apt-pkg/contrib/cdromutl.cc

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: cdromutl.cc,v 1.9 1999/08/30 07:48:04 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    return ExecWait(Child,"mount",true);
  97 }
  98                                                                         /*}}}*/
  99 // MountCdrom - Mount a cdrom                                           /*{{{*/
 100 // ---------------------------------------------------------------------
 101 /* We fork mount and drop all messages */
 102 bool MountCdrom(string Path)
 103 {
 104    if (IsMounted(Path) == true)
 105       return true;
 106
 107    int Child = ExecFork();
 108
 109    // The child
 110    if (Child == 0)
 111    {
 112       // Make all the fds /dev/null
 113       for (int I = 0; I != 3; I++)
 114          dup2(open("/dev/null",O_RDWR),I);
 115
 116       if (_config->Exists("Acquire::cdrom::"+Path+"::Mount") == true)
 117       {
 118          if (system(_config->Find("Acquire::cdrom::"+Path+"::Mount").c_str()) != 0)
 119             _exit(100);
 120          _exit(0);
 121       }
 122       else
 123       {
 124          const char *Args[10];
 125          Args[0] = "mount";
 126          Args[1] = Path.c_str();
 127          Args[2] = 0;
 128          execvp(Args[0],(char **)Args);
 129          _exit(100);
 130       }
 131    }
 132
 133    // Wait for mount
 134    return ExecWait(Child,"mount",true);
 135 }
 136                                                                         /*}}}*/
 137 // IdentCdrom - Generate a unique string for this CD                    /*{{{*/
 138 // ---------------------------------------------------------------------
 139 /* We convert everything we hash into a string, this prevents byte size/order
 140    from effecting the outcome. */
 141 bool IdentCdrom(string CD,string &Res,unsigned int Version)
 142 {
 143    MD5Summation Hash;
 144
 145    string StartDir = SafeGetCWD();
 146    if (chdir(CD.c_str()) != 0)
 147       return _error->Errno("chdir","Unable to change to %s",CD.c_str());
 148
 149    DIR *D = opendir(".");
 150    if (D == 0)
 151       return _error->Errno("opendir","Unable to read %s",CD.c_str());
 152
 153    /* Run over the directory, we assume that the reader order will never
 154       change as the media is read-only. In theory if the kernel did
 155       some sort of wacked caching this might not be true.. */
 156    char S[300];
 157    for (struct dirent *Dir = readdir(D); Dir != 0; Dir = readdir(D))
 158    {
 159       // Skip some files..
 160       if (strcmp(Dir->d_name,".") == 0 ||
 161           strcmp(Dir->d_name,"..") == 0)
 162          continue;
 163
 164       if (Version <= 1)
 165       {
 166          sprintf(S,"%lu",(unsigned long)Dir->d_ino);
 167       }
 168       else
 169       {
 170          struct stat Buf;
 171          if (stat(Dir->d_name,&Buf) != 0)
 172             continue;
 173          sprintf(S,"%lu",Buf.st_mtime);
 174       }
 175
 176       Hash.Add(S);
 177       Hash.Add(Dir->d_name);
 178    };
 179
 180    chdir(StartDir.c_str());
 181    closedir(D);
 182
 183    // Some stats from the fsys
 184    if (_config->FindB("Debug::identcdrom",false) == false)
 185    {
 186       struct statfs Buf;
 187       if (statfs(CD.c_str(),&Buf) != 0)
 188          return _error->Errno("statfs","Failed to stat the cdrom");
 189
 190       // We use a kilobyte block size to advoid overflow
 191       sprintf(S,"%lu %lu",(long)(Buf.f_blocks*(Buf.f_bsize/1024)),
 192               (long)(Buf.f_bfree*(Buf.f_bsize/1024)));
 193       Hash.Add(S);
 194       sprintf(S,"-%u",Version);
 195    }
 196    else
 197       sprintf(S,"-%u.debug",Version);
 198
 199    Res = Hash.Result().Value() + S;
 200    return true;
 201 }
 202                                                                         /*}}}*/