apt-pkg/contrib/fileutl.cc

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: fileutl.cc,v 1.42 2002/09/14 05:29:22 jgg Exp $
   4 /* ######################################################################
   5
   6    File Utilities
   7
   8    CopyFile - Buffered copy of a single file
   9    GetLock - dpkg compatible lock file manipulation (fcntl)
  10
  11    This source is placed in the Public Domain, do with it what you will
  12    It was originally written by Jason Gunthorpe <jgg@debian.org>.
  13
  14    ##################################################################### */
  15                                                                         /*}}}*/
  16 // Include Files                                                        /*{{{*/
  17 #include <apt-pkg/fileutl.h>
  18 #include <apt-pkg/error.h>
  19 #include <apt-pkg/sptr.h>
  20 #include <apt-pkg/configuration.h>
  21
  22 #include <apti18n.h>
  23
  24 #include <cstdlib>
  25 #include <cstring>
  26
  27 #include <iostream>
  28 #include <unistd.h>
  29 #include <fcntl.h>
  30 #include <sys/stat.h>
  31 #include <sys/types.h>
  32 #include <sys/time.h>
  33 #include <sys/wait.h>
  34 #include <signal.h>
  35 #include <errno.h>
  36 #include <set>
  37                                                                         /*}}}*/
  38
  39 using namespace std;
  40
  41 // CopyFile - Buffered copy of a file                                   /*{{{*/
  42 // ---------------------------------------------------------------------
  43 /* The caller is expected to set things so that failure causes erasure */
  44 bool CopyFile(FileFd &From,FileFd &To)
  45 {
  46    if (From.IsOpen() == false || To.IsOpen() == false)
  47       return false;
  48
  49    // Buffered copy between fds
  50    SPtrArray<unsigned char> Buf = new unsigned char[64000];
  51    unsigned long Size = From.Size();
  52    while (Size != 0)
  53    {
  54       unsigned long ToRead = Size;
  55       if (Size > 64000)
  56          ToRead = 64000;
  57
  58       if (From.Read(Buf,ToRead) == false ||
  59           To.Write(Buf,ToRead) == false)
  60          return false;
  61
  62       Size -= ToRead;
  63    }
  64
  65    return true;
  66 }
  67                                                                         /*}}}*/
  68 // GetLock - Gets a lock file                                           /*{{{*/
  69 // ---------------------------------------------------------------------
  70 /* This will create an empty file of the given name and lock it. Once this
  71    is done all other calls to GetLock in any other process will fail with
  72    -1. The return result is the fd of the file, the call should call
  73    close at some time. */
  74 int GetLock(string File,bool Errors)
  75 {
  76    int FD = open(File.c_str(),O_RDWR | O_CREAT | O_TRUNC,0640);
  77    if (FD < 0)
  78    {
  79       // Read only .. cant have locking problems there.
  80       if (errno == EROFS)
  81       {
  82          _error->Warning(_("Not using locking for read only lock file %s"),File.c_str());
  83          return dup(0);       // Need something for the caller to close
  84       }
  85
  86       if (Errors == true)
  87          _error->Errno("open",_("Could not open lock file %s"),File.c_str());
  88
  89       // Feh.. We do this to distinguish the lock vs open case..
  90       errno = EPERM;
  91       return -1;
  92    }
  93    SetCloseExec(FD,true);
  94
  95    // Aquire a write lock
  96    struct flock fl;
  97    fl.l_type = F_WRLCK;
  98    fl.l_whence = SEEK_SET;
  99    fl.l_start = 0;
 100    fl.l_len = 0;
 101    if (fcntl(FD,F_SETLK,&fl) == -1)
 102    {
 103       if (errno == ENOLCK)
 104       {
 105          _error->Warning(_("Not using locking for nfs mounted lock file %s"),File.c_str());
 106          return dup(0);       // Need something for the caller to close
 107       }
 108       if (Errors == true)
 109          _error->Errno("open",_("Could not get lock %s"),File.c_str());
 110
 111       int Tmp = errno;
 112       close(FD);
 113       errno = Tmp;
 114       return -1;
 115    }
 116
 117    return FD;
 118 }
 119                                                                         /*}}}*/
 120 // FileExists - Check if a file exists                                  /*{{{*/
 121 // ---------------------------------------------------------------------
 122 /* */
 123 bool FileExists(string File)
 124 {
 125    struct stat Buf;
 126    if (stat(File.c_str(),&Buf) != 0)
 127       return false;
 128    return true;
 129 }
 130                                                                         /*}}}*/
 131 // SafeGetCWD - This is a safer getcwd that returns a dynamic string    /*{{{*/
 132 // ---------------------------------------------------------------------
 133 /* We return / on failure. */
 134 string SafeGetCWD()
 135 {
 136    // Stash the current dir.
 137    char S[300];
 138    S[0] = 0;
 139    if (getcwd(S,sizeof(S)-2) == 0)
 140       return "/";
 141    unsigned int Len = strlen(S);
 142    S[Len] = '/';
 143    S[Len+1] = 0;
 144    return S;
 145 }
 146                                                                         /*}}}*/
 147 // flNotDir - Strip the directory from the filename                     /*{{{*/
 148 // ---------------------------------------------------------------------
 149 /* */
 150 string flNotDir(string File)
 151 {
 152    string::size_type Res = File.rfind('/');
 153    if (Res == string::npos)
 154       return File;
 155    Res++;
 156    return string(File,Res,Res - File.length());
 157 }
 158                                                                         /*}}}*/
 159 // flNotFile - Strip the file from the directory name                   /*{{{*/
 160 // ---------------------------------------------------------------------
 161 /* Result ends in a / */
 162 string flNotFile(string File)
 163 {
 164    string::size_type Res = File.rfind('/');
 165    if (Res == string::npos)
 166       return "./";
 167    Res++;
 168    return string(File,0,Res);
 169 }
 170                                                                         /*}}}*/
 171 // flExtension - Return the extension for the file                      /*{{{*/
 172 // ---------------------------------------------------------------------
 173 /* */
 174 string flExtension(string File)
 175 {
 176    string::size_type Res = File.rfind('.');
 177    if (Res == string::npos)
 178       return File;
 179    Res++;
 180    return string(File,Res,Res - File.length());
 181 }
 182                                                                         /*}}}*/
 183 // flNoLink - If file is a symlink then deref it                        /*{{{*/
 184 // ---------------------------------------------------------------------
 185 /* If the name is not a link then the returned path is the input. */
 186 string flNoLink(string File)
 187 {
 188    struct stat St;
 189    if (lstat(File.c_str(),&St) != 0 || S_ISLNK(St.st_mode) == 0)
 190       return File;
 191    if (stat(File.c_str(),&St) != 0)
 192       return File;
 193
 194    /* Loop resolving the link. There is no need to limit the number of
 195       loops because the stat call above ensures that the symlink is not
 196       circular */
 197    char Buffer[1024];
 198    string NFile = File;
 199    while (1)
 200    {
 201       // Read the link
 202       int Res;
 203       if ((Res = readlink(NFile.c_str(),Buffer,sizeof(Buffer))) <= 0 ||
 204           (unsigned)Res >= sizeof(Buffer))
 205           return File;
 206
 207       // Append or replace the previous path
 208       Buffer[Res] = 0;
 209       if (Buffer[0] == '/')
 210          NFile = Buffer;
 211       else
 212          NFile = flNotFile(NFile) + Buffer;
 213
 214       // See if we are done
 215       if (lstat(NFile.c_str(),&St) != 0)
 216          return File;
 217       if (S_ISLNK(St.st_mode) == 0)
 218          return NFile;
 219    }
 220 }
 221                                                                         /*}}}*/
 222 // flCombine - Combine a file and a directory                           /*{{{*/
 223 // ---------------------------------------------------------------------
 224 /* If the file is an absolute path then it is just returned, otherwise
 225    the directory is pre-pended to it. */
 226 string flCombine(string Dir,string File)
 227 {
 228    if (File.empty() == true)
 229       return string();
 230
 231    if (File[0] == '/' || Dir.empty() == true)
 232       return File;
 233    if (File.length() >= 2 && File[0] == '.' && File[1] == '/')
 234       return File;
 235    if (Dir[Dir.length()-1] == '/')
 236       return Dir + File;
 237    return Dir + '/' + File;
 238 }
 239                                                                         /*}}}*/
 240 // SetCloseExec - Set the close on exec flag                            /*{{{*/
 241 // ---------------------------------------------------------------------
 242 /* */
 243 void SetCloseExec(int Fd,bool Close)
 244 {
 245    if (fcntl(Fd,F_SETFD,(Close == false)?0:FD_CLOEXEC) != 0)
 246    {
 247       cerr << "FATAL -> Could not set close on exec " << strerror(errno) << endl;
 248       exit(100);
 249    }
 250 }
 251                                                                         /*}}}*/
 252 // SetNonBlock - Set the nonblocking flag                               /*{{{*/
 253 // ---------------------------------------------------------------------
 254 /* */
 255 void SetNonBlock(int Fd,bool Block)
 256 {
 257    int Flags = fcntl(Fd,F_GETFL) & (~O_NONBLOCK);
 258    if (fcntl(Fd,F_SETFL,Flags | ((Block == false)?0:O_NONBLOCK)) != 0)
 259    {
 260       cerr << "FATAL -> Could not set non-blocking flag " << strerror(errno) << endl;
 261       exit(100);
 262    }
 263 }
 264                                                                         /*}}}*/
 265 // WaitFd - Wait for a FD to become readable                            /*{{{*/
 266 // ---------------------------------------------------------------------
 267 /* This waits for a FD to become readable using select. It is useful for
 268    applications making use of non-blocking sockets. The timeout is
 269    in seconds. */
 270 bool WaitFd(int Fd,bool write,unsigned long timeout)
 271 {
 272    fd_set Set;
 273    struct timeval tv;
 274    FD_ZERO(&Set);
 275    FD_SET(Fd,&Set);
 276    tv.tv_sec = timeout;
 277    tv.tv_usec = 0;
 278    if (write == true)
 279    {
 280       int Res;
 281       do
 282       {
 283          Res = select(Fd+1,0,&Set,0,(timeout != 0?&tv:0));
 284       }
 285       while (Res < 0 && errno == EINTR);
 286
 287       if (Res <= 0)
 288          return false;
 289    }
 290    else
 291    {
 292       int Res;
 293       do
 294       {
 295          Res = select(Fd+1,&Set,0,0,(timeout != 0?&tv:0));
 296       }
 297       while (Res < 0 && errno == EINTR);
 298
 299       if (Res <= 0)
 300          return false;
 301    }
 302
 303    return true;
 304 }
 305                                                                         /*}}}*/
 306 // ExecFork - Magical fork that sanitizes the context before execing    /*{{{*/
 307 // ---------------------------------------------------------------------
 308 /* This is used if you want to cleanse the environment for the forked
 309    child, it fixes up the important signals and nukes all of the fds,
 310    otherwise acts like normal fork. */
 311 pid_t ExecFork()
 312 {
 313    // Fork off the process
 314    pid_t Process = fork();
 315    if (Process < 0)
 316    {
 317       cerr << "FATAL -> Failed to fork." << endl;
 318       exit(100);
 319    }
 320
 321    // Spawn the subprocess
 322    if (Process == 0)
 323    {
 324       // Setup the signals
 325       signal(SIGPIPE,SIG_DFL);
 326       signal(SIGQUIT,SIG_DFL);
 327       signal(SIGINT,SIG_DFL);
 328       signal(SIGWINCH,SIG_DFL);
 329       signal(SIGCONT,SIG_DFL);
 330       signal(SIGTSTP,SIG_DFL);
 331
 332       set<int> KeepFDs;
 333       Configuration::Item const *Opts = _config->Tree("APT::Keep-Fds");
 334       if (Opts != 0 && Opts->Child != 0)
 335       {
 336          Opts = Opts->Child;
 337          for (; Opts != 0; Opts = Opts->Next)
 338          {
 339             if (Opts->Value.empty() == true)
 340                continue;
 341             int fd = atoi(Opts->Value.c_str());
 342             KeepFDs.insert(fd);
 343          }
 344       }
 345
 346       // Close all of our FDs - just in case
 347       for (int K = 3; K != 40; K++)
 348       {
 349          if(KeepFDs.find(K) == KeepFDs.end())
 350             fcntl(K,F_SETFD,FD_CLOEXEC);
 351       }
 352    }
 353
 354    return Process;
 355 }
 356                                                                         /*}}}*/
 357 // ExecWait - Fancy waitpid                                             /*{{{*/
 358 // ---------------------------------------------------------------------
 359 /* Waits for the given sub process. If Reap is set then no errors are
 360    generated. Otherwise a failed subprocess will generate a proper descriptive
 361    message */
 362 bool ExecWait(pid_t Pid,const char *Name,bool Reap)
 363 {
 364    if (Pid <= 1)
 365       return true;
 366
 367    // Wait and collect the error code
 368    int Status;
 369    while (waitpid(Pid,&Status,0) != Pid)
 370    {
 371       if (errno == EINTR)
 372          continue;
 373
 374       if (Reap == true)
 375          return false;
 376
 377       return _error->Error(_("Waited for %s but it wasn't there"),Name);
 378    }
 379
 380
 381    // Check for an error code.
 382    if (WIFEXITED(Status) == 0 || WEXITSTATUS(Status) != 0)
 383    {
 384       if (Reap == true)
 385          return false;
 386       if (WIFSIGNALED(Status) != 0 && WTERMSIG(Status) == SIGSEGV)
 387          return _error->Error(_("Sub-process %s received a segmentation fault."),Name);
 388
 389       if (WIFEXITED(Status) != 0)
 390          return _error->Error(_("Sub-process %s returned an error code (%u)"),Name,WEXITSTATUS(Status));
 391
 392       return _error->Error(_("Sub-process %s exited unexpectedly"),Name);
 393    }
 394
 395    return true;
 396 }
 397                                                                         /*}}}*/
 398
 399 // FileFd::Open - Open a file                                           /*{{{*/
 400 // ---------------------------------------------------------------------
 401 /* The most commonly used open mode combinations are given with Mode */
 402 bool FileFd::Open(string FileName,OpenMode Mode, unsigned long Perms)
 403 {
 404    Close();
 405    Flags = AutoClose;
 406    switch (Mode)
 407    {
 408       case ReadOnly:
 409       iFd = open(FileName.c_str(),O_RDONLY);
 410       break;
 411
 412       case WriteEmpty:
 413       {
 414          struct stat Buf;
 415          if (lstat(FileName.c_str(),&Buf) == 0 && S_ISLNK(Buf.st_mode))
 416             unlink(FileName.c_str());
 417          iFd = open(FileName.c_str(),O_RDWR | O_CREAT | O_TRUNC,Perms);
 418          break;
 419       }
 420
 421       case WriteExists:
 422       iFd = open(FileName.c_str(),O_RDWR);
 423       break;
 424
 425       case WriteAny:
 426       iFd = open(FileName.c_str(),O_RDWR | O_CREAT,Perms);
 427       break;
 428
 429       case WriteTemp:
 430       unlink(FileName.c_str());
 431       iFd = open(FileName.c_str(),O_RDWR | O_CREAT | O_EXCL,Perms);
 432       break;
 433    }
 434
 435    if (iFd < 0)
 436       return _error->Errno("open",_("Could not open file %s"),FileName.c_str());
 437
 438    this->FileName = FileName;
 439    SetCloseExec(iFd,true);
 440    return true;
 441 }
 442                                                                         /*}}}*/
 443 // FileFd::~File - Closes the file                                      /*{{{*/
 444 // ---------------------------------------------------------------------
 445 /* If the proper modes are selected then we close the Fd and possibly
 446    unlink the file on error. */
 447 FileFd::~FileFd()
 448 {
 449    Close();
 450 }
 451                                                                         /*}}}*/
 452 // FileFd::Read - Read a bit of the file                                /*{{{*/
 453 // ---------------------------------------------------------------------
 454 /* We are carefull to handle interruption by a signal while reading
 455    gracefully. */
 456 bool FileFd::Read(void *To,unsigned long Size,unsigned long *Actual)
 457 {
 458    int Res;
 459    errno = 0;
 460    if (Actual != 0)
 461       *Actual = 0;
 462
 463    do
 464    {
 465       Res = read(iFd,To,Size);
 466       if (Res < 0 && errno == EINTR)
 467          continue;
 468       if (Res < 0)
 469       {
 470          Flags |= Fail;
 471          return _error->Errno("read",_("Read error"));
 472       }
 473
 474       To = (char *)To + Res;
 475       Size -= Res;
 476       if (Actual != 0)
 477          *Actual += Res;
 478    }
 479    while (Res > 0 && Size > 0);
 480
 481    if (Size == 0)
 482       return true;
 483
 484    // Eof handling
 485    if (Actual != 0)
 486    {
 487       Flags |= HitEof;
 488       return true;
 489    }
 490
 491    Flags |= Fail;
 492    return _error->Error(_("read, still have %lu to read but none left"),Size);
 493 }
 494                                                                         /*}}}*/
 495 // FileFd::Write - Write to the file                                    /*{{{*/
 496 // ---------------------------------------------------------------------
 497 /* */
 498 bool FileFd::Write(const void *From,unsigned long Size)
 499 {
 500    int Res;
 501    errno = 0;
 502    do
 503    {
 504       Res = write(iFd,From,Size);
 505       if (Res < 0 && errno == EINTR)
 506          continue;
 507       if (Res < 0)
 508       {
 509          Flags |= Fail;
 510          return _error->Errno("write",_("Write error"));
 511       }
 512
 513       From = (char *)From + Res;
 514       Size -= Res;
 515    }
 516    while (Res > 0 && Size > 0);
 517
 518    if (Size == 0)
 519       return true;
 520
 521    Flags |= Fail;
 522    return _error->Error(_("write, still have %lu to write but couldn't"),Size);
 523 }
 524                                                                         /*}}}*/
 525 // FileFd::Seek - Seek in the file                                      /*{{{*/
 526 // ---------------------------------------------------------------------
 527 /* */
 528 bool FileFd::Seek(unsigned long To)
 529 {
 530    if (lseek(iFd,To,SEEK_SET) != (signed)To)
 531    {
 532       Flags |= Fail;
 533       return _error->Error("Unable to seek to %lu",To);
 534    }
 535
 536    return true;
 537 }
 538                                                                         /*}}}*/
 539 // FileFd::Skip - Seek in the file                                      /*{{{*/
 540 // ---------------------------------------------------------------------
 541 /* */
 542 bool FileFd::Skip(unsigned long Over)
 543 {
 544    if (lseek(iFd,Over,SEEK_CUR) < 0)
 545    {
 546       Flags |= Fail;
 547       return _error->Error("Unable to seek ahead %lu",Over);
 548    }
 549
 550    return true;
 551 }
 552                                                                         /*}}}*/
 553 // FileFd::Truncate - Truncate the file                                 /*{{{*/
 554 // ---------------------------------------------------------------------
 555 /* */
 556 bool FileFd::Truncate(unsigned long To)
 557 {
 558    if (ftruncate(iFd,To) != 0)
 559    {
 560       Flags |= Fail;
 561       return _error->Error("Unable to truncate to %lu",To);
 562    }
 563
 564    return true;
 565 }
 566                                                                         /*}}}*/
 567 // FileFd::Tell - Current seek position                                 /*{{{*/
 568 // ---------------------------------------------------------------------
 569 /* */
 570 unsigned long FileFd::Tell()
 571 {
 572    off_t Res = lseek(iFd,0,SEEK_CUR);
 573    if (Res == (off_t)-1)
 574       _error->Errno("lseek","Failed to determine the current file position");
 575    return Res;
 576 }
 577                                                                         /*}}}*/
 578 // FileFd::Size - Return the size of the file                           /*{{{*/
 579 // ---------------------------------------------------------------------
 580 /* */
 581 unsigned long FileFd::Size()
 582 {
 583    struct stat Buf;
 584    if (fstat(iFd,&Buf) != 0)
 585       return _error->Errno("fstat","Unable to determine the file size");
 586    return Buf.st_size;
 587 }
 588                                                                         /*}}}*/
 589 // FileFd::Close - Close the file if the close flag is set              /*{{{*/
 590 // ---------------------------------------------------------------------
 591 /* */
 592 bool FileFd::Close()
 593 {
 594    bool Res = true;
 595    if ((Flags & AutoClose) == AutoClose)
 596       if (iFd >= 0 && close(iFd) != 0)
 597          Res &= _error->Errno("close",_("Problem closing the file"));
 598    iFd = -1;
 599
 600    if ((Flags & Fail) == Fail && (Flags & DelOnFail) == DelOnFail &&
 601        FileName.empty() == false)
 602       if (unlink(FileName.c_str()) != 0)
 603          Res &= _error->WarningE("unlnk",_("Problem unlinking the file"));
 604    return Res;
 605 }
 606                                                                         /*}}}*/
 607 // FileFd::Sync - Sync the file                                         /*{{{*/
 608 // ---------------------------------------------------------------------
 609 /* */
 610 bool FileFd::Sync()
 611 {
 612 #ifdef _POSIX_SYNCHRONIZED_IO
 613    if (fsync(iFd) != 0)
 614       return _error->Errno("sync",_("Problem syncing the file"));
 615 #endif
 616    return true;
 617 }
 618                                                                         /*}}}*/