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