR) ||
 253                (s.st_mode & S_IXGRP)))
 254             return TRUE;
 255         }
 256     }
 257
 258   return FALSE;
 259 #endif
 260 }
 261
 262 #ifdef G_OS_WIN32
 263
 264 #undef g_file_test
 265
 266 /* Binary compatibility version. Not for newly compiled code. */
 267
 268 gboolean
 269 g_file_test (const gchar *filename,
 270              GFileTest    test)
 271 {
 272   gchar *utf8_filename = g_locale_to_utf8 (filename, -1, NULL, NULL, NULL);
 273   gboolean retval;
 274
 275   if (utf8_filename == NULL)
 276     return FALSE;
 277
 278   retval = g_file_test_utf8 (utf8_filename, test);
 279
 280   g_free (utf8_filename);
 281
 282   return retval;
 283 }
 284
 285 #endif
 286
 287 GQuark
 288 g_file_error_quark (void)
 289 {
 290   static GQuark q = 0;
 291   if (q == 0)
 292     q = g_quark_from_static_string ("g-file-error-quark");
 293
 294   return q;
 295 }
 296
 297 /**
 298  * g_file_error_from_errno:
 299  * @err_no: an "errno" value
 300  *
 301  * Gets a #GFileError constant based on the passed-in @errno.
 302  * For example, if you pass in %EEXIST this function returns
 303  * #G_FILE_ERROR_EXIST. Unlike @errno values, you can portably
 304  * assume that all #GFileError values will exist.
 305  *
 306  * Normally a #GFileError value goes into a #GError returned
 307  * from a function that manipulates files. So you would use
 308  * g_file_error_from_errno() when constructing a #GError.
 309  *
 310  * Return value: #GFileError corresponding to the given @errno
 311  **/
 312 GFileError
 313 g_file_error_from_errno (gint err_no)
 314 {
 315   switch (err_no)
 316     {
 317 #ifdef EEXIST
 318     case EEXIST:
 319       return G_FILE_ERROR_EXIST;
 320       break;
 321 #endif
 322
 323 #ifdef EISDIR
 324     case EISDIR:
 325       return G_FILE_ERROR_ISDIR;
 326       break;
 327 #endif
 328
 329 #ifdef EACCES
 330     case EACCES:
 331       return G_FILE_ERROR_ACCES;
 332       break;
 333 #endif
 334
 335 #ifdef ENAMETOOLONG
 336     case ENAMETOOLONG:
 337       return G_FILE_ERROR_NAMETOOLONG;
 338       break;
 339 #endif
 340
 341 #ifdef ENOENT
 342     case ENOENT:
 343       return G_FILE_ERROR_NOENT;
 344       break;
 345 #endif
 346
 347 #ifdef ENOTDIR
 348     case ENOTDIR:
 349       return G_FILE_ERROR_NOTDIR;
 350       break;
 351 #endif
 352
 353 #ifdef ENXIO
 354     case ENXIO:
 355       return G_FILE_ERROR_NXIO;
 356       break;
 357 #endif
 358
 359 #ifdef ENODEV
 360     case ENODEV:
 361       return G_FILE_ERROR_NODEV;
 362       break;
 363 #endif
 364
 365 #ifdef EROFS
 366     case EROFS:
 367       return G_FILE_ERROR_ROFS;
 368       break;
 369 #endif
 370
 371 #ifdef ETXTBSY
 372     case ETXTBSY:
 373       return G_FILE_ERROR_TXTBSY;
 374       break;
 375 #endif
 376
 377 #ifdef EFAULT
 378     case EFAULT:
 379       return G_FILE_ERROR_FAULT;
 380       break;
 381 #endif
 382
 383 #ifdef ELOOP
 384     case ELOOP:
 385       return G_FILE_ERROR_LOOP;
 386       break;
 387 #endif
 388
 389 #ifdef ENOSPC
 390     case ENOSPC:
 391       return G_FILE_ERROR_NOSPC;
 392       break;
 393 #endif
 394
 395 #ifdef ENOMEM
 396     case ENOMEM:
 397       return G_FILE_ERROR_NOMEM;
 398       break;
 399 #endif
 400
 401 #ifdef EMFILE
 402     case EMFILE:
 403       return G_FILE_ERROR_MFILE;
 404       break;
 405 #endif
 406
 407 #ifdef ENFILE
 408     case ENFILE:
 409       return G_FILE_ERROR_NFILE;
 410       break;
 411 #endif
 412
 413 #ifdef EBADF
 414     case EBADF:
 415       return G_FILE_ERROR_BADF;
 416       break;
 417 #endif
 418
 419 #ifdef EINVAL
 420     case EINVAL:
 421       return G_FILE_ERROR_INVAL;
 422       break;
 423 #endif
 424
 425 #ifdef EPIPE
 426     case EPIPE:
 427       return G_FILE_ERROR_PIPE;
 428       break;
 429 #endif
 430
 431 #ifdef EAGAIN
 432     case EAGAIN:
 433       return G_FILE_ERROR_AGAIN;
 434       break;
 435 #endif
 436
 437 #ifdef EINTR
 438     case EINTR:
 439       return G_FILE_ERROR_INTR;
 440       break;
 441 #endif
 442
 443 #ifdef EIO
 444     case EIO:
 445       return G_FILE_ERROR_IO;
 446       break;
 447 #endif
 448
 449 #ifdef EPERM
 450     case EPERM:
 451       return G_FILE_ERROR_PERM;
 452       break;
 453 #endif
 454
 455 #ifdef ENOSYS
 456     case ENOSYS:
 457       return G_FILE_ERROR_NOSYS;
 458       break;
 459 #endif
 460
 461     default:
 462       return G_FILE_ERROR_FAILED;
 463       break;
 464     }
 465 }
 466
 467 static gboolean
 468 get_contents_stdio (const gchar *display_filename,
 469                     FILE        *f,
 470                     gchar      **contents,
 471                     gsize       *length,
 472                     GError     **error)
 473 {
 474   gchar buf[2048];
 475   size_t bytes;
 476   char *str;
 477   size_t total_bytes;
 478   size_t total_allocated;
 479
 480   g_assert (f != NULL);
 481
 482 #define STARTING_ALLOC 64
 483
 484   total_bytes = 0;
 485   total_allocated = STARTING_ALLOC;
 486   str = g_malloc (STARTING_ALLOC);
 487
 488   while (!feof (f))
 489     {
 490       bytes = fread (buf, 1, 2048, f);
 491
 492       while ((total_bytes + bytes + 1) > total_allocated)
 493         {
 494           total_allocated *= 2;
 495           str = g_try_realloc (str, total_allocated);
 496
 497           if (str == NULL)
 498             {
 499               g_set_error (error,
 500                            G_FILE_ERROR,
 501                            G_FILE_ERROR_NOMEM,
 502                            _("Could not allocate %lu bytes to read file \"%s\""),
 503                            (gulong) total_allocated,
 504                            display_filename);
 505
 506               goto error;
 507             }
 508         }
 509
 510       if (ferror (f))
 511         {
 512           g_set_error (error,
 513                        G_FILE_ERROR,
 514                        g_file_error_from_errno (errno),
 515                        _("Error reading file '%s': %s"),
 516                        display_filename,
 517                        g_strerror (errno));
 518
 519           goto error;
 520         }
 521
 522       memcpy (str + total_bytes, buf, bytes);
 523       total_bytes += bytes;
 524     }
 525
 526   fclose (f);
 527
 528   str[total_bytes] = '\0';
 529
 530   if (length)
 531     *length = total_bytes;
 532
 533   *contents = str;
 534
 535   return TRUE;
 536
 537  error:
 538
 539   g_free (str);
 540   fclose (f);
 541
 542   return FALSE;
 543 }
 544
 545 #ifndef G_OS_WIN32
 546
 547 static gboolean
 548 get_contents_regfile (const gchar *display_filename,
 549                       struct stat *stat_buf,
 550                       gint         fd,
 551                       gchar      **contents,
 552                       gsize       *length,
 553                       GError     **error)
 554 {
 555   gchar *buf;
 556   size_t bytes_read;
 557   size_t size;
 558   size_t alloc_size;
 559
 560   size = stat_buf->st_size;
 561
 562   alloc_size = size + 1;
 563   buf = g_try_malloc (alloc_size);
 564
 565   if (buf == NULL)
 566     {
 567       g_set_error (error,
 568                    G_FILE_ERROR,
 569                    G_FILE_ERROR_NOMEM,
 570                    _("Could not allocate %lu bytes to read file \"%s\""),
 571                    (gulong) alloc_size,
 572                    display_filename);
 573
 574       goto error;
 575     }
 576
 577   bytes_read = 0;
 578   while (bytes_read < size)
 579     {
 580       gssize rc;
 581
 582       rc = read (fd, buf + bytes_read, size - bytes_read);
 583
 584       if (rc < 0)
 585         {
 586           if (errno != EINTR)
 587             {
 588               g_free (buf);
 589               g_set_error (error,
 590                            G_FILE_ERROR,
 591                            g_file_error_from_errno (errno),
 592                            _("Failed to read from file '%s': %s"),
 593                            display_filename,
 594                            g_strerror (errno));
 595
 596               goto error;
 597             }
 598         }
 599       else if (rc == 0)
 600         break;
 601       else
 602         bytes_read += rc;
 603     }
 604
 605   buf[bytes_read] = '\0';
 606
 607   if (length)
 608     *length = bytes_read;
 609
 610   *contents = buf;
 611
 612   close (fd);
 613
 614   return TRUE;
 615
 616  error:
 617
 618   close (fd);
 619
 620   return FALSE;
 621 }
 622
 623 static gboolean
 624 get_contents_posix (const gchar *filename,
 625                     gchar      **contents,
 626                     gsize       *length,
 627                     GError     **error)
 628 {
 629   struct stat stat_buf;
 630   gint fd;
 631   gchar *display_filename = g_filename_display_name (filename);
 632
 633   /* O_BINARY useful on Cygwin */
 634   fd = open (filename, O_RDONLY|O_BINARY);
 635
 636   if (fd < 0)
 637     {
 638       g_set_error (error,
 639                    G_FILE_ERROR,
 640                    g_file_error_from_errno (errno),
 641                    _("Failed to open file '%s': %s"),
 642                    display_filename,
 643                    g_strerror (errno));
 644       g_free (display_filename);
 645
 646       return FALSE;
 647     }
 648
 649   /* I don't think this will ever fail, aside from ENOMEM, but. */
 650   if (fstat (fd, &stat_buf) < 0)
 651     {
 652       close (fd);
 653       g_set_error (error,
 654                    G_FILE_ERROR,
 655                    g_file_error_from_errno (errno),
 656                    _("Failed to get attributes of file '%s': fstat() failed: %s"),
 657                    display_filename,
 658                    g_strerror (errno));
 659       g_free (display_filename);
 660
 661       return FALSE;
 662     }
 663
 664   if (stat_buf.st_size > 0 && S_ISREG (stat_buf.st_mode))
 665     {
 666       gboolean retval = get_contents_regfile (display_filename,
 667                                               &stat_buf,
 668                                               fd,
 669                                               contents,
 670                                               length,
 671                                               error);
 672       g_free (display_filename);
 673
 674       return retval;
 675     }
 676   else
 677     {
 678       FILE *f;
 679       gboolean retval;
 680
 681       f = fdopen (fd, "r");
 682
 683       if (f == NULL)
 684         {
 685           g_set_error (error,
 686                        G_FILE_ERROR,
 687                        g_file_error_from_errno (errno),
 688                        _("Failed to open file '%s': fdopen() failed: %s"),
 689                        display_filename,
 690                        g_strerror (errno));
 691           g_free (display_filename);
 692
 693           return FALSE;
 694         }
 695
 696       retval = get_contents_stdio (display_filename, f, contents, length, error);
 697       g_free (display_filename);
 698
 699       return retval;
 700     }
 701 }
 702
 703 #else  /* G_OS_WIN32 */
 704
 705 static gboolean
 706 get_contents_win32 (const gchar *filename,
 707                     gchar      **contents,
 708                     gsize       *length,
 709                     GError     **error)
 710 {
 711   FILE *f;
 712   gboolean retval;
 713   wchar_t *wfilename = g_utf8_to_utf16 (filename, -1, NULL, NULL, NULL);
 714   gchar *display_filename = g_filename_display_name (filename);
 715
 716   f = _wfopen (wfilename, L"rb");
 717   g_free (wfilename);
 718
 719   if (f == NULL)
 720     {
 721       g_set_error (error,
 722                    G_FILE_ERROR,
 723                    g_file_error_from_errno (errno),
 724                    _("Failed to open file '%s': %s"),
 725                    display_filename,
 726                    g_strerror (errno));
 727       g_free (display_filename);
 728
 729       return FALSE;
 730     }
 731
 732   retval = get_contents_stdio (display_filename, f, contents, length, error);
 733   g_free (display_filename);
 734
 735   return retval;
 736 }
 737
 738 #endif
 739
 740 /**
 741  * g_file_get_contents:
 742  * @filename: name of a file to read contents from, in the GLib file name encoding
 743  * @contents: location to store an allocated string
 744  * @length: location to store length in bytes of the contents
 745  * @error: return location for a #GError
 746  *
 747  * Reads an entire file into allocated memory, with good error
 748  * checking. If @error is set, %FALSE is returned, and @contents is set
 749  * to %NULL. If %TRUE is returned, @error will not be set, and @contents
 750  * will be set to the file contents.  The string stored in @contents
 751  * will be nul-terminated, so for text files you can pass %NULL for the
 752  * @length argument.  The error domain is #G_FILE_ERROR. Possible
 753  * error codes are those in the #GFileError enumeration.
 754  *
 755  * Return value: %TRUE on success, %FALSE if error is set
 756  **/
 757 gboolean
 758 g_file_get_contents (const gchar *filename,
 759                      gchar      **contents,
 760                      gsize       *length,
 761                      GError     **error)
 762 {
 763   g_return_val_if_fail (filename != NULL, FALSE);
 764   g_return_val_if_fail (contents != NULL, FALSE);
 765
 766   *contents = NULL;
 767   if (length)
 768     *length = 0;
 769
 770 #ifdef G_OS_WIN32
 771   return get_contents_win32 (filename, contents, length, error);
 772 #else
 773   return get_contents_posix (filename, contents, length, error);
 774 #endif
 775 }
 776
 777 #ifdef G_OS_WIN32
 778
 779 #undef g_file_get_contents
 780
 781 /* Binary compatibility version. Not for newly compiled code. */
 782
 783 gboolean
 784 g_file_get_contents (const gchar *filename,
 785                      gchar      **contents,
 786                      gsize       *length,
 787                      GError     **error)
 788 {
 789   gchar *utf8_filename = g_locale_to_utf8 (filename, -1, NULL, NULL, error);
 790   gboolean retval;
 791
 792   if (utf8_filename == NULL)
 793     return FALSE;
 794
 795   retval = g_file_get_contents (utf8_filename, contents, length, error);
 796
 797   g_free (utf8_filename);
 798
 799   return retval;
 800 }
 801
 802 #endif
 803
 804 /*
 805  * mkstemp() implementation is from the GNU C library.
 806  * Copyright (C) 1991,92,93,94,95,96,97,98,99 Free Software Foundation, Inc.
 807  */
 808 /**
 809  * g_mkstemp:
 810  * @tmpl: template filename
 811  *
 812  * Opens a temporary file. See the mkstemp() documentation
 813  * on most UNIX-like systems. This is a portability wrapper, which simply calls
 814  * mkstemp() on systems that have it, and implements
 815  * it in GLib otherwise.
 816  *
 817  * The parameter is a string that should match the rules for
 818  * mkstemp(), i.e. end in "XXXXXX". The X string will
 819  * be modified to form the name of a file that didn't exist.
 820  * The string should be in the GLib file name encoding. Most importantly,
 821  * on Windows it should be in UTF-8.
 822  *
 823  * Return value: A file handle (as from open()) to the file
 824  * opened for reading and writing. The file is opened in binary mode
 825  * on platforms where there is a difference. The file handle should be
 826  * closed with close(). In case of errors, -1 is returned.
 827  */
 828 gint
 829 g_mkstemp (gchar *tmpl)
 830 {
 831 #ifdef HAVE_MKSTEMP
 832   return mkstemp (tmpl);
 833 #else
 834   int len;
 835   char *XXXXXX;
 836   int count, fd;
 837   static const char letters[] =
 838     "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
 839   static const int NLETTERS = sizeof (letters) - 1;
 840   glong value;
 841   GTimeVal tv;
 842   static int counter = 0;
 843
 844   len = strlen (tmpl);
 845   if (len < 6 || strcmp (&tmpl[len - 6], "XXXXXX"))
 846     return -1;
 847
 848   /* This is where the Xs start.  */
 849   XXXXXX = &tmpl[len - 6];
 850
 851   /* Get some more or less random data.  */
 852   g_get_current_time (&tv);
 853   value = (tv.tv_usec ^ tv.tv_sec) + counter++;
 854
 855   for (count = 0; count < 100; value += 7777, ++count)
 856     {
 857       glong v = value;
 858
 859       /* Fill in the random bits.  */
 860       XXXXXX[0] = letters[v % NLETTERS];
 861       v /= NLETTERS;
 862       XXXXXX[1] = letters[v % NLETTERS];
 863       v /= NLETTERS;
 864       XXXXXX[2] = letters[v % NLETTERS];
 865       v /= NLETTERS;
 866       XXXXXX[3] = letters[v % NLETTERS];
 867       v /= NLETTERS;
 868       XXXXXX[4] = letters[v % NLETTERS];
 869       v /= NLETTERS;
 870       XXXXXX[5] = letters[v % NLETTERS];
 871
 872       /* tmpl is in UTF-8 on Windows, thus use g_open() */
 873       fd = g_open (tmpl, O_RDWR | O_CREAT | O_EXCL | O_BINARY, 0600);
 874
 875       if (fd >= 0)
 876         return fd;
 877       else if (errno != EEXIST)
 878         /* Any other error will apply also to other names we might
 879          *  try, and there are 2^32 or so of them, so give up now.
 880          */
 881         return -1;
 882     }
 883
 884   /* We got out of the loop because we ran out of combinations to try.  */
 885   return -1;
 886 #endif
 887 }
 888
 889 #ifdef G_OS_WIN32
 890
 891 #undef g_mkstemp
 892
 893 /* Binary compatibility version. Not for newly compiled code. */
 894
 895 gint
 896 g_mkstemp (gchar *tmpl)
 897 {
 898   int len;
 899   char *XXXXXX;
 900   int count, fd;
 901   static const char letters[] =
 902     "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
 903   static const int NLETTERS = sizeof (letters) - 1;
 904   glong value;
 905   GTimeVal tv;
 906   static int counter = 0;
 907
 908   len = strlen (tmpl);
 909   if (len < 6 || strcmp (&tmpl[len - 6], "XXXXXX"))
 910     return -1;
 911
 912   /* This is where the Xs start.  */
 913   XXXXXX = &tmpl[len - 6];
 914
 915   /* Get some more or less random data.  */
 916   g_get_current_time (&tv);
 917   value = (tv.tv_usec ^ tv.tv_sec) + counter++;
 918
 919   for (count = 0; count < 100; value += 7777, ++count)
 920     {
 921       glong v = value;
 922
 923       /* Fill in the random bits.  */
 924       XXXXXX[0] = letters[v % NLETTERS];
 925       v /= NLETTERS;
 926       XXXXXX[1] = letters[v % NLETTERS];
 927       v /= NLETTERS;
 928       XXXXXX[2] = letters[v % NLETTERS];
 929       v /= NLETTERS;
 930       XXXXXX[3] = letters[v % NLETTERS];
 931       v /= NLETTERS;
 932       XXXXXX[4] = letters[v % NLETTERS];
 933       v /= NLETTERS;
 934       XXXXXX[5] = letters[v % NLETTERS];
 935
 936       /* This is the backward compatibility system codepage version,
 937        * thus use normal open().
 938        */
 939       fd = open (tmpl, O_RDWR | O_CREAT | O_EXCL | O_BINARY, 0600);
 940
 941       if (fd >= 0)
 942         return fd;
 943       else if (errno != EEXIST)
 944         /* Any other error will apply also to other names we might
 945          *  try, and there are 2^32 or so of them, so give up now.
 946          */
 947         return -1;
 948     }
 949
 950   /* We got out of the loop because we ran out of combinations to try.  */
 951   return -1;
 952 }
 953
 954 #endif
 955
 956 /**
 957  * g_file_open_tmp:
 958  * @tmpl: Template for file name, as in g_mkstemp(), basename only
 959  * @name_used: location to store actual name used
 960  * @error: return location for a #GError
 961  *
 962  * Opens a file for writing in the preferred directory for temporary
 963  * files (as returned by g_get_tmp_dir()).
 964  *
 965  * @tmpl should be a string in the GLib file name encoding ending with
 966  * six 'X' characters, as the parameter to g_mkstemp() (or mkstemp()).
 967  * However, unlike these functions, the template should only be a
 968  * basename, no directory components are allowed. If template is
 969  * %NULL, a default template is used.
 970  *
 971  * Note that in contrast to g_mkstemp() (and mkstemp())
 972  * @tmpl is not modified, and might thus be a read-only literal string.
 973  *
 974  * The actual name used is returned in @name_used if non-%NULL. This
 975  * string should be freed with g_free() when not needed any longer.
 976  * The returned name is in the GLib file name encoding.
 977  *
 978  * Return value: A file handle (as from open()) to
 979  * the file opened for reading and writing. The file is opened in binary
 980  * mode on platforms where there is a difference. The file handle should be
 981  * closed with close(). In case of errors, -1 is returned
 982  * and @error will be set.
 983  **/
 984 gint
 985 g_file_open_tmp (const gchar *tmpl,
 986                  gchar      **name_used,
 987                  GError     **error)
 988 {
 989   int retval;
 990   const char *tmpdir;
 991   char *sep;
 992   char *fulltemplate;
 993   const char *slash;
 994
 995   if (tmpl == NULL)
 996     tmpl = ".XXXXXX";
 997
 998   if ((slash = strchr (tmpl, G_DIR_SEPARATOR)) != NULL
 999 #ifdef G_OS_WIN32
1000       || (strchr (tmpl, '/') != NULL && (slash = "/"))
1001 #endif
1002       )
1003     {
1004       gchar *display_tmpl = g_filename_display_name (tmpl);
1005       char c[2];
1006       c[0] = *slash;
1007       c[1] = '\0';
1008
1009       g_set_error (error,
1010                    G_FILE_ERROR,
1011                    G_FILE_ERROR_FAILED,
1012                    _("Template '%s' invalid, should not contain a '%s'"),
1013                    display_tmpl, c);
1014       g_free (display_tmpl);
1015
1016       return -1;
1017     }
1018
1019   if (strlen (tmpl) < 6 ||
1020       strcmp (tmpl + strlen (tmpl) - 6, "XXXXXX") != 0)
1021     {
1022       gchar *display_tmpl = g_filename_display_name (tmpl);
1023       g_set_error (error,
1024                    G_FILE_ERROR,
1025                    G_FILE_ERROR_FAILED,
1026                    _("Template '%s' doesn't end with XXXXXX"),
1027                    display_tmpl);
1028       g_free (display_tmpl);
1029       return -1;
1030     }
1031
1032   tmpdir = g_get_tmp_dir ();
1033
1034   if (G_IS_DIR_SEPARATOR (tmpdir [strlen (tmpdir) - 1]))
1035     sep = "";
1036   else
1037     sep = G_DIR_SEPARATOR_S;
1038
1039   fulltemplate = g_strconcat (tmpdir, sep, tmpl, NULL);
1040
1041   retval = g_mkstemp (fulltemplate);
1042
1043   if (retval == -1)
1044     {
1045       gchar *display_fulltemplate = g_filename_display_name (fulltemplate);
1046       g_set_error (error,
1047                    G_FILE_ERROR,
1048                    g_file_error_from_errno (errno),
1049                    _("Failed to create file '%s': %s"),
1050                    display_fulltemplate, g_strerror (errno));
1051       g_free (display_fulltemplate);
1052       g_free (fulltemplate);
1053       return -1;
1054     }
1055
1056   if (name_used)
1057     *name_used = fulltemplate;
1058   else
1059     g_free (fulltemplate);
1060
1061   return retval;
1062 }
1063
1064 #ifdef G_OS_WIN32
1065
1066 #undef g_file_open_tmp
1067
1068 /* Binary compatibility version. Not for newly compiled code. */
1069
1070 gint
1071 g_file_open_tmp (const gchar *tmpl,
1072                  gchar      **name_used,
1073                  GError     **error)
1074 {
1075   gchar *utf8_tmpl = g_locale_to_utf8 (tmpl, -1, NULL, NULL, error);
1076   gchar *utf8_name_used;
1077   gint retval;
1078
1079   if (utf8_tmpl == NULL)
1080     return -1;
1081
1082   retval = g_file_open_tmp_utf8 (utf8_tmpl, &utf8_name_used, error);
1083
1084   if (retval == -1)
1085     return -1;
1086
1087   if (name_used)
1088     *name_used = g_locale_from_utf8 (utf8_name_used, -1, NULL, NULL, NULL);
1089
1090   g_free (utf8_name_used);
1091
1092   return retval;
1093 }
1094
1095 #endif
1096
1097 static gchar *
1098 g_build_pathv (const gchar *separator,
1099                const gchar *first_element,
1100                va_list      args)
1101 {
1102   GString *result;
1103   gint separator_len = strlen (separator);
1104   gboolean is_first = TRUE;
1105   gboolean have_leading = FALSE;
1106   const gchar *single_element = NULL;
1107   const gchar *next_element;
1108   const gchar *last_trailing = NULL;
1109
1110   result = g_string_new (NULL);
1111
1112   next_element = first_element;
1113
1114   while (TRUE)
1115     {
1116       const gchar *element;
1117       const gchar *start;
1118       const gchar *end;
1119
1120       if (next_element)
1121         {
1122           element = next_element;
1123           next_element = va_arg (args, gchar *);
1124         }
1125       else
1126         break;
1127
1128       /* Ignore empty elements */
1129       if (!*element)
1130         continue;
1131
1132       start = element;
1133
1134       if (separator_len)
1135         {
1136           while (start &&
1137                  strncmp (start, separator, separator_len) == 0)
1138             start += separator_len;
1139         }
1140
1141       end = start + strlen (start);
1142
1143       if (separator_len)
1144         {
1145           while (end >= start + separator_len &&
1146                  strncmp (end - separator_len, separator, separator_len) == 0)
1147             end -= separator_len;
1148
1149           last_trailing = end;
1150           while (last_trailing >= element + separator_len &&
1151                  strncmp (last_trailing - separator_len, separator, separator_len) == 0)
1152             last_trailing -= separator_len;
1153
1154           if (!have_leading)
1155             {
1156               /* If the leading and trailing separator strings are in the
1157                * same element and overlap, the result is exactly that element
1158                */
1159               if (last_trailing <= start)
1160                 single_element = element;
1161
1162               g_string_append_len (result, element, start - element);
1163               have_leading = TRUE;
1164             }
1165           else
1166             single_element = NULL;
1167         }
1168
1169       if (end == start)
1170         continue;
1171
1172       if (!is_first)
1173         g_string_append (result, separator);
1174
1175       g_string_append_len (result, start, end - start);
1176       is_first = FALSE;
1177     }
1178
1179   if (single_element)
1180     {
1181       g_string_free (result, TRUE);
1182       return g_strdup (single_element);
1183     }
1184   else
1185     {
1186       if (last_trailing)
1187         g_string_append (result, last_trailing);
1188
1189       return g_string_free (result, FALSE);
1190     }
1191 }
1192
1193 /**
1194  * g_build_path:
1195  * @separator: a string used to separator the elements of the path.
1196  * @first_element: the first element in the path
1197  * @Varargs: remaining elements in path, terminated by %NULL
1198  *
1199  * Creates a path from a series of elements using @separator as the
1200  * separator between elements. At the boundary between two elements,
1201  * any trailing occurrences of separator in the first element, or
1202  * leading occurrences of separator in the second element are removed
1203  * and exactly one copy of the separator is inserted.
1204  *
1205  * Empty elements are ignored.
1206  *
1207  * The number of leading copies of the separator on the result is
1208  * the same as the number of leading copies of the separator on
1209  * the first non-empty element.
1210  *
1211  * The number of trailing copies of the separator on the result is
1212  * the same as the number of trailing copies of the separator on
1213  * the last non-empty element. (Determination of the number of
1214  * trailing copies is done without stripping leading copies, so
1215  * if the separator is <literal>ABA</literal>, <literal>ABABA</literal>
1216  * has 1 trailing copy.)
1217  *
1218  * However, if there is only a single non-empty element, and there
1219  * are no characters in that element not part of the leading or
1220  * trailing separators, then the result is exactly the original value
1221  * of that element.
1222  *
1223  * Other than for determination of the number of leading and trailing
1224  * copies of the separator, elements consisting only of copies
1225  * of the separator are ignored.
1226  *
1227  * Return value: a newly-allocated string that must be freed with g_free().
1228  **/
1229 gchar *
1230 g_build_path (const gchar *separator,
1231               const gchar *first_element,
1232               ...)
1233 {
1234   gchar *str;
1235   va_list args;
1236
1237   g_return_val_if_fail (separator != NULL, NULL);
1238
1239   va_start (args, first_element);
1240   str = g_build_pathv (separator, first_element, args);
1241   va_end (args);
1242
1243   return str;
1244 }
1245
1246 /**
1247  * g_build_filename:
1248  * @first_element: the first element in the path
1249  * @Varargs: remaining elements in path, terminated by %NULL
1250  *
1251  * Creates a filename from a series of elements using the correct
1252  * separator for filenames.
1253  *
1254  * On Unix, this function behaves identically to <literal>g_build_path
1255  * (G_DIR_SEPARATOR_S, first_element, ....)</literal>.
1256  *
1257  * On Windows, it takes into account that either the backslash
1258  * (<literal>\</literal> or slash (<literal>/</literal>) can be used
1259  * as separator in filenames, but otherwise behaves as on Unix. When
1260  * file pathname separators need to be inserted, the one that last
1261  * previously occurred in the parameters (reading from left to right)
1262  * is used.
1263  *
1264  * No attempt is made to force the resulting filename to be an absolute
1265  * path. If the first element is a relative path, the result will
1266  * be a relative path.
1267  *
1268  * Return value: a newly-allocated string that must be freed with g_free().
1269  **/
1270 gchar *
1271 g_build_filename (const gchar *first_element,
1272                   ...)
1273 {
1274 #ifndef G_OS_WIN32
1275   gchar *str;
1276   va_list args;
1277
1278   va_start (args, first_element);
1279   str = g_build_pathv (G_DIR_SEPARATOR_S, first_element, args);
1280   va_end (args);
1281
1282   return str;
1283 #else
1284   /* Code copied from g_build_pathv(), and modifed to use two
1285    * alternative single-character separators.
1286    */
1287   va_list args;
1288   GString *result;
1289   gboolean is_first = TRUE;
1290   gboolean have_leading = FALSE;
1291   const gchar *single_element = NULL;
1292   const gchar *next_element;
1293   const gchar *last_trailing = NULL;
1294   gchar current_separator = '\\';
1295
1296   va_start (args, first_element);
1297
1298   result = g_string_new (NULL);
1299
1300   next_element = first_element;
1301
1302   while (TRUE)
1303     {
1304       const gchar *element;
1305       const gchar *start;
1306       const gchar *end;
1307
1308       if (next_element)
1309         {
1310           element = next_element;
1311           next_element = va_arg (args, gchar *);
1312         }
1313       else
1314         break;
1315
1316       /* Ignore empty elements */
1317       if (!*element)
1318         continue;
1319
1320       start = element;
1321
1322       if (TRUE)
1323         {
1324           while (start &&
1325                  (*start == '\\' || *start == '/'))
1326             {
1327               current_separator = *start;
1328               start++;
1329             }
1330         }
1331
1332       end = start + strlen (start);
1333
1334       if (TRUE)
1335         {
1336           while (end >= start + 1 &&
1337                  (end[-1] == '\\' || end[-1] == '/'))
1338             {
1339               current_separator = end[-1];
1340               end--;
1341             }
1342
1343           last_trailing = end;
1344           while (last_trailing >= element + 1 &&
1345                  (last_trailing[-1] == '\\' || last_trailing[-1] == '/'))
1346             last_trailing--;
1347
1348           if (!have_leading)
1349             {
1350               /* If the leading and trailing separator strings are in the
1351                * same element and overlap, the result is exactly that element
1352                */
1353               if (last_trailing <= start)
1354                 single_element = element;
1355
1356               g_string_append_len (result, element, start - element);
1357               have_leading = TRUE;
1358             }
1359           else
1360             single_element = NULL;
1361         }
1362
1363       if (end == start)
1364         continue;
1365
1366       if (!is_first)
1367         g_string_append_len (result, &current_separator, 1);
1368
1369       g_string_append_len (result, start, end - start);
1370       is_first = FALSE;
1371     }
1372
1373   va_end (args);
1374
1375   if (single_element)
1376     {
1377       g_string_free (result, TRUE);
1378       return g_strdup (single_element);
1379     }
1380   else
1381     {
1382       if (last_trailing)
1383         g_string_append (result, last_trailing);
1384
1385       return g_string_free (result, FALSE);
1386     }
1387 #endif
1388 }
1389
1390 /**
1391  * g_file_read_link:
1392  * @filename: the symbolic link
1393  * @error: return location for a #GError
1394  *
1395  * Reads the contents of the symbolic link @filename like the POSIX
1396  * readlink() function.  The returned string is in the encoding used
1397  * for filenames. Use g_filename_to_utf8() to convert it to UTF-8.
1398  *
1399  * Returns: A newly allocated string with the contents of the symbolic link,
1400  *          or %NULL if an error occurred.
1401  *
1402  * Since: 2.4
1403  */
1404 gchar *
1405 g_file_read_link (const gchar *filename,
1406                   GError     **error)
1407 {
1408 #ifdef HAVE_READLINK
1409   gchar *buffer;
1410   guint size;
1411   gint read_size;
1412
1413   size = 256;
1414   buffer = g_malloc (size);
1415
1416   while (TRUE)
1417     {
1418       read_size = readlink (filename, buffer, size);
1419       if (read_size < 0) {
1420         gchar *display_filename = g_filename_display_name (filename);
1421         g_free (buffer);
1422         g_set_error (error,
1423                      G_FILE_ERROR,
1424                      g_file_error_from_errno (errno),
1425                      _("Failed to read the symbolic link '%s': %s"),
1426                      display_filename,
1427                      g_strerror (errno));
1428         g_free (display_filename);
1429
1430         return NULL;
1431       }
1432
1433       if (read_size < size)
1434         {
1435           buffer[read_size] = 0;
1436           return buffer;
1437         }
1438
1439       size *= 2;
1440       buffer = g_realloc (buffer, size);
1441     }
1442 #else
1443   g_set_error (error,
1444                G_FILE_ERROR,
1445                G_FILE_ERROR_INVAL,
1446                _("Symbolic links not supported"));
1447
1448   return NULL;
1449 #endif
1450 }