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// -*- mode: cpp; mode: fold -*-
// Description /*{{{*/
// $Id: extracttar.cc,v 1.8.2.1 2004/01/16 18:58:50 mdz Exp $
/* ######################################################################
Extract a Tar - Tar Extractor
Some performance measurements showed that zlib performed quite poorly
in comparison to a forked gzip process. This tar extractor makes use
of the fact that dup'd file descriptors have the same seek pointer
and that gzip will not read past the end of a compressed stream,
even if there is more data. We use the dup property to track extraction
progress and the gzip feature to just feed gzip a fd in the middle
of an AR file.
##################################################################### */
/*}}}*/
// Include Files /*{{{*/
#include<config.h>
#include <apt-pkg/dirstream.h>
#include <apt-pkg/extracttar.h>
#include <apt-pkg/error.h>
#include <apt-pkg/strutl.h>
#include <apt-pkg/configuration.h>
#include <apt-pkg/fileutl.h>
#include <string.h>
#include <algorithm>
#include <string>
#include <unistd.h>
#include <signal.h>
#include <fcntl.h>
#include <iostream>
#include <apti18n.h>
/*}}}*/
using namespace std;
// The on disk header for a tar file.
struct ExtractTar::TarHeader
{
char Name[100];
char Mode[8];
char UserID[8];
char GroupID[8];
char Size[12];
char MTime[12];
char Checksum[8];
char LinkFlag;
char LinkName[100];
char MagicNumber[8];
char UserName[32];
char GroupName[32];
char Major[8];
char Minor[8];
};
// ExtractTar::ExtractTar - Constructor /*{{{*/
// ---------------------------------------------------------------------
/* */
ExtractTar::ExtractTar(FileFd &Fd,unsigned long long Max,string DecompressionProgram)
: File(Fd), MaxInSize(Max), DecompressProg(DecompressionProgram)
{
GZPid = -1;
Eof = false;
}
/*}}}*/
// ExtractTar::ExtractTar - Destructor /*{{{*/
// ---------------------------------------------------------------------
/* */
ExtractTar::~ExtractTar()
{
// Error close
Done(true);
}
/*}}}*/
// ExtractTar::Done - Reap the gzip sub process /*{{{*/
// ---------------------------------------------------------------------
/* If the force flag is given then error messages are suppressed - this
means we hit the end of the tar file but there was still gzip data. */
bool ExtractTar::Done(bool Force)
{
return InFd.Close();
}
/*}}}*/
// ExtractTar::StartGzip - Startup gzip /*{{{*/
// ---------------------------------------------------------------------
/* This creates a gzip sub process that has its input as the file itself.
If this tar file is embedded into something like an ar file then
gzip will efficiently ignore the extra bits. */
bool ExtractTar::StartGzip()
{
if (DecompressProg.empty())
{
InFd.OpenDescriptor(File.Fd(), FileFd::ReadOnly, FileFd::None, false);
return true;
}
std::vector<APT::Configuration::Compressor> const compressors = APT::Configuration::getCompressors();
std::vector<APT::Configuration::Compressor>::const_iterator compressor = compressors.begin();
for (; compressor != compressors.end(); compressor++) {
if (compressor->Name == DecompressProg) {
return InFd.OpenDescriptor(File.Fd(), FileFd::ReadOnly, *compressor, false);
}
}
return _error->Error(_("Cannot find a configured compressor for '%s'"),
DecompressProg.c_str());
}
/*}}}*/
// ExtractTar::Go - Perform extraction /*{{{*/
// ---------------------------------------------------------------------
/* This reads each 512 byte block from the archive and extracts the header
information into the Item structure. Then it resolves the UID/GID and
invokes the correct processing function. */
bool ExtractTar::Go(pkgDirStream &Stream)
{
if (StartGzip() == false)
return false;
// Loop over all blocks
string LastLongLink, ItemLink;
string LastLongName, ItemName;
while (1)
{
bool BadRecord = false;
unsigned char Block[512];
if (InFd.Read(Block,sizeof(Block),true) == false)
return false;
if (InFd.Eof() == true)
break;
// Get the checksum
TarHeader *Tar = (TarHeader *)Block;
unsigned long CheckSum;
if (StrToNum(Tar->Checksum,CheckSum,sizeof(Tar->Checksum),8) == false)
return _error->Error(_("Corrupted archive"));
/* Compute the checksum field. The actual checksum is blanked out
with spaces so it is not included in the computation */
unsigned long NewSum = 0;
memset(Tar->Checksum,' ',sizeof(Tar->Checksum));
for (int I = 0; I != sizeof(Block); I++)
NewSum += Block[I];
/* Check for a block of nulls - in this case we kill gzip, GNU tar
does this.. */
if (NewSum == ' '*sizeof(Tar->Checksum))
return Done(true);
if (NewSum != CheckSum)
return _error->Error(_("Tar checksum failed, archive corrupted"));
// Decode all of the fields
pkgDirStream::Item Itm;
if (StrToNum(Tar->Mode,Itm.Mode,sizeof(Tar->Mode),8) == false ||
(Base256ToNum(Tar->UserID,Itm.UID,8) == false &&
StrToNum(Tar->UserID,Itm.UID,sizeof(Tar->UserID),8) == false) ||
(Base256ToNum(Tar->GroupID,Itm.GID,8) == false &&
StrToNum(Tar->GroupID,Itm.GID,sizeof(Tar->GroupID),8) == false) ||
(Base256ToNum(Tar->Size,Itm.Size,12) == false &&
StrToNum(Tar->Size,Itm.Size,sizeof(Tar->Size),8) == false) ||
(Base256ToNum(Tar->MTime,Itm.MTime,12) == false &&
StrToNum(Tar->MTime,Itm.MTime,sizeof(Tar->MTime),8) == false) ||
StrToNum(Tar->Major,Itm.Major,sizeof(Tar->Major),8) == false ||
StrToNum(Tar->Minor,Itm.Minor,sizeof(Tar->Minor),8) == false)
return _error->Error(_("Corrupted archive"));
// Grab the filename and link target: use last long name if one was
// set, otherwise use the header value as-is, but remember that it may
// fill the entire 100-byte block and needs to be zero-terminated.
// See Debian Bug #689582.
if (LastLongName.empty() == false)
Itm.Name = (char *)LastLongName.c_str();
else
Itm.Name = (char *)ItemName.assign(Tar->Name, sizeof(Tar->Name)).c_str();
if (Itm.Name[0] == '.' && Itm.Name[1] == '/' && Itm.Name[2] != 0)
Itm.Name += 2;
if (LastLongLink.empty() == false)
Itm.LinkTarget = (char *)LastLongLink.c_str();
else
Itm.LinkTarget = (char *)ItemLink.assign(Tar->LinkName, sizeof(Tar->LinkName)).c_str();
// Convert the type over
switch (Tar->LinkFlag)
{
case NormalFile0:
case NormalFile:
Itm.Type = pkgDirStream::Item::File;
break;
case HardLink:
Itm.Type = pkgDirStream::Item::HardLink;
break;
case SymbolicLink:
Itm.Type = pkgDirStream::Item::SymbolicLink;
break;
case CharacterDevice:
Itm.Type = pkgDirStream::Item::CharDevice;
break;
case BlockDevice:
Itm.Type = pkgDirStream::Item::BlockDevice;
break;
case Directory:
Itm.Type = pkgDirStream::Item::Directory;
break;
case FIFO:
Itm.Type = pkgDirStream::Item::FIFO;
break;
case GNU_LongLink:
{
unsigned long long Length = Itm.Size;
unsigned char Block[512];
while (Length > 0)
{
if (InFd.Read(Block,sizeof(Block),true) == false)
return false;
if (Length <= sizeof(Block))
{
LastLongLink.append(Block,Block+sizeof(Block));
break;
}
LastLongLink.append(Block,Block+sizeof(Block));
Length -= sizeof(Block);
}
continue;
}
case GNU_LongName:
{
unsigned long long Length = Itm.Size;
unsigned char Block[512];
while (Length > 0)
{
if (InFd.Read(Block,sizeof(Block),true) == false)
return false;
if (Length < sizeof(Block))
{
LastLongName.append(Block,Block+sizeof(Block));
break;
}
LastLongName.append(Block,Block+sizeof(Block));
Length -= sizeof(Block);
}
continue;
}
default:
BadRecord = true;
_error->Warning(_("Unknown TAR header type %u, member %s"),(unsigned)Tar->LinkFlag,Tar->Name);
break;
}
int Fd = -1;
if (BadRecord == false)
if (Stream.DoItem(Itm,Fd) == false)
return false;
// Copy the file over the FD
unsigned long long Size = Itm.Size;
while (Size != 0)
{
unsigned char Junk[32*1024];
unsigned long Read = min(Size, (unsigned long long)sizeof(Junk));
if (InFd.Read(Junk,((Read+511)/512)*512) == false)
return false;
if (BadRecord == false)
{
if (Fd > 0)
{
if (write(Fd,Junk,Read) != (signed)Read)
return Stream.Fail(Itm,Fd);
}
else
{
/* An Fd of -2 means to send to a special processing
function */
if (Fd == -2)
if (Stream.Process(Itm,Junk,Read,Itm.Size - Size) == false)
return Stream.Fail(Itm,Fd);
}
}
Size -= Read;
}
// And finish up
if (BadRecord == false)
if (Stream.FinishedFile(Itm,Fd) == false)
return false;
LastLongName.erase();
LastLongLink.erase();
}
return Done(false);
}
/*}}}*/