apt-pkg/contrib/fileutl.cc

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: fileutl.cc,v 1.10 1998/10/20 04:33:16 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.
  13
  14    ##################################################################### */
  15                                                                         /*}}}*/
  16 // Include Files                                                        /*{{{*/
  17 #ifdef __GNUG__
  18 #pragma implementation "apt-pkg/fileutl.h"
  19 #endif
  20 #include <apt-pkg/fileutl.h>
  21 #include <apt-pkg/error.h>
  22
  23 #include <unistd.h>
  24 #include <sys/stat.h>
  25 #include <sys/fcntl.h>
  26 #include <sys/types.h>
  27                                                                         /*}}}*/
  28
  29 // CopyFile - Buffered copy of a file                                   /*{{{*/
  30 // ---------------------------------------------------------------------
  31 /* The caller is expected to set things so that failure causes erasure */
  32 bool CopyFile(FileFd From,FileFd To)
  33 {
  34    if (From.IsOpen() == false || To.IsOpen() == false)
  35       return false;
  36
  37    // Buffered copy between fds
  38    unsigned char *Buf = new unsigned char[64000];
  39    long Size;
  40    while ((Size = read(From.Fd(),Buf,64000)) > 0)
  41    {
  42       if (To.Write(Buf,Size) == false)
  43       {
  44          delete [] Buf;
  45          return false;
  46       }
  47    }
  48
  49    delete [] Buf;
  50    return true;
  51 }
  52                                                                         /*}}}*/
  53 // GetLock - Gets a lock file                                           /*{{{*/
  54 // ---------------------------------------------------------------------
  55 /* This will create an empty file of the given name and lock it. Once this
  56    is done all other calls to GetLock in any other process will fail with
  57    -1. The return result is the fd of the file, the call should call
  58    close at some time. */
  59 int GetLock(string File,bool Errors)
  60 {
  61    int FD = open(File.c_str(),O_RDWR | O_CREAT | O_TRUNC,0640);
  62    if (FD < 0)
  63    {
  64       if (Errors == true)
  65          _error->Errno("open","Could not open lock file %s",File.c_str());
  66       return -1;
  67    }
  68
  69    // Aquire a write lock
  70    struct flock fl;
  71    fl.l_type= F_WRLCK;
  72    fl.l_whence= SEEK_SET;
  73    fl.l_start= 0;
  74    fl.l_len= 1;
  75    if (fcntl(FD,F_SETLK,&fl) == -1)
  76    {
  77       if (Errors == true)
  78          _error->Errno("open","Could not get lock %s",File.c_str());
  79       close(FD);
  80       return -1;
  81    }
  82
  83    return FD;
  84 }
  85                                                                         /*}}}*/
  86 // FileExists - Check if a file exists                                  /*{{{*/
  87 // ---------------------------------------------------------------------
  88 /* */
  89 bool FileExists(string File)
  90 {
  91    struct stat Buf;
  92    if (stat(File.c_str(),&Buf) != 0)
  93       return false;
  94    return true;
  95 }
  96                                                                         /*}}}*/
  97 // SafeGetCWD - This is a safer getcwd that returns a dynamic string    /*{{{*/
  98 // ---------------------------------------------------------------------
  99 /* We return / on failure. */
 100 string SafeGetCWD()
 101 {
 102    // Stash the current dir.
 103    char S[300];
 104    S[0] = 0;
 105    if (getcwd(S,sizeof(S)) == 0)
 106       return "/";
 107    return S;
 108 }
 109                                                                         /*}}}*/
 110 // flNotDir - Strip the directory from the filename                     /*{{{*/
 111 // ---------------------------------------------------------------------
 112 /* */
 113 string flNotDir(string File)
 114 {
 115    string::size_type Res = File.rfind('/');
 116    if (Res == string::npos)
 117       return File;
 118    Res++;
 119    return string(File,Res,Res - File.length());
 120 }
 121                                                                         /*}}}*/
 122 // SetCloseExec - Set the close on exec flag                            /*{{{*/
 123 // ---------------------------------------------------------------------
 124 /* */
 125 void SetCloseExec(int Fd,bool Close)
 126 {
 127    if (fcntl(Fd,F_SETFD,(Close == false)?0:FD_CLOEXEC) != 0)
 128    {
 129       cerr << "FATAL -> Could not set close on exec " << strerror(errno) << endl;
 130       exit(100);
 131    }
 132 }
 133                                                                         /*}}}*/
 134 // SetNonBlock - Set the nonblocking flag                               /*{{{*/
 135 // ---------------------------------------------------------------------
 136 /* */
 137 void SetNonBlock(int Fd,bool Block)
 138 {
 139    int Flags = fcntl(Fd,F_GETFL);
 140    if (fcntl(Fd,F_SETFL,(Flags  & ~O_NONBLOCK) | (Block == false)?0:O_NONBLOCK) != 0)
 141    {
 142       cerr << "FATAL -> Could not set non-blocking flag " << strerror(errno) << endl;
 143       exit(100);
 144    }
 145 }
 146                                                                         /*}}}*/
 147 // WaitFd - Wait for a FD to become readable                            /*{{{*/
 148 // ---------------------------------------------------------------------
 149 /* This waits for a FD to become readable using select. It is usefull for
 150    applications making use of non-blocking sockets. */
 151 bool WaitFd(int Fd)
 152 {
 153    fd_set Set;
 154    FD_ZERO(&Set);
 155    FD_SET(Fd,&Set);
 156    if (select(Fd+1,&Set,0,0,0) <= 0)
 157       return false;
 158    return true;
 159 }
 160                                                                         /*}}}*/
 161
 162 // FileFd::FileFd - Open a file                                         /*{{{*/
 163 // ---------------------------------------------------------------------
 164 /* The most commonly used open mode combinations are given with Mode */
 165 FileFd::FileFd(string FileName,OpenMode Mode, unsigned long Perms)
 166 {
 167    Flags = AutoClose;
 168    switch (Mode)
 169    {
 170       case ReadOnly:
 171       iFd = open(FileName.c_str(),O_RDONLY);
 172       break;
 173
 174       case WriteEmpty:
 175       unlink(FileName.c_str());
 176       iFd = open(FileName.c_str(),O_RDWR | O_CREAT | O_EXCL,Perms);
 177       break;
 178
 179       case WriteExists:
 180       iFd = open(FileName.c_str(),O_RDWR);
 181       break;
 182
 183       case WriteAny:
 184       iFd = open(FileName.c_str(),O_RDWR | O_CREAT,Perms);
 185       break;
 186
 187       // Dont use this in public directories
 188       case LockEmpty:
 189       iFd = open(FileName.c_str(),O_RDWR | O_CREAT | O_TRUNC,Perms);
 190       break;
 191    }
 192
 193    if (iFd < 0)
 194       _error->Errno("open","Could not open file %s",FileName.c_str());
 195    else
 196       this->FileName = FileName;
 197    SetCloseExec(iFd,true);
 198 }
 199                                                                         /*}}}*/
 200 // FileFd::~File - Closes the file                                      /*{{{*/
 201 // ---------------------------------------------------------------------
 202 /* If the proper modes are selected then we close the Fd and possibly
 203    unlink the file on error. */
 204 FileFd::~FileFd()
 205 {
 206    Close();
 207 }
 208                                                                         /*}}}*/
 209 // FileFd::Read - Read a bit of the file                                /*{{{*/
 210 // ---------------------------------------------------------------------
 211 /* */
 212 bool FileFd::Read(void *To,unsigned long Size)
 213 {
 214    if (read(iFd,To,Size) != (signed)Size)
 215    {
 216       Flags |= Fail;
 217       return _error->Errno("read","Read error");
 218    }
 219
 220    return true;
 221 }
 222                                                                         /*}}}*/
 223 // FileFd::Write - Write to the file                                    /*{{{*/
 224 // ---------------------------------------------------------------------
 225 /* */
 226 bool FileFd::Write(void *From,unsigned long Size)
 227 {
 228    if (write(iFd,From,Size) != (signed)Size)
 229    {
 230       Flags |= Fail;
 231       return _error->Errno("write","Write error");
 232    }
 233
 234    return true;
 235 }
 236                                                                         /*}}}*/
 237 // FileFd::Seek - Seek in the file                                      /*{{{*/
 238 // ---------------------------------------------------------------------
 239 /* */
 240 bool FileFd::Seek(unsigned long To)
 241 {
 242    if (lseek(iFd,To,SEEK_SET) != (signed)To)
 243    {
 244       Flags |= Fail;
 245       return _error->Error("Unable to seek to %u",To);
 246    }
 247
 248    return true;
 249 }
 250                                                                         /*}}}*/
 251 // FileFd::Size - Return the size of the file                           /*{{{*/
 252 // ---------------------------------------------------------------------
 253 /* */
 254 unsigned long FileFd::Size()
 255 {
 256    struct stat Buf;
 257    if (fstat(iFd,&Buf) != 0)
 258       return _error->Errno("fstat","Unable to determine the file size");
 259    return Buf.st_size;
 260 }
 261                                                                         /*}}}*/
 262 // FileFd::Close - Close the file if the close flag is set              /*{{{*/
 263 // ---------------------------------------------------------------------
 264 /* */
 265 bool FileFd::Close()
 266 {
 267    bool Res = true;
 268    if ((Flags & AutoClose) == AutoClose)
 269       if (iFd >= 0 && close(iFd) != 0)
 270          Res &= _error->Errno("close","Problem closing the file");
 271    iFd = -1;
 272
 273    if ((Flags & Fail) == Fail && (Flags & DelOnFail) == DelOnFail &&
 274        FileName.empty() == false)
 275       if (unlink(FileName.c_str()) != 0)
 276          Res &= _error->Warning("unlnk","Problem unlinking the file");
 277    return Res;
 278 }
 279                                                                         /*}}}*/