src/filesys.cpp

   1 /*
   2 Minetest
   3 Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
   4
   5 This program is free software; you can redistribute it and/or modify
   6 it under the terms of the GNU Lesser General Public License as published by
   7 the Free Software Foundation; either version 2.1 of the License, or
   8 (at your option) any later version.
   9
  10 This program 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
  13 GNU Lesser General Public License for more details.
  14
  15 You should have received a copy of the GNU Lesser General Public License along
  16 with this program; if not, write to the Free Software Foundation, Inc.,
  17 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18 */
  19
  20 #include "filesys.h"
  21 #include "util/string.h"
  22 #include <iostream>
  23 #include <cstdio>
  24 #include <cstring>
  25 #include <cerrno>
  26 #include <fstream>
  27 #include "log.h"
  28 #include "config.h"
  29 #include "porting.h"
  30 #ifdef __ANDROID__
  31 #include "settings.h" // For g_settings
  32 #endif
  33
  34 namespace fs
  35 {
  36
  37 #ifdef _WIN32 // WINDOWS
  38
  39 #define _WIN32_WINNT 0x0501
  40 #include <windows.h>
  41 #include <shlwapi.h>
  42
  43 std::vector<DirListNode> GetDirListing(const std::string &pathstring)
  44 {
  45         std::vector<DirListNode> listing;
  46
  47         WIN32_FIND_DATA FindFileData;
  48         HANDLE hFind = INVALID_HANDLE_VALUE;
  49         DWORD dwError;
  50
  51         std::string dirSpec = pathstring + "\\*";
  52
  53         // Find the first file in the directory.
  54         hFind = FindFirstFile(dirSpec.c_str(), &FindFileData);
  55
  56         if (hFind == INVALID_HANDLE_VALUE) {
  57                 dwError = GetLastError();
  58                 if (dwError != ERROR_FILE_NOT_FOUND && dwError != ERROR_PATH_NOT_FOUND) {
  59                         errorstream << "GetDirListing: FindFirstFile error."
  60                                         << " Error is " << dwError << std::endl;
  61                 }
  62         } else {
  63                 // NOTE:
  64                 // Be very sure to not include '..' in the results, it will
  65                 // result in an epic failure when deleting stuff.
  66
  67                 DirListNode node;
  68                 node.name = FindFileData.cFileName;
  69                 node.dir = FindFileData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY;
  70                 if (node.name != "." && node.name != "..")
  71                         listing.push_back(node);
  72
  73                 // List all the other files in the directory.
  74                 while (FindNextFile(hFind, &FindFileData) != 0) {
  75                         DirListNode node;
  76                         node.name = FindFileData.cFileName;
  77                         node.dir = FindFileData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY;
  78                         if(node.name != "." && node.name != "..")
  79                                 listing.push_back(node);
  80                 }
  81
  82                 dwError = GetLastError();
  83                 FindClose(hFind);
  84                 if (dwError != ERROR_NO_MORE_FILES) {
  85                         errorstream << "GetDirListing: FindNextFile error."
  86                                         << " Error is " << dwError << std::endl;
  87                         listing.clear();
  88                         return listing;
  89                 }
  90         }
  91         return listing;
  92 }
  93
  94 bool CreateDir(const std::string &path)
  95 {
  96         bool r = CreateDirectory(path.c_str(), NULL);
  97         if(r == true)
  98                 return true;
  99         if(GetLastError() == ERROR_ALREADY_EXISTS)
 100                 return true;
 101         return false;
 102 }
 103
 104 bool PathExists(const std::string &path)
 105 {
 106         return (GetFileAttributes(path.c_str()) != INVALID_FILE_ATTRIBUTES);
 107 }
 108
 109 bool IsPathAbsolute(const std::string &path)
 110 {
 111         return !PathIsRelative(path.c_str());
 112 }
 113
 114 bool IsDir(const std::string &path)
 115 {
 116         DWORD attr = GetFileAttributes(path.c_str());
 117         return (attr != INVALID_FILE_ATTRIBUTES &&
 118                         (attr & FILE_ATTRIBUTE_DIRECTORY));
 119 }
 120
 121 bool IsDirDelimiter(char c)
 122 {
 123         return c == '/' || c == '\\';
 124 }
 125
 126 bool RecursiveDelete(const std::string &path)
 127 {
 128         infostream<<"Recursively deleting \""<<path<<"\""<<std::endl;
 129
 130         DWORD attr = GetFileAttributes(path.c_str());
 131         bool is_directory = (attr != INVALID_FILE_ATTRIBUTES &&
 132                         (attr & FILE_ATTRIBUTE_DIRECTORY));
 133         if(!is_directory)
 134         {
 135                 infostream<<"RecursiveDelete: Deleting file "<<path<<std::endl;
 136                 //bool did = DeleteFile(path.c_str());
 137                 bool did = true;
 138                 if(!did){
 139                         errorstream<<"RecursiveDelete: Failed to delete file "
 140                                         <<path<<std::endl;
 141                         return false;
 142                 }
 143         }
 144         else
 145         {
 146                 infostream<<"RecursiveDelete: Deleting content of directory "
 147                                 <<path<<std::endl;
 148                 std::vector<DirListNode> content = GetDirListing(path);
 149                 for(size_t i=0; i<content.size(); i++){
 150                         const DirListNode &n = content[i];
 151                         std::string fullpath = path + DIR_DELIM + n.name;
 152                         bool did = RecursiveDelete(fullpath);
 153                         if(!did){
 154                                 errorstream<<"RecursiveDelete: Failed to recurse to "
 155                                                 <<fullpath<<std::endl;
 156                                 return false;
 157                         }
 158                 }
 159                 infostream<<"RecursiveDelete: Deleting directory "<<path<<std::endl;
 160                 //bool did = RemoveDirectory(path.c_str();
 161                 bool did = true;
 162                 if(!did){
 163                         errorstream<<"Failed to recursively delete directory "
 164                                         <<path<<std::endl;
 165                         return false;
 166                 }
 167         }
 168         return true;
 169 }
 170
 171 bool DeleteSingleFileOrEmptyDirectory(const std::string &path)
 172 {
 173         DWORD attr = GetFileAttributes(path.c_str());
 174         bool is_directory = (attr != INVALID_FILE_ATTRIBUTES &&
 175                         (attr & FILE_ATTRIBUTE_DIRECTORY));
 176         if(!is_directory)
 177         {
 178                 bool did = DeleteFile(path.c_str());
 179                 return did;
 180         }
 181         else
 182         {
 183                 bool did = RemoveDirectory(path.c_str());
 184                 return did;
 185         }
 186 }
 187
 188 std::string TempPath()
 189 {
 190         DWORD bufsize = GetTempPath(0, NULL);
 191         if(bufsize == 0){
 192                 errorstream<<"GetTempPath failed, error = "<<GetLastError()<<std::endl;
 193                 return "";
 194         }
 195         std::vector<char> buf(bufsize);
 196         DWORD len = GetTempPath(bufsize, &buf[0]);
 197         if(len == 0 || len > bufsize){
 198                 errorstream<<"GetTempPath failed, error = "<<GetLastError()<<std::endl;
 199                 return "";
 200         }
 201         return std::string(buf.begin(), buf.begin() + len);
 202 }
 203
 204 #else // POSIX
 205
 206 #include <sys/types.h>
 207 #include <dirent.h>
 208 #include <sys/stat.h>
 209 #include <sys/wait.h>
 210 #include <unistd.h>
 211
 212 std::vector<DirListNode> GetDirListing(const std::string &pathstring)
 213 {
 214         std::vector<DirListNode> listing;
 215
 216         DIR *dp;
 217         struct dirent *dirp;
 218         if((dp = opendir(pathstring.c_str())) == NULL) {
 219                 //infostream<<"Error("<<errno<<") opening "<<pathstring<<std::endl;
 220                 return listing;
 221         }
 222
 223         while ((dirp = readdir(dp)) != NULL) {
 224                 // NOTE:
 225                 // Be very sure to not include '..' in the results, it will
 226                 // result in an epic failure when deleting stuff.
 227                 if(strcmp(dirp->d_name, ".") == 0 || strcmp(dirp->d_name, "..") == 0)
 228                         continue;
 229
 230                 DirListNode node;
 231                 node.name = dirp->d_name;
 232
 233                 int isdir = -1; // -1 means unknown
 234
 235                 /*
 236                         POSIX doesn't define d_type member of struct dirent and
 237                         certain filesystems on glibc/Linux will only return
 238                         DT_UNKNOWN for the d_type member.
 239
 240                         Also we don't know whether symlinks are directories or not.
 241                 */
 242 #ifdef _DIRENT_HAVE_D_TYPE
 243                 if(dirp->d_type != DT_UNKNOWN && dirp->d_type != DT_LNK)
 244                         isdir = (dirp->d_type == DT_DIR);
 245 #endif /* _DIRENT_HAVE_D_TYPE */
 246
 247                 /*
 248                         Was d_type DT_UNKNOWN, DT_LNK or nonexistent?
 249                         If so, try stat().
 250                 */
 251                 if(isdir == -1) {
 252                         struct stat statbuf{};
 253                         if (stat((pathstring + "/" + node.name).c_str(), &statbuf))
 254                                 continue;
 255                         isdir = ((statbuf.st_mode & S_IFDIR) == S_IFDIR);
 256                 }
 257                 node.dir = isdir;
 258                 listing.push_back(node);
 259         }
 260         closedir(dp);
 261
 262         return listing;
 263 }
 264
 265 bool CreateDir(const std::string &path)
 266 {
 267         int r = mkdir(path.c_str(), S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH);
 268         if (r == 0) {
 269                 return true;
 270         }
 271
 272         // If already exists, return true
 273         if (errno == EEXIST)
 274                 return true;
 275         return false;
 276
 277 }
 278
 279 bool PathExists(const std::string &path)
 280 {
 281         struct stat st{};
 282         return (stat(path.c_str(),&st) == 0);
 283 }
 284
 285 bool IsPathAbsolute(const std::string &path)
 286 {
 287         return path[0] == '/';
 288 }
 289
 290 bool IsDir(const std::string &path)
 291 {
 292         struct stat statbuf{};
 293         if(stat(path.c_str(), &statbuf))
 294                 return false; // Actually error; but certainly not a directory
 295         return ((statbuf.st_mode & S_IFDIR) == S_IFDIR);
 296 }
 297
 298 bool IsDirDelimiter(char c)
 299 {
 300         return c == '/';
 301 }
 302
 303 bool RecursiveDelete(const std::string &path)
 304 {
 305         /*
 306                 Execute the 'rm' command directly, by fork() and execve()
 307         */
 308
 309         infostream<<"Removing \""<<path<<"\""<<std::endl;
 310
 311         //return false;
 312
 313         pid_t child_pid = fork();
 314
 315         if(child_pid == 0)
 316         {
 317                 // Child
 318                 char argv_data[3][10000];
 319                 strcpy(argv_data[0], "/bin/rm");
 320                 strcpy(argv_data[1], "-rf");
 321                 strncpy(argv_data[2], path.c_str(), 10000);
 322                 char *argv[4];
 323                 argv[0] = argv_data[0];
 324                 argv[1] = argv_data[1];
 325                 argv[2] = argv_data[2];
 326                 argv[3] = NULL;
 327
 328                 verbosestream<<"Executing '"<<argv[0]<<"' '"<<argv[1]<<"' '"
 329                                 <<argv[2]<<"'"<<std::endl;
 330
 331                 execv(argv[0], argv);
 332
 333                 // Execv shouldn't return. Failed.
 334                 _exit(1);
 335         }
 336         else
 337         {
 338                 // Parent
 339                 int child_status;
 340                 pid_t tpid;
 341                 do{
 342                         tpid = wait(&child_status);
 343                         //if(tpid != child_pid) process_terminated(tpid);
 344                 }while(tpid != child_pid);
 345                 return (child_status == 0);
 346         }
 347 }
 348
 349 bool DeleteSingleFileOrEmptyDirectory(const std::string &path)
 350 {
 351         if (IsDir(path)) {
 352                 bool did = (rmdir(path.c_str()) == 0);
 353                 if (!did)
 354                         errorstream << "rmdir errno: " << errno << ": " << strerror(errno)
 355                                         << std::endl;
 356                 return did;
 357         }
 358
 359         bool did = (unlink(path.c_str()) == 0);
 360         if (!did)
 361                 errorstream << "unlink errno: " << errno << ": " << strerror(errno)
 362                                 << std::endl;
 363         return did;
 364 }
 365
 366 std::string TempPath()
 367 {
 368         /*
 369                 Should the environment variables TMPDIR, TMP and TEMP
 370                 and the macro P_tmpdir (if defined by stdio.h) be checked
 371                 before falling back on /tmp?
 372
 373                 Probably not, because this function is intended to be
 374                 compatible with lua's os.tmpname which under the default
 375                 configuration hardcodes mkstemp("/tmp/lua_XXXXXX").
 376         */
 377 #ifdef __ANDROID__
 378         return g_settings->get("TMPFolder");
 379 #else
 380         return DIR_DELIM "tmp";
 381 #endif
 382 }
 383
 384 #endif
 385
 386 void GetRecursiveDirs(std::vector<std::string> &dirs, const std::string &dir)
 387 {
 388         static const std::set<char> chars_to_ignore = { '_', '.' };
 389         if (dir.empty() || !IsDir(dir))
 390                 return;
 391         dirs.push_back(dir);
 392         fs::GetRecursiveSubPaths(dir, dirs, false, chars_to_ignore);
 393 }
 394
 395 std::vector<std::string> GetRecursiveDirs(const std::string &dir)
 396 {
 397         std::vector<std::string> result;
 398         GetRecursiveDirs(result, dir);
 399         return result;
 400 }
 401
 402 void GetRecursiveSubPaths(const std::string &path,
 403                   std::vector<std::string> &dst,
 404                   bool list_files,
 405                   const std::set<char> &ignore)
 406 {
 407         std::vector<DirListNode> content = GetDirListing(path);
 408         for (const auto &n : content) {
 409                 std::string fullpath = path + DIR_DELIM + n.name;
 410                 if (ignore.count(n.name[0]))
 411                         continue;
 412                 if (list_files || n.dir)
 413                         dst.push_back(fullpath);
 414                 if (n.dir)
 415                         GetRecursiveSubPaths(fullpath, dst, list_files, ignore);
 416         }
 417 }
 418
 419 bool DeletePaths(const std::vector<std::string> &paths)
 420 {
 421         bool success = true;
 422         // Go backwards to succesfully delete the output of GetRecursiveSubPaths
 423         for(int i=paths.size()-1; i>=0; i--){
 424                 const std::string &path = paths[i];
 425                 bool did = DeleteSingleFileOrEmptyDirectory(path);
 426                 if(!did){
 427                         errorstream<<"Failed to delete "<<path<<std::endl;
 428                         success = false;
 429                 }
 430         }
 431         return success;
 432 }
 433
 434 bool RecursiveDeleteContent(const std::string &path)
 435 {
 436         infostream<<"Removing content of \""<<path<<"\""<<std::endl;
 437         std::vector<DirListNode> list = GetDirListing(path);
 438         for (const DirListNode &dln : list) {
 439                 if(trim(dln.name) == "." || trim(dln.name) == "..")
 440                         continue;
 441                 std::string childpath = path + DIR_DELIM + dln.name;
 442                 bool r = RecursiveDelete(childpath);
 443                 if(!r) {
 444                         errorstream << "Removing \"" << childpath << "\" failed" << std::endl;
 445                         return false;
 446                 }
 447         }
 448         return true;
 449 }
 450
 451 bool CreateAllDirs(const std::string &path)
 452 {
 453
 454         std::vector<std::string> tocreate;
 455         std::string basepath = path;
 456         while(!PathExists(basepath))
 457         {
 458                 tocreate.push_back(basepath);
 459                 basepath = RemoveLastPathComponent(basepath);
 460                 if(basepath.empty())
 461                         break;
 462         }
 463         for(int i=tocreate.size()-1;i>=0;i--)
 464                 if(!CreateDir(tocreate[i]))
 465                         return false;
 466         return true;
 467 }
 468
 469 bool CopyFileContents(const std::string &source, const std::string &target)
 470 {
 471         FILE *sourcefile = fopen(source.c_str(), "rb");
 472         if(sourcefile == NULL){
 473                 errorstream<<source<<": can't open for reading: "
 474                         <<strerror(errno)<<std::endl;
 475                 return false;
 476         }
 477
 478         FILE *targetfile = fopen(target.c_str(), "wb");
 479         if(targetfile == NULL){
 480                 errorstream<<target<<": can't open for writing: "
 481                         <<strerror(errno)<<std::endl;
 482                 fclose(sourcefile);
 483                 return false;
 484         }
 485
 486         size_t total = 0;
 487         bool retval = true;
 488         bool done = false;
 489         char readbuffer[BUFSIZ];
 490         while(!done){
 491                 size_t readbytes = fread(readbuffer, 1,
 492                                 sizeof(readbuffer), sourcefile);
 493                 total += readbytes;
 494                 if(ferror(sourcefile)){
 495                         errorstream<<source<<": IO error: "
 496                                 <<strerror(errno)<<std::endl;
 497                         retval = false;
 498                         done = true;
 499                 }
 500                 if(readbytes > 0){
 501                         fwrite(readbuffer, 1, readbytes, targetfile);
 502                 }
 503                 if(feof(sourcefile) || ferror(sourcefile)){
 504                         // flush destination file to catch write errors
 505                         // (e.g. disk full)
 506                         fflush(targetfile);
 507                         done = true;
 508                 }
 509                 if(ferror(targetfile)){
 510                         errorstream<<target<<": IO error: "
 511                                         <<strerror(errno)<<std::endl;
 512                         retval = false;
 513                         done = true;
 514                 }
 515         }
 516         infostream<<"copied "<<total<<" bytes from "
 517                 <<source<<" to "<<target<<std::endl;
 518         fclose(sourcefile);
 519         fclose(targetfile);
 520         return retval;
 521 }
 522
 523 bool CopyDir(const std::string &source, const std::string &target)
 524 {
 525         if(PathExists(source)){
 526                 if(!PathExists(target)){
 527                         fs::CreateAllDirs(target);
 528                 }
 529                 bool retval = true;
 530                 std::vector<DirListNode> content = fs::GetDirListing(source);
 531
 532                 for (const auto &dln : content) {
 533                         std::string sourcechild = source + DIR_DELIM + dln.name;
 534                         std::string targetchild = target + DIR_DELIM + dln.name;
 535                         if(dln.dir){
 536                                 if(!fs::CopyDir(sourcechild, targetchild)){
 537                                         retval = false;
 538                                 }
 539                         }
 540                         else {
 541                                 if(!fs::CopyFileContents(sourcechild, targetchild)){
 542                                         retval = false;
 543                                 }
 544                         }
 545                 }
 546                 return retval;
 547         }
 548
 549         return false;
 550 }
 551
 552 bool PathStartsWith(const std::string &path, const std::string &prefix)
 553 {
 554         size_t pathsize = path.size();
 555         size_t pathpos = 0;
 556         size_t prefixsize = prefix.size();
 557         size_t prefixpos = 0;
 558         for(;;){
 559                 bool delim1 = pathpos == pathsize
 560                         || IsDirDelimiter(path[pathpos]);
 561                 bool delim2 = prefixpos == prefixsize
 562                         || IsDirDelimiter(prefix[prefixpos]);
 563
 564                 if(delim1 != delim2)
 565                         return false;
 566
 567                 if(delim1){
 568                         while(pathpos < pathsize &&
 569                                         IsDirDelimiter(path[pathpos]))
 570                                 ++pathpos;
 571                         while(prefixpos < prefixsize &&
 572                                         IsDirDelimiter(prefix[prefixpos]))
 573                                 ++prefixpos;
 574                         if(prefixpos == prefixsize)
 575                                 return true;
 576                         if(pathpos == pathsize)
 577                                 return false;
 578                 }
 579                 else{
 580                         size_t len = 0;
 581                         do{
 582                                 char pathchar = path[pathpos+len];
 583                                 char prefixchar = prefix[prefixpos+len];
 584                                 if(FILESYS_CASE_INSENSITIVE){
 585                                         pathchar = tolower(pathchar);
 586                                         prefixchar = tolower(prefixchar);
 587                                 }
 588                                 if(pathchar != prefixchar)
 589                                         return false;
 590                                 ++len;
 591                         } while(pathpos+len < pathsize
 592                                         && !IsDirDelimiter(path[pathpos+len])
 593                                         && prefixpos+len < prefixsize
 594                                         && !IsDirDelimiter(
 595                                                 prefix[prefixpos+len]));
 596                         pathpos += len;
 597                         prefixpos += len;
 598                 }
 599         }
 600 }
 601
 602 std::string RemoveLastPathComponent(const std::string &path,
 603                 std::string *removed, int count)
 604 {
 605         if(removed)
 606                 *removed = "";
 607
 608         size_t remaining = path.size();
 609
 610         for(int i = 0; i < count; ++i){
 611                 // strip a dir delimiter
 612                 while(remaining != 0 && IsDirDelimiter(path[remaining-1]))
 613                         remaining--;
 614                 // strip a path component
 615                 size_t component_end = remaining;
 616                 while(remaining != 0 && !IsDirDelimiter(path[remaining-1]))
 617                         remaining--;
 618                 size_t component_start = remaining;
 619                 // strip a dir delimiter
 620                 while(remaining != 0 && IsDirDelimiter(path[remaining-1]))
 621                         remaining--;
 622                 if(removed){
 623                         std::string component = path.substr(component_start,
 624                                         component_end - component_start);
 625                         if(i)
 626                                 *removed = component + DIR_DELIM + *removed;
 627                         else
 628                                 *removed = component;
 629                 }
 630         }
 631         return path.substr(0, remaining);
 632 }
 633
 634 std::string RemoveRelativePathComponents(std::string path)
 635 {
 636         size_t pos = path.size();
 637         size_t dotdot_count = 0;
 638         while (pos != 0) {
 639                 size_t component_with_delim_end = pos;
 640                 // skip a dir delimiter
 641                 while (pos != 0 && IsDirDelimiter(path[pos-1]))
 642                         pos--;
 643                 // strip a path component
 644                 size_t component_end = pos;
 645                 while (pos != 0 && !IsDirDelimiter(path[pos-1]))
 646                         pos--;
 647                 size_t component_start = pos;
 648
 649                 std::string component = path.substr(component_start,
 650                                 component_end - component_start);
 651                 bool remove_this_component = false;
 652                 if (component == ".") {
 653                         remove_this_component = true;
 654                 } else if (component == "..") {
 655                         remove_this_component = true;
 656                         dotdot_count += 1;
 657                 } else if (dotdot_count != 0) {
 658                         remove_this_component = true;
 659                         dotdot_count -= 1;
 660                 }
 661
 662                 if (remove_this_component) {
 663                         while (pos != 0 && IsDirDelimiter(path[pos-1]))
 664                                 pos--;
 665                         if (component_start == 0) {
 666                                 // We need to remove the delemiter too
 667                                 path = path.substr(component_with_delim_end, std::string::npos);
 668                         } else {
 669                                 path = path.substr(0, pos) + DIR_DELIM +
 670                                         path.substr(component_with_delim_end, std::string::npos);
 671                         }
 672                         if (pos > 0)
 673                                 pos++;
 674                 }
 675         }
 676
 677         if (dotdot_count > 0)
 678                 return "";
 679
 680         // remove trailing dir delimiters
 681         pos = path.size();
 682         while (pos != 0 && IsDirDelimiter(path[pos-1]))
 683                 pos--;
 684         return path.substr(0, pos);
 685 }
 686
 687 std::string AbsolutePath(const std::string &path)
 688 {
 689 #ifdef _WIN32
 690         char *abs_path = _fullpath(NULL, path.c_str(), MAX_PATH);
 691 #else
 692         char *abs_path = realpath(path.c_str(), NULL);
 693 #endif
 694         if (!abs_path) return "";
 695         std::string abs_path_str(abs_path);
 696         free(abs_path);
 697         return abs_path_str;
 698 }
 699
 700 const char *GetFilenameFromPath(const char *path)
 701 {
 702         const char *filename = strrchr(path, DIR_DELIM_CHAR);
 703         return filename ? filename + 1 : path;
 704 }
 705
 706 bool safeWriteToFile(const std::string &path, const std::string &content)
 707 {
 708         std::string tmp_file = path + ".~mt";
 709
 710         // Write to a tmp file
 711         std::ofstream os(tmp_file.c_str(), std::ios::binary);
 712         if (!os.good())
 713                 return false;
 714         os << content;
 715         os.flush();
 716         os.close();
 717         if (os.fail()) {
 718                 // Remove the temporary file because writing it failed and it's useless.
 719                 remove(tmp_file.c_str());
 720                 return false;
 721         }
 722
 723         bool rename_success = false;
 724
 725         // Move the finished temporary file over the real file
 726 #ifdef _WIN32
 727         // When creating the file, it can cause Windows Search indexer, virus scanners and other apps
 728         // to query the file. This can make the move file call below fail.
 729         // We retry up to 5 times, with a 1ms sleep between, before we consider the whole operation failed
 730         int number_attempts = 0;
 731         while (number_attempts < 5) {
 732                 rename_success = MoveFileEx(tmp_file.c_str(), path.c_str(),
 733                                 MOVEFILE_REPLACE_EXISTING | MOVEFILE_WRITE_THROUGH);
 734                 if (rename_success)
 735                         break;
 736                 sleep_ms(1);
 737                 ++number_attempts;
 738         }
 739 #else
 740         // On POSIX compliant systems rename() is specified to be able to swap the
 741         // file in place of the destination file, making this a truly error-proof
 742         // transaction.
 743         rename_success = rename(tmp_file.c_str(), path.c_str()) == 0;
 744 #endif
 745         if (!rename_success) {
 746                 warningstream << "Failed to write to file: " << path.c_str() << std::endl;
 747                 // Remove the temporary file because moving it over the target file
 748                 // failed.
 749                 remove(tmp_file.c_str());
 750                 return false;
 751         }
 752
 753         return true;
 754 }
 755
 756 bool Rename(const std::string &from, const std::string &to)
 757 {
 758         return rename(from.c_str(), to.c_str()) == 0;
 759 }
 760
 761 } // namespace fs
 762