pkgutil.cc

   1 //
   2 //  pkgutils
   3 //
   4 //  Copyright (c) 2000-2005 Per Liden
   5 //
   6 //  This program is free software; you can redistribute it and/or modify
   7 //  it under the terms of the GNU General Public License as published by
   8 //  the Free Software Foundation; either version 2 of the License, or
   9 //  (at your option) any later version.
  10 //
  11 //  This program is distributed in the hope that it will be useful,
  12 //  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 //  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 //  GNU General Public License for more details.
  15 //
  16 //  You should have received a copy of the GNU General Public License
  17 //  along with this program; if not, write to the Free Software
  18 //  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  19 //  USA.
  20 //
  21
  22 #include "pkgutil.h"
  23 #include <iostream>
  24 #include <fstream>
  25 #include <iterator>
  26 #include <algorithm>
  27 #include <cstdio>
  28 #include <cstring>
  29 #include <cerrno>
  30 #include <csignal>
  31 #include <ext/stdio_filebuf.h>
  32 #include <pwd.h>
  33 #include <grp.h>
  34 #include <sys/types.h>
  35 #include <sys/stat.h>
  36 #include <sys/wait.h>
  37 #include <sys/file.h>
  38 #include <sys/param.h>
  39 #include <unistd.h>
  40 #include <fcntl.h>
  41 #include <zlib.h>
  42 #include <libgen.h>
  43 #include <libtar.h>
  44
  45 using __gnu_cxx::stdio_filebuf;
  46
  47 static tartype_t gztype = {
  48         (openfunc_t)unistd_gzopen,
  49         (closefunc_t)gzclose,
  50         (readfunc_t)gzread,
  51         (writefunc_t)gzwrite
  52 };
  53
  54 pkgutil::pkgutil(const string& name)
  55         : utilname(name)
  56 {
  57         // Ignore signals
  58         struct sigaction sa;
  59         memset(&sa, 0, sizeof(sa));
  60         sa.sa_handler = SIG_IGN;
  61         sigaction(SIGHUP, &sa, 0);
  62         sigaction(SIGINT, &sa, 0);
  63         sigaction(SIGQUIT, &sa, 0);
  64         sigaction(SIGTERM, &sa, 0);
  65 }
  66
  67 void pkgutil::db_open(const string& path)
  68 {
  69         // Read database
  70         root = trim_filename(path + "/");
  71         const string filename = root + PKG_DB;
  72
  73         int fd = open(filename.c_str(), O_RDONLY);
  74         if (fd == -1)
  75                 throw runtime_error_with_errno("could not open " + filename);
  76
  77         stdio_filebuf<char> filebuf(fd, ios::in, getpagesize());
  78         istream in(&filebuf);
  79         if (!in)
  80                 throw runtime_error_with_errno("could not read " + filename);
  81
  82         while (!in.eof()) {
  83                 // Read record
  84                 string name;
  85                 pkginfo_t info;
  86                 getline(in, name);
  87                 getline(in, info.version);
  88                 for (;;) {
  89                         string file;
  90                         getline(in, file);
  91
  92                         if (file.empty())
  93                                 break; // End of record
  94
  95                         info.files.insert(info.files.end(), file);
  96                 }
  97                 if (!info.files.empty())
  98                         packages[name] = info;
  99         }
 100
 101 #ifndef NDEBUG
 102         cerr << packages.size() << " packages found in database" << endl;
 103 #endif
 104 }
 105
 106 void pkgutil::db_commit()
 107 {
 108         const string dbfilename = root + PKG_DB;
 109         const string dbfilename_new = dbfilename + ".incomplete_transaction";
 110         const string dbfilename_bak = dbfilename + ".backup";
 111
 112         // Remove failed transaction (if it exists)
 113         if (unlink(dbfilename_new.c_str()) == -1 && errno != ENOENT)
 114                 throw runtime_error_with_errno("could not remove " + dbfilename_new);
 115
 116         // Write new database
 117         int fd_new = creat(dbfilename_new.c_str(), 0444);
 118         if (fd_new == -1)
 119                 throw runtime_error_with_errno("could not create " + dbfilename_new);
 120
 121         stdio_filebuf<char> filebuf_new(fd_new, ios::out, getpagesize());
 122         ostream db_new(&filebuf_new);
 123         for (packages_t::const_iterator i = packages.begin(); i != packages.end(); ++i) {
 124                 if (!i->second.files.empty()) {
 125                         db_new << i->first << "\n";
 126                         db_new << i->second.version << "\n";
 127                         copy(i->second.files.begin(), i->second.files.end(), ostream_iterator<string>(db_new, "\n"));
 128                         db_new << "\n";
 129                 }
 130         }
 131
 132         db_new.flush();
 133
 134         // Make sure the new database was successfully written
 135         if (!db_new)
 136                 throw runtime_error("could not write " + dbfilename_new);
 137
 138         // Synchronize file to disk
 139         if (fsync(fd_new) == -1)
 140                 throw runtime_error_with_errno("could not synchronize " + dbfilename_new);
 141
 142         // Relink database backup
 143         if (unlink(dbfilename_bak.c_str()) == -1 && errno != ENOENT)
 144                 throw runtime_error_with_errno("could not remove " + dbfilename_bak);
 145         if (link(dbfilename.c_str(), dbfilename_bak.c_str()) == -1)
 146                 throw runtime_error_with_errno("could not create " + dbfilename_bak);
 147
 148         // Move new database into place
 149         if (rename(dbfilename_new.c_str(), dbfilename.c_str()) == -1)
 150                 throw runtime_error_with_errno("could not rename " + dbfilename_new + " to " + dbfilename);
 151
 152 #ifndef NDEBUG
 153         cerr << packages.size() << " packages written to database" << endl;
 154 #endif
 155 }
 156
 157 void pkgutil::db_add_pkg(const string& name, const pkginfo_t& info)
 158 {
 159         packages[name] = info;
 160 }
 161
 162 bool pkgutil::db_find_pkg(const string& name)
 163 {
 164         return (packages.find(name) != packages.end());
 165 }
 166
 167 void pkgutil::db_rm_pkg(const string& name)
 168 {
 169         set<string> files = packages[name].files;
 170         packages.erase(name);
 171
 172 #ifndef NDEBUG
 173         cerr << "Removing package phase 1 (all files in package):" << endl;
 174         copy(files.begin(), files.end(), ostream_iterator<string>(cerr, "\n"));
 175         cerr << endl;
 176 #endif
 177
 178         // Don't delete files that still have references
 179         for (packages_t::const_iterator i = packages.begin(); i != packages.end(); ++i)
 180                 for (set<string>::const_iterator j = i->second.files.begin(); j != i->second.files.end(); ++j)
 181                         files.erase(*j);
 182
 183 #ifndef NDEBUG
 184         cerr << "Removing package phase 2 (files that still have references excluded):" << endl;
 185         copy(files.begin(), files.end(), ostream_iterator<string>(cerr, "\n"));
 186         cerr << endl;
 187 #endif
 188
 189         // Delete the files
 190         for (set<string>::const_reverse_iterator i = files.rbegin(); i != files.rend(); ++i) {
 191                 const string filename = root + *i;
 192                 if (file_exists(filename) && remove(filename.c_str()) == -1) {
 193                         const char* msg = strerror(errno);
 194                         cerr << utilname << ": could not remove " << filename << ": " << msg << endl;
 195                 }
 196         }
 197 }
 198
 199 void pkgutil::db_rm_pkg(const string& name, const set<string>& keep_list)
 200 {
 201         set<string> files = packages[name].files;
 202         packages.erase(name);
 203
 204 #ifndef NDEBUG
 205         cerr << "Removing package phase 1 (all files in package):" << endl;
 206         copy(files.begin(), files.end(), ostream_iterator<string>(cerr, "\n"));
 207         cerr << endl;
 208 #endif
 209
 210         // Don't delete files found in the keep list
 211         for (set<string>::const_iterator i = keep_list.begin(); i != keep_list.end(); ++i)
 212                 files.erase(*i);
 213
 214 #ifndef NDEBUG
 215         cerr << "Removing package phase 2 (files that is in the keep list excluded):" << endl;
 216         copy(files.begin(), files.end(), ostream_iterator<string>(cerr, "\n"));
 217         cerr << endl;
 218 #endif
 219
 220         // Don't delete files that still have references
 221         for (packages_t::const_iterator i = packages.begin(); i != packages.end(); ++i)
 222                 for (set<string>::const_iterator j = i->second.files.begin(); j != i->second.files.end(); ++j)
 223                         files.erase(*j);
 224
 225 #ifndef NDEBUG
 226         cerr << "Removing package phase 3 (files that still have references excluded):" << endl;
 227         copy(files.begin(), files.end(), ostream_iterator<string>(cerr, "\n"));
 228         cerr << endl;
 229 #endif
 230
 231         // Delete the files
 232         for (set<string>::const_reverse_iterator i = files.rbegin(); i != files.rend(); ++i) {
 233                 const string filename = root + *i;
 234                 if (file_exists(filename) && remove(filename.c_str()) == -1) {
 235                         if (errno == ENOTEMPTY)
 236                                 continue;
 237                         const char* msg = strerror(errno);
 238                         cerr << utilname << ": could not remove " << filename << ": " << msg << endl;
 239                 }
 240         }
 241 }
 242
 243 void pkgutil::db_rm_files(set<string> files, const set<string>& keep_list)
 244 {
 245         // Remove all references
 246         for (packages_t::iterator i = packages.begin(); i != packages.end(); ++i)
 247                 for (set<string>::const_iterator j = files.begin(); j != files.end(); ++j)
 248                         i->second.files.erase(*j);
 249
 250 #ifndef NDEBUG
 251         cerr << "Removing files:" << endl;
 252         copy(files.begin(), files.end(), ostream_iterator<string>(cerr, "\n"));
 253         cerr << endl;
 254 #endif
 255
 256         // Don't delete files found in the keep list
 257         for (set<string>::const_iterator i = keep_list.begin(); i != keep_list.end(); ++i)
 258                 files.erase(*i);
 259
 260         // Delete the files
 261         for (set<string>::const_reverse_iterator i = files.rbegin(); i != files.rend(); ++i) {
 262                 const string filename = root + *i;
 263                 if (file_exists(filename) && remove(filename.c_str()) == -1) {
 264                         if (errno == ENOTEMPTY)
 265                                 continue;
 266                         const char* msg = strerror(errno);
 267                         cerr << utilname << ": could not remove " << filename << ": " << msg << endl;
 268                 }
 269         }
 270 }
 271
 272 set<string> pkgutil::db_find_conflicts(const string& name, const pkginfo_t& info)
 273 {
 274         set<string> files;
 275
 276         // Find conflicting files in database
 277         for (packages_t::const_iterator i = packages.begin(); i != packages.end(); ++i) {
 278                 if (i->first != name) {
 279                         set_intersection(info.files.begin(), info.files.end(),
 280                                          i->second.files.begin(), i->second.files.end(),
 281                                          inserter(files, files.end()));
 282                 }
 283         }
 284
 285 #ifndef NDEBUG
 286         cerr << "Conflicts phase 1 (conflicts in database):" << endl;
 287         copy(files.begin(), files.end(), ostream_iterator<string>(cerr, "\n"));
 288         cerr << endl;
 289 #endif
 290
 291         // Find conflicting files in filesystem
 292         for (set<string>::iterator i = info.files.begin(); i != info.files.end(); ++i) {
 293                 const string filename = root + *i;
 294                 if (file_exists(filename) && files.find(*i) == files.end())
 295                         files.insert(files.end(), *i);
 296         }
 297
 298 #ifndef NDEBUG
 299         cerr << "Conflicts phase 2 (conflicts in filesystem added):" << endl;
 300         copy(files.begin(), files.end(), ostream_iterator<string>(cerr, "\n"));
 301         cerr << endl;
 302 #endif
 303
 304         // Exclude directories
 305         set<string> tmp = files;
 306         for (set<string>::const_iterator i = tmp.begin(); i != tmp.end(); ++i) {
 307                 if ((*i)[i->length() - 1] == '/')
 308                         files.erase(*i);
 309         }
 310
 311 #ifndef NDEBUG
 312         cerr << "Conflicts phase 3 (directories excluded):" << endl;
 313         copy(files.begin(), files.end(), ostream_iterator<string>(cerr, "\n"));
 314         cerr << endl;
 315 #endif
 316
 317         // If this is an upgrade, remove files already owned by this package
 318         if (packages.find(name) != packages.end()) {
 319                 for (set<string>::const_iterator i = packages[name].files.begin(); i != packages[name].files.end(); ++i)
 320                         files.erase(*i);
 321
 322 #ifndef NDEBUG
 323                 cerr << "Conflicts phase 4 (files already owned by this package excluded):" << endl;
 324                 copy(files.begin(), files.end(), ostream_iterator<string>(cerr, "\n"));
 325                 cerr << endl;
 326 #endif
 327         }
 328
 329         return files;
 330 }
 331
 332 pair<string, pkgutil::pkginfo_t> pkgutil::pkg_open(const string& filename) const
 333 {
 334         pair<string, pkginfo_t> result;
 335         unsigned int i;
 336         TAR* t;
 337
 338         // Extract name and version from filename
 339         string basename(filename, filename.rfind('/') + 1);
 340         string name(basename, 0, basename.find(VERSION_DELIM));
 341         string version(basename, 0, basename.rfind(PKG_EXT));
 342         version.erase(0, version.find(VERSION_DELIM) == string::npos ? string::npos : version.find(VERSION_DELIM) + 1);
 343
 344         if (name.empty() || version.empty())
 345                 throw runtime_error("could not determine name and/or version of " + basename + ": Invalid package name");
 346
 347         result.first = name;
 348         result.second.version = version;
 349
 350         if (tar_open(&t, const_cast<char*>(filename.c_str()), &gztype, O_RDONLY, 0, TAR_GNU) == -1)
 351                 throw runtime_error_with_errno("could not open " + filename);
 352
 353         for (i = 0; !th_read(t); ++i) {
 354                 result.second.files.insert(result.second.files.end(), th_get_pathname(t));
 355                 if (TH_ISREG(t) && tar_skip_regfile(t))
 356                         throw runtime_error_with_errno("could not read " + filename);
 357         }
 358
 359         if (i == 0) {
 360                 if (errno == 0)
 361                         throw runtime_error("empty package");
 362                 else
 363                         throw runtime_error("could not read " + filename);
 364         }
 365
 366         tar_close(t);
 367
 368         return result;
 369 }
 370
 371 void pkgutil::pkg_install(const string& filename, const set<string>& keep_list, const set<string>& non_install_list) const
 372 {
 373         TAR* t;
 374         unsigned int i;
 375
 376         if (tar_open(&t, const_cast<char*>(filename.c_str()), &gztype, O_RDONLY, 0, TAR_GNU) == -1)
 377                 throw runtime_error_with_errno("could not open " + filename);
 378
 379         for (i = 0; !th_read(t); ++i) {
 380                 string archive_filename = th_get_pathname(t);
 381                 string reject_dir = trim_filename(root + string("/") + string(PKG_REJECTED));
 382                 string original_filename = trim_filename(root + string("/") + archive_filename);
 383                 string real_filename = original_filename;
 384
 385                 // Check if file is filtered out via INSTALL
 386                 if (non_install_list.find(archive_filename) != non_install_list.end()) {
 387                         cout << utilname << ": ignoring " << archive_filename << endl;
 388
 389                         if (TH_ISREG(t))
 390                                 tar_skip_regfile(t);
 391
 392                         continue;
 393                 }
 394
 395                 // Check if file should be rejected
 396                 if (file_exists(real_filename) && keep_list.find(archive_filename) != keep_list.end())
 397                         real_filename = trim_filename(reject_dir + string("/") + archive_filename);
 398
 399                 // Extract file
 400                 if (tar_extract_file(t, const_cast<char*>(real_filename.c_str()))) {
 401                         // If a file fails to install we just print an error message and
 402                         // continue trying to install the rest of the package.
 403                         const char* msg = strerror(errno);
 404                         cerr << utilname << ": could not install " + archive_filename << ": " << msg << endl;
 405                         continue;
 406                 }
 407
 408                 // Check rejected file
 409                 if (real_filename != original_filename) {
 410                         bool remove_file = false;
 411
 412                         // Directory
 413                         if (TH_ISDIR(t))
 414                                 remove_file = permissions_equal(real_filename, original_filename);
 415                         // Other files
 416                         else
 417                                 remove_file = permissions_equal(real_filename, original_filename) &&
 418                                         (file_empty(real_filename) || file_equal(real_filename, original_filename));
 419
 420                         // Remove rejected file or signal about its existence
 421                         if (remove_file)
 422                                 file_remove(reject_dir, real_filename);
 423                         else
 424                                 cout << utilname << ": rejecting " << archive_filename << ", keeping existing version" << endl;
 425                 }
 426         }
 427
 428         if (i == 0) {
 429                 if (errno == 0)
 430                         throw runtime_error("empty package");
 431                 else
 432                         throw runtime_error("could not read " + filename);
 433         }
 434
 435         tar_close(t);
 436 }
 437
 438 void pkgutil::ldconfig() const
 439 {
 440         // Only execute ldconfig if /etc/ld.so.conf exists
 441         if (file_exists(root + LDCONFIG_CONF)) {
 442                 pid_t pid = fork();
 443
 444                 if (pid == -1)
 445                         throw runtime_error_with_errno("fork() failed");
 446
 447                 if (pid == 0) {
 448                         execl(LDCONFIG, LDCONFIG, "-r", root.c_str(), (char *) 0);
 449                         const char* msg = strerror(errno);
 450                         cerr << utilname << ": could not execute " << LDCONFIG << ": " << msg << endl;
 451                         exit(EXIT_FAILURE);
 452                 } else {
 453                         if (waitpid(pid, 0, 0) == -1)
 454                                 throw runtime_error_with_errno("waitpid() failed");
 455                 }
 456         }
 457 }
 458
 459 void pkgutil::pkg_footprint(string& filename) const
 460 {
 461         unsigned int i;
 462         TAR* t;
 463
 464         if (tar_open(&t, const_cast<char*>(filename.c_str()), &gztype, O_RDONLY, 0, TAR_GNU) == -1)
 465                 throw runtime_error_with_errno("could not open " + filename);
 466
 467         for (i = 0; !th_read(t); ++i) {
 468                 // Access permissions
 469                 if (TH_ISSYM(t)) {
 470                         // Access permissions on symlinks differ among filesystems, e.g. XFS and ext2 have different.
 471                         // To avoid getting different footprints we always use "lrwxrwxrwx".
 472                         cout << "lrwxrwxrwx";
 473                 } else {
 474                         cout << mtos(th_get_mode(t));
 475                 }
 476
 477                 cout << '\t';
 478
 479                 // User
 480                 uid_t uid = th_get_uid(t);
 481                 struct passwd* pw = getpwuid(uid);
 482                 if (pw)
 483                         cout << pw->pw_name;
 484                 else
 485                         cout << uid;
 486
 487                 cout << '/';
 488
 489                 // Group
 490                 gid_t gid = th_get_gid(t);
 491                 struct group* gr = getgrgid(gid);
 492                 if (gr)
 493                         cout << gr->gr_name;
 494                 else
 495                         cout << gid;
 496
 497                 // Filename
 498                 cout << '\t' << th_get_pathname(t);
 499
 500                 // Special cases
 501                 if (TH_ISSYM(t)) {
 502                         // Symlink
 503                         cout << " -> " << th_get_linkname(t);
 504                 } else if (TH_ISCHR(t) || TH_ISBLK(t)) {
 505                         // Device
 506                         cout << " (" << th_get_devmajor(t) << ", " << th_get_devminor(t) << ")";
 507                 } else if (TH_ISREG(t) && !th_get_size(t)) {
 508                         // Empty regular file
 509                         cout << " (EMPTY)";
 510                 }
 511
 512                 cout << '\n';
 513
 514                 if (TH_ISREG(t) && tar_skip_regfile(t))
 515                         throw runtime_error_with_errno("could not read " + filename);
 516         }
 517
 518         if (i == 0) {
 519                 if (errno == 0)
 520                         throw runtime_error("empty package");
 521                 else
 522                         throw runtime_error("could not read " + filename);
 523         }
 524
 525         tar_close(t);
 526 }
 527
 528 void pkgutil::print_version() const
 529 {
 530         cout << utilname << " (pkgutils) " << VERSION << endl;
 531 }
 532
 533 db_lock::db_lock(const string& root, bool exclusive)
 534         : dir(0)
 535 {
 536         const string dirname = trim_filename(root + string("/") + PKG_DIR);
 537
 538         if (!(dir = opendir(dirname.c_str())))
 539                 throw runtime_error_with_errno("could not read directory " + dirname);
 540
 541         if (flock(dirfd(dir), (exclusive ? LOCK_EX : LOCK_SH) | LOCK_NB) == -1) {
 542                 if (errno == EWOULDBLOCK)
 543                         throw runtime_error("package database is currently locked by another process");
 544                 else
 545                         throw runtime_error_with_errno("could not lock directory " + dirname);
 546         }
 547 }
 548
 549 db_lock::~db_lock()
 550 {
 551         if (dir) {
 552                 flock(dirfd(dir), LOCK_UN);
 553                 closedir(dir);
 554         }
 555 }
 556
 557 void assert_argument(char** argv, int argc, int index)
 558 {
 559         if (argc - 1 < index + 1)
 560                 throw runtime_error("option " + string(argv[index]) + " requires an argument");
 561 }
 562
 563 string itos(unsigned int value)
 564 {
 565         static char buf[20];
 566         sprintf(buf, "%u", value);
 567         return buf;
 568 }
 569
 570 string mtos(mode_t mode)
 571 {
 572         string s;
 573
 574         // File type
 575         switch (mode & S_IFMT) {
 576         case S_IFREG:  s += '-'; break; // Regular
 577         case S_IFDIR:  s += 'd'; break; // Directory
 578         case S_IFLNK:  s += 'l'; break; // Symbolic link
 579         case S_IFCHR:  s += 'c'; break; // Character special
 580         case S_IFBLK:  s += 'b'; break; // Block special
 581         case S_IFSOCK: s += 's'; break; // Socket
 582         case S_IFIFO:  s += 'p'; break; // Fifo
 583         default:       s += '?'; break; // Unknown
 584         }
 585
 586         // User permissions
 587         s += (mode & S_IRUSR) ? 'r' : '-';
 588         s += (mode & S_IWUSR) ? 'w' : '-';
 589         switch (mode & (S_IXUSR | S_ISUID)) {
 590         case S_IXUSR:           s += 'x'; break;
 591         case S_ISUID:           s += 'S'; break;
 592         case S_IXUSR | S_ISUID: s += 's'; break;
 593         default:                s += '-'; break;
 594         }
 595
 596         // Group permissions
 597         s += (mode & S_IRGRP) ? 'r' : '-';
 598         s += (mode & S_IWGRP) ? 'w' : '-';
 599         switch (mode & (S_IXGRP | S_ISGID)) {
 600         case S_IXGRP:           s += 'x'; break;
 601         case S_ISGID:           s += 'S'; break;
 602         case S_IXGRP | S_ISGID: s += 's'; break;
 603         default:                s += '-'; break;
 604         }
 605
 606         // Other permissions
 607         s += (mode & S_IROTH) ? 'r' : '-';
 608         s += (mode & S_IWOTH) ? 'w' : '-';
 609         switch (mode & (S_IXOTH | S_ISVTX)) {
 610         case S_IXOTH:           s += 'x'; break;
 611         case S_ISVTX:           s += 'T'; break;
 612         case S_IXOTH | S_ISVTX: s += 't'; break;
 613         default:                s += '-'; break;
 614         }
 615
 616         return s;
 617 }
 618
 619 int unistd_gzopen(char* pathname, int flags, mode_t mode)
 620 {
 621         char* gz_mode;
 622
 623         switch (flags & O_ACCMODE) {
 624         case O_WRONLY:
 625                 gz_mode = "w";
 626                 break;
 627
 628         case O_RDONLY:
 629                 gz_mode = "r";
 630                 break;
 631
 632         case O_RDWR:
 633         default:
 634                 errno = EINVAL;
 635                 return -1;
 636         }
 637
 638         int fd;
 639         gzFile gz_file;
 640
 641         if ((fd = open(pathname, flags, mode)) == -1)
 642                 return -1;
 643
 644         if ((flags & O_CREAT) && fchmod(fd, mode))
 645                 return -1;
 646
 647         if (!(gz_file = gzdopen(fd, gz_mode))) {
 648                 errno = ENOMEM;
 649                 return -1;
 650         }
 651
 652         return (int)gz_file;
 653 }
 654
 655 string trim_filename(const string& filename)
 656 {
 657         string search("//");
 658         string result = filename;
 659
 660         for (string::size_type pos = result.find(search); pos != string::npos; pos = result.find(search))
 661                 result.replace(pos, search.size(), "/");
 662
 663         return result;
 664 }
 665
 666 bool file_exists(const string& filename)
 667 {
 668         struct stat buf;
 669         return !lstat(filename.c_str(), &buf);
 670 }
 671
 672 bool file_empty(const string& filename)
 673 {
 674         struct stat buf;
 675
 676         if (lstat(filename.c_str(), &buf) == -1)
 677                 return false;
 678
 679         return (S_ISREG(buf.st_mode) && buf.st_size == 0);
 680 }
 681
 682 bool file_equal(const string& file1, const string& file2)
 683 {
 684         struct stat buf1, buf2;
 685
 686         if (lstat(file1.c_str(), &buf1) == -1)
 687                 return false;
 688
 689         if (lstat(file2.c_str(), &buf2) == -1)
 690                 return false;
 691
 692         // Regular files
 693         if (S_ISREG(buf1.st_mode) && S_ISREG(buf2.st_mode)) {
 694                 ifstream f1(file1.c_str());
 695                 ifstream f2(file2.c_str());
 696
 697                 if (!f1 || !f2)
 698                         return false;
 699
 700                 while (!f1.eof()) {
 701                         char buffer1[4096];
 702                         char buffer2[4096];
 703                         f1.read(buffer1, 4096);
 704                         f2.read(buffer2, 4096);
 705                         if (f1.gcount() != f2.gcount() ||
 706                             memcmp(buffer1, buffer2, f1.gcount()) ||
 707                             f1.eof() != f2.eof())
 708                                 return false;
 709                 }
 710
 711                 return true;
 712         }
 713         // Symlinks
 714         else if (S_ISLNK(buf1.st_mode) && S_ISLNK(buf2.st_mode)) {
 715                 char symlink1[MAXPATHLEN];
 716                 char symlink2[MAXPATHLEN];
 717
 718                 memset(symlink1, 0, MAXPATHLEN);
 719                 memset(symlink2, 0, MAXPATHLEN);
 720
 721                 if (readlink(file1.c_str(), symlink1, MAXPATHLEN - 1) == -1)
 722                         return false;
 723
 724                 if (readlink(file2.c_str(), symlink2, MAXPATHLEN - 1) == -1)
 725                         return false;
 726
 727                 return !strncmp(symlink1, symlink2, MAXPATHLEN);
 728         }
 729         // Character devices
 730         else if (S_ISCHR(buf1.st_mode) && S_ISCHR(buf2.st_mode)) {
 731                 return buf1.st_dev == buf2.st_dev;
 732         }
 733         // Block devices
 734         else if (S_ISBLK(buf1.st_mode) && S_ISBLK(buf2.st_mode)) {
 735                 return buf1.st_dev == buf2.st_dev;
 736         }
 737
 738         return false;
 739 }
 740
 741 bool permissions_equal(const string& file1, const string& file2)
 742 {
 743         struct stat buf1;
 744         struct stat buf2;
 745
 746         if (lstat(file1.c_str(), &buf1) == -1)
 747                 return false;
 748
 749         if (lstat(file2.c_str(), &buf2) == -1)
 750                 return false;
 751
 752         return(buf1.st_mode == buf2.st_mode) &&
 753                 (buf1.st_uid == buf2.st_uid) &&
 754                 (buf1.st_gid == buf2.st_gid);
 755 }
 756
 757 void file_remove(const string& basedir, const string& filename)
 758 {
 759         if (filename != basedir && !remove(filename.c_str())) {
 760                 char* path = strdup(filename.c_str());
 761                 file_remove(basedir, dirname(path));
 762                 free(path);
 763         }
 764 }