1 files changed, 192 insertions, 0 deletions
diff --git a/file_index.cc b/file_index.cc
new file mode 100644
index 0000000..4a1759c
--- /dev/null
+++ b/file_index.cc
@@ -0,0 +1,192 @@
+/*  Lzip - LZMA lossless data compressor
+    Copyright (C) 2008-2017 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 <algorithm>
+#include <cerrno>
+#include <cstdio>
+#include <cstring>
+#include <string>
+#include <vector>
+#include <stdint.h>
+#include <unistd.h>
+
+#include "lzip.h"
+#include "file_index.h"
+
+
+namespace {
+
+int seek_read( const int fd, uint8_t * const buf, const int size,
+               const long long pos )
+  {
+  if( lseek( fd, pos, SEEK_SET ) == pos )
+    return readblock( fd, buf, size );
+  return 0;
+  }
+
+} // end namespace
+
+
+void File_index::set_errno_error( const char * const msg )
+  {
+  error_ = msg; error_ += std::strerror( errno );
+  retval_ = 1;
+  }
+
+void File_index::set_num_error( const char * const msg, unsigned long long num )
+  {
+  char buf[80];
+  snprintf( buf, sizeof buf, "%s%llu", msg, num );
+  error_ = buf;
+  retval_ = 2;
+  }
+
+
+// If successful, push last member and set pos to member header.
+bool File_index::skip_trailing_data( const int fd, long long & pos )
+  {
+  enum { block_size = 16384,
+         buffer_size = block_size + File_trailer::size - 1 + File_header::size };
+  uint8_t buffer[buffer_size];
+  if( pos < min_member_size ) return false;
+  int bsize = pos % block_size;			// total bytes in buffer
+  if( bsize <= buffer_size - block_size ) bsize += block_size;
+  int search_size = bsize;			// bytes to search for trailer
+  int rd_size = bsize;				// bytes to read from file
+  unsigned long long ipos = pos - rd_size;	// aligned to block_size
+
+  while( true )
+    {
+    if( seek_read( fd, buffer, rd_size, ipos ) != rd_size )
+      { set_errno_error( "Error seeking member trailer: " ); return false; }
+    const uint8_t max_msb = ( ipos + search_size ) >> 56;
+    for( int i = search_size; i >= File_trailer::size; --i )
+      if( buffer[i-1] <= max_msb )	// most significant byte of member_size
+        {
+        File_trailer & trailer =
+          *(File_trailer *)( buffer + i - File_trailer::size );
+        const unsigned long long member_size = trailer.member_size();
+        if( member_size == 0 )
+          { while( i > File_trailer::size && buffer[i-9] == 0 ) --i; continue; }
+        if( member_size < min_member_size || member_size > ipos + i )
+          continue;
+        File_header header;
+        if( seek_read( fd, header.data, File_header::size,
+                       ipos + i - member_size ) != File_header::size )
+          { set_errno_error( "Error reading member header: " ); return false; }
+        const unsigned dictionary_size = header.dictionary_size();
+        if( !header.verify_magic() || !header.verify_version() ||
+            !isvalid_ds( dictionary_size ) ) continue;
+        if( (*(File_header *)( buffer + i )).verify_prefix( bsize - i ) )
+          {
+          error_ = "Last member in input file is truncated or corrupt.";
+          retval_ = 2; return false;
+          }
+        pos = ipos + i - member_size;
+        member_vector.push_back( Member( 0, trailer.data_size(), pos,
+                                         member_size, dictionary_size ) );
+        return true;
+        }
+    if( ipos <= 0 )
+      { set_num_error( "Member size in trailer is corrupt at pos ", pos - 8 );
+        return false; }
+    bsize = buffer_size;
+    search_size = bsize - File_header::size;
+    rd_size = block_size;
+    ipos -= rd_size;
+    std::memcpy( buffer + rd_size, buffer, buffer_size - rd_size );
+    }
+  }
+
+
+File_index::File_index( const int infd, const bool ignore_trailing )
+  : isize( lseek( infd, 0, SEEK_END ) ), retval_( 0 )
+  {
+  if( isize < 0 )
+    { set_errno_error( "Input file is not seekable: " ); return; }
+  if( isize < min_member_size )
+    { error_ = "Input file is too short."; retval_ = 2; return; }
+  if( isize > INT64_MAX )
+    { error_ = "Input file is too long (2^63 bytes or more).";
+      retval_ = 2; return; }
+
+  File_header header;
+  if( seek_read( infd, header.data, File_header::size, 0 ) != File_header::size )
+    { set_errno_error( "Error reading member header: " ); return; }
+  if( !header.verify_magic() )
+    { error_ = bad_magic_msg; retval_ = 2; return; }
+  if( !header.verify_version() )
+    { error_ = bad_version( header.version() ); retval_ = 2; return; }
+  if( !isvalid_ds( header.dictionary_size() ) )
+    { error_ = bad_dict_msg; retval_ = 2; return; }
+
+  long long pos = isize;	// always points to a header or to EOF
+  while( pos >= min_member_size )
+    {
+    File_trailer trailer;
+    if( seek_read( infd, trailer.data, File_trailer::size,
+                   pos - File_trailer::size ) != File_trailer::size )
+      { set_errno_error( "Error reading member trailer: " ); break; }
+    const unsigned long long member_size = trailer.member_size();
+    if( member_size < min_member_size || member_size > (unsigned long long)pos )
+      {
+      if( !member_vector.empty() )
+        set_num_error( "Member size in trailer is corrupt at pos ", pos - 8 );
+      else if( skip_trailing_data( infd, pos ) )
+        { if( ignore_trailing ) continue;
+          error_ = trailing_msg; retval_ = 2; return; }
+      break;
+      }
+    if( seek_read( infd, header.data, File_header::size,
+                   pos - member_size ) != File_header::size )
+      { set_errno_error( "Error reading member header: " ); break; }
+    const unsigned dictionary_size = header.dictionary_size();
+    if( !header.verify_magic() || !header.verify_version() ||
+        !isvalid_ds( dictionary_size ) )
+      {
+      if( !member_vector.empty() )
+        set_num_error( "Bad header at pos ", pos - member_size );
+      else if( skip_trailing_data( infd, pos ) )
+        { if( ignore_trailing ) continue;
+          error_ = trailing_msg; retval_ = 2; return; }
+      break;
+      }
+    pos -= member_size;
+    member_vector.push_back( Member( 0, trailer.data_size(), pos,
+                                     member_size, dictionary_size ) );
+    }
+  if( pos != 0 || member_vector.empty() )
+    {
+    member_vector.clear();
+    if( retval_ == 0 ) { error_ = "Can't create file index."; retval_ = 2; }
+    return;
+    }
+  std::reverse( member_vector.begin(), member_vector.end() );
+  for( unsigned long i = 0; i < member_vector.size() - 1; ++i )
+    {
+    const long long end = member_vector[i].dblock.end();
+    if( end < 0 || end > INT64_MAX )
+      {
+      member_vector.clear();
+      error_ = "Data in input file is too long (2^63 bytes or more).";
+      retval_ = 2; return;
+      }
+    member_vector[i+1].dblock.pos( end );
+    }
+  }