CDROM patches from bluehorn

[apt.git] / apt-pkg / contrib / cdromutl.cc

// -*- mode: cpp; mode: fold -*-
// Description								/*{{{*/
// $Id: cdromutl.cc,v 1.2 1999/03/28 01:37:26 jgg Exp $
/* ######################################################################
   
   CDROM Utilities - Some functions to manipulate CDROM mounts.
   
   These are here for the cdrom method and apt-cdrom.
   
   ##################################################################### */
									/*}}}*/
// Include Files							/*{{{*/
#ifdef __GNUG__
#pragma implementation "apt-pkg/cdromutl.h"
#endif
#include <apt-pkg/cdromutl.h>
#include <apt-pkg/error.h>
#include <apt-pkg/md5.h>
#include <apt-pkg/fileutl.h>

#include <sys/wait.h>
#include <sys/errno.h>
#include <sys/vfs.h>
#include <dirent.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>
									/*}}}*/

// UnmountCdrom - Unmount a cdrom					/*{{{*/
// ---------------------------------------------------------------------
/* Forking umount works much better than the umount syscall which can 
   leave /etc/mtab inconsitant. We drop all messages this produces. */
bool UnmountCdrom(string Path)
{
   if (Path.empty() == true)
      return false;
   
   // Need that trailing slash for directories
   if (Path[Path.length() - 1] != '/')
      Path += '/';
   
   /* First we check if the path is actualy mounted, we do this by
      stating the path and the previous directory (carefull of links!)
      and comparing their device fields. */
   struct stat Buf,Buf2;
   if (stat(Path.c_str(),&Buf) != 0 || 
       stat((Path + "../").c_str(),&Buf2) != 0)
      return _error->Errno("stat","Unable to stat the mount point %s",Path.c_str());

   if (Buf.st_dev == Buf2.st_dev)
      return true;
   
   int Child = fork();
   if (Child < -1)
      return _error->Errno("fork","Failed to fork");

   // The child
   if (Child == 0)
   {
      // Make all the fds /dev/null
      for (int I = 0; I != 10; I++)
	 close(I);
      for (int I = 0; I != 3; I++)
	 dup2(open("/dev/null",O_RDWR),I);

      const char *Args[10];
      Args[0] = "umount";
      Args[1] = Path.c_str();
      Args[2] = 0;
      execvp(Args[0],(char **)Args);      
      exit(100);
   }

   // Wait for mount
   int Status = 0;
   while (waitpid(Child,&Status,0) != Child)
   {
      if (errno == EINTR)
	 continue;
      return _error->Errno("waitpid","Couldn't wait for subprocess");
   }
   
   // Check for an error code.
   if (WIFEXITED(Status) == 0 || WEXITSTATUS(Status) != 0)
      return false;
   return true;
}
									/*}}}*/
// MountCdrom - Mount a cdrom						/*{{{*/
// ---------------------------------------------------------------------
/* We fork mount and drop all messages */
bool MountCdrom(string Path)
{
   int Child = fork();
   if (Child < -1)
      return _error->Errno("fork","Failed to fork");

   // The child
   if (Child == 0)
   {
      // Make all the fds /dev/null
      for (int I = 0; I != 10; I++)
	 close(I);      
      for (int I = 0; I != 3; I++)
	 dup2(open("/dev/null",O_RDWR),I);
      
      const char *Args[10];
      Args[0] = "mount";
      Args[1] = Path.c_str();
      Args[2] = 0;
      execvp(Args[0],(char **)Args);      
      exit(100);
   }

   // Wait for mount
   int Status = 0;
   while (waitpid(Child,&Status,0) != Child)
   {
      if (errno == EINTR)
	 continue;
      return _error->Errno("waitpid","Couldn't wait for subprocess");
   }
   
   // Check for an error code.
   if (WIFEXITED(Status) == 0 || WEXITSTATUS(Status) != 0)
      return false;
   return true;
}
									/*}}}*/
// IdentCdrom - Generate a unique string for this CD			/*{{{*/
// ---------------------------------------------------------------------
/* We convert everything we hash into a string, this prevents byte size/order
   from effecting the outcome. */
bool IdentCdrom(string CD,string &Res)
{
   MD5Summation Hash;

   string StartDir = SafeGetCWD();
   if (chdir(CD.c_str()) != 0)
      return _error->Errno("chdir","Unable to change to %s",CD.c_str());
   
   DIR *D = opendir(".");
   if (D == 0)
      return _error->Errno("opendir","Unable to read %s",CD.c_str());
      
   /* Run over the directory, we assume that the reader order will never
      change as the media is read-only. In theory if the kernel did
      some sort of wacked caching this might not be true.. */
   char S[300];
   for (struct dirent *Dir = readdir(D); Dir != 0; Dir = readdir(D))
   {
      // Skip some files..
      if (strcmp(Dir->d_name,".") == 0 ||
	  strcmp(Dir->d_name,"..") == 0)
	 continue;
   
      sprintf(S,"%lu",Dir->d_ino);
      Hash.Add(S);
      Hash.Add(Dir->d_name);
   };
   
   chdir(StartDir.c_str());
   closedir(D);
   
   // Some stats from the fsys
   struct statfs Buf;
   if (statfs(CD.c_str(),&Buf) != 0)
      return _error->Errno("statfs","Failed to stat the cdrom");

   // We use a kilobyte block size to advoid overflow
   sprintf(S,"%u %u",Buf.f_blocks*(Buf.f_bsize/1024),
	   Buf.f_bfree*(Buf.f_bsize/1024));
   Hash.Add(S);
   
   Res = Hash.Result().Value();
   return true;   
}
									/*}}}*/