apt-pkg/contrib/cdromutl.cc

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: cdromutl.cc,v 1.4 1999/04/20 05:02:09 jgg Exp $
   4 /* ######################################################################
   5
   6    CDROM Utilities - Some functions to manipulate CDROM mounts.
   7
   8    These are here for the cdrom method and apt-cdrom.
   9
  10    ##################################################################### */
  11                                                                         /*}}}*/
  12 // Include Files                                                        /*{{{*/
  13 #ifdef __GNUG__
  14 #pragma implementation "apt-pkg/cdromutl.h"
  15 #endif
  16 #include <apt-pkg/cdromutl.h>
  17 #include <apt-pkg/error.h>
  18 #include <apt-pkg/md5.h>
  19 #include <apt-pkg/fileutl.h>
  20 #include <apt-pkg/configuration.h>
  21
  22 #include <sys/wait.h>
  23 #include <sys/errno.h>
  24 #include <sys/vfs.h>
  25 #include <dirent.h>
  26 #include <fcntl.h>
  27 #include <sys/stat.h>
  28 #include <unistd.h>
  29 #include <stdio.h>
  30                                                                         /*}}}*/
  31
  32 // IsMounted - Returns true if the mount point is mounted               /*{{{*/
  33 // ---------------------------------------------------------------------
  34 /* This is a simple algorithm that should always work, we stat the mount point
  35    and the '..' file in the mount point and see if they are on the same device.
  36    By definition if they are the same then it is not mounted. This should
  37    account for symlinked mount points as well. */
  38 bool IsMounted(string &Path)
  39 {
  40    if (Path.empty() == true)
  41       return false;
  42
  43    // Need that trailing slash for directories
  44    if (Path[Path.length() - 1] != '/')
  45       Path += '/';
  46
  47    /* First we check if the path is actualy mounted, we do this by
  48       stating the path and the previous directory (carefull of links!)
  49       and comparing their device fields. */
  50    struct stat Buf,Buf2;
  51    if (stat(Path.c_str(),&Buf) != 0 ||
  52        stat((Path + "../").c_str(),&Buf2) != 0)
  53       return _error->Errno("stat","Unable to stat the mount point %s",Path.c_str());
  54
  55    if (Buf.st_dev == Buf2.st_dev)
  56       return false;
  57    return true;
  58 }
  59                                                                         /*}}}*/
  60 // UnmountCdrom - Unmount a cdrom                                       /*{{{*/
  61 // ---------------------------------------------------------------------
  62 /* Forking umount works much better than the umount syscall which can
  63    leave /etc/mtab inconsitant. We drop all messages this produces. */
  64 bool UnmountCdrom(string Path)
  65 {
  66    if (IsMounted(Path) == false)
  67       return true;
  68
  69    int Child = ExecFork();
  70
  71    // The child
  72    if (Child == 0)
  73    {
  74       // Make all the fds /dev/null
  75       for (int I = 0; I != 3; I++)
  76          dup2(open("/dev/null",O_RDWR),I);
  77
  78       if (_config->Exists("Acquire::cdrom::"+Path+"::UMount") == true)
  79       {
  80          if (system(_config->Find("Acquire::cdrom::"+Path+"::UMount").c_str()) != 0)
  81             _exit(100);
  82          _exit(0);
  83       }
  84       else
  85       {
  86          const char *Args[10];
  87          Args[0] = "umount";
  88          Args[1] = Path.c_str();
  89          Args[2] = 0;
  90          execvp(Args[0],(char **)Args);
  91          _exit(100);
  92       }
  93    }
  94
  95    // Wait for mount
  96    int Status = 0;
  97    while (waitpid(Child,&Status,0) != Child)
  98    {
  99       if (errno == EINTR)
 100          continue;
 101       return _error->Errno("waitpid","Couldn't wait for subprocess");
 102    }
 103
 104    // Check for an error code.
 105    if (WIFEXITED(Status) == 0 || WEXITSTATUS(Status) != 0)
 106       return false;
 107    return true;
 108 }
 109                                                                         /*}}}*/
 110 // MountCdrom - Mount a cdrom                                           /*{{{*/
 111 // ---------------------------------------------------------------------
 112 /* We fork mount and drop all messages */
 113 bool MountCdrom(string Path)
 114 {
 115    if (IsMounted(Path) == true)
 116       return true;
 117
 118    int Child = ExecFork();
 119
 120    // The child
 121    if (Child == 0)
 122    {
 123       // Make all the fds /dev/null
 124       for (int I = 0; I != 3; I++)
 125          dup2(open("/dev/null",O_RDWR),I);
 126
 127       if (_config->Exists("Acquire::cdrom::"+Path+"::Mount") == true)
 128       {
 129          if (system(_config->Find("Acquire::cdrom::"+Path+"::Mount").c_str()) != 0)
 130             _exit(100);
 131          _exit(0);
 132       }
 133       else
 134       {
 135          const char *Args[10];
 136          Args[0] = "mount";
 137          Args[1] = Path.c_str();
 138          Args[2] = 0;
 139          execvp(Args[0],(char **)Args);
 140          _exit(100);
 141       }
 142    }
 143
 144    // Wait for mount
 145    int Status = 0;
 146    while (waitpid(Child,&Status,0) != Child)
 147    {
 148       if (errno == EINTR)
 149          continue;
 150       return _error->Errno("waitpid","Couldn't wait for subprocess");
 151    }
 152
 153    // Check for an error code.
 154    if (WIFEXITED(Status) == 0 || WEXITSTATUS(Status) != 0)
 155       return false;
 156    return true;
 157 }
 158                                                                         /*}}}*/
 159 // IdentCdrom - Generate a unique string for this CD                    /*{{{*/
 160 // ---------------------------------------------------------------------
 161 /* We convert everything we hash into a string, this prevents byte size/order
 162    from effecting the outcome. */
 163 bool IdentCdrom(string CD,string &Res)
 164 {
 165    MD5Summation Hash;
 166
 167    string StartDir = SafeGetCWD();
 168    if (chdir(CD.c_str()) != 0)
 169       return _error->Errno("chdir","Unable to change to %s",CD.c_str());
 170
 171    DIR *D = opendir(".");
 172    if (D == 0)
 173       return _error->Errno("opendir","Unable to read %s",CD.c_str());
 174
 175    /* Run over the directory, we assume that the reader order will never
 176       change as the media is read-only. In theory if the kernel did
 177       some sort of wacked caching this might not be true.. */
 178    char S[300];
 179    for (struct dirent *Dir = readdir(D); Dir != 0; Dir = readdir(D))
 180    {
 181       // Skip some files..
 182       if (strcmp(Dir->d_name,".") == 0 ||
 183           strcmp(Dir->d_name,"..") == 0)
 184          continue;
 185
 186       sprintf(S,"%lu",Dir->d_ino);
 187       Hash.Add(S);
 188       Hash.Add(Dir->d_name);
 189    };
 190
 191    chdir(StartDir.c_str());
 192    closedir(D);
 193
 194    // Some stats from the fsys
 195    struct statfs Buf;
 196    if (statfs(CD.c_str(),&Buf) != 0)
 197       return _error->Errno("statfs","Failed to stat the cdrom");
 198
 199    // We use a kilobyte block size to advoid overflow
 200    sprintf(S,"%u %u",Buf.f_blocks*(Buf.f_bsize/1024),
 201            Buf.f_bfree*(Buf.f_bsize/1024));
 202    Hash.Add(S);
 203
 204    Res = Hash.Result().Value();
 205    return true;
 206 }
 207                                                                         /*}}}*/