1 files changed, 210 insertions, 0 deletions
diff --git a/lzip_index.cc b/lzip_index.cc
new file mode 100644
index 0000000..bcdc54f
--- /dev/null
+++ b/lzip_index.cc
@@ -0,0 +1,210 @@
+/* Tarlz - Archiver with multimember lzip compression
+   Copyright (C) 2013-2024 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 <unistd.h>
+
+#include "tarlz.h"
+#include "lzip_index.h"
+
+
+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;
+  }
+
+namespace {
+
+const char * bad_version( const unsigned version )
+  {
+  static char buf[80];
+  snprintf( buf, sizeof buf, "Version %u member format not supported.",
+            version );
+  return buf;
+  }
+
+} // end namespace
+
+
+bool Lzip_index::check_header( const Lzip_header & header, const bool first )
+  {
+  if( !header.check_magic() )
+    { error_ = bad_magic_msg; retval_ = 2; if( first ) bad_magic_ = true;
+      return false; }
+  if( !header.check_version() )
+    { error_ = bad_version( header.version() ); retval_ = 2; return false; }
+  if( !isvalid_ds( header.dictionary_size() ) )
+    { error_ = bad_dict_msg; retval_ = 2; return false; }
+  return true;
+  }
+
+void Lzip_index::set_errno_error( const char * const msg )
+  {
+  error_ = msg; error_ += std::strerror( errno );
+  retval_ = 1;
+  }
+
+void Lzip_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;
+  }
+
+
+bool Lzip_index::read_header( const int fd, Lzip_header & header,
+                              const long long pos )
+  {
+  if( seek_read( fd, header.data, header.size, pos ) != header.size )
+    { set_errno_error( "Error reading member header: " ); return false; }
+  return true;
+  }
+
+
+// If successful, push last member and set pos to member header.
+bool Lzip_index::skip_trailing_data( const int fd, unsigned long long & pos )
+  {
+  if( pos < min_member_size ) return false;
+  enum { block_size = 16384,
+         buffer_size = block_size + Lzip_trailer::size - 1 + Lzip_header::size };
+  uint8_t buffer[buffer_size];
+  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 >= Lzip_trailer::size; --i )
+      if( buffer[i-1] <= max_msb )	// most significant byte of member_size
+        {
+        const Lzip_trailer & trailer =
+          *(const Lzip_trailer *)( buffer + i - trailer.size );
+        const unsigned long long member_size = trailer.member_size();
+        if( member_size == 0 )			// skip trailing zeros
+          { while( i > trailer.size && buffer[i-9] == 0 ) --i; continue; }
+        if( member_size > ipos + i || !trailer.check_consistency() ) continue;
+        Lzip_header header;
+        if( !read_header( fd, header, ipos + i - member_size ) ) return false;
+        if( !header.check() ) continue;
+        const Lzip_header & header2 = *(const Lzip_header *)( buffer + i );
+        const bool full_h2 = bsize - i >= header.size;
+        if( header2.check_prefix( bsize - i ) )	// last member
+          {
+          if( !full_h2 ) error_ = "Last member in input file is truncated.";
+          else if( check_header( header2, false ) )
+            error_ = "Last member in input file is truncated or corrupt.";
+          retval_ = 2; return false;
+          }
+        if( full_h2 && header2.check_corrupt() )
+          { error_ = corrupt_mm_msg; retval_ = 2; return false; }
+        pos = ipos + i - member_size;			// good member
+        const unsigned dictionary_size = header.dictionary_size();
+        if( dictionary_size_ < dictionary_size )
+          dictionary_size_ = dictionary_size;
+        member_vector.push_back( Member( 0, trailer.data_size(), pos,
+                                         member_size, dictionary_size ) );
+        return true;
+        }
+    if( ipos == 0 )
+      { set_num_error( "Bad trailer at pos ", pos - Lzip_trailer::size );
+        return false; }
+    bsize = buffer_size;
+    search_size = bsize - Lzip_header::size;
+    rd_size = block_size;
+    ipos -= rd_size;
+    std::memcpy( buffer + rd_size, buffer, buffer_size - rd_size );
+    }
+  }
+
+
+Lzip_index::Lzip_index( const int infd )
+  : insize( lseek( infd, 0, SEEK_END ) ), retval_( 0 ), dictionary_size_( 0 ),
+    bad_magic_( false )
+  {
+  if( insize < 0 )
+    { set_errno_error( "Input file is not seekable: " ); return; }
+  if( insize < min_member_size )
+    { error_ = "Input file is too short."; retval_ = 2; return; }
+  if( insize > INT64_MAX )
+    { error_ = "Input file is too long (2^63 bytes or more).";
+      retval_ = 2; return; }
+
+  Lzip_header header;
+  if( !read_header( infd, header, 0 ) ||
+      !check_header( header, true ) ) return;
+
+  unsigned long long pos = insize;	// always points to a header or to EOF
+  while( pos >= min_member_size )
+    {
+    Lzip_trailer trailer;
+    if( seek_read( infd, trailer.data, trailer.size, pos - trailer.size ) !=
+        trailer.size )
+      { set_errno_error( "Error reading member trailer: " ); break; }
+    const unsigned long long member_size = trailer.member_size();
+    if( member_size > pos || !trailer.check_consistency() )	// bad trailer
+      {
+      if( member_vector.empty() )
+        { if( skip_trailing_data( infd, pos ) ) continue; return; }
+      set_num_error( "Bad trailer at pos ", pos - trailer.size ); break;
+      }
+    if( !read_header( infd, header, pos - member_size ) ) break;
+    if( !header.check() )				// bad header
+      {
+      if( member_vector.empty() )
+        { if( skip_trailing_data( infd, pos ) ) continue; return; }
+      set_num_error( "Bad header at pos ", pos - member_size ); break;
+      }
+    pos -= member_size;					// good member
+    const unsigned dictionary_size = header.dictionary_size();
+    if( dictionary_size_ < dictionary_size )
+      dictionary_size_ = dictionary_size;
+    member_vector.push_back( Member( 0, trailer.data_size(), pos,
+                                     member_size, dictionary_size ) );
+    }
+  if( pos != 0 || member_vector.empty() || retval_ != 0 )
+    {
+    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 )
+    {
+    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;
+      }
+    if( i + 1 >= member_vector.size() ) break;
+    member_vector[i+1].dblock.pos( end );
+    }
+  }