path: root/extended.cc

/*  Tarlz - Archiver with multimember lzip compression
    Copyright (C) 2013-2019 Antonio Diaz Diaz.

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#define _FILE_OFFSET_BITS 64

#include <cctype>
#include <climits>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <vector>
#include <pthread.h>
#include <stdint.h>

#include "tarlz.h"


namespace {

unsigned decimal_digits( unsigned long long value )
  {
  unsigned digits = 1;
  while( value >= 10 ) { value /= 10; ++digits; }
  return digits;
  }


unsigned long long record_size( const unsigned keyword_size,
                                const unsigned long value_size )
  {
  // size = ' ' + keyword + '=' + value + '\n'
  unsigned long long size = 1 + keyword_size + 1 + value_size + 1;
  const unsigned d1 = decimal_digits( size );
  size += decimal_digits( d1 + size );
  return size;
  }


unsigned long long parse_decimal( const char * const ptr,
                                  const char ** const tailp,
                                  const unsigned long long size )
  {
  unsigned long long result = 0;
  unsigned long long i = 0;
  while( i < size && std::isspace( ptr[i] ) ) ++i;
  if( !std::isdigit( (unsigned char)ptr[i] ) )
    { if( tailp ) *tailp = ptr; return 0; }
  for( ; i < size && std::isdigit( (unsigned char)ptr[i] ); ++i )
    {
    const unsigned long long prev = result;
    result *= 10; result += ptr[i] - '0';
    if( result < prev || result > LLONG_MAX )		// overflow
      { if( tailp ) *tailp = ptr; return 0; }
    }
  if( tailp ) *tailp = ptr + i;
  return result;
  }


uint32_t parse_record_crc( const char * const ptr )
  {
  uint32_t crc = 0;
  for( int i = 0; i < 8; ++i )
    {
    crc <<= 4;
    if( ptr[i] >= '0' && ptr[i] <= '9' ) crc += ptr[i] - '0';
    else if( ptr[i] >= 'A' && ptr[i] <= 'F' ) crc += ptr[i] + 10 - 'A';
    else if( ptr[i] >= 'a' && ptr[i] <= 'f' ) crc += ptr[i] + 10 - 'a';
    else { crc = 0; break; }		// invalid digit in crc string
    }
  return crc;
  }


unsigned char xdigit( const unsigned value )
  {
  if( value <= 9 ) return '0' + value;
  if( value <= 15 ) return 'A' + value - 10;
  return 0;
  }

void print_hex( char * const buf, int size, unsigned long long num )
  {
  while( --size >= 0 ) { buf[size] = xdigit( num & 0x0F ); num >>= 4; }
  }

void print_decimal( char * const buf, int size, unsigned long long num )
  { while( --size >= 0 ) { buf[size] = '0' + ( num % 10 ); num /= 10; } }


bool print_record( char * const buf, const unsigned long long size,
                   const char * keyword, const std::string & value )
  {
  // "size keyword=value\n"
  unsigned long long pos = decimal_digits( size );
  print_decimal( buf, pos, size ); buf[pos++] = ' ';
  while( *keyword ) { buf[pos++] = *keyword; ++keyword; } buf[pos++] = '=';
  std::memcpy( buf + pos, value.c_str(), value.size() );
  pos += value.size(); buf[pos++] = '\n';
  return pos == size;
  }

bool print_record( char * const buf, const int size,
                   const char * keyword, const unsigned long long value )
  {
  // "size keyword=value\n"
  int pos = decimal_digits( size );
  print_decimal( buf, pos, size ); buf[pos++] = ' ';
  while( *keyword ) { buf[pos++] = *keyword; ++keyword; } buf[pos++] = '=';
  const int vd =  decimal_digits( value );
  print_decimal( buf + pos, vd, value ); pos += vd; buf[pos++] = '\n';
  return pos == size;
  }

} // end namespace


const std::string Extended::crc_record( "22 GNU.crc32=00000000\n" );

void Extended::calculate_sizes() const
  {
  linkpath_recsize_ = linkpath_.size() ? record_size( 8, linkpath_.size() ) : 0;
  path_recsize_ = path_.size() ? record_size( 4, path_.size() ) : 0;
  file_size_recsize_ =
    ( file_size_ > 0 ) ? record_size( 4, decimal_digits( file_size_ ) ) : 0;
  edsize_ = linkpath_recsize_ + path_recsize_ + file_size_recsize_ +
            crc_record.size();
  padded_edsize_ = round_up( edsize_ );
  full_size_ = header_size + padded_edsize_;
  }


// Returns the extended block size, or -1 if error.
long long Extended::format_block( Resizable_buffer & rbuf ) const
  {
  if( empty() ) return 0;			// no extended data
  const unsigned long long bufsize = full_size();	// recalculate sizes
  if( edsize_ <= 0 ) return 0;			// no extended data
  if( edsize_ >= 1LL << 33 ) return -1;		// too much extended data
  if( !rbuf.resize( bufsize ) ) return -1;	// extended block buffer
  uint8_t * const header = (uint8_t *)rbuf();	// extended header
  char * const buf = rbuf() + header_size;	// extended records
  init_tar_header( header );
  header[typeflag_o] = tf_extended;		// fill only required fields
  print_octal( header + size_o, size_l - 1, edsize_ );
  print_octal( header + chksum_o, chksum_l - 1, ustar_chksum( header ) );

  if( path_recsize_ && !print_record( buf, path_recsize_, "path", path_ ) )
    return -1;
  long long pos = path_recsize_;
  if( linkpath_recsize_ &&
      !print_record( buf + pos, linkpath_recsize_, "linkpath", linkpath_ ) )
    return -1;
  pos += linkpath_recsize_;
  if( file_size_recsize_ &&
      !print_record( buf + pos, file_size_recsize_, "size", file_size_ ) )
    return -1;
  pos += file_size_recsize_;
  const unsigned crc_size = Extended::crc_record.size();
  std::memcpy( buf + pos, Extended::crc_record.c_str(), crc_size );
  pos += crc_size;
  if( pos != edsize_ ) return -1;
  print_hex( buf + edsize_ - 9, 8,
             crc32c.windowed_crc( (const uint8_t *)buf, edsize_ - 9, edsize_ ) );
  if( padded_edsize_ > edsize_ )			// wipe padding
    std::memset( buf + edsize_, 0, padded_edsize_ - edsize_ );
  crc_present_ = true;
  return bufsize;
  }


bool Extended::parse( const char * const buf, const unsigned long long edsize,
                      const bool permissive )
  {
  reset(); full_size_ = -1;			// invalidate cached sizes
  for( unsigned long long pos = 0; pos < edsize; )	// parse records
    {
    const char * tail;
    const unsigned long long rsize =
      parse_decimal( buf + pos, &tail, edsize - pos );
    if( rsize == 0 || rsize > edsize - pos ||
        tail[0] != ' ' || buf[pos+rsize-1] != '\n' ) return false;
    ++tail;	// point to keyword
    // rest = length of (keyword + '=' + value) without the final newline
    const unsigned long long rest = ( buf + ( pos + rsize - 1 ) ) - tail;
    if( rest > 5 && std::memcmp( tail, "path=", 5 ) == 0 )
      {
      if( path_.size() && !permissive ) return false;
      path_.assign( tail + 5, rest - 5 );
      // this also truncates path_ at the first embedded null character
      path_.assign( remove_leading_dotslash( path_.c_str() ) );
      }
    else if( rest > 9 && std::memcmp( tail, "linkpath=", 9 ) == 0 )
      {
      if( linkpath_.size() && !permissive ) return false;
      unsigned long long len = rest - 9;
      while( len > 1 && tail[9+len-1] == '/' ) --len;	// trailing '/'
      linkpath_.assign( tail + 9, len );
      }
    else if( rest > 5 && std::memcmp( tail, "size=", 5 ) == 0 )
      {
      if( file_size_ != 0 && !permissive ) return false;
      file_size_ = parse_decimal( tail + 5, &tail, rest - 5 );
      // parse error or size fits in ustar header
      if( file_size_ < 1ULL << 33 || tail != buf + ( pos + rsize - 1 ) )
        return false;
      }
    else if( rest > 10 && std::memcmp( tail, "GNU.crc32=", 10 ) == 0 )
      {
      if( crc_present_ && !permissive ) return false;
      if( rsize != crc_record.size() ) return false;
      crc_present_ = true;
      const uint32_t stored_crc = parse_record_crc( tail + 10 );
      const uint32_t computed_crc =
        crc32c.windowed_crc( (const uint8_t *)buf, pos + rsize - 9, edsize );
      if( stored_crc != computed_crc )
        {
        if( verbosity >= 2 )
          std::fprintf( stderr, "CRC32C = %08X\n", (unsigned)computed_crc );
        return false;
        }
      }
    pos += rsize;
    }
  return true;
  }


// if needed, copy linkpath, path and file_size from ustar header
void Extended::fill_from_ustar( const Tar_header header )
  {
  if( linkpath_.empty() )		// copy linkpath from ustar header
    {
    int len = 0;
    while( len < linkname_l && header[linkname_o+len] ) ++len;
    while( len > 1 && header[linkname_o+len-1] == '/' ) --len;	// trailing '/'
    if( len > 0 )
      {
      linkpath_.assign( (const char *)header + linkname_o, len );
      full_size_ = -1;
      }
    }

  if( path_.empty() )			// copy path from ustar header
    {
    char stored_name[prefix_l+1+name_l+1];
    int len = 0;
    while( len < prefix_l && header[prefix_o+len] )
      { stored_name[len] = header[prefix_o+len]; ++len; }
    if( len && header[name_o] ) stored_name[len++] = '/';
    for( int i = 0; i < name_l && header[name_o+i]; ++i )
      { stored_name[len] = header[name_o+i]; ++len; }
    while( len > 0 && stored_name[len-1] == '/' ) --len;	// trailing '/'
    stored_name[len] = 0;
    path( remove_leading_dotslash( stored_name ) );
    }

  const Typeflag typeflag = (Typeflag)header[typeflag_o];
  if( file_size_ == 0 &&		// copy file_size from ustar header
      ( typeflag == tf_regular || typeflag == tf_hiperf ) )
    file_size( parse_octal( header + size_o, size_l ) );
  }