apt-pkg/contrib/fileutl.cc

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: fileutl.cc,v 1.5 1998/07/15 05:56:43 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(File From,File 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
 111 // File::File - Open a file                                             /*{{{*/
 112 // ---------------------------------------------------------------------
 113 /* The most commonly used open mode combinations are given with Mode */
 114 File::File(string FileName,OpenMode Mode, unsigned long Perms)
 115 {
 116    Flags = AutoClose;
 117    switch (Mode)
 118    {
 119       case ReadOnly:
 120       iFd = open(FileName.c_str(),O_RDONLY);
 121       break;
 122
 123       case WriteEmpty:
 124       unlink(FileName.c_str());
 125       iFd = open(FileName.c_str(),O_RDWR | O_CREAT | O_EXCL,Perms);
 126       break;
 127
 128       case WriteExists:
 129       iFd = open(FileName.c_str(),O_RDWR);
 130       break;
 131    }
 132
 133    if (iFd < 0)
 134       _error->Errno("open","Could not open file %s",FileName.c_str());
 135    else
 136       this->FileName = FileName;
 137 }
 138                                                                         /*}}}*/
 139 // File::~File - Closes the file                                        /*{{{*/
 140 // ---------------------------------------------------------------------
 141 /* If the proper modes are selected then we close the Fd and possibly
 142    unlink the file on error. */
 143 File::~File()
 144 {
 145    Close();
 146 }
 147                                                                         /*}}}*/
 148 // File::Read - Read a bit of the file                                  /*{{{*/
 149 // ---------------------------------------------------------------------
 150 /* */
 151 bool File::Read(void *To,unsigned long Size)
 152 {
 153    if (read(iFd,To,Size) != (signed)Size)
 154    {
 155       Flags |= Fail;
 156       return _error->Errno("read","Read error");
 157    }
 158
 159    return true;
 160 }
 161                                                                         /*}}}*/
 162 // File::Write - Write to the file                                      /*{{{*/
 163 // ---------------------------------------------------------------------
 164 /* */
 165 bool File::Write(void *From,unsigned long Size)
 166 {
 167    if (write(iFd,From,Size) != (signed)Size)
 168    {
 169       Flags |= Fail;
 170       return _error->Errno("write","Write error");
 171    }
 172
 173    return true;
 174 }
 175                                                                         /*}}}*/
 176 // File::Seek - Seek in the file                                        /*{{{*/
 177 // ---------------------------------------------------------------------
 178 /* */
 179 bool File::Seek(unsigned long To)
 180 {
 181    if (lseek(iFd,To,SEEK_SET) != (signed)To)
 182    {
 183       Flags |= Fail;
 184       return _error->Error("Unable to seek to %u",To);
 185    }
 186
 187    return true;
 188 }
 189                                                                         /*}}}*/
 190 // File::Size - Return the size of the file                             /*{{{*/
 191 // ---------------------------------------------------------------------
 192 /* */
 193 unsigned long File::Size()
 194 {
 195    struct stat Buf;
 196    if (fstat(iFd,&Buf) != 0)
 197       return _error->Errno("fstat","Unable to determine the file size");
 198    return Buf.st_size;
 199 }
 200                                                                         /*}}}*/
 201 // File::Close - Close the file if the close flag is set                /*{{{*/
 202 // ---------------------------------------------------------------------
 203 /* */
 204 bool File::Close()
 205 {
 206    bool Res = true;
 207    if ((Flags & AutoClose) == AutoClose)
 208       if (iFd >= 0 && close(iFd) != 0)
 209          Res &= _error->Errno("close","Problem closing the file");
 210    iFd = -1;
 211
 212    if ((Flags & Fail) == Fail && (Flags & DelOnFail) == DelOnFail &&
 213        FileName.empty() == false)
 214       if (unlink(FileName.c_str()) != 0)
 215          Res &= _error->Warning("unlnk","Problem unlinking the file");
 216    return Res;
 217 }
 218                                                                         /*}}}*/