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                         if (TH_ISREG(t))
 388                                 tar_skip_regfile(t);
 389
 390                         continue;
 391                 }
 392
 393                 // Check if file should be rejected
 394                 if (file_exists(real_filename) && keep_list.find(archive_filename) != keep_list.end())
 395                         real_filename = trim_filename(reject_dir + string("/") + archive_filename);
 396
 397                 // Extract file
 398                 if (tar_extract_file(t, const_cast<char*>(real_filename.c_str()))) {
 399                         // If a file fails to install we just print an error message and
 400                         // continue trying to install the rest of the package.
 401                         const char* msg = strerror(errno);
 402                         cerr << utilname << ": could not install " + archive_filename << ": " << msg << endl;
 403                         continue;
 404                 }
 405
 406                 // Check rejected file
 407                 if (real_filename != original_filename) {
 408                         bool remove_file = false;
 409
 410                         // Directory
 411                         if (TH_ISDIR(t))
 412                                 remove_file = permissions_equal(real_filename, original_filename);
 413                         // Other files
 414                         else
 415                                 remove_file = permissions_equal(real_filename, original_filename) &&
 416                                         (file_empty(real_filename) || file_equal(real_filename, original_filename));
 417
 418                         // Remove rejected file or signal about its existence
 419                         if (remove_file)
 420                                 file_remove(reject_dir, real_filename);
 421                         else
 422                                 cout << utilname << ": rejecting " << archive_filename << ", keeping existing version" << endl;
 423                 }
 424         }
 425
 426         if (i == 0) {
 427                 if (errno == 0)
 428                         throw runtime_error("empty package");
 429                 else
 430                         throw runtime_error("could not read " + filename);
 431         }
 432
 433         tar_close(t);
 434 }
 435
 436 void pkgutil::ldconfig() const
 437 {
 438         // Only execute ldconfig if /etc/ld.so.conf exists
 439         if (file_exists(root + LDCONFIG_CONF)) {
 440                 pid_t pid = fork();
 441
 442                 if (pid == -1)
 443                         throw runtime_error_with_errno("fork() failed");
 444
 445                 if (pid == 0) {
 446                         execl(LDCONFIG, LDCONFIG, "-r", root.c_str(), (char *) 0);
 447                         const char* msg = strerror(errno);
 448                         cerr << utilname << ": could not execute " << LDCONFIG << ": " << msg << endl;
 449                         exit(EXIT_FAILURE);
 450                 } else {
 451                         if (waitpid(pid, 0, 0) == -1)
 452                                 throw runtime_error_with_errno("waitpid() failed");
 453                 }
 454         }
 455 }
 456
 457 void pkgutil::pkg_footprint(string& filename) const
 458 {
 459         unsigned int i;
 460         TAR* t;
 461
 462         if (tar_open(&t, const_cast<char*>(filename.c_str()), &gztype, O_RDONLY, 0, TAR_GNU) == -1)
 463                 throw runtime_error_with_errno("could not open " + filename);
 464
 465         for (i = 0; !th_read(t); ++i) {
 466                 // Access permissions
 467                 if (TH_ISSYM(t)) {
 468                         // Access permissions on symlinks differ among filesystems, e.g. XFS and ext2 have different.
 469                         // To avoid getting different footprints we always use "lrwxrwxrwx".
 470                         cout << "lrwxrwxrwx";
 471                 } else {
 472                         cout << mtos(th_get_mode(t));
 473                 }
 474
 475                 cout << '\t';
 476
 477                 // User
 478                 uid_t uid = th_get_uid(t);
 479                 struct passwd* pw = getpwuid(uid);
 480                 if (pw)
 481                         cout << pw->pw_name;
 482                 else
 483                         cout << uid;
 484
 485                 cout << '/';
 486
 487                 // Group
 488                 gid_t gid = th_get_gid(t);
 489                 struct group* gr = getgrgid(gid);
 490                 if (gr)
 491                         cout << gr->gr_name;
 492                 else
 493                         cout << gid;
 494
 495                 // Filename
 496                 cout << '\t' << th_get_pathname(t);
 497
 498                 // Special cases
 499                 if (TH_ISSYM(t)) {
 500                         // Symlink
 501                         cout << " -> " << th_get_linkname(t);
 502                 } else if (TH_ISCHR(t) || TH_ISBLK(t)) {
 503                         // Device
 504                         cout << " (" << th_get_devmajor(t) << ", " << th_get_devminor(t) << ")";
 505                 } else if (TH_ISREG(t) && !th_get_size(t)) {
 506                         // Empty regular file
 507                         cout << " (EMPTY)";
 508                 }
 509
 510                 cout << '\n';
 511
 512                 if (TH_ISREG(t) && tar_skip_regfile(t))
 513                         throw runtime_error_with_errno("could not read " + filename);
 514         }
 515
 516         if (i == 0) {
 517                 if (errno == 0)
 518                         throw runtime_error("empty package");
 519                 else
 520                         throw runtime_error("could not read " + filename);
 521         }
 522
 523         tar_close(t);
 524 }
 525
 526 void pkgutil::print_version() const
 527 {
 528         cout << utilname << " (pkgutils) " << VERSION << endl;
 529 }
 530
 531 db_lock::db_lock(const string& root, bool exclusive)
 532         : dir(0)
 533 {
 534         const string dirname = trim_filename(root + string("/") + PKG_DIR);
 535
 536         if (!(dir = opendir(dirname.c_str())))
 537                 throw runtime_error_with_errno("could not read directory " + dirname);
 538
 539         if (flock(dirfd(dir), (exclusive ? LOCK_EX : LOCK_SH) | LOCK_NB) == -1) {
 540                 if (errno == EWOULDBLOCK)
 541                         throw runtime_error("package database is currently locked by another process");
 542                 else
 543                         throw runtime_error_with_errno("could not lock directory " + dirname);
 544         }
 545 }
 546
 547 db_lock::~db_lock()
 548 {
 549         if (dir) {
 550                 flock(dirfd(dir), LOCK_UN);
 551                 closedir(dir);
 552         }
 553 }
 554
 555 void assert_argument(char** argv, int argc, int index)
 556 {
 557         if (argc - 1 < index + 1)
 558                 throw runtime_error("option " + string(argv[index]) + " requires an argument");
 559 }
 560
 561 string itos(unsigned int value)
 562 {
 563         static char buf[20];
 564         sprintf(buf, "%u", value);
 565         return buf;
 566 }
 567
 568 string mtos(mode_t mode)
 569 {
 570         string s;
 571
 572         // File type
 573         switch (mode & S_IFMT) {
 574         case S_IFREG:  s += '-'; break; // Regular
 575         case S_IFDIR:  s += 'd'; break; // Directory
 576         case S_IFLNK:  s += 'l'; break; // Symbolic link
 577         case S_IFCHR:  s += 'c'; break; // Character special
 578         case S_IFBLK:  s += 'b'; break; // Block special
 579         case S_IFSOCK: s += 's'; break; // Socket
 580         case S_IFIFO:  s += 'p'; break; // Fifo
 581         default:       s += '?'; break; // Unknown
 582         }
 583
 584         // User permissions
 585         s += (mode & S_IRUSR) ? 'r' : '-';
 586         s += (mode & S_IWUSR) ? 'w' : '-';
 587         switch (mode & (S_IXUSR | S_ISUID)) {
 588         case S_IXUSR:           s += 'x'; break;
 589         case S_ISUID:           s += 'S'; break;
 590         case S_IXUSR | S_ISUID: s += 's'; break;
 591         default:                s += '-'; break;
 592         }
 593
 594         // Group permissions
 595         s += (mode & S_IRGRP) ? 'r' : '-';
 596         s += (mode & S_IWGRP) ? 'w' : '-';
 597         switch (mode & (S_IXGRP | S_ISGID)) {
 598         case S_IXGRP:           s += 'x'; break;
 599         case S_ISGID:           s += 'S'; break;
 600         case S_IXGRP | S_ISGID: s += 's'; break;
 601         default:                s += '-'; break;
 602         }
 603
 604         // Other permissions
 605         s += (mode & S_IROTH) ? 'r' : '-';
 606         s += (mode & S_IWOTH) ? 'w' : '-';
 607         switch (mode & (S_IXOTH | S_ISVTX)) {
 608         case S_IXOTH:           s += 'x'; break;
 609         case S_ISVTX:           s += 'T'; break;
 610         case S_IXOTH | S_ISVTX: s += 't'; break;
 611         default:                s += '-'; break;
 612         }
 613
 614         return s;
 615 }
 616
 617 int unistd_gzopen(char* pathname, int flags, mode_t mode)
 618 {
 619         char* gz_mode;
 620
 621         switch (flags & O_ACCMODE) {
 622         case O_WRONLY:
 623                 gz_mode = "w";
 624                 break;
 625
 626         case O_RDONLY:
 627                 gz_mode = "r";
 628                 break;
 629
 630         case O_RDWR:
 631         default:
 632                 errno = EINVAL;
 633                 return -1;
 634         }
 635
 636         int fd;
 637         gzFile gz_file;
 638
 639         if ((fd = open(pathname, flags, mode)) == -1)
 640                 return -1;
 641
 642         if ((flags & O_CREAT) && fchmod(fd, mode))
 643                 return -1;
 644
 645         if (!(gz_file = gzdopen(fd, gz_mode))) {
 646                 errno = ENOMEM;
 647                 return -1;
 648         }
 649
 650         return (int)gz_file;
 651 }
 652
 653 string trim_filename(const string& filename)
 654 {
 655         string search("//");
 656         string result = filename;
 657
 658         for (string::size_type pos = result.find(search); pos != string::npos; pos = result.find(search))
 659                 result.replace(pos, search.size(), "/");
 660
 661         return result;
 662 }
 663
 664 bool file_exists(const string& filename)
 665 {
 666         struct stat buf;
 667         return !lstat(filename.c_str(), &buf);
 668 }
 669
 670 bool file_empty(const string& filename)
 671 {
 672         struct stat buf;
 673
 674         if (lstat(filename.c_str(), &buf) == -1)
 675                 return false;
 676
 677         return (S_ISREG(buf.st_mode) && buf.st_size == 0);
 678 }
 679
 680 bool file_equal(const string& file1, const string& file2)
 681 {
 682         struct stat buf1, buf2;
 683
 684         if (lstat(file1.c_str(), &buf1) == -1)
 685                 return false;
 686
 687         if (lstat(file2.c_str(), &buf2) == -1)
 688                 return false;
 689
 690         // Regular files
 691         if (S_ISREG(buf1.st_mode) && S_ISREG(buf2.st_mode)) {
 692                 ifstream f1(file1.c_str());
 693                 ifstream f2(file2.c_str());
 694
 695                 if (!f1 || !f2)
 696                         return false;
 697
 698                 while (!f1.eof()) {
 699                         char buffer1[4096];
 700                         char buffer2[4096];
 701                         f1.read(buffer1, 4096);
 702                         f2.read(buffer2, 4096);
 703                         if (f1.gcount() != f2.gcount() ||
 704                             memcmp(buffer1, buffer2, f1.gcount()) ||
 705                             f1.eof() != f2.eof())
 706                                 return false;
 707                 }
 708
 709                 return true;
 710         }
 711         // Symlinks
 712         else if (S_ISLNK(buf1.st_mode) && S_ISLNK(buf2.st_mode)) {
 713                 char symlink1[MAXPATHLEN];
 714                 char symlink2[MAXPATHLEN];
 715
 716                 memset(symlink1, 0, MAXPATHLEN);
 717                 memset(symlink2, 0, MAXPATHLEN);
 718
 719                 if (readlink(file1.c_str(), symlink1, MAXPATHLEN - 1) == -1)
 720                         return false;
 721
 722                 if (readlink(file2.c_str(), symlink2, MAXPATHLEN - 1) == -1)
 723                         return false;
 724
 725                 return !strncmp(symlink1, symlink2, MAXPATHLEN);
 726         }
 727         // Character devices
 728         else if (S_ISCHR(buf1.st_mode) && S_ISCHR(buf2.st_mode)) {
 729                 return buf1.st_dev == buf2.st_dev;
 730         }
 731         // Block devices
 732         else if (S_ISBLK(buf1.st_mode) && S_ISBLK(buf2.st_mode)) {
 733                 return buf1.st_dev == buf2.st_dev;
 734         }
 735
 736         return false;
 737 }
 738
 739 bool permissions_equal(const string& file1, const string& file2)
 740 {
 741         struct stat buf1;
 742         struct stat buf2;
 743
 744         if (lstat(file1.c_str(), &buf1) == -1)
 745                 return false;
 746
 747         if (lstat(file2.c_str(), &buf2) == -1)
 748                 return false;
 749
 750         return(buf1.st_mode == buf2.st_mode) &&
 751                 (buf1.st_uid == buf2.st_uid) &&
 752                 (buf1.st_gid == buf2.st_gid);
 753 }
 754
 755 void file_remove(const string& basedir, const string& filename)
 756 {
 757         if (filename != basedir && !remove(filename.c_str())) {
 758                 char* path = strdup(filename.c_str());
 759                 file_remove(basedir, dirname(path));
 760                 free(path);
 761         }
 762 }