apt-pkg/contrib/cdromutl.cc

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: cdromutl.cc,v 1.12 2001/02/20 07:03:17 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 #include<config.h>
  14
  15 #include <apt-pkg/cdromutl.h>
  16 #include <apt-pkg/error.h>
  17 #include <apt-pkg/md5.h>
  18 #include <apt-pkg/fileutl.h>
  19 #include <apt-pkg/configuration.h>
  20 #include <apt-pkg/strutl.h>
  21
  22 #include <sys/wait.h>
  23 #include <sys/statvfs.h>
  24 #include <dirent.h>
  25 #include <fcntl.h>
  26 #include <sys/stat.h>
  27 #include <unistd.h>
  28 #include <stdio.h>
  29
  30 #include <apti18n.h>
  31                                                                         /*}}}*/
  32
  33 using std::string;
  34
  35 // IsMounted - Returns true if the mount point is mounted               /*{{{*/
  36 // ---------------------------------------------------------------------
  37 /* This is a simple algorithm that should always work, we stat the mount point
  38    and the '..' file in the mount point and see if they are on the same device.
  39    By definition if they are the same then it is not mounted. This should
  40    account for symlinked mount points as well. */
  41 bool IsMounted(string &Path)
  42 {
  43    if (Path.empty() == true)
  44       return false;
  45
  46    // Need that trailing slash for directories
  47    if (Path[Path.length() - 1] != '/')
  48       Path += '/';
  49
  50    /* First we check if the path is actualy mounted, we do this by
  51       stating the path and the previous directory (carefull of links!)
  52       and comparing their device fields. */
  53    struct stat Buf,Buf2;
  54    if (stat(Path.c_str(),&Buf) != 0 ||
  55        stat((Path + "../").c_str(),&Buf2) != 0)
  56       return _error->Errno("stat",_("Unable to stat the mount point %s"),Path.c_str());
  57
  58    if (Buf.st_dev == Buf2.st_dev)
  59       return false;
  60    return true;
  61 }
  62                                                                         /*}}}*/
  63 // UnmountCdrom - Unmount a cdrom                                       /*{{{*/
  64 // ---------------------------------------------------------------------
  65 /* Forking umount works much better than the umount syscall which can
  66    leave /etc/mtab inconsitant. We drop all messages this produces. */
  67 bool UnmountCdrom(string Path)
  68 {
  69    if (IsMounted(Path) == false)
  70       return true;
  71
  72    for (int i=0;i<3;i++)
  73    {
  74
  75       int Child = ExecFork();
  76
  77       // The child
  78       if (Child == 0)
  79       {
  80          // Make all the fds /dev/null
  81          for (int I = 0; I != 3; I++)
  82             dup2(open("/dev/null",O_RDWR),I);
  83
  84          if (_config->Exists("Acquire::cdrom::"+Path+"::UMount") == true)
  85          {
  86             if (system(_config->Find("Acquire::cdrom::"+Path+"::UMount").c_str()) != 0)
  87                _exit(100);
  88             _exit(0);
  89          }
  90          else
  91          {
  92             const char *Args[10];
  93             Args[0] = "umount";
  94             Args[1] = Path.c_str();
  95             Args[2] = 0;
  96             execvp(Args[0],(char **)Args);
  97             _exit(100);
  98          }
  99       }
 100
 101       // if it can not be umounted, give it a bit more time
 102       // this can happen when auto-mount magic or fs/cdrom prober attack
 103       if (ExecWait(Child,"umount",true) == true)
 104          return true;
 105       sleep(1);
 106    }
 107
 108    return false;
 109 }
 110                                                                         /*}}}*/
 111 // MountCdrom - Mount a cdrom                                           /*{{{*/
 112 // ---------------------------------------------------------------------
 113 /* We fork mount and drop all messages */
 114 bool MountCdrom(string Path, string DeviceName)
 115 {
 116    if (IsMounted(Path) == true)
 117       return true;
 118
 119    int Child = ExecFork();
 120
 121    // The child
 122    if (Child == 0)
 123    {
 124       // Make all the fds /dev/null
 125       int null_fd = open("/dev/null",O_RDWR);
 126       for (int I = 0; I != 3; I++)
 127          dup2(null_fd, I);
 128
 129       if (_config->Exists("Acquire::cdrom::"+Path+"::Mount") == true)
 130       {
 131          if (system(_config->Find("Acquire::cdrom::"+Path+"::Mount").c_str()) != 0)
 132             _exit(100);
 133          _exit(0);
 134       }
 135       else
 136       {
 137          const char *Args[10];
 138          Args[0] = "mount";
 139          if (DeviceName == "")
 140          {
 141             Args[1] = Path.c_str();
 142             Args[2] = 0;
 143          } else {
 144             Args[1] = DeviceName.c_str();
 145             Args[2] = Path.c_str();
 146             Args[3] = 0;
 147          }
 148          execvp(Args[0],(char **)Args);
 149          _exit(100);
 150       }
 151    }
 152
 153    // Wait for mount
 154    return ExecWait(Child,"mount",true);
 155 }
 156                                                                         /*}}}*/
 157 // IdentCdrom - Generate a unique string for this CD                    /*{{{*/
 158 // ---------------------------------------------------------------------
 159 /* We convert everything we hash into a string, this prevents byte size/order
 160    from effecting the outcome. */
 161 bool IdentCdrom(string CD,string &Res,unsigned int Version)
 162 {
 163    MD5Summation Hash;
 164    bool writable_media = false;
 165
 166    // if we are on a writable medium (like a usb-stick) that is just
 167    // used like a cdrom don't use "." as it will constantly change,
 168    // use .disk instead
 169    if (access(CD.c_str(), W_OK) == 0 && DirectoryExists(CD+string("/.disk")))
 170    {
 171       writable_media = true;
 172       CD = CD.append("/.disk");
 173       if (_config->FindB("Debug::aptcdrom",false) == true)
 174          std::clog << "Found writable cdrom, using alternative path: " << CD
 175                    << std::endl;
 176    }
 177
 178    string StartDir = SafeGetCWD();
 179    if (chdir(CD.c_str()) != 0)
 180       return _error->Errno("chdir",_("Unable to change to %s"),CD.c_str());
 181
 182    DIR *D = opendir(".");
 183    if (D == 0)
 184       return _error->Errno("opendir",_("Unable to read %s"),CD.c_str());
 185
 186    /* Run over the directory, we assume that the reader order will never
 187       change as the media is read-only. In theory if the kernel did
 188       some sort of wacked caching this might not be true.. */
 189    char S[300];
 190    for (struct dirent *Dir = readdir(D); Dir != 0; Dir = readdir(D))
 191    {
 192       // Skip some files..
 193       if (strcmp(Dir->d_name,".") == 0 ||
 194           strcmp(Dir->d_name,"..") == 0)
 195          continue;
 196
 197       if (Version <= 1)
 198       {
 199          sprintf(S,"%lu",(unsigned long)Dir->d_ino);
 200       }
 201       else
 202       {
 203          struct stat Buf;
 204          if (stat(Dir->d_name,&Buf) != 0)
 205             continue;
 206          sprintf(S,"%lu",(unsigned long)Buf.st_mtime);
 207       }
 208
 209       Hash.Add(S);
 210       Hash.Add(Dir->d_name);
 211    };
 212
 213    if (chdir(StartDir.c_str()) != 0) {
 214       _error->Errno("chdir",_("Unable to change to %s"),StartDir.c_str());
 215       closedir(D);
 216       return false;
 217    }
 218    closedir(D);
 219
 220    // Some stats from the fsys
 221    if (_config->FindB("Debug::identcdrom",false) == false)
 222    {
 223       struct statvfs Buf;
 224       if (statvfs(CD.c_str(),&Buf) != 0)
 225          return _error->Errno("statfs",_("Failed to stat the cdrom"));
 226
 227       // We use a kilobyte block size to advoid overflow
 228       if (writable_media)
 229       {
 230          sprintf(S,"%lu",(long)(Buf.f_blocks*(Buf.f_bsize/1024)));
 231       } else {
 232          sprintf(S,"%lu %lu",(long)(Buf.f_blocks*(Buf.f_bsize/1024)),
 233                  (long)(Buf.f_bfree*(Buf.f_bsize/1024)));
 234       }
 235       Hash.Add(S);
 236       sprintf(S,"-%u",Version);
 237    }
 238    else
 239       sprintf(S,"-%u.debug",Version);
 240
 241    Res = Hash.Result().Value() + S;
 242    return true;
 243 }
 244                                                                         /*}}}*/
 245
 246 // FindMountPointForDevice - Find mountpoint for the given device       /*{{{*/
 247 string FindMountPointForDevice(const char *devnode)
 248 {
 249    char buf[255];
 250    char *out[10];
 251    int i=0;
 252
 253    // this is the order that mount uses as well
 254    const char *mount[] = { "/etc/mtab",
 255                            "/proc/mount",
 256                            NULL };
 257
 258    for (i=0; mount[i] != NULL; i++) {
 259       if (FileExists(mount[i])) {
 260          FILE *f=fopen(mount[i], "r");
 261          while ( fgets(buf, sizeof(buf), f) != NULL) {
 262             if (strncmp(buf, devnode, strlen(devnode)) == 0) {
 263                if(TokSplitString(' ', buf, out, 10))
 264                {
 265                   fclose(f);
 266                   // unescape the \0XXX chars in the path
 267                   string mount_point = out[1];
 268                   return DeEscapeString(mount_point);
 269                }
 270             }
 271          }
 272          fclose(f);
 273       }
 274    }
 275
 276    return string();
 277 }
 278                                                                         /*}}}*/