apt-pkg/contrib/fileutl.cc

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: fileutl.cc,v 1.11 1998/10/22 04:56:47 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) & (~O_NONBLOCK);
 140    if (fcntl(Fd,F_SETFL,Flags | ((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
 157    if (select(Fd+1,&Set,0,0,0) <= 0)
 158       return false;
 159
 160    return true;
 161 }
 162                                                                         /*}}}*/
 163
 164 // FileFd::FileFd - Open a file                                         /*{{{*/
 165 // ---------------------------------------------------------------------
 166 /* The most commonly used open mode combinations are given with Mode */
 167 FileFd::FileFd(string FileName,OpenMode Mode, unsigned long Perms)
 168 {
 169    Flags = AutoClose;
 170    switch (Mode)
 171    {
 172       case ReadOnly:
 173       iFd = open(FileName.c_str(),O_RDONLY);
 174       break;
 175
 176       case WriteEmpty:
 177       unlink(FileName.c_str());
 178       iFd = open(FileName.c_str(),O_RDWR | O_CREAT | O_EXCL,Perms);
 179       break;
 180
 181       case WriteExists:
 182       iFd = open(FileName.c_str(),O_RDWR);
 183       break;
 184
 185       case WriteAny:
 186       iFd = open(FileName.c_str(),O_RDWR | O_CREAT,Perms);
 187       break;
 188
 189       // Dont use this in public directories
 190       case LockEmpty:
 191       iFd = open(FileName.c_str(),O_RDWR | O_CREAT | O_TRUNC,Perms);
 192       break;
 193    }
 194
 195    if (iFd < 0)
 196       _error->Errno("open","Could not open file %s",FileName.c_str());
 197    else
 198       this->FileName = FileName;
 199    SetCloseExec(iFd,true);
 200 }
 201                                                                         /*}}}*/
 202 // FileFd::~File - Closes the file                                      /*{{{*/
 203 // ---------------------------------------------------------------------
 204 /* If the proper modes are selected then we close the Fd and possibly
 205    unlink the file on error. */
 206 FileFd::~FileFd()
 207 {
 208    Close();
 209 }
 210                                                                         /*}}}*/
 211 // FileFd::Read - Read a bit of the file                                /*{{{*/
 212 // ---------------------------------------------------------------------
 213 /* */
 214 bool FileFd::Read(void *To,unsigned long Size)
 215 {
 216    if (read(iFd,To,Size) != (signed)Size)
 217    {
 218       Flags |= Fail;
 219       return _error->Errno("read","Read error");
 220    }
 221
 222    return true;
 223 }
 224                                                                         /*}}}*/
 225 // FileFd::Write - Write to the file                                    /*{{{*/
 226 // ---------------------------------------------------------------------
 227 /* */
 228 bool FileFd::Write(void *From,unsigned long Size)
 229 {
 230    if (write(iFd,From,Size) != (signed)Size)
 231    {
 232       Flags |= Fail;
 233       return _error->Errno("write","Write error");
 234    }
 235
 236    return true;
 237 }
 238                                                                         /*}}}*/
 239 // FileFd::Seek - Seek in the file                                      /*{{{*/
 240 // ---------------------------------------------------------------------
 241 /* */
 242 bool FileFd::Seek(unsigned long To)
 243 {
 244    if (lseek(iFd,To,SEEK_SET) != (signed)To)
 245    {
 246       Flags |= Fail;
 247       return _error->Error("Unable to seek to %u",To);
 248    }
 249
 250    return true;
 251 }
 252                                                                         /*}}}*/
 253 // FileFd::Size - Return the size of the file                           /*{{{*/
 254 // ---------------------------------------------------------------------
 255 /* */
 256 unsigned long FileFd::Size()
 257 {
 258    struct stat Buf;
 259    if (fstat(iFd,&Buf) != 0)
 260       return _error->Errno("fstat","Unable to determine the file size");
 261    return Buf.st_size;
 262 }
 263                                                                         /*}}}*/
 264 // FileFd::Close - Close the file if the close flag is set              /*{{{*/
 265 // ---------------------------------------------------------------------
 266 /* */
 267 bool FileFd::Close()
 268 {
 269    bool Res = true;
 270    if ((Flags & AutoClose) == AutoClose)
 271       if (iFd >= 0 && close(iFd) != 0)
 272          Res &= _error->Errno("close","Problem closing the file");
 273    iFd = -1;
 274
 275    if ((Flags & Fail) == Fail && (Flags & DelOnFail) == DelOnFail &&
 276        FileName.empty() == false)
 277       if (unlink(FileName.c_str()) != 0)
 278          Res &= _error->Warning("unlnk","Problem unlinking the file");
 279    return Res;
 280 }
 281                                                                         /*}}}*/