apt/apt-pkg/contrib/fileutl.cc

// -*- mode: cpp; mode: fold -*-
// Description								/*{{{*/
// $Id: fileutl.cc,v 1.26 1999/03/21 07:24:14 jgg Exp $
/* ######################################################################
   
   File Utilities
   
   CopyFile - Buffered copy of a single file
   GetLock - dpkg compatible lock file manipulation (fcntl)
   
   This source is placed in the Public Domain, do with it what you will
   It was originally written by Jason Gunthorpe.
   
   ##################################################################### */
									/*}}}*/
// Include Files							/*{{{*/
#ifdef __GNUG__
#pragma implementation "apt-pkg/fileutl.h"
#endif 
#include <apt-pkg/fileutl.h>
#include <apt-pkg/error.h>

#include <unistd.h>
#include <sys/stat.h>
#include <sys/fcntl.h>
#include <sys/types.h>
#include <sys/time.h>
#include <errno.h>
									/*}}}*/

// CopyFile - Buffered copy of a file					/*{{{*/
// ---------------------------------------------------------------------
/* The caller is expected to set things so that failure causes erasure */
bool CopyFile(FileFd &From,FileFd &To)
{
   if (From.IsOpen() == false || To.IsOpen() == false)
      return false;
   
   // Buffered copy between fds
   unsigned char *Buf = new unsigned char[64000];
   unsigned long Size = From.Size();
   while (Size != 0)
   {
      unsigned long ToRead = Size;
      if (Size > 64000)
	 ToRead = 64000;
      
      if (From.Read(Buf,ToRead) == false || 
	  To.Write(Buf,ToRead) == false)
      {
	 delete [] Buf;
	 return false;
      }
      
      Size -= ToRead;
   }

   delete [] Buf;
   return true;   
}
									/*}}}*/
// GetLock - Gets a lock file						/*{{{*/
// ---------------------------------------------------------------------
/* This will create an empty file of the given name and lock it. Once this
   is done all other calls to GetLock in any other process will fail with
   -1. The return result is the fd of the file, the call should call
   close at some time. */
int GetLock(string File,bool Errors)
{
   int FD = open(File.c_str(),O_RDWR | O_CREAT | O_TRUNC,0640);
   if (FD < 0)
   {
      if (Errors == true)
	 _error->Errno("open","Could not open lock file %s",File.c_str());
      return -1;
   }
   
   // Aquire a write lock
   struct flock fl;
   fl.l_type = F_WRLCK;
   fl.l_whence = SEEK_SET;
   fl.l_start = 0;
   fl.l_len = 0;
   if (fcntl(FD,F_SETLK,&fl) == -1)
   {
      if (errno == ENOLCK)
      {
	 _error->Warning("Not using locking for nfs mounted lock file %s",File.c_str());
	 return true;
      }      
      if (Errors == true)
	 _error->Errno("open","Could not get lock %s",File.c_str());
      close(FD);
      return -1;
   }

   return FD;
}
									/*}}}*/
// FileExists - Check if a file exists					/*{{{*/
// ---------------------------------------------------------------------
/* */
bool FileExists(string File)
{
   struct stat Buf;
   if (stat(File.c_str(),&Buf) != 0)
      return false;
   return true;
}
									/*}}}*/
// SafeGetCWD - This is a safer getcwd that returns a dynamic string	/*{{{*/
// ---------------------------------------------------------------------
/* We return / on failure. */
string SafeGetCWD()
{
   // Stash the current dir.
   char S[300];
   S[0] = 0;
   if (getcwd(S,sizeof(S)-2) == 0)
      return "/";
   unsigned int Len = strlen(S);
   S[Len] = '/';
   S[Len+1] = 0;
   return S;
}
									/*}}}*/
// flNotDir - Strip the directory from the filename			/*{{{*/
// ---------------------------------------------------------------------
/* */
string flNotDir(string File)
{
   string::size_type Res = File.rfind('/');
   if (Res == string::npos)
      return File;
   Res++;
   return string(File,Res,Res - File.length());
}
									/*}}}*/
// flNotFile - Strip the file from the directory name			/*{{{*/
// ---------------------------------------------------------------------
/* */
string flNotFile(string File)
{
   string::size_type Res = File.rfind('/');
   if (Res == string::npos)
      return File;
   Res++;
   return string(File,0,Res);
}
									/*}}}*/
// SetCloseExec - Set the close on exec flag				/*{{{*/
// ---------------------------------------------------------------------
/* */
void SetCloseExec(int Fd,bool Close)
{   
   if (fcntl(Fd,F_SETFD,(Close == false)?0:FD_CLOEXEC) != 0)
   {
      cerr << "FATAL -> Could not set close on exec " << strerror(errno) << endl;
      exit(100);
   }
}
									/*}}}*/
// SetNonBlock - Set the nonblocking flag				/*{{{*/
// ---------------------------------------------------------------------
/* */
void SetNonBlock(int Fd,bool Block)
{   
   int Flags = fcntl(Fd,F_GETFL) & (~O_NONBLOCK);
   if (fcntl(Fd,F_SETFL,Flags | ((Block == false)?0:O_NONBLOCK)) != 0)
   {
      cerr << "FATAL -> Could not set non-blocking flag " << strerror(errno) << endl;
      exit(100);
   }
}
									/*}}}*/
// WaitFd - Wait for a FD to become readable				/*{{{*/
// ---------------------------------------------------------------------
/* This waits for a FD to become readable using select. It is usefull for
   applications making use of non-blocking sockets. The timeout is 
   in seconds. */
bool WaitFd(int Fd,bool write,unsigned long timeout)
{
   fd_set Set;
   struct timeval tv;
   FD_ZERO(&Set);
   FD_SET(Fd,&Set);
   tv.tv_sec = timeout;
   tv.tv_usec = 0;
   if (write == true) 
   {      
      int Res;
      do
      {
	 Res = select(Fd+1,0,&Set,0,(timeout != 0?&tv:0));
      }
      while (Res < 0 && errno == EINTR);
      
      if (Res <= 0)
	 return false;
   } 
   else 
   {
      int Res;
      do
      {
	 Res = select(Fd+1,&Set,0,0,(timeout != 0?&tv:0));
      }
      while (Res < 0 && errno == EINTR);
      
      if (Res <= 0)
	 return false;
   }
   
   return true;
}
									/*}}}*/

// FileFd::FileFd - Open a file						/*{{{*/
// ---------------------------------------------------------------------
/* The most commonly used open mode combinations are given with Mode */
FileFd::FileFd(string FileName,OpenMode Mode, unsigned long Perms)
{
   Flags = AutoClose;
   switch (Mode)
   {
      case ReadOnly:
      iFd = open(FileName.c_str(),O_RDONLY);
      break;
      
      case WriteEmpty:
      {
	 struct stat Buf;
	 if (stat(FileName.c_str(),&Buf) == 0 && S_ISLNK(Buf.st_mode))
	    unlink(FileName.c_str());
	 iFd = open(FileName.c_str(),O_RDWR | O_CREAT | O_TRUNC,Perms);
	 break;
      }
      
      case WriteExists:
      iFd = open(FileName.c_str(),O_RDWR);
      break;

      case WriteAny:
      iFd = open(FileName.c_str(),O_RDWR | O_CREAT,Perms);
      break;      
   }  

   if (iFd < 0)
      _error->Errno("open","Could not open file %s",FileName.c_str());
   else
   {
      this->FileName = FileName;
      SetCloseExec(iFd,true);
   }   
}
									/*}}}*/
// FileFd::~File - Closes the file					/*{{{*/
// ---------------------------------------------------------------------
/* If the proper modes are selected then we close the Fd and possibly
   unlink the file on error. */
FileFd::~FileFd()
{
   Close();
}
									/*}}}*/
// FileFd::Read - Read a bit of the file				/*{{{*/
// ---------------------------------------------------------------------
/* We are carefull to handle interruption by a signal while reading 
   gracefully. */
bool FileFd::Read(void *To,unsigned long Size)
{
   int Res;
   errno = 0;
   do
   {
      Res = read(iFd,To,Size);
      if (Res < 0 && errno == EINTR)
	 continue;
      if (Res < 0)
      {
	 Flags |= Fail;
	 return _error->Errno("read","Read error");
      }
      
      To = (char *)To + Res;
      Size -= Res;
   }
   while (Res > 0 && Size > 0);
   
   if (Size == 0)
      return true;
   
   Flags |= Fail;
   return _error->Error("read, still have %u to read but none left",Size);
}
									/*}}}*/
// FileFd::Write - Write to the file					/*{{{*/
// ---------------------------------------------------------------------
/* */
bool FileFd::Write(const void *From,unsigned long Size)
{
   int Res;
   errno = 0;
   do
   {
      Res = write(iFd,From,Size);
      if (Res < 0 && errno == EINTR)
	 continue;
      if (Res < 0)
      {
	 Flags |= Fail;
	 return _error->Errno("write","Write error");
      }
      
      From = (char *)From + Res;
      Size -= Res;
   }
   while (Res > 0 && Size > 0);
   
   if (Size == 0)
      return true;
   
   Flags |= Fail;
   return _error->Error("write, still have %u to write but couldn't",Size);
}
									/*}}}*/
// FileFd::Seek - Seek in the file					/*{{{*/
// ---------------------------------------------------------------------
/* */
bool FileFd::Seek(unsigned long To)
{
   if (lseek(iFd,To,SEEK_SET) != (signed)To)
   {
      Flags |= Fail;
      return _error->Error("Unable to seek to %u",To);
   }
   
   return true;
}
									/*}}}*/
// FileFd::Truncate - Truncate the file 				/*{{{*/
// ---------------------------------------------------------------------
/* */
bool FileFd::Truncate(unsigned long To)
{
   if (ftruncate(iFd,To) != 0)
   {
      Flags |= Fail;
      return _error->Error("Unable to truncate to %u",To);
   }
   
   return true;
}
									/*}}}*/
// FileFd::Tell - Current seek position					/*{{{*/
// ---------------------------------------------------------------------
/* */
unsigned long FileFd::Tell()
{
   off_t Res = lseek(iFd,0,SEEK_CUR);
   if (Res == (off_t)-1)
      _error->Errno("lseek","Failed to determine the current file position");
   return Res;
}
									/*}}}*/
// FileFd::Size - Return the size of the file				/*{{{*/
// ---------------------------------------------------------------------
/* */
unsigned long FileFd::Size()
{
   struct stat Buf;
   if (fstat(iFd,&Buf) != 0)
      return _error->Errno("fstat","Unable to determine the file size");
   return Buf.st_size;
}
									/*}}}*/
// FileFd::Close - Close the file if the close flag is set		/*{{{*/
// ---------------------------------------------------------------------
/* */
bool FileFd::Close()
{
   bool Res = true;
   if ((Flags & AutoClose) == AutoClose)
      if (iFd >= 0 && close(iFd) != 0)
	 Res &= _error->Errno("close","Problem closing the file");
   iFd = -1;
   
   if ((Flags & Fail) == Fail && (Flags & DelOnFail) == DelOnFail &&
       FileName.empty() == false)
      if (unlink(FileName.c_str()) != 0)
	 Res &= _error->Warning("unlnk","Problem unlinking the file");
   return Res;
}
									/*}}}*/