path: root/decode.cc

/* Tarlz - Archiver with multimember lzip compression
   Copyright (C) 2013-2022 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 <cctype>
#include <cerrno>
#include <cstdio>
#include <cstdlib>
#include <stdint.h>	// for lzlib.h
#include <unistd.h>
#include <utime.h>
#include <sys/stat.h>
#if !defined __FreeBSD__ && !defined __OpenBSD__ && !defined __NetBSD__ && \
    !defined __DragonFly__ && !defined __APPLE__ && !defined __OS2__
#include <sys/sysmacros.h>		// for major, minor, makedev
#endif
#include <lzlib.h>

#include "tarlz.h"
#include "arg_parser.h"
#include "lzip_index.h"
#include "archive_reader.h"


namespace {

Resizable_buffer grbuf;

bool skip_warn( const bool reset = false )	// avoid duplicate warnings
  {
  static bool skipping = false;

  if( reset ) skipping = false;
  else if( !skipping )
    { skipping = true; show_error( "Skipping to next header." ); return true; }
  return false;
  }


void read_error( const Archive_reader & ar )
  {
  show_file_error( ar.ad.namep, ar.e_msg(), ar.e_code() );
  if( ar.e_skip() ) skip_warn();
  }


int skip_member( Archive_reader & ar, const Extended & extended )
  {
  const int ret = ar.skip_member( extended );
  if( ret != 0 ) { read_error( ar ); if( ret == 2 ) return 2; }
  return 0;
  }


int compare_member( const Cl_options & cl_opts, Archive_reader & ar,
                    const Extended & extended, const Tar_header header )
  {
  if( !show_member_name( extended, header, 1, grbuf ) ) return 1;
  std::string estr, ostr;
  const bool stat_differs =
    !compare_file_type( estr, ostr, cl_opts, extended, header );
  if( estr.size() ) std::fputs( estr.c_str(), stderr );
  if( ostr.size() ) { std::fputs( ostr.c_str(), stdout ); std::fflush( stdout ); }
  if( extended.file_size() <= 0 ) return 0;
  const Typeflag typeflag = (Typeflag)header[typeflag_o];
  if( ( typeflag != tf_regular && typeflag != tf_hiperf ) || stat_differs )
    return skip_member( ar, extended );
  // else compare file contents
  const char * const filename = extended.path().c_str();
  const int infd2 = open_instream( filename );
  if( infd2 < 0 )
    { set_error_status( 1 ); return skip_member( ar, extended ); }
  int retval = compare_file_contents( estr, ostr, ar, extended.file_size(),
                                      filename, infd2 );
  if( retval ) { read_error( ar ); if( retval != 2 ) retval = 0; }
  else { if( estr.size() ) std::fputs( estr.c_str(), stderr );
         if( ostr.size() )
           { std::fputs( ostr.c_str(), stdout ); std::fflush( stdout ); } }
  return retval;
  }


int list_member( Archive_reader & ar,
                 const Extended & extended, const Tar_header header )
  {
  if( !show_member_name( extended, header, 0, grbuf ) ) return 1;
  return skip_member( ar, extended );
  }


int extract_member( const Cl_options & cl_opts, Archive_reader & ar,
                    const Extended & extended, const Tar_header header )
  {
  const char * const filename = extended.path().c_str();
  if( contains_dotdot( filename ) )
    {
    show_file_error( filename, "Contains a '..' component, skipping." );
    return skip_member( ar, extended );
    }
  mode_t mode = parse_octal( header + mode_o, mode_l );	 // 12 bits
  if( geteuid() != 0 && !cl_opts.preserve_permissions ) mode &= ~get_umask();
  const time_t mtime = parse_octal( header + mtime_o, mtime_l ); // 33 bits
  const Typeflag typeflag = (Typeflag)header[typeflag_o];
  const bool islink = ( typeflag == tf_link || typeflag == tf_symlink );
  int outfd = -1;

  if( !show_member_name( extended, header, 1, grbuf ) ) return 1;
  std::remove( filename );
  make_path( filename );
  switch( typeflag )
    {
    case tf_regular:
    case tf_hiperf:
      outfd = open_outstream( filename );
      if( outfd < 0 ) return 2;
      break;
    case tf_link:
    case tf_symlink:
      {
      const char * const linkname = extended.linkpath().c_str();
      const bool hard = typeflag == tf_link;
      if( ( hard && link( linkname, filename ) != 0 ) ||
          ( !hard && symlink( linkname, filename ) != 0 ) )
        {
        if( verbosity >= 0 )
          std::fprintf( stderr, "Can't %slink '%s' to '%s': %s.\n",
                        hard ? "" : "sym", linkname, filename,
                        std::strerror( errno ) );
        return 2;
        }
      } break;
    case tf_directory:
      if( mkdir( filename, mode ) != 0 && errno != EEXIST )
        {
        show_file_error( filename, "Can't create directory", errno );
        return 2;
        }
      break;
    case tf_chardev:
    case tf_blockdev:
      {
      const unsigned dev =
        makedev( parse_octal( header + devmajor_o, devmajor_l ),
                 parse_octal( header + devminor_o, devminor_l ) );
      const int dmode = ( typeflag == tf_chardev ? S_IFCHR : S_IFBLK ) | mode;
      if( mknod( filename, dmode, dev ) != 0 )
        {
        show_file_error( filename, "Can't create device node", errno );
        return 2;
        }
      break;
      }
    case tf_fifo:
      if( mkfifo( filename, mode ) != 0 && errno != EEXIST )
        {
        show_file_error( filename, "Can't create FIFO file", errno );
        return 2;
        }
      break;
    default:
      if( verbosity >= 0 )
        std::fprintf( stderr, "File type '%c' not supported for file '%s'.\n",
                      typeflag, filename );
      return 2;
    }

  const uid_t uid = (uid_t)parse_octal( header + uid_o, uid_l );
  const gid_t gid = (gid_t)parse_octal( header + gid_o, gid_l );
  if( !islink && chown( filename, uid, gid ) != 0 &&
      errno != EPERM && errno != EINVAL )
    {
    show_file_error( filename, "Can't change file owner", errno );
    return 2;
    }

  if( typeflag == tf_regular || typeflag == tf_hiperf )
    fchmod( outfd, mode );			// ignore errors

  const int bufsize = 32 * header_size;
  uint8_t buf[bufsize];
  long long rest = extended.file_size();
  const int rem = rest % header_size;
  const int padding = rem ? header_size - rem : 0;
  while( rest > 0 )
    {
    const int rsize = ( rest >= bufsize ) ? bufsize : rest + padding;
    const int ret = ar.read( buf, rsize );
    if( ret != 0 )
      {
      read_error( ar );
      if( outfd >= 0 )
        {
        if( cl_opts.keep_damaged )
          { writeblock( outfd, buf, std::min( rest, (long long)ar.e_size() ) );
            close( outfd ); }
        else { close( outfd ); std::remove( filename ); }
        }
      if( ret == 2 ) return 2; else return 0;
      }
    const int wsize = ( rest >= bufsize ) ? bufsize : rest;
    if( outfd >= 0 && writeblock( outfd, buf, wsize ) != wsize )
      { show_file_error( filename, "Error writing file", errno ); return 2; }
    rest -= wsize;
    }
  if( outfd >= 0 && close( outfd ) != 0 )
    { show_file_error( filename, "Error closing file", errno ); return 2; }
  if( !islink )
    {
    struct utimbuf t;
    t.actime = mtime;
    t.modtime = mtime;
    utime( filename, &t );			// ignore errors
    }
  return 0;
  }


void format_file_diff( std::string & ostr, const char * const filename,
                       const char * const msg )
  {
  if( verbosity < 0 ) return;
    { ostr += filename; ostr += ": "; ostr += msg; ostr += '\n'; }
  }

} // end namespace


bool compare_file_type( std::string & estr, std::string & ostr,
                        const Cl_options & cl_opts,
                        const Extended & extended, const Tar_header header )
  {
  const char * const filename = extended.path().c_str();
  const Typeflag typeflag = (Typeflag)header[typeflag_o];
  struct stat st;
  bool diff = false, size_differs = false, type_differs = true;
  if( hstat( filename, &st, cl_opts.dereference ) != 0 )
    format_file_error( estr, filename, "warning: Can't stat", errno );
  else if( ( typeflag == tf_regular || typeflag == tf_hiperf ) &&
           !S_ISREG( st.st_mode ) )
    format_file_diff( ostr, filename, "Is not a regular file" );
  else if( typeflag == tf_symlink && !S_ISLNK( st.st_mode ) )
    format_file_diff( ostr, filename, "Is not a symlink" );
  else if( typeflag == tf_chardev && !S_ISCHR( st.st_mode ) )
    format_file_diff( ostr, filename, "Is not a character device" );
  else if( typeflag == tf_blockdev && !S_ISBLK( st.st_mode ) )
    format_file_diff( ostr, filename, "Is not a block device" );
  else if( typeflag == tf_directory && !S_ISDIR( st.st_mode ) )
    format_file_diff( ostr, filename, "Is not a directory" );
  else if( typeflag == tf_fifo && !S_ISFIFO( st.st_mode ) )
    format_file_diff( ostr, filename, "Is not a FIFO" );
  else
    {
    type_differs = false;
    if( typeflag != tf_symlink )
      {
      const mode_t mode = parse_octal( header + mode_o, mode_l );  // 12 bits
      if( mode != ( st.st_mode & ( S_ISUID | S_ISGID | S_ISVTX |
                                   S_IRWXU | S_IRWXG | S_IRWXO ) ) )
        { format_file_diff( ostr, filename, "Mode differs" ); diff = true; }
      }
    if( !cl_opts.ignore_ids )
      {
      if( (uid_t)parse_octal( header + uid_o, uid_l ) != st.st_uid )
        { format_file_diff( ostr, filename, "Uid differs" ); diff = true; }
      if( (gid_t)parse_octal( header + gid_o, gid_l ) != st.st_gid )
        { format_file_diff( ostr, filename, "Gid differs" ); diff = true; }
      }
    if( typeflag != tf_symlink )
      {
      if( typeflag != tf_directory )
        {
        const time_t mtime = parse_octal( header + mtime_o, mtime_l ); // 33 bits
        if( mtime != st.st_mtime )
          { format_file_diff( ostr, filename, "Mod time differs" ); diff = true; }
        }
      if( ( typeflag == tf_regular || typeflag == tf_hiperf ) &&
          extended.file_size() != st.st_size )	// don't compare contents
        { format_file_diff( ostr, filename, "Size differs" ); size_differs = true; }
      if( ( typeflag == tf_chardev || typeflag == tf_blockdev ) &&
          ( parse_octal( header + devmajor_o, devmajor_l ) !=
            (unsigned)major( st.st_rdev ) ||
            parse_octal( header + devminor_o, devminor_l ) !=
            (unsigned)minor( st.st_rdev ) ) )
        { format_file_diff( ostr, filename, "Device number differs" ); diff = true; }
      }
    else
      {
      char * const buf = new char[st.st_size+1];
      long len = readlink( filename, buf, st.st_size );
      bool e = ( len != st.st_size );
      if( !e )
        {
        while( len > 1 && buf[len-1] == '/' ) --len;	// trailing '/'
        buf[len] = 0;
        if( extended.linkpath() != buf ) e = true;
        }
      delete[] buf;
      if( e ) { format_file_diff( ostr, filename, "Symlink differs" ); diff = true; }
      }
    }
  if( diff || size_differs || type_differs ) set_error_status( 1 );
  return !( size_differs || type_differs );
  }


bool compare_file_contents( std::string & estr, std::string & ostr,
                            Archive_reader_base & ar, const long long file_size,
                            const char * const filename, const int infd2 )
  {
  long long rest = file_size;
  const int rem = rest % header_size;
  const int padding = rem ? header_size - rem : 0;
  const int bufsize = 32 * header_size;
  uint8_t buf1[bufsize];
  uint8_t buf2[bufsize];
  int retval = 0;
  bool diff = false;
  estr.clear(); ostr.clear();
  while( rest > 0 )
    {
    const int rsize1 = ( rest >= bufsize ) ? bufsize : rest + padding;
    const int rsize2 = ( rest >= bufsize ) ? bufsize : rest;
    if( ( retval = ar.read( buf1, rsize1 ) ) != 0 ) { diff = true; break; }
    if( !diff )
      {
      const int rd = readblock( infd2, buf2, rsize2 );
      if( rd != rsize2 )
        {
        if( errno ) format_file_error( estr, filename, "Read error", errno );
        else format_file_diff( ostr, filename, "EOF found in file" );
        diff = true;
        }
      else
        {
        int i = 0; while( i < rsize2 && buf1[i] == buf2[i] ) ++i;
        if( i < rsize2 )
          { format_file_diff( ostr, filename, "Contents differ" ); diff = true; }
        }
      }
    if( rest < bufsize ) break;
    rest -= rsize1;
    }
  close( infd2 );
  if( diff ) set_error_status( 1 );
  return retval;
  }


int decode( const Cl_options & cl_opts )
  {
  // open archive before changing working directory
  const Archive_descriptor ad( cl_opts.archive_name );
  if( ad.infd < 0 ) return 1;

  // Execute -C options and mark filenames to be compared, extracted or listed.
  // name_pending is of type char instead of bool to allow concurrent update.
  std::vector< char > name_pending( cl_opts.parser.arguments(), false );
  for( int i = 0; i < cl_opts.parser.arguments(); ++i )
    {
    const int code = cl_opts.parser.code( i );
    if( code == 'C' && cl_opts.program_mode != m_list )
      {
      const char * const dir = cl_opts.parser.argument( i ).c_str();
      if( chdir( dir ) != 0 )
        { show_file_error( dir, "Error changing working directory", errno );
          return 1; }
      }
    if( !code && cl_opts.parser.argument( i ).size() &&
        !Exclude::excluded( cl_opts.parser.argument( i ).c_str() ) )
      name_pending[i] = true;
    }

  // multi-threaded --list is faster even with 1 thread and 1 file in archive
  // but multi-threaded --diff and --extract probably need at least 2 of each
  if( ( cl_opts.program_mode == m_diff || cl_opts.program_mode == m_list ||
        cl_opts.program_mode == m_extract ) && cl_opts.num_workers > 0 )
    {
    if( ad.indexed && ad.lzip_index.members() >= 2 )	// one file + eof
      {
      // show_file_error( ad.namep, "Is compressed seekable" );
      return decode_lz( cl_opts, ad, name_pending );
      }
    }

  Archive_reader ar( ad );
  Extended extended;			// metadata from extended records
  int retval = 0;
  bool prev_extended = false;		// prev header was extended
  while( true )				// process one tar header per iteration
    {
    Tar_header header;
    const int ret = ar.read( header, header_size );
    if( ret != 0 ) { read_error( ar ); if( ret == 2 ) { retval = 2; break; } }
    if( ret != 0 || !verify_ustar_chksum( header ) )
      {
      if( ret == 0 && block_is_zero( header, header_size ) )
        {
        if( !prev_extended || cl_opts.permissive ) break;	// EOF
        show_file_error( ad.namep, fv_msg1 );
        retval = 2; break;
        }
      if( skip_warn() && verbosity >= 2 )
        std::fprintf( stderr, "ustar chksum = %07o\n", ustar_chksum( header ) );
      set_error_status( 2 ); continue;
      }
    skip_warn( true );				// reset warning

    const Typeflag typeflag = (Typeflag)header[typeflag_o];
    if( typeflag == tf_global )
      {
      if( prev_extended && !cl_opts.permissive )
        { show_file_error( ad.namep, fv_msg2 ); retval = 2; break; }
      Extended dummy;		// global headers are parsed and ignored
      const int ret = ar.parse_records( dummy, header, grbuf, true );
      if( ret != 0 ) { show_file_error( ad.namep, gblrec_msg ); skip_warn();
                       set_error_status( ret ); }
      continue;
      }
    if( typeflag == tf_extended )
      {
      if( prev_extended && !cl_opts.permissive )
        { show_file_error( ad.namep, fv_msg3 ); retval = 2; break; }
      const int ret = ar.parse_records( extended, header, grbuf,
                                        cl_opts.permissive );
      if( ret != 0 ) { show_file_error( ad.namep, extrec_msg ); skip_warn();
                       extended.reset(); set_error_status( ret ); }
      else if( !extended.crc_present() && cl_opts.missing_crc )
        { show_file_error( ad.namep, mcrc_msg ); retval = 2; break; }
      prev_extended = true;
      continue;
      }
    prev_extended = false;

    extended.fill_from_ustar( header );		// copy metadata from header

    // members without name are skipped except when listing
    if( check_skip_filename( cl_opts, name_pending, extended.path().c_str() ) )
      retval = skip_member( ar, extended );
    else if( cl_opts.program_mode == m_list )
      retval = list_member( ar, extended, header );
    else if( extended.path().empty() ) retval = skip_member( ar, extended );
    else if( cl_opts.program_mode == m_diff )
      retval = compare_member( cl_opts, ar, extended, header );
    else retval = extract_member( cl_opts, ar, extended, header );
    extended.reset();
    if( retval )
      { show_error( "Error is not recoverable: exiting now." ); break; }
    }

  if( close( ad.infd ) != 0 && !retval )
    { show_file_error( ad.namep, "Error closing archive", errno );
      retval = 1; }

  if( retval == 0 )
    for( int i = 0; i < cl_opts.parser.arguments(); ++i )
      if( nonempty_arg( cl_opts.parser, i ) && name_pending[i] )
        { show_file_error( cl_opts.parser.argument( i ).c_str(),
                           "Not found in archive." ); retval = 1; }
  return final_exit_status( retval, cl_opts.program_mode != m_diff );
  }