apt-pkg/contrib/fileutl.cc

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: fileutl.cc,v 1.1 1998/07/02 02:58:13 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 #include <fileutl.h>
  18 #include <pkglib/error.h>
  19
  20 #include <unistd.h>
  21 #include <sys/stat.h>
  22 #include <sys/fcntl.h>
  23 #include <sys/types.h>
  24                                                                         /*}}}*/
  25
  26 // CopyFile - Buffered copy of a file                                   /*{{{*/
  27 // ---------------------------------------------------------------------
  28 /* The caller is expected to set things so that failure causes erasure */
  29 bool CopyFile(File From,File To)
  30 {
  31    if (From.IsOpen() == false || To.IsOpen() == false)
  32       return false;
  33
  34    // Buffered copy between fds
  35    unsigned char *Buf = new unsigned char[64000];
  36    long Size;
  37    while ((Size = read(From.Fd(),Buf,64000)) > 0)
  38    {
  39       if (To.Write(Buf,Size) == false)
  40       {
  41          delete [] Buf;
  42          return false;
  43       }
  44    }
  45
  46    delete [] Buf;
  47    return true;
  48 }
  49                                                                         /*}}}*/
  50 // GetLock - Gets a lock file                                           /*{{{*/
  51 // ---------------------------------------------------------------------
  52 /* This will create an empty file of the given name and lock it. Once this
  53    is done all other calls to GetLock in any other process will fail with
  54    -1. The return result is the fd of the file, the call should call
  55    close at some time. */
  56 int GetLock(string File,bool Errors)
  57 {
  58    int FD = open(File.c_str(),O_RDWR | O_CREAT | O_TRUNC,0640);
  59    if (FD < 0)
  60    {
  61       if (Errors == true)
  62          _error->Errno("open","Could not open lock file %s",File.c_str());
  63       return -1;
  64    }
  65
  66    // Aquire a write lock
  67    struct flock fl;
  68    fl.l_type= F_WRLCK;
  69    fl.l_whence= SEEK_SET;
  70    fl.l_start= 0;
  71    fl.l_len= 1;
  72    if (fcntl(FD,F_SETLK,&fl) == -1)
  73    {
  74       if (Errors == true)
  75          _error->Errno("open","Could not get lock %s",File.c_str());
  76       close(FD);
  77       return -1;
  78    }
  79
  80    return FD;
  81 }
  82                                                                         /*}}}*/
  83 // FileExists - Check if a file exists                                  /*{{{*/
  84 // ---------------------------------------------------------------------
  85 /* */
  86 bool FileExists(string File)
  87 {
  88    struct stat Buf;
  89    if (stat(File.c_str(),&Buf) != 0)
  90       return false;
  91    return true;
  92 }
  93                                                                         /*}}}*/
  94 // SafeGetCWD - This is a safer getcwd that returns a dynamic string    /*{{{*/
  95 // ---------------------------------------------------------------------
  96 /* We return / on failure. */
  97 string SafeGetCWD()
  98 {
  99    // Stash the current dir.
 100    char S[300];
 101    S[0] = 0;
 102    if (getcwd(S,sizeof(S)) == 0)
 103       return "/";
 104    return S;
 105 }
 106                                                                         /*}}}*/
 107
 108 // File::File - Open a file                                             /*{{{*/
 109 // ---------------------------------------------------------------------
 110 /* The most commonly used open mode combinations are given with Mode */
 111 File::File(string FileName,OpenMode Mode, unsigned long Perms)
 112 {
 113    Flags = 0;
 114    switch (Mode)
 115    {
 116       case ReadOnly:
 117       iFd = open(FileName.c_str(),O_RDONLY);
 118       break;
 119
 120       case WriteEmpty:
 121       unlink(FileName.c_str());
 122       iFd = open(FileName.c_str(),O_RDWR | O_CREAT | O_EXCL,Perms);
 123       break;
 124
 125       case WriteExists:
 126       iFd = open(FileName.c_str(),O_RDWR);
 127       break;
 128    }
 129
 130    if (iFd < 0)
 131       _error->Errno("open","Could not open file %s",FileName.c_str());
 132    else
 133       this->FileName = FileName;
 134 }
 135                                                                         /*}}}*/
 136 // File::~File - Closes the file                                        /*{{{*/
 137 // ---------------------------------------------------------------------
 138 /* If the proper modes are selected then we close the Fd and possibly
 139    unlink the file on error. */
 140 File::~File()
 141 {
 142    Close();
 143 }
 144                                                                         /*}}}*/
 145 // File::Read - Read a bit of the file                                  /*{{{*/
 146 // ---------------------------------------------------------------------
 147 /* */
 148 bool File::Read(void *To,unsigned long Size)
 149 {
 150    if (read(iFd,To,Size) != (signed)Size)
 151    {
 152       Flags |= Fail;
 153       return _error->Errno("read","Read error");
 154    }
 155
 156    return true;
 157 }
 158                                                                         /*}}}*/
 159 // File::Write - Write to the file                                      /*{{{*/
 160 // ---------------------------------------------------------------------
 161 /* */
 162 bool File::Write(void *From,unsigned long Size)
 163 {
 164    if (write(iFd,From,Size) != (signed)Size)
 165    {
 166       Flags |= Fail;
 167       return _error->Errno("write","Write error");
 168    }
 169
 170    return true;
 171 }
 172                                                                         /*}}}*/
 173 // File::Seek - Seek in the file                                        /*{{{*/
 174 // ---------------------------------------------------------------------
 175 /* */
 176 bool File::Seek(unsigned long To)
 177 {
 178    if (lseek(iFd,To,SEEK_SET) != (signed)To)
 179    {
 180       Flags |= Fail;
 181       return _error->Error("Unable to seek to %u",To);
 182    }
 183
 184    return true;
 185 }
 186                                                                         /*}}}*/
 187 // File::Size - Return the size of the file                             /*{{{*/
 188 // ---------------------------------------------------------------------
 189 /* */
 190 unsigned long File::Size()
 191 {
 192    struct stat Buf;
 193    if (fstat(iFd,&Buf) != 0)
 194       return _error->Errno("fstat","Unable to determine the file size");
 195    return Buf.st_size;
 196 }
 197                                                                         /*}}}*/
 198 // File::Close - Close the file if the close flag is set                /*{{{*/
 199 // ---------------------------------------------------------------------
 200 /* */
 201 bool File::Close()
 202 {
 203    bool Res = true;
 204    if ((Flags & AutoClose) == AutoClose)
 205       if (close(iFd) != 0)
 206          Res &= _error->Errno("close","Problem closing the file");
 207
 208    if ((Flags & Fail) == Fail && (Flags & DelOnFail) == DelOnFail &&
 209        FileName.empty() == false)
 210       if (unlink(FileName.c_str()) != 0)
 211          Res &= _error->Warning("unlnk","Problem unlinking the file");
 212    return Res;
 213 }
 214                                                                         /*}}}*/