Merging upstream version 1.15~pre1.

Signed-off-by: Daniel Baumann <mail@daniel-baumann.ch>

36 files changed, 785 insertions, 487 deletions

diff --git a/ChangeLog b/ChangeLog
index acbbb44..f2f71e7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2013-06-17  Antonio Diaz Diaz  <antonio@gnu.org>
+
+	* Version 1.15-pre1 released.
+	* repair.cc: Repair multi-member files with up to one byte error
+	  per member.
+	* merge.cc: Merge multi-member files.
+	* Added chapters 'Repairing Files' and 'Merging Files' to the manual.
+
 2013-05-31  Antonio Diaz Diaz  <antonio@gnu.org>
 
 	* Version 1.14 released.
diff --git a/INSTALL b/INSTALL
index cc04763..465a543 100644
--- a/INSTALL
+++ b/INSTALL
@@ -1,7 +1,7 @@
 Requirements
 ------------
 You will need a C++ compiler.
-I use gcc 4.8.0 and 3.3.6, but the code should compile with any
+I use gcc 4.8.1 and 3.3.6, but the code should compile with any
 standards compliant compiler.
 Gcc is available at http://gcc.gnu.org.
 
diff --git a/Makefile.in b/Makefile.in
index e769333..bb69807 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -42,7 +42,7 @@ file_index.o : lzip.h file_index.h
 main.o       : arg_parser.h lzip.h decoder.h
 merge.o      : lzip.h decoder.h file_index.h
 range_dec.o  : lzip.h decoder.h file_index.h
-repair.o     : lzip.h
+repair.o     : lzip.h file_index.h
 split.o      : lzip.h
 unzcrash.o   : arg_parser.h Makefile
 
@@ -115,12 +115,13 @@ dist : doc
 	  $(DISTNAME)/doc/$(pkgname).info \
 	  $(DISTNAME)/doc/$(pkgname).texinfo \
 	  $(DISTNAME)/testsuite/check.sh \
-	  $(DISTNAME)/testsuite/fox5_bad.lz \
-	  $(DISTNAME)/testsuite/fox5_bad.txt \
+	  $(DISTNAME)/testsuite/fox5.lz \
+	  $(DISTNAME)/testsuite/fox5_bad[1-5].lz \
+	  $(DISTNAME)/testsuite/fox5_bad1.txt \
 	  $(DISTNAME)/testsuite/test.txt \
+	  $(DISTNAME)/testsuite/test.txt.lz \
 	  $(DISTNAME)/testsuite/test921-1921.txt \
 	  $(DISTNAME)/testsuite/test_bad[1-5].lz \
-	  $(DISTNAME)/testsuite/test_v[01].lz \
 	  $(DISTNAME)/testsuite/unzcrash.cc \
 	  $(DISTNAME)/*.h \
 	  $(DISTNAME)/*.cc
diff --git a/NEWS b/NEWS
index 1558dc8..70b39a1 100644
--- a/NEWS
+++ b/NEWS
@@ -1,23 +1,10 @@
-Changes in version 1.14:
+Changes in version 1.15:
 
-The new option "-i, --ignore-errors", which in conjunction with "-D"
-decompresses all the recoverable data in all members of a file without
-having to split it first, has been added.
+Lziprecover can now repair multi-member files with up to one byte error
+per member, without having to split them first.
 
-Option "-l, --list" now accepts more than one file.
+Lziprecover can now merge multi-member files without having to split
+them first even if some copies have the header and the trailer damaged.
 
-Decompression time has been reduced by 12%.
-
-"--split" now uses as few digits as possible in the names of the files
-produced, depending on the number of members in the input file.
-
-"--split" in verbose mode now shows the names of files being created.
-
-When decompressing or testing, file version is now shown only if
-verbosity >= 4.
-
-"configure" now accepts options with a separate argument.
-
-The target "install-as-lzip" has been added to the Makefile.
-
-The target "install-bin" has been added to the Makefile.
+The chapters "Repairing Files" and "Merging Files" have been added to
+the manual.
diff --git a/README b/README
index e5b3641..e96690f 100644
--- a/README
+++ b/README
@@ -2,14 +2,15 @@ Description
 
 Lziprecover is a data recovery tool and decompressor for files in the
 lzip compressed data format (.lz) able to repair slightly damaged files,
-recover badly damaged files from two or more copies, extract undamaged
-members from multi-member files, decompress files and test integrity of
-files.
+recover badly damaged files from two or more copies, extract data from
+damaged files, decompress files and test integrity of files.
 
 Lziprecover is able to recover or decompress files produced by any of
 the compressors in the lzip family; lzip, plzip, minilzip/lzlib, clzip
-and pdlzip. This recovery capability contributes to make the lzip format
-one of the best options for long-term data archiving.
+and pdlzip. It makes lzip files resistant to bit-flip, one of the most
+common forms of data corruption, and its recovery capabilities
+contribute to make of the lzip format one of the best options for
+long-term data archiving.
 
 Lziprecover is able to efficiently extract a range of bytes from a
 multi-member file, because it only decompresses the members containing
diff --git a/configure b/configure
index 7faf560..da0011b 100755
--- a/configure
+++ b/configure
@@ -6,7 +6,7 @@
 # to copy, distribute and modify it.
 
 pkgname=lziprecover
-pkgversion=1.14
+pkgversion=1.15-pre1
 progname=lziprecover
 srctrigger=doc/lziprecover.texinfo
 
@@ -100,7 +100,7 @@ while [ $# != 0 ] ; do
 	*=* | *-*-*) ;;
 	*)
 		echo "configure: unrecognized option: '${option}'" 1>&2
-		echo "Try 'configure --help' for more information."
+		echo "Try 'configure --help' for more information." 1>&2
 		exit 1 ;;
 	esac
 
@@ -125,10 +125,8 @@ if [ -z "${srcdir}" ] ; then
 fi
 
 if [ ! -r "${srcdir}/${srctrigger}" ] ; then
-	exec 1>&2
-	echo
-	echo "configure: Can't find sources in ${srcdir} ${srcdirtext}"
-	echo "configure: (At least ${srctrigger} is missing)."
+	echo "configure: Can't find sources in ${srcdir} ${srcdirtext}" 1>&2
+	echo "configure: (At least ${srctrigger} is missing)." 1>&2
 	exit 1
 fi
 
diff --git a/decoder.cc b/decoder.cc
index 8ed1aae..497471c 100644
--- a/decoder.cc
+++ b/decoder.cc
@@ -126,7 +126,7 @@ void LZ_decoder::flush_data()
 bool LZ_decoder::verify_trailer( const Pretty_print & pp ) const
   {
   File_trailer trailer;
-  const int trailer_size = File_trailer::size( member_version );
+  const int trailer_size = File_trailer::size;
   const unsigned long long member_size =
     rdec.member_position() + trailer_size;
   bool error = false;
@@ -144,8 +144,6 @@ bool LZ_decoder::verify_trailer( const Pretty_print & pp ) const
     while( size < trailer_size ) trailer.data[size++] = 0;
     }
 
-  if( member_version == 0 ) trailer.member_size( member_size );
-
   if( !rdec.code_is_zero() )
     {
     error = true;
@@ -220,7 +218,7 @@ int LZ_decoder::decode_member( const Pretty_print & pp )
   while( !rdec.finished() )
     {
     const int pos_state = data_position() & pos_state_mask;
-    if( rdec.decode_bit( bm_match[state()][pos_state] ) == 0 )
+    if( rdec.decode_bit( bm_match[state()][pos_state] ) == 0 )	// 1st bit
       {
       const uint8_t prev_byte = get_prev_byte();
       if( state.is_char() )
@@ -233,21 +231,21 @@ int LZ_decoder::decode_member( const Pretty_print & pp )
     else
       {
       int len;
-      if( rdec.decode_bit( bm_rep[state()] ) == 1 )
+      if( rdec.decode_bit( bm_rep[state()] ) == 1 )		// 2nd bit
         {
-        if( rdec.decode_bit( bm_rep0[state()] ) == 0 )
+        if( rdec.decode_bit( bm_rep0[state()] ) == 0 )		// 3rd bit
           {
-          if( rdec.decode_bit( bm_len[state()][pos_state] ) == 0 )
+          if( rdec.decode_bit( bm_len[state()][pos_state] ) == 0 ) // 4th bit
             { state.set_short_rep(); put_byte( get_byte( rep0 ) ); continue; }
           }
         else
           {
           unsigned distance;
-          if( rdec.decode_bit( bm_rep1[state()] ) == 0 )
+          if( rdec.decode_bit( bm_rep1[state()] ) == 0 )	// 4th bit
             distance = rep1;
           else
             {
-            if( rdec.decode_bit( bm_rep2[state()] ) == 0 )
+            if( rdec.decode_bit( bm_rep2[state()] ) == 0 )	// 5th bit
               distance = rep2;
             else
               { distance = rep3; rep3 = rep2; }
diff --git a/decoder.h b/decoder.h
index a153bcb..0c4697b 100644
--- a/decoder.h
+++ b/decoder.h
@@ -176,11 +176,11 @@ public:
       match_byte <<= 1;
       const int match_bit = match_byte & 0x100;
       const int bit = decode_bit( bm1[match_bit+symbol] );
-      symbol = ( symbol << 1 ) + bit;
+      symbol = ( symbol << 1 ) | bit;
       if( match_bit != bit << 8 )
         {
         while( symbol < 0x100 )
-          symbol = ( symbol << 1 ) + decode_bit( bm[symbol] );
+          symbol = ( symbol << 1 ) | decode_bit( bm[symbol] );
         break;
         }
       }
@@ -213,7 +213,6 @@ class LZ_decoder
   int stream_pos;		// first byte not yet written to file
   uint32_t crc_;
   const int outfd;		// output file descriptor
-  const int member_version;
 
   unsigned long long stream_position() const { return partial_data_pos + stream_pos; }
   void flush_data();
@@ -273,8 +272,7 @@ public:
     pos( 0 ),
     stream_pos( 0 ),
     crc_( 0xFFFFFFFFU ),
-    outfd( ofd ),
-    member_version( header.version() )
+    outfd( ofd )
     { buffer[buffer_size-1] = 0; }	// prev_byte of first_byte
 
   ~LZ_decoder() { delete[] buffer; }
diff --git a/doc/lziprecover.1 b/doc/lziprecover.1
index f62094a..fce7640 100644
--- a/doc/lziprecover.1
+++ b/doc/lziprecover.1
@@ -1,5 +1,5 @@
 .\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.37.1.
-.TH LZIPRECOVER "1" "May 2013" "Lziprecover 1.14" "User Commands"
+.TH LZIPRECOVER "1" "June 2013" "Lziprecover 1.15-pre1" "User Commands"
 .SH NAME
 Lziprecover \- recovers data from damaged lzip files
 .SH SYNOPSIS
diff --git a/doc/lziprecover.info b/doc/lziprecover.info
index 83267d5..0d39838 100644
--- a/doc/lziprecover.info
+++ b/doc/lziprecover.info
@@ -12,16 +12,18 @@ File: lziprecover.info,  Node: Top,  Next: Introduction,  Up: (dir)
 Lziprecover Manual
 ******************
 
-This manual is for Lziprecover (version 1.14, 31 May 2013).
+This manual is for Lziprecover (version 1.15-pre1, 17 June 2013).
 
 * Menu:
 
-* Introduction::          Purpose and features of lziprecover
-* Invoking Lziprecover::  Command line interface
-* File Format::           Detailed format of the compressed file
-* Examples::              A small tutorial with examples
-* Problems::              Reporting bugs
-* Concept Index::         Index of concepts
+* Introduction::           Purpose and features of lziprecover
+* Invoking Lziprecover::   Command line interface
+* Repairing Files::        Fixing bit-flip and similar errors
+* Merging Files::          Fixing several damaged copies
+* File Format::            Detailed format of the compressed file
+* Examples::               A small tutorial with examples
+* Problems::               Reporting bugs
+* Concept Index::          Index of concepts
 
 
    Copyright (C) 2009, 2010, 2011, 2012, 2013 Antonio Diaz Diaz.
@@ -37,14 +39,15 @@ File: lziprecover.info,  Node: Introduction,  Next: Invoking Lziprecover,  Prev:
 
 Lziprecover is a data recovery tool and decompressor for files in the
 lzip compressed data format (.lz) able to repair slightly damaged files,
-recover badly damaged files from two or more copies, extract undamaged
-members from multi-member files, decompress files and test integrity of
-files.
+recover badly damaged files from two or more copies, extract data from
+damaged files, decompress files and test integrity of files.
 
    Lziprecover is able to recover or decompress files produced by any of
 the compressors in the lzip family; lzip, plzip, minilzip/lzlib, clzip
-and pdlzip. This recovery capability contributes to make the lzip format
-one of the best options for long-term data archiving.
+and pdlzip. It makes lzip files resistant to bit-flip, one of the most
+common forms of data corruption, and its recovery capabilities
+contribute to make of the lzip format one of the best options for
+long-term data archiving.
 
    Lziprecover is able to efficiently extract a range of bytes from a
 multi-member file, because it only decompresses the members containing
@@ -61,19 +64,22 @@ damaged files themselves are never modified.
    When decompressing or testing file integrity, lziprecover behaves
 like lzip or lunzip.
 
-   If the files are too damaged for lziprecover to repair them, data
-from damaged members can be partially recovered writing it to stdout as
-shown in the following example (the resulting file may contain some
-garbage data at the end):
+   If a file is too damaged for lziprecover to repair it, all the
+recoverable data in all members of the file can be extracted with the
+following command (the resulting file may contain errors and some
+garbage data may be produced at the end of each member):
 
-     lziprecover -cd rec01file.lz > rec01file
+     lziprecover -D0 -i -o file -q file.lz
 
    If the cause of file corruption is damaged media, the combination
 GNU ddrescue + lziprecover is the best option for recovering data from
 multiple damaged copies. *Note ddrescue-example::, for an example.
 
+   Lziprecover is not a replacement for regular backups, but a last
+line of defense for the case where the backups are also damaged.
+
 
-File: lziprecover.info,  Node: Invoking Lziprecover,  Next: File Format,  Prev: Introduction,  Up: Top
+File: lziprecover.info,  Node: Invoking Lziprecover,  Next: Repairing Files,  Prev: Introduction,  Up: Top
 
 2 Invoking Lziprecover
 **********************
@@ -141,18 +147,10 @@ The format for running lziprecover is:
 `-m'
 `--merge'
      Try to produce a correct file merging the good parts of two or more
-     damaged copies. The copies must be single-member files. The merge
-     will fail if the copies have too many damaged areas or if the same
-     byte is damaged in all copies. If successful, a repaired copy is
-     written to the file `FILE_fixed.lz'. The exit status is 0 if the
-     file could be repaired, 2 otherwise.
-
-     To give you an idea of its possibilities, when merging two copies
-     each of them with one damaged area affecting 1 percent of the
-     copy, the probability of obtaining a correct file is about 98
-     percent. With three such copies the probability rises to 99.97
-     percent. For large files with small errors, the probability
-     approaches 100 percent even with only two copies.
+     damaged copies. If successful, a repaired copy is written to the
+     file `FILE_fixed.lz'. The exit status is 0 if a correct file could
+     be produced, 2 otherwise. See the chapter Merging Files (*note
+     Merging Files::) for a complete description of the merge mode.
 
 `-o FILE'
 `--output=FILE'
@@ -168,10 +166,12 @@ The format for running lziprecover is:
 
 `-R'
 `--repair'
-     Try to repair a small error, affecting only one byte, in a
-     single-member FILE. If successful, a repaired copy is written to
-     the file `FILE_fixed.lz'. `FILE' is not modified at all.  The exit
-     status is 0 if the file could be repaired, 2 otherwise.
+     Try to repair a file with small errors (up to one byte error per
+     member).  If successful, a repaired copy is written to the file
+     `FILE_fixed.lz'. `FILE' is not modified at all.  The exit status
+     is 0 if the file could be repaired, 2 otherwise.  See the chapter
+     Repairing Files (*note Repairing Files::) for a complete
+     description of the repair mode.
 
 `-s'
 `--split'
@@ -227,9 +227,52 @@ invalid input file, 3 for an internal consistency error (eg, bug) which
 caused lziprecover to panic.
 
 
-File: lziprecover.info,  Node: File Format,  Next: Examples,  Prev: Invoking Lziprecover,  Up: Top
+File: lziprecover.info,  Node: Repairing Files,  Next: Merging Files,  Prev: Invoking Lziprecover,  Up: Top
+
+3 Repairing Files
+*****************
+
+Lziprecover is able to repair files with small errors (up to one byte
+error per member). The error may be located anywhere in the file except
+in the header (first 6 bytes of each member) or in the `Member size'
+field of the trailer (last 8 bytes of each member). This makes lzip
+files resistant to bit-flip, one of the most common forms of data
+corruption.
+
+   Bit-flip happens when one bit in the file is changed from 0 to 1 or
+vice versa. It may be caused by bad RAM or even by natural radiation. I
+have seen a case of bit-flip in a file stored in an USB flash drive.
+
+
+File: lziprecover.info,  Node: Merging Files,  Next: File Format,  Prev: Repairing Files,  Up: Top
+
+4 Merging Files
+***************
+
+If you have several copies of a file but all of them are too damaged to
+repair them (*note Repairing Files::), lziprecover can try to produce a
+correct file merging the good parts of the damaged copies.
+
+   The merge may succeed even if some copies of the file have all the
+headers and trailers damaged, as long as there is at least one copy of
+every header and trailer intact, even if they are in different copies of
+the file.
+
+   The merge will fail if the damaged areas overlap (at least one byte
+is damaged in all copies), or are adjacent and the boundary can't be
+determined, or if the copies have too many damaged areas.
+
+   To give you an idea of its possibilities, when merging two copies
+each of them with one damaged area affecting 1 percent of the copy, the
+probability of obtaining a correct file is about 98 percent. With three
+such copies the probability rises to 99.97 percent. For large files with
+small errors, the probability approaches 100 percent even with only two
+copies.
+
+
+File: lziprecover.info,  Node: File Format,  Next: Examples,  Prev: Merging Files,  Up: Top
 
-3 File Format
+5 File Format
 *************
 
 Perfection is reached, not when there is no longer anything to add, but
@@ -302,7 +345,7 @@ additional information before, between, or after them.
 
 File: lziprecover.info,  Node: Examples,  Next: Problems,  Prev: File Format,  Up: Top
 
-4 A small tutorial with examples
+6 A small tutorial with examples
 ********************************
 
 Example 1: Restore a regular file from its compressed version
@@ -329,9 +372,8 @@ to decompressed byte 15000 (5000 bytes are produced).
      lziprecover -D 10000-15000 file.lz
 
 
-Example 5: Repair a one-byte corruption in the single-member file
-`file.lz'. (Indented lines are abridged error messages from
-lziprecover).
+Example 5: Repair small errors in the file `file.lz'. (Indented lines
+are abridged diagnostic messages from lziprecover).
 
      lziprecover -v -R file.lz
        Copy of input file repaired successfully.
@@ -365,31 +407,16 @@ error-checked merging of copies (*Note GNU ddrescue manual:
 Example 8: Recover the first volume of those created with the command
 `lzip -b 32MiB -S 650MB big_db' from two copies, `big_db1_00001.lz' and
 `big_db2_00001.lz', with member 07 damaged in the first copy, member 18
-damaged in the second copy, and member 12 damaged in both copies. Two
-correct copies are produced and compared.
-
-     lziprecover -s big_db1_00001.lz
-     lziprecover -s big_db2_00001.lz
-     lziprecover -t rec*big_db1_00001.lz
-       rec07big_db1_00001.lz: crc mismatch
-       rec12big_db1_00001.lz: crc mismatch
-     lziprecover -t rec*big_db2_00001.lz
-       rec12big_db2_00001.lz: crc mismatch
-       rec18big_db2_00001.lz: crc mismatch
-     lziprecover -m -v rec12big_db1_00001.lz rec12big_db2_00001.lz
+damaged in the second copy, and member 12 damaged in both copies. The
+correct file produced is saved in `big_db_00001.lz'.
+
+     lziprecover -m -v -o big_db_00001.lz big_db1_00001.lz big_db2_00001.lz
        Input files merged successfully
-     cp rec07big_db2_00001.lz rec07big_db1_00001.lz
-     cp rec12big_db1_00001_fixed.lz rec12big_db1_00001.lz
-     cp rec12big_db1_00001_fixed.lz rec12big_db2_00001.lz
-     cp rec18big_db1_00001.lz rec18big_db2_00001.lz
-     cat rec*big_db1_00001.lz > big_db3_00001.lz
-     cat rec*big_db2_00001.lz > big_db4_00001.lz
-     zcmp big_db3_00001.lz big_db4_00001.lz
 
 
 File: lziprecover.info,  Node: Problems,  Next: Concept Index,  Prev: Examples,  Up: Top
 
-5 Reporting Bugs
+7 Reporting Bugs
 ****************
 
 There are probably bugs in lziprecover. There are certainly errors and
@@ -415,19 +442,23 @@ Concept Index
 * file format:                           File Format.           (line 6)
 * getting help:                          Problems.              (line 6)
 * introduction:                          Introduction.          (line 6)
-* invoking lziprecover:                  Invoking Lziprecover.  (line 6)
+* invoking:                              Invoking Lziprecover.  (line 6)
+* merging files:                         Merging Files.         (line 6)
+* repairing files:                       Repairing Files.       (line 6)
 
 
 
 Tag Table:
 Node: Top231
-Node: Introduction901
-Node: Invoking Lziprecover2685
-Node: File Format8447
-Node: Examples10938
-Ref: ddrescue-example12158
-Node: Problems13938
-Node: Concept Index14488
+Node: Introduction1032
+Node: Invoking Lziprecover3052
+Node: Repairing Files8489
+Node: Merging Files9208
+Node: File Format10338
+Node: Examples12822
+Ref: ddrescue-example14024
+Node: Problems15134
+Node: Concept Index15684
 
 End Tag Table
 
diff --git a/doc/lziprecover.texinfo b/doc/lziprecover.texinfo
index 142cdae..54834e9 100644
--- a/doc/lziprecover.texinfo
+++ b/doc/lziprecover.texinfo
@@ -6,8 +6,8 @@
 @finalout
 @c %**end of header
 
-@set UPDATED 31 May 2013
-@set VERSION 1.14
+@set UPDATED 17 June 2013
+@set VERSION 1.15-pre1
 
 @dircategory Data Compression
 @direntry
@@ -35,12 +35,14 @@
 This manual is for Lziprecover (version @value{VERSION}, @value{UPDATED}).
 
 @menu
-* Introduction::          Purpose and features of lziprecover
-* Invoking Lziprecover::  Command line interface
-* File Format::           Detailed format of the compressed file
-* Examples::              A small tutorial with examples
-* Problems::              Reporting bugs
-* Concept Index::         Index of concepts
+* Introduction::           Purpose and features of lziprecover
+* Invoking Lziprecover::   Command line interface
+* Repairing Files::        Fixing bit-flip and similar errors
+* Merging Files::          Fixing several damaged copies
+* File Format::            Detailed format of the compressed file
+* Examples::               A small tutorial with examples
+* Problems::               Reporting bugs
+* Concept Index::          Index of concepts
 @end menu
 
 @sp 1
@@ -56,14 +58,15 @@ to copy, distribute and modify it.
 
 Lziprecover is a data recovery tool and decompressor for files in the
 lzip compressed data format (.lz) able to repair slightly damaged files,
-recover badly damaged files from two or more copies, extract undamaged
-members from multi-member files, decompress files and test integrity of
-files.
+recover badly damaged files from two or more copies, extract data from
+damaged files, decompress files and test integrity of files.
 
 Lziprecover is able to recover or decompress files produced by any of
 the compressors in the lzip family; lzip, plzip, minilzip/lzlib, clzip
-and pdlzip. This recovery capability contributes to make the lzip format
-one of the best options for long-term data archiving.
+and pdlzip. It makes lzip files resistant to bit-flip, one of the most
+common forms of data corruption, and its recovery capabilities
+contribute to make of the lzip format one of the best options for
+long-term data archiving.
 
 Lziprecover is able to efficiently extract a range of bytes from a
 multi-member file, because it only decompresses the members containing
@@ -80,23 +83,26 @@ damaged files themselves are never modified.
 When decompressing or testing file integrity, lziprecover behaves like
 lzip or lunzip.
 
-If the files are too damaged for lziprecover to repair them, data from
-damaged members can be partially recovered writing it to stdout as shown
-in the following example (the resulting file may contain some garbage
-data at the end):
+If a file is too damaged for lziprecover to repair it, all the
+recoverable data in all members of the file can be extracted with the
+following command (the resulting file may contain errors and some
+garbage data may be produced at the end of each member):
 
 @example
-lziprecover -cd rec01file.lz > rec01file
+lziprecover -D0 -i -o file -q file.lz
 @end example
 
 If the cause of file corruption is damaged media, the combination
 @w{GNU ddrescue + lziprecover} is the best option for recovering data
 from multiple damaged copies. @xref{ddrescue-example}, for an example.
 
+Lziprecover is not a replacement for regular backups, but a last line of
+defense for the case where the backups are also damaged.
+
 
 @node Invoking Lziprecover
 @chapter Invoking Lziprecover
-@cindex invoking lziprecover
+@cindex invoking
 
 The format for running lziprecover is:
 
@@ -164,18 +170,10 @@ information about the members in the file.
 @item -m
 @itemx --merge
 Try to produce a correct file merging the good parts of two or more
-damaged copies. The copies must be single-member files. The merge will
-fail if the copies have too many damaged areas or if the same byte is
-damaged in all copies. If successful, a repaired copy is written to the
-file @samp{@var{file}_fixed.lz}. The exit status is 0 if the file could
-be repaired, 2 otherwise.
-
-To give you an idea of its possibilities, when merging two copies each
-of them with one damaged area affecting 1 percent of the copy, the
-probability of obtaining a correct file is about 98 percent. With three
-such copies the probability rises to 99.97 percent. For large files with
-small errors, the probability approaches 100 percent even with only two
-copies.
+damaged copies. If successful, a repaired copy is written to the file
+@samp{@var{file}_fixed.lz}. The exit status is 0 if a correct file could
+be produced, 2 otherwise. See the chapter Merging Files (@pxref{Merging
+Files}) for a complete description of the merge mode.
 
 @item -o @var{file}
 @itemx --output=@var{file}
@@ -192,10 +190,12 @@ Quiet operation. Suppress all messages.
 
 @item -R
 @itemx --repair
-Try to repair a small error, affecting only one byte, in a single-member
-@var{file}. If successful, a repaired copy is written to the file
+Try to repair a file with small errors (up to one byte error per member).
+If successful, a repaired copy is written to the file
 @samp{@var{file}_fixed.lz}. @samp{@var{file}} is not modified at all.
 The exit status is 0 if the file could be repaired, 2 otherwise.
+See the chapter Repairing Files (@pxref{Repairing Files}) for a complete
+description of the repair mode.
 
 @item -s
 @itemx --split
@@ -252,6 +252,47 @@ invalid input file, 3 for an internal consistency error (eg, bug) which
 caused lziprecover to panic.
 
 
+@node Repairing Files
+@chapter Repairing Files
+@cindex repairing files
+
+Lziprecover is able to repair files with small errors (up to one byte
+error per member). The error may be located anywhere in the file except
+in the header (first 6 bytes of each member) or in the @samp{Member
+size} field of the trailer (last 8 bytes of each member). This makes
+lzip files resistant to bit-flip, one of the most common forms of data
+corruption.
+
+Bit-flip happens when one bit in the file is changed from 0 to 1 or vice
+versa. It may be caused by bad RAM or even by natural radiation. I have
+seen a case of bit-flip in a file stored in an USB flash drive.
+
+
+@node Merging Files
+@chapter Merging Files
+@cindex merging files
+
+If you have several copies of a file but all of them are too damaged to
+repair them (@pxref{Repairing Files}), lziprecover can try to produce a
+correct file merging the good parts of the damaged copies.
+
+The merge may succeed even if some copies of the file have all the
+headers and trailers damaged, as long as there is at least one copy of
+every header and trailer intact, even if they are in different copies of
+the file.
+
+The merge will fail if the damaged areas overlap (at least one byte is
+damaged in all copies), or are adjacent and the boundary can't be
+determined, or if the copies have too many damaged areas.
+
+To give you an idea of its possibilities, when merging two copies each
+of them with one damaged area affecting 1 percent of the copy, the
+probability of obtaining a correct file is about 98 percent. With three
+such copies the probability rises to 99.97 percent. For large files with
+small errors, the probability approaches 100 percent even with only two
+copies.
+
+
 @node File Format
 @chapter File Format
 @cindex file format
@@ -368,9 +409,8 @@ lziprecover -D 10000-15000 file.lz
 
 @sp 1
 @noindent
-Example 5: Repair a one-byte corruption in the single-member file
-@samp{file.lz}. (Indented lines are abridged error messages from
-lziprecover).
+Example 5: Repair small errors in the file @samp{file.lz}. (Indented
+lines are abridged diagnostic messages from lziprecover).
 
 @example
 lziprecover -v -R file.lz
@@ -422,27 +462,12 @@ Example 8: Recover the first volume of those created with the command
 @w{@code{lzip -b 32MiB -S 650MB big_db}} from two copies,
 @samp{big_db1_00001.lz} and @samp{big_db2_00001.lz}, with member 07
 damaged in the first copy, member 18 damaged in the second copy, and
-member 12 damaged in both copies. Two correct copies are produced and
-compared.
+member 12 damaged in both copies. The correct file produced is saved in
+@samp{big_db_00001.lz}.
 
 @example
-lziprecover -s big_db1_00001.lz
-lziprecover -s big_db2_00001.lz
-lziprecover -t rec*big_db1_00001.lz
-  rec07big_db1_00001.lz: crc mismatch
-  rec12big_db1_00001.lz: crc mismatch
-lziprecover -t rec*big_db2_00001.lz
-  rec12big_db2_00001.lz: crc mismatch
-  rec18big_db2_00001.lz: crc mismatch
-lziprecover -m -v rec12big_db1_00001.lz rec12big_db2_00001.lz
+lziprecover -m -v -o big_db_00001.lz big_db1_00001.lz big_db2_00001.lz
   Input files merged successfully
-cp rec07big_db2_00001.lz rec07big_db1_00001.lz
-cp rec12big_db1_00001_fixed.lz rec12big_db1_00001.lz
-cp rec12big_db1_00001_fixed.lz rec12big_db2_00001.lz
-cp rec18big_db1_00001.lz rec18big_db2_00001.lz
-cat rec*big_db1_00001.lz > big_db3_00001.lz
-cat rec*big_db2_00001.lz > big_db4_00001.lz
-zcmp big_db3_00001.lz big_db4_00001.lz
 @end example
 
 
diff --git a/file_index.cc b/file_index.cc
index 41bee41..997003a 100644
--- a/file_index.cc
+++ b/file_index.cc
@@ -52,21 +52,32 @@ const char * format_num( unsigned long long num,
   }
 
 
-File_index::File_index( const int infd ) : retval_( 0 )
+Block Block::split( const long long pos )
+  {
+  if( pos_ < pos && end() > pos )
+    {
+    const Block b( pos_, pos - pos_ );
+    pos_ = pos; size_ -= b.size_;
+    return b;
+    }
+  return Block( 0, 0 );
+  }
+
+
+File_index::File_index( const int infd )
+  :
+  isize( lseek( infd, 0, SEEK_END ) ), retval_( 0 )
   {
-  const long long isize = lseek( infd, 0, SEEK_END );
   if( isize < 0 )
     { error_ = "Input file is not seekable :";
       error_ += std::strerror( errno ); retval_ = 1; 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; }
-  long long pos = isize;		// always points to a header or EOF
-  File_header header;
-  File_trailer trailer;
 
-  if( isize < min_member_size )
-    { error_ = "Input file is too short."; retval_ = 2; return; }
+  File_header header;
   if( seek_read( infd, header.data, File_header::size, 0 ) != File_header::size )
     { error_ = "Error reading member header :";
       error_ += std::strerror( errno ); retval_ = 1; return; }
@@ -77,10 +88,12 @@ File_index::File_index( const int infd ) : retval_( 0 )
     { error_ = "Version "; error_ += format_num( header.version() );
       error_ += "member format not supported."; retval_ = 2; return; }
 
+  long long pos = isize;		// always points to a header or to EOF
   while( pos >= min_member_size )
     {
-    if( seek_read( infd, trailer.data, File_trailer::size(),
-                   pos - File_trailer::size() ) != File_trailer::size() )
+    File_trailer trailer;
+    if( seek_read( infd, trailer.data, File_trailer::size,
+                   pos - File_trailer::size ) != File_trailer::size )
       { error_ = "Error reading member trailer :";
         error_ += std::strerror( errno ); retval_ = 1; break; }
     const long long member_size = trailer.member_size();
@@ -105,14 +118,113 @@ File_index::File_index( const int infd ) : retval_( 0 )
     if( member_vector.size() == 0 && isize - pos > File_header::size &&
         seek_read( infd, header.data, File_header::size, pos ) == File_header::size &&
         header.verify_magic() && header.verify_version() )
-      {					// last trailer is corrupt
-      error_ = "Member size in trailer is corrupt at pos ";
-      error_ += format_num( isize - 8 ); retval_ = 2; break;
+      {
+      error_ = "Last member in input file is truncated or corrupt.";
+      retval_ = 2; break;
+      }
+    pos -= member_size;
+    member_vector.push_back( Member( 0, trailer.data_size(),
+                                     pos, member_size ) );
+    }
+  if( pos != 0 || member_vector.size() == 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 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 );
+    }
+  }
+
+
+// All files in 'infd_vector' must be at least 'fsize' bytes long.
+File_index::File_index( const std::vector< int > & infd_vector,
+                        const long long fsize )
+  :
+  isize( fsize ), retval_( 0 )
+  {
+  if( isize < 0 )
+    { error_ = "Input file is not seekable :";
+      error_ += std::strerror( errno ); retval_ = 1; 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; }
+
+  const int files = infd_vector.size();
+  File_header header;
+  bool done = false;
+  for( int i = 0; i < files && !done; ++i )
+    {
+    const int infd = infd_vector[i];
+    if( seek_read( infd, header.data, File_header::size, 0 ) != File_header::size )
+      { error_ = "Error reading member header :";
+        error_ += std::strerror( errno ); retval_ = 1; return; }
+    if( header.verify_magic() && header.verify_version() ) done = true;
+    }
+  if( !done )
+    { error_ = "Bad magic number (file not in lzip format).";
+      retval_ = 2; return; }
+
+  long long pos = isize;		// always points to a header or to EOF
+  while( pos >= min_member_size )
+    {
+    long long member_size;
+    File_trailer trailer;
+    done = false;
+    for( int it = 0; it < files && !done; ++it )
+      {
+      const int tfd = infd_vector[it];
+      if( seek_read( tfd, trailer.data, File_trailer::size,
+                     pos - File_trailer::size ) != File_trailer::size )
+        { error_ = "Error reading member trailer :";
+          error_ += std::strerror( errno ); retval_ = 1; goto error; }
+      member_size = trailer.member_size();
+      if( member_size >= min_member_size && member_size <= pos )
+        for( int ih = 0; ih < files && !done; ++ih )
+          {
+          const int hfd = infd_vector[ih];
+          if( seek_read( hfd, header.data, File_header::size,
+                         pos - member_size ) != File_header::size )
+            { error_ = "Error reading member header :";
+              error_ += std::strerror( errno ); retval_ = 1; goto error; }
+          if( header.verify_magic() && header.verify_version() ) done = true;
+          }
+      }
+    if( !done )
+      {
+      if( member_vector.size() == 0 )		// maybe trailing garbage
+        { --pos; continue; }
+      error_ = "Member size in trailer may be corrupt at pos ";
+      error_ += format_num( pos - 8 ); retval_ = 2; break;
       }
+    if( member_vector.size() == 0 && isize - pos > File_header::size )
+      for( int i = 0; i < files; ++i )
+        {
+        const int infd = infd_vector[i];
+        if( seek_read( infd, header.data, File_header::size, pos ) == File_header::size &&
+            header.verify_magic() && header.verify_version() )
+          {
+          error_ = "Last member in input file is truncated or corrupt.";
+          retval_ = 2; goto error;
+          }
+        }
     pos -= member_size;
     member_vector.push_back( Member( 0, trailer.data_size(),
                                      pos, member_size ) );
     }
+error:
   if( pos != 0 || member_vector.size() == 0 )
     {
     member_vector.clear();
diff --git a/file_index.h b/file_index.h
index 2f055b1..92cf11c 100644
--- a/file_index.h
+++ b/file_index.h
@@ -25,7 +25,8 @@ class Block
   long long pos_, size_;		// pos + size <= INT64_MAX
 
 public:
-  Block( const long long p, const long long s ) : pos_( p ), size_( s ) {}
+  Block( const long long p, const long long s )
+    : pos_( p ), size_( s ) {}
 
   long long pos() const { return pos_; }
   long long size() const { return size_; }
@@ -34,9 +35,17 @@ public:
   void pos( const long long p ) { pos_ = p; }
   void size( const long long s ) { size_ = s; }
 
+  bool operator==( const Block & b ) const
+    { return pos_ == b.pos_ && size_ == b.size_; }
+  bool operator!=( const Block & b ) const
+    { return pos_ != b.pos_ || size_ != b.size_; }
+
+  bool operator<( const Block & b ) const { return pos_ < b.pos_; }
+
   bool overlaps( const Block & b ) const
     { return ( pos_ < b.end() && b.pos_ < end() ); }
   void shift( Block & b ) { ++size_; ++b.pos_; --b.size_; }
+  Block split( const long long pos );
   };
 
 
@@ -49,18 +58,35 @@ class File_index
     Member( const long long dp, const long long ds,
             const long long mp, const long long ms )
       : dblock( dp, ds ), mblock( mp, ms ) {}
+
+    bool operator==( const Member & m ) const { return ( mblock == m.mblock ); }
+    bool operator!=( const Member & m ) const { return ( mblock != m.mblock ); }
     };
 
   std::vector< Member > member_vector;
   std::string error_;
+  long long isize;
   int retval_;
 
 public:
-  File_index( const int infd );
+  File_index() : error_( "No index." ), isize( 0 ), retval_( 2 ) {}
+  explicit File_index( const int infd );
+  File_index( const std::vector< int > & infd_vector, const long long fsize );
 
+  int members() const { return member_vector.size(); }
   const std::string & error() const { return error_; }
   int retval() const { return retval_; }
 
+  bool operator==( const File_index & fi ) const
+    {
+    if( retval_ || fi.retval_ || isize != fi.isize ||
+        member_vector.size() != fi.member_vector.size() ) return false;
+    for( unsigned i = 0; i < member_vector.size(); ++i )
+      if( member_vector[i] != fi.member_vector[i] ) return false;
+    return true;
+    }
+  bool operator!=( const File_index & fi ) const { return !( *this == fi ); }
+
   long long data_end() const
     { if( member_vector.size() ) return member_vector.back().dblock.end();
       else return 0; }
@@ -69,11 +95,14 @@ public:
     { if( member_vector.size() ) return member_vector.back().mblock.end();
       else return 0; }
 
+  // total size including trailing garbage (if any)
+  long long file_size() const
+    { if( isize >= 0 ) return isize; else return 0; }
+
   const Block & dblock( const int i ) const
     { return member_vector[i].dblock; }
   const Block & mblock( const int i ) const
     { return member_vector[i].mblock; }
-  int members() const { return (int)member_vector.size(); }
   };
 
 
diff --git a/lzip.h b/lzip.h
index fcad09e..ea02a5f 100644
--- a/lzip.h
+++ b/lzip.h
@@ -195,7 +195,7 @@ struct File_header
     { return ( std::memcmp( data, magic_string, 4 ) == 0 ); }
 
   uint8_t version() const { return data[4]; }
-  bool verify_version() const { return ( data[4] <= 1 ); }
+  bool verify_version() const { return ( data[4] == 1 ); }
 
   unsigned dictionary_size() const
     {
@@ -231,8 +231,7 @@ struct File_trailer
 			//  4-11 size of the uncompressed data
 			// 12-19 member size including header and trailer
 
-  static int size( const int version = 1 )
-    { return ( ( version >= 1 ) ? 20 : 12 ); }
+  enum { size = 20 };
 
   unsigned data_crc() const
     {
@@ -301,16 +300,15 @@ void cleanup_and_fail( const std::string & output_filename,
                        const int outfd, const int retval );
 bool copy_file( const int infd, const int outfd,
                 const long long max_size = -1 );
-bool try_decompress( const int fd, const unsigned long long file_size,
-                     long long * failure_posp = 0 );
+bool try_decompress_member( const int fd, const unsigned long long msize,
+                            long long * failure_posp = 0 );
 bool verify_header( const File_header & header, const int verbosity );
-bool verify_single_member( const int fd, const long long file_size,
-                           const int verbosity );
 int merge_files( const std::vector< std::string > & filenames,
                  const std::string & output_filename, const int verbosity,
                  const bool force );
 
 // defined in range_dec.cc
+bool safe_seek( const int fd, const long long pos );
 int list_files( const std::vector< std::string > & filenames,
                 const int verbosity );
 int range_decompress( const std::string & input_filename,
diff --git a/main.cc b/main.cc
index b3e6474..21a5b04 100644
--- a/main.cc
+++ b/main.cc
@@ -113,7 +113,6 @@ void show_help()
                "  -R, --repair                    try to repair a small error in file\n"
                "  -s, --split                     split multi-member file in single-member files\n"
                "  -t, --test                      test compressed file integrity\n"
-//               "  -u, --update                    convert file from version 0 to version 1\n"
                "  -v, --verbose                   be verbose (a 2nd -v gives more)\n"
                "Numbers may be followed by a multiplier: k = kB = 10^3 = 1000,\n"
                "Ki = KiB = 2^10 = 1024, M = 10^6, Mi = 2^20, G = 10^9, Gi = 2^30, etc...\n"
diff --git a/merge.cc b/merge.cc
index c254a59..c216870 100644
--- a/merge.cc
+++ b/merge.cc
@@ -35,70 +35,107 @@
 
 namespace {
 
-bool copy_and_diff_file( const std::vector< int > & infd_vector,
-                         const int outfd, std::vector< Block > & block_vector )
+// Add 'bv' to 'block_vector' splitting blocks as needed to keep all the
+// edges (pos and end of every block).
+// 'block_vector' contains the result. 'bv' is destroyed.
+void combine( std::vector< Block > & block_vector, std::vector< Block > & bv )
   {
+  if( block_vector.empty() ) { block_vector.swap( bv ); return; }
+  unsigned i1 = 0, i2 = 0;
+  while( i1 < block_vector.size() && i2 < bv.size() )
+    {
+    Block & b1 = block_vector[i1];
+    Block & b2 = bv[i2];
+    if( b1.overlaps( b2 ) )
+      {
+      if( b1 < b2 )
+        {
+        Block b = b1.split( b2.pos() );
+        block_vector.insert( block_vector.begin() + i1, b ); ++i1;
+        }
+      else if( b2 < b1 )
+        {
+        Block b( b2.pos(), b1.pos() - b2.pos() );
+        b2.split( b1.pos() );
+        block_vector.insert( block_vector.begin() + i1, b ); ++i1;
+        }
+      else if( b1.end() < b2.end() ) { b2.split( b1.end() ); ++i1; }
+      else if( b2.end() < b1.end() )
+        {
+        Block b = b1.split( b2.end() );
+        block_vector.insert( block_vector.begin() + i1, b ); ++i1; ++i2;
+        }
+      else { ++i1; ++i2; }		// blocks are identical
+      }
+    else if( b1 < b2 ) ++i1;
+    else { block_vector.insert( block_vector.begin() + i1, b2 ); ++i1; ++i2; }
+    }
+  if( i2 < bv.size() )				// tail copy
+    block_vector.insert( block_vector.end(), bv.begin() + i2, bv.end() );
+  }
+
+
+bool diff_member( const long long mpos, const long long msize,
+                  const std::vector< int > & infd_vector,
+                  std::vector< Block > & block_vector )
+  {
+  const int files = infd_vector.size();
   const int buffer_size = 65536;
-  std::vector< uint8_t * > buffer_vector( infd_vector.size() );
-  for( unsigned i = 0; i < infd_vector.size(); ++i )
-    buffer_vector[i] = new uint8_t[buffer_size];
-  Block b( 0, 0 );
-  long long partial_pos = 0;
-  int equal_bytes = 0;
-  bool error = false;
+  uint8_t * const buffer1 = new uint8_t[buffer_size];
+  uint8_t * const buffer2 = new uint8_t[buffer_size];
 
-  while( true )
+  bool error = false;
+  for( int i1 = 0; i1 + 1 < files && !error; ++i1 )
     {
-    const int rd = readblock( infd_vector[0], buffer_vector[0], buffer_size );
-    if( rd != buffer_size && errno )
-      { show_error( "Error reading input file", errno ); error = true; break; }
-    if( rd > 0 )
+    for( int i2 = i1 + 1; i2 < files && !error; ++i2 )
       {
-      for( unsigned i = 1; i < infd_vector.size(); ++i )
-        if( readblock( infd_vector[i], buffer_vector[i], rd ) != rd )
-          { show_error( "Error reading input file", errno );
-            error = true; break; }
-      if( error ) break;
-      const int wr = writeblock( outfd, buffer_vector[0], rd );
-      if( wr != rd )
-        { show_error( "Error writing output file", errno );
-          error = true; break; }
-      for( int i = 0; i < rd; ++i )
+      std::vector< Block > bv;
+      long long partial_pos = 0;
+      const int fd1 = infd_vector[i1], fd2 = infd_vector[i2];
+      int begin = -1;			// begin of block. -1 means no block
+      bool prev_equal = true;
+      if( !safe_seek( fd1, mpos ) || !safe_seek( fd2, mpos ) )
+        { error = true; break; }
+
+      while( msize > partial_pos )
         {
-        while( i < rd && b.pos() == 0 )
-          {
-          for( unsigned j = 1; j < infd_vector.size(); ++j )
-            if( buffer_vector[0][i] != buffer_vector[j][i] )
-              { b.pos( partial_pos + i ); break; }	// begin block
-          ++i;
-          }
-        while( i < rd && b.pos() > 0 )
+        const int size = std::min( (long long)buffer_size, msize - partial_pos );
+        const int rd = readblock( fd1, buffer1, size );
+        if( rd != size && errno )
+          { show_error( "Error reading input file", errno ); error = true; break; }
+        if( rd > 0 )
           {
-          ++equal_bytes;
-          for( unsigned j = 1; j < infd_vector.size(); ++j )
-            if( buffer_vector[0][i] != buffer_vector[j][i] )
-              { equal_bytes = 0; break; }
-          if( equal_bytes >= 2 )			// end block
+          if( readblock( fd2, buffer2, rd ) != rd )
+            { show_error( "Error reading input file", errno );
+              error = true; break; }
+          for( int i = 0; i < rd; ++i )
             {
-            b.size( partial_pos + i - ( equal_bytes - 1 ) - b.pos() );
-            block_vector.push_back( b );
-            b.pos( 0 );
-            equal_bytes = 0;
+            if( buffer1[i] != buffer2[i] )
+              {
+              prev_equal = false;
+              if( begin < 0 ) begin = partial_pos + i;	// begin block
+              }
+            else if( !prev_equal ) prev_equal = true;
+            else if( begin >= 0 )			// end block
+              {
+              Block b( mpos + begin, partial_pos + i - 1 - begin );
+              begin = -1;
+              bv.push_back( b );
+              }
             }
-          ++i;
+          partial_pos += rd;
           }
+        if( rd < buffer_size ) break;			// EOF
         }
-      partial_pos += rd;
+      if( begin >= 0 )					// finish last block
+        {
+        Block b( mpos + begin, partial_pos - prev_equal - begin );
+        bv.push_back( b );
+        }
+      combine( block_vector, bv );
       }
-    if( rd < buffer_size ) break;			// EOF
-    }
-  if( b.pos() > 0 )					// finish last block
-    {
-    b.size( partial_pos - b.pos() );
-    block_vector.push_back( b );
     }
-  for( unsigned i = 0; i < infd_vector.size(); ++i )
-    delete[] buffer_vector[i];
+  delete[] buffer2; delete[] buffer1;
   return !error;
   }
 
@@ -116,15 +153,16 @@ int ipow( const unsigned base, const unsigned exponent )
 
 
 int open_input_files( const std::vector< std::string > & filenames,
-                      std::vector< int > & infd_vector, long long & isize,
-                      const int verbosity )
+                      std::vector< int > & infd_vector,
+                      File_index & file_index, const int verbosity )
   {
+  const int files = filenames.size();
   bool identical = false;
-  for( unsigned i = 1; i < filenames.size(); ++i )
+  for( int i = 1; i < files; ++i )
     if( filenames[0] == filenames[i] )
       { identical = true; break; }
   if( !identical )
-    for( unsigned i = 0; i < filenames.size(); ++i )
+    for( int i = 0; i < files; ++i )
       {
       struct stat in_stats;
       ino_t st_ino0 = 0;
@@ -137,15 +175,27 @@ int open_input_files( const std::vector< std::string > & filenames,
       }
   if( identical ) { show_error( "Two input files are the same." ); return 2; }
 
-  isize = 0;
-  for( unsigned i = 0; i < filenames.size(); ++i )
+  long long isize = 0;
+  for( int i = 0; i < files; ++i )
     {
-    const long long tmp = lseek( infd_vector[i], 0, SEEK_END );
-    if( tmp < 0 )
+    long long tmp;
+    const File_index fi( infd_vector[i] );
+    if( fi.retval() == 0 )		// file format is intact
+      {
+      if( file_index.retval() != 0 ) file_index = fi;
+      else if( file_index != fi )
+        { show_error( "Input files are different." ); return 2; }
+      tmp = file_index.file_size();
+      }
+    else				// file format is damaged
       {
-      if( verbosity >= 0 )
-        std::fprintf( stderr, "File '%s' is not seekable.\n", filenames[i].c_str() );
-      return 1;
+      tmp = lseek( infd_vector[i], 0, SEEK_END );
+      if( tmp < 0 )
+        {
+        if( verbosity >= 0 )
+          std::fprintf( stderr, "File '%s' is not seekable.\n", filenames[i].c_str() );
+        return 1;
+        }
       }
     if( i == 0 )
       {
@@ -157,23 +207,33 @@ int open_input_files( const std::vector< std::string > & filenames,
       { show_error( "Sizes of input files are different." ); return 2; }
     }
 
-  for( unsigned i = 0; i < filenames.size(); ++i )
-    if( !verify_single_member( infd_vector[i], isize, verbosity ) )
-      return 2;
+  if( file_index.retval() != 0 )
+    {
+    const File_index fi( infd_vector, isize );
+    if( fi.retval() == 0 )		// file format could be recovered
+      file_index = fi;
+    else
+      { show_error( "Format damaged in all input files." ); return 2; }
+    }
 
-  for( unsigned i = 0; i < filenames.size(); ++i )
+  for( int i = 0; i < files; ++i )
     {
-    if( lseek( infd_vector[i], 0, SEEK_SET ) < 0 )
-      { show_error( "Seek error in input file", errno ); return 1; }
-    if( try_decompress( infd_vector[i], isize ) )
+    const int infd = infd_vector[i];
+    bool error = false;
+    for( int j = 0; j < file_index.members(); ++j )
+      {
+      const long long mpos = file_index.mblock( j ).pos();
+      const long long msize = file_index.mblock( j ).size();
+      if( !safe_seek( infd, mpos ) ) return 1;
+      if( !try_decompress_member( infd, msize ) ) { error = true; break; }
+      }
+    if( !error )
       {
       if( verbosity >= 1 )
         std::printf( "File '%s' has no errors. Recovery is not needed.\n",
                      filenames[i].c_str() );
       return 0;
       }
-    if( lseek( infd_vector[i], 0, SEEK_SET ) < 0 )
-      { show_error( "Seek error in input file", errno ); return 1; }
     }
   return -1;
   }
@@ -221,16 +281,15 @@ bool copy_file( const int infd, const int outfd, const long long max_size )
   }
 
 
-bool try_decompress( const int fd, const unsigned long long file_size,
-                     long long * failure_posp )
+bool try_decompress_member( const int fd, const unsigned long long msize,
+                            long long * failure_posp )
   {
   try {
     Range_decoder rdec( fd );
     File_header header;
     rdec.read_data( header.data, File_header::size );
     if( !rdec.finished() &&			// End Of File
-        header.verify_magic() &&
-        header.version() == 1 &&
+        header.verify_magic() && header.verify_version() &&
         header.dictionary_size() >= min_dictionary_size &&
         header.dictionary_size() <= max_dictionary_size )
       {
@@ -238,7 +297,7 @@ bool try_decompress( const int fd, const unsigned long long file_size,
       Pretty_print dummy( "", -1 );
 
       if( decoder.decode_member( dummy ) == 0 &&
-          rdec.member_position() == file_size ) return true;
+          rdec.member_position() == msize ) return true;
       if( failure_posp ) *failure_posp = rdec.member_position();
       }
     }
@@ -259,12 +318,7 @@ bool verify_header( const File_header & header, const int verbosity )
     show_error( "Bad magic number (file not in lzip format)." );
     return false;
     }
-  if( header.version() == 0 )
-    {
-    show_error( "Version 0 member format can't be recovered." );
-    return false;
-    }
-  if( header.version() != 1 )
+  if( !header.verify_version() )
     {
     if( verbosity >= 0 )
       std::fprintf( stderr, "Version %d member format not supported.\n",
@@ -275,116 +329,106 @@ bool verify_header( const File_header & header, const int verbosity )
   }
 
 
-bool verify_single_member( const int fd, const long long file_size,
-                           const int verbosity )
-  {
-  File_header header;
-  if( lseek( fd, 0, SEEK_SET ) < 0 ||
-      readblock( fd, header.data, File_header::size ) != File_header::size )
-    { show_error( "Error reading member header", errno ); return false; }
-  if( !verify_header( header, verbosity ) ) return false;
-
-  File_trailer trailer;
-  if( lseek( fd, -File_trailer::size(), SEEK_END ) < 0 ||
-      readblock( fd, trailer.data, File_trailer::size() ) != File_trailer::size() )
-    { show_error( "Error reading member trailer", errno ); return false; }
-  const long long member_size = trailer.member_size();
-  if( member_size != file_size )
-    {
-    if( member_size < file_size &&
-        lseek( fd, -member_size, SEEK_END ) > 0 &&
-        readblock( fd, header.data, File_header::size ) == File_header::size &&
-        verify_header( header, verbosity ) )
-      show_error( "Input file has more than 1 member. Split it first." );
-    else
-      show_error( "Member size in input file trailer is corrupt." );
-    return false;
-    }
-  return true;
-  }
-
-
 int merge_files( const std::vector< std::string > & filenames,
                  const std::string & output_filename, const int verbosity,
                  const bool force )
   {
-  std::vector< int > infd_vector( filenames.size() );
-  long long isize = 0;
-  const int retval = open_input_files( filenames, infd_vector, isize, verbosity );
+  const int files = filenames.size();
+  std::vector< int > infd_vector( files );
+  File_index file_index;
+  const int retval =
+    open_input_files( filenames, infd_vector, file_index, verbosity );
   if( retval >= 0 ) return retval;
+  if( !safe_seek( infd_vector[0], 0 ) ) return 1;
 
   const int outfd = open_outstream_rw( output_filename, force );
   if( outfd < 0 ) return 1;
-
-  // vector of data blocks differing among the copies of the input file.
-  std::vector< Block > block_vector;
-  if( !copy_and_diff_file( infd_vector, outfd, block_vector ) )
+  if( !copy_file( infd_vector[0], outfd ) )		// copy whole file
     cleanup_and_fail( output_filename, outfd, 1 );
 
-  if( block_vector.size() == 0 )
-    { show_error( "Input files are identical. Recovery is not possible." );
-      cleanup_and_fail( output_filename, outfd, 2 ); }
-
-  const bool single_block = ( block_vector.size() == 1 );
-  if( single_block && block_vector[0].size() < 2 )
-    { show_error( "Input files have the same byte damaged."
-                  " Try repairing one of them." );
-      cleanup_and_fail( output_filename, outfd, 2 ); }
+  for( int j = 0; j < file_index.members(); ++j )
+    {
+    const long long mpos = file_index.mblock( j ).pos();
+    const long long msize = file_index.mblock( j ).size();
+    // vector of data blocks differing among the copies of the current member
+    std::vector< Block > block_vector;
+    if( !diff_member( mpos, msize, infd_vector, block_vector ) ||
+        !safe_seek( outfd, mpos ) )
+      cleanup_and_fail( output_filename, outfd, 1 );
+
+    if( block_vector.size() == 0 )
+      {
+      if( file_index.members() > 1 && try_decompress_member( outfd, msize ) )
+        continue;
+      show_error( "Input files are (partially) identical. Recovery is not possible." );
+      cleanup_and_fail( output_filename, outfd, 2 );
+      }
 
-  if( ipow( filenames.size(), block_vector.size() ) >= INT_MAX ||
-      ( single_block &&
-        ipow( filenames.size(), 2 ) >= INT_MAX / block_vector[0].size() ) )
-    { show_error( "Input files are too damaged. Recovery is not possible." );
-      cleanup_and_fail( output_filename, outfd, 2 ); }
+    const int size0 = block_vector[0].size();
+    const bool single_block = ( block_vector.size() == 1 );
+    if( ipow( files, block_vector.size() ) >= INT_MAX ||
+        ( single_block && ipow( files, 2 ) >= INT_MAX / size0 ) )
+      { show_error( "Input files are too damaged. Recovery is not possible." );
+        cleanup_and_fail( output_filename, outfd, 2 ); }
 
-  const int shifts = ( single_block ? block_vector[0].size() - 1 : 1 );
-  if( single_block )
-    {
-    Block b( block_vector[0].pos() + 1, block_vector[0].size() - 1 );
-    block_vector[0].size( 1 );
-    block_vector.push_back( b );
-    }
+    const int shifts = ( single_block && size0 > 1 ) ? size0 - 1 : 1;
+    if( single_block && size0 > 1 )
+      {
+      Block b( block_vector[0].pos() + 1, size0 - 1 );
+      block_vector[0].size( 1 );
+      block_vector.push_back( b );
+      }
 
-  const int base_variations = ipow( filenames.size(), block_vector.size() );
-  const int variations = ( base_variations * shifts ) - 2;
-  bool done = false;
-  for( int var = 1; var <= variations; ++var )
-    {
-    if( verbosity >= 1 )
+    if( verbosity >= 1 && file_index.members() > 1 )
       {
-      std::printf( "Trying variation %d of %d \r", var, variations );
+      std::printf( "Merging member %d\n", j + 1 );
       std::fflush( stdout );
       }
-    int tmp = var;
-    for( unsigned i = 0; i < block_vector.size(); ++i )
+    const int base_variations = ipow( files, block_vector.size() );
+    const int variations = base_variations * shifts;
+    bool done = false;
+    for( int var = 0; var < variations; ++var )
       {
-      const int infd = infd_vector[tmp % filenames.size()];
-      tmp /= filenames.size();
-      if( lseek( infd, block_vector[i].pos(), SEEK_SET ) < 0 ||
-          lseek( outfd, block_vector[i].pos(), SEEK_SET ) < 0 ||
-          !copy_file( infd, outfd, block_vector[i].size() ) )
-        { show_error( "Error reading output file", errno );
-          cleanup_and_fail( output_filename, outfd, 1 ); }
+      if( verbosity >= 1 )
+        {
+        std::printf( "Trying variation %d of %d \r", var + 1, variations );
+        std::fflush( stdout );
+        }
+      int tmp = var;
+      for( unsigned i = 0; i < block_vector.size(); ++i )
+        {
+        const int infd = infd_vector[tmp % files];
+        tmp /= files;
+        if( lseek( infd, block_vector[i].pos(), SEEK_SET ) < 0 ||
+            lseek( outfd, block_vector[i].pos(), SEEK_SET ) < 0 ||
+            !copy_file( infd, outfd, block_vector[i].size() ) )
+          { show_error( "Error reading output file", errno );
+            cleanup_and_fail( output_filename, outfd, 1 ); }
+        }
+      if( !safe_seek( outfd, mpos ) )
+        cleanup_and_fail( output_filename, outfd, 1 );
+      if( try_decompress_member( outfd, msize ) )
+        { done = true; break; }
+      if( var > 0 && var % base_variations == 0 )
+        block_vector[0].shift( block_vector[1] );
+      }
+    if( verbosity >= 1 ) std::printf( "\n" );
+    if( !done )
+      {
+      if( verbosity >= 2 )
+        for( unsigned i = 0; i < block_vector.size(); ++i )
+          std::fprintf( stderr, "area %2d from offset %6lld to %6lld\n", i + 1,
+                        block_vector[i].pos(), block_vector[i].end() - 1 );
+      show_error( "Some error areas overlap. Can't recover input file." );
+      cleanup_and_fail( output_filename, outfd, 2 );
       }
-    if( lseek( outfd, 0, SEEK_SET ) < 0 )
-      { show_error( "Seek error in output file", errno );
-        cleanup_and_fail( output_filename, outfd, 1 ); }
-    if( try_decompress( outfd, isize ) )
-      { done = true; break; }
-    if( var % base_variations == 0 ) block_vector[0].shift( block_vector[1] );
     }
-  if( verbosity >= 1 ) std::printf( "\n" );
 
   if( close( outfd ) != 0 )
     {
     show_error( "Error closing output file", errno );
     cleanup_and_fail( output_filename, -1, 1 );
     }
-  if( !done )
-    {
-    show_error( "Some error areas overlap. Can't recover input file." );
-    cleanup_and_fail( output_filename, -1, 2 );
-    }
   if( verbosity >= 1 )
     std::printf( "Input files merged successfully.\n" );
   return 0;
diff --git a/range_dec.cc b/range_dec.cc
index 59be01f..27ceba3 100644
--- a/range_dec.cc
+++ b/range_dec.cc
@@ -101,13 +101,6 @@ void parse_range( const char * const ptr, Block & range )
   }
 
 
-bool safe_seek( const int fd, const long long pos )
-  {
-  if( lseek( fd, pos, SEEK_SET ) == pos ) return true;
-  show_error( "Seek error", errno ); return false;
-  }
-
-
 int decompress_member( const int infd, const int outfd,
                        const Pretty_print & pp,
                        const unsigned long long mpos,
@@ -170,7 +163,7 @@ int list_file( const std::string & input_filename, const Pretty_print & pp )
   const int infd = open_instream( input_filename, &in_stats, true, true );
   if( infd < 0 ) return 1;
 
-  File_index file_index( infd );
+  const File_index file_index( infd );
   close( infd );
   if( file_index.retval() != 0 )
     { show_error( file_index.error().c_str() ); return file_index.retval(); }
@@ -208,6 +201,13 @@ int list_file( const std::string & input_filename, const Pretty_print & pp )
 } // end namespace
 
 
+bool safe_seek( const int fd, const long long pos )
+  {
+  if( lseek( fd, pos, SEEK_SET ) == pos ) return true;
+  show_error( "Seek error", errno ); return false;
+  }
+
+
 int list_files( const std::vector< std::string > & filenames,
                 const int verbosity )
   {
@@ -234,7 +234,7 @@ int range_decompress( const std::string & input_filename,
   const int infd = open_instream( input_filename, &in_stats, true, true );
   if( infd < 0 ) return 1;
 
-  File_index file_index( infd );
+  const File_index file_index( infd );
   if( file_index.retval() != 0 )
     { show_error( file_index.error().c_str() ); return file_index.retval(); }
 
@@ -259,6 +259,7 @@ int range_decompress( const std::string & input_filename,
   else
     { outfd = open_outstream_rw( output_filename, force );
       if( outfd < 0 ) return 1; }
+
   Pretty_print pp( input_filename, verbosity );
   int retval = 0;
   for( int i = 0; i < file_index.members(); ++i )
diff --git a/repair.cc b/repair.cc
index e9cef61..712002b 100644
--- a/repair.cc
+++ b/repair.cc
@@ -28,6 +28,7 @@
 #include <sys/stat.h>
 
 #include "lzip.h"
+#include "file_index.h"
 
 
 int seek_read( const int fd, uint8_t * const buf, const int size,
@@ -55,72 +56,84 @@ int repair_file( const std::string & input_filename,
   struct stat in_stats;
   const int infd = open_instream( input_filename, &in_stats, true, true );
   if( infd < 0 ) return 1;
-  const long long isize = lseek( infd, 0, SEEK_END );
-  if( isize < 0 )
-    { show_error( "Input file is not seekable", errno ); return 1; }
-  if( isize < min_member_size )
-    { show_error( "Input file is too short." ); return 2; }
-  if( !verify_single_member( infd, isize, verbosity ) ) return 2;
-  if( lseek( infd, 0, SEEK_SET ) < 0 )
-    { show_error( "Seek error in input file", errno ); return 1; }
-
-  long long failure_pos = 0;
-  if( try_decompress( infd, isize, &failure_pos ) )
-    {
-    if( verbosity >= 1 )
-      std::printf( "Input file has no errors. Recovery is not needed.\n" );
-    return 0;
-    }
-  if( failure_pos >= isize - 8 ) failure_pos = isize - 8 - 1;
-  if( failure_pos < File_header::size )
-    { show_error( "Can't repair error in input file." ); return 2; }
-
-  if( lseek( infd, 0, SEEK_SET ) < 0 )
-    { show_error( "Seek error in input file", errno ); return 1; }
-
-  const int outfd = open_outstream_rw( output_filename, force );
-  if( outfd < 0 ) { close( infd ); return 1; }
-  if( !copy_file( infd, outfd ) )
-    cleanup_and_fail( output_filename, outfd, 1 );
-
-  const long long min_pos =
-    std::max( (long long)File_header::size, failure_pos - 1000 );
-  bool done = false;
-  for( long long pos = failure_pos; pos >= min_pos && !done ; --pos )
+
+  const File_index file_index( infd );
+  if( file_index.retval() != 0 )
+    { show_error( file_index.error().c_str() ); return file_index.retval(); }
+
+  int outfd = -1;
+  for( int i = 0; i < file_index.members(); ++i )
     {
+    const long long mpos = file_index.mblock( i ).pos();
+    const long long msize = file_index.mblock( i ).size();
+    if( !safe_seek( infd, mpos ) )
+      cleanup_and_fail( output_filename, outfd, 1 );
+    long long failure_pos = 0;
+    if( try_decompress_member( infd, msize, &failure_pos ) ) continue;
+    if( failure_pos >= msize - 8 ) failure_pos = msize - 8 - 1;
+    if( failure_pos < File_header::size )
+      { show_error( "Can't repair error in input file." );
+        cleanup_and_fail( output_filename, outfd, 2 ); }
+
+    if( outfd < 0 )			// first damaged member found
+      {
+      if( !safe_seek( infd, 0 ) ) return 1;
+      outfd = open_outstream_rw( output_filename, force );
+      if( outfd < 0 ) { close( infd ); return 1; }
+      if( !copy_file( infd, outfd ) )		// copy whole file
+        cleanup_and_fail( output_filename, outfd, 1 );
+      }
+
     if( verbosity >= 1 )
       {
-      std::printf( "Trying position %llu \r", pos );
+      std::printf( "Repairing member %d\n", i + 1 );
       std::fflush( stdout );
       }
-    uint8_t byte;
-    if( seek_read( outfd, &byte, 1, pos ) != 1 )
-      { show_error( "Error reading output file", errno );
-        cleanup_and_fail( output_filename, outfd, 1 ); }
-    for( int i = 0; i < 256; ++i )
+    const long long min_pos =
+      std::max( (long long)File_header::size, failure_pos - 1000 );
+    bool done = false;
+    for( long long pos = failure_pos; pos >= min_pos && !done ; --pos )
       {
-      ++byte;
-      if( seek_write( outfd, &byte, 1, pos ) != 1 ||
-          lseek( outfd, 0, SEEK_SET ) < 0 )
-        { show_error( "Error writing output file", errno );
+      if( verbosity >= 1 )
+        {
+        std::printf( "Trying position %llu \r", mpos + pos );
+        std::fflush( stdout );
+        }
+      uint8_t byte;
+      if( seek_read( outfd, &byte, 1, mpos + pos ) != 1 )
+        { show_error( "Error reading output file", errno );
           cleanup_and_fail( output_filename, outfd, 1 ); }
-      if( i == 255 ) break;
-      if( try_decompress( outfd, isize ) )
-        { done = true; break; }
+      for( int i = 0; i < 256; ++i )
+        {
+        ++byte;
+        if( seek_write( outfd, &byte, 1, mpos + pos ) != 1 ||
+            lseek( outfd, mpos, SEEK_SET ) < 0 )
+          { show_error( "Error writing output file", errno );
+            cleanup_and_fail( output_filename, outfd, 1 ); }
+        if( i == 255 ) break;
+        if( try_decompress_member( outfd, msize ) )
+          { done = true; break; }
+        }
+      }
+    if( verbosity >= 1 ) std::printf( "\n" );
+    if( !done )
+      {
+      show_error( "Error is larger than 1 byte. Can't repair input file." );
+      cleanup_and_fail( output_filename, outfd, 2 );
       }
     }
-  if( verbosity >= 1 ) std::printf( "\n" );
 
+  if( outfd < 0 )
+    {
+    if( verbosity >= 1 )
+      std::printf( "Input file has no errors. Recovery is not needed.\n" );
+    return 0;
+    }
   if( close( outfd ) != 0 )
     {
     show_error( "Error closing output file", errno );
     cleanup_and_fail( output_filename, -1, 1 );
     }
-  if( !done )
-    {
-    show_error( "Error is larger than 1 byte. Can't repair input file." );
-    cleanup_and_fail( output_filename, -1, 2 );
-    }
   if( verbosity >= 1 )
     std::printf( "Copy of input file repaired successfully.\n" );
   return 0;
diff --git a/split.cc b/split.cc
index ac7627d..bec8a26 100644
--- a/split.cc
+++ b/split.cc
@@ -90,7 +90,7 @@ int do_split_file( const std::string & input_filename, uint8_t * & base_buffer,
                    const int verbosity, const bool force )
   {
   const int hsize = File_header::size;
-  const int tsize = File_trailer::size();
+  const int tsize = File_trailer::size;
   const int buffer_size = 65536;
   const int base_buffer_size = tsize + buffer_size + hsize;
   base_buffer = new uint8_t[base_buffer_size];
@@ -99,7 +99,8 @@ int do_split_file( const std::string & input_filename, uint8_t * & base_buffer,
   struct stat in_stats;
   const int infd = open_instream( input_filename, &in_stats, true, true );
   if( infd < 0 ) return 1;
-  File_index file_index( infd );
+  const File_index file_index( infd );
+  if( file_index.retval() != 0 ) show_error( file_index.error().c_str() );
   const int max_members = ( file_index.retval() ? 999999 : file_index.members() );
   int max_digits = 1;
   for( int i = max_members; i >= 10; i /= 10 ) ++max_digits;
diff --git a/testsuite/check.sh b/testsuite/check.sh
index ea6e768..4ac7f59 100755
--- a/testsuite/check.sh
+++ b/testsuite/check.sh
@@ -23,10 +23,15 @@ mkdir tmp
 cd "${objdir}"/tmp
 
 in="${testdir}"/test.txt
-in_lz="${testdir}"/test_v1.lz
+in_lz="${testdir}"/test.txt.lz
 inD="${testdir}"/test921-1921.txt
-fox5="${testdir}"/fox5_bad.txt
-fox5_lz="${testdir}"/fox5_bad.lz
+fox5_lz="${testdir}"/fox5.lz
+f5b1="${testdir}"/fox5_bad1.txt
+f5b1_lz="${testdir}"/fox5_bad1.lz
+f5b2_lz="${testdir}"/fox5_bad2.lz
+f5b3_lz="${testdir}"/fox5_bad3.lz
+f5b4_lz="${testdir}"/fox5_bad4.lz
+f5b5_lz="${testdir}"/fox5_bad5.lz
 bad1_lz="${testdir}"/test_bad1.lz
 bad2_lz="${testdir}"/test_bad2.lz
 bad3_lz="${testdir}"/test_bad3.lz
@@ -35,91 +40,140 @@ bad5_lz="${testdir}"/test_bad5.lz
 fail=0
 
 # Description of test files for lziprecover:
-# fox5_bad.lz: byte at offset 188 changed from 0x34 to 0x33
+# fox5_bad1.lz: byte at offset  62 changed from 0x50 to 0x70 (CRC)
+#               byte at offset 144 changed from 0x2D to 0x2E (data_size)
+#               byte at offset 188 changed from 0x34 to 0x33 (mid stream)
+#               byte at offset 247 changed from 0x2A to 0x2B (first byte)
+#               byte at offset 378 changed from 0xA0 to 0x20 (EOS marker)
+# fox5_bad2.lz: [ 30- 49] --> zeroed;
+# fox5_bad3.lz: [100-299] --> zeroed;
+# fox5_bad4.lz: [250-349] --> zeroed;
+# fox5_bad5.lz: [300-399] --> zeroed;
 # test_bad1.lz: byte at offset 67 changed from 0xCC to 0x33
-# test_bad2.lz: [  34-  66) --> copy of bytes [  68- 100)
-# test_bad3.lz: [ 512-1536) --> zeroed;       [2560-3584) --> zeroed
-# test_bad4.lz: [3072-4096) --> random data;  [4608-5632) --> zeroed
-# test_bad5.lz: [1024-2048) --> random data;  [5120-6144) --> random data
+# test_bad2.lz: [  34-  65] --> copy of bytes [  68-  99]
+# test_bad3.lz: [ 512-1535] --> zeroed;       [2560-3583] --> zeroed
+# test_bad4.lz: [3072-4095] --> random data;  [4608-5631] --> zeroed
+# test_bad5.lz: [1024-2047] --> random data;  [5120-6143] --> random data
 
 printf "testing lziprecover-%s..." "$2"
 
 "${LZIPRECOVER}" -lq
-if [ $? != 1 ] ; then fail=1 ; printf - ; else printf . ; fi
+if [ $? = 1 ] ; then printf . ; else fail=1 ; printf - ; fi
 "${LZIPRECOVER}" -mq "${bad1_lz}"
-if [ $? != 1 ] ; then fail=1 ; printf - ; else printf . ; fi
+if [ $? = 1 ] ; then printf . ; else fail=1 ; printf - ; fi
 "${LZIPRECOVER}" -Rq
-if [ $? != 1 ] ; then fail=1 ; printf - ; else printf . ; fi
+if [ $? = 1 ] ; then printf . ; else fail=1 ; printf - ; fi
 "${LZIPRECOVER}" -sq
-if [ $? != 1 ] ; then fail=1 ; printf - ; else printf . ; fi
+if [ $? = 1 ] ; then printf . ; else fail=1 ; printf - ; fi
 
-"${LZIP}" -t "${testdir}"/test_v0.lz || fail=1
-printf .
-"${LZIP}" -cd "${testdir}"/test_v0.lz > copy || fail=1
-cmp "${in}" copy || fail=1
-printf .
-
-"${LZIP}" -t "${testdir}"/test_v1.lz || fail=1
-printf .
-"${LZIP}" -cd "${testdir}"/test_v1.lz > copy || fail=1
+"${LZIP}" -t "${testdir}"/test.txt.lz || fail=1
+"${LZIP}" -cd "${testdir}"/test.txt.lz > copy || fail=1
 cmp "${in}" copy || fail=1
 printf .
 
 "${LZIPRECOVER}" -D 921-1921 -fo copy "${in_lz}" || fail=1
 cmp "${inD}" copy || fail=1
-printf .
 "${LZIPRECOVER}" -D 921,1000 "${in_lz}" > copy || fail=1
 cmp "${inD}" copy || fail=1
 printf .
-"${LZIPRECOVER}" -D0 -iq -fo copy "${fox5_lz}"
-if [ $? = 2 ] && cmp "${fox5}" copy ; then printf . ; else fail=1 ; printf - ; fi
-"${LZIPRECOVER}" -D0 -iq "${fox5_lz}" > copy
-if [ $? = 2 ] && cmp "${fox5}" copy ; then printf . ; else fail=1 ; printf - ; fi
-
+"${LZIPRECOVER}" -D0 -iq "${f5b1_lz}" -fo copy
+if [ $? = 2 ] && cmp "${f5b1}" copy ; then printf . ; else fail=1 ; printf - ; fi
+"${LZIPRECOVER}" -D0 -iq "${f5b1_lz}" > copy
+if [ $? = 2 ] && cmp "${f5b1}" copy ; then printf . ; else fail=1 ; printf - ; fi
+
+rm -f copy.lz
+"${LZIPRECOVER}" -m -o copy.lz "${fox5_lz}" "${f5b1_lz}"
+if [ $? = 0 ] && [ ! -e copy.lz ] ; then printf . ; else fail=1 ; printf - ; fi
+"${LZIPRECOVER}" -m -o copy.lz "${f5b1_lz}" "${fox5_lz}"
+if [ $? = 0 ] && [ ! -e copy.lz ] ; then printf . ; else fail=1 ; printf - ; fi
 "${LZIPRECOVER}" -m -o copy.lz "${bad1_lz}" "${bad2_lz}" "${bad1_lz}" -q
-if [ $? != 2 ] ; then fail=1 ; printf - ; else printf . ; fi
-"${LZIPRECOVER}" -m -o copy.lz "${bad1_lz}" "${bad2_lz}" || fail=1
-"${LZIPRECOVER}" -df copy.lz || fail=1
-cmp "${in}" copy || fail=1
+if [ $? = 2 ] && [ ! -e copy.lz ] ; then printf . ; else fail=1 ; printf - ; fi
+"${LZIPRECOVER}" -m -o copy.lz "${f5b1_lz}" "${f5b5_lz}" -q
+if [ $? = 2 ] && [ ! -e copy.lz ] ; then printf . ; else fail=1 ; printf - ; fi
+"${LZIPRECOVER}" -m -o copy.lz "${f5b3_lz}" "${f5b5_lz}" -q
+if [ $? = 2 ] && [ ! -e copy.lz ] ; then printf . ; else fail=1 ; printf - ; fi
+"${LZIPRECOVER}" -m -o copy.lz "${bad3_lz}" "${bad4_lz}" -q
+if [ $? = 2 ] && [ ! -e copy.lz ] ; then printf . ; else fail=1 ; printf - ; fi
+
+for i in "${f5b1_lz}" "${f5b3_lz}" "${f5b4_lz}" "${f5b5_lz}" ; do
+	"${LZIPRECOVER}" -mf -o copy.lz "${f5b2_lz}" "${i}" || fail=1
+	cmp "${fox5_lz}" copy.lz || fail=1
+	"${LZIPRECOVER}" -mf -o copy.lz "${i}" "${f5b2_lz}" || fail=1
+	cmp "${fox5_lz}" copy.lz || fail=1
+	printf .
+done
+
+for i in "${f5b3_lz}" "${f5b4_lz}" "${f5b5_lz}" ; do
+	"${LZIPRECOVER}" -mf -o copy.lz "${f5b1_lz}" "${f5b2_lz}" "${i}" || fail=1
+	cmp "${fox5_lz}" copy.lz || fail=1
+	"${LZIPRECOVER}" -mf -o copy.lz "${f5b1_lz}" "${i}" "${f5b2_lz}" || fail=1
+	cmp "${fox5_lz}" copy.lz || fail=1
+	"${LZIPRECOVER}" -mf -o copy.lz "${f5b2_lz}" "${f5b1_lz}" "${i}" || fail=1
+	cmp "${fox5_lz}" copy.lz || fail=1
+	"${LZIPRECOVER}" -mf -o copy.lz "${f5b2_lz}" "${i}" "${f5b1_lz}" || fail=1
+	cmp "${fox5_lz}" copy.lz || fail=1
+	"${LZIPRECOVER}" -mf -o copy.lz "${i}" "${f5b1_lz}" "${f5b2_lz}" || fail=1
+	cmp "${fox5_lz}" copy.lz || fail=1
+	"${LZIPRECOVER}" -mf -o copy.lz "${i}" "${f5b2_lz}" "${f5b1_lz}" || fail=1
+	cmp "${fox5_lz}" copy.lz || fail=1
+	printf .
+done
+
+"${LZIPRECOVER}" -mf -o copy.lz "${f5b3_lz}" "${f5b4_lz}" "${f5b5_lz}" || fail=1
+cmp "${fox5_lz}" copy.lz || fail=1
+"${LZIPRECOVER}" -mf -o copy.lz "${f5b1_lz}" "${f5b3_lz}" "${f5b4_lz}" "${f5b5_lz}" || fail=1
+cmp "${fox5_lz}" copy.lz || fail=1
+"${LZIPRECOVER}" -mf -o copy.lz "${f5b2_lz}" "${f5b3_lz}" "${f5b4_lz}" "${f5b5_lz}" || fail=1
+cmp "${fox5_lz}" copy.lz || fail=1
+"${LZIPRECOVER}" -mf -o copy.lz "${f5b1_lz}" "${f5b2_lz}" "${f5b3_lz}" "${f5b4_lz}" "${f5b5_lz}" || fail=1
+cmp "${fox5_lz}" copy.lz || fail=1
 printf .
-"${LZIPRECOVER}" -m -o copy.lz "${bad2_lz}" "${bad1_lz}" || fail=1
-"${LZIPRECOVER}" -df copy.lz || fail=1
-cmp "${in}" copy || fail=1
+
+"${LZIPRECOVER}" -mf -o copy.lz "${bad1_lz}" "${bad2_lz}" || fail=1
+cmp "${in_lz}" copy.lz || fail=1
+"${LZIPRECOVER}" -mf -o copy.lz "${bad2_lz}" "${bad1_lz}" || fail=1
+cmp "${in_lz}" copy.lz || fail=1
 printf .
 
 for i in "${bad1_lz}" "${bad2_lz}" ; do
 	for j in "${bad3_lz}" "${bad4_lz}" "${bad5_lz}" ; do
-		"${LZIPRECOVER}" -m -o copy.lz "${i}" "${j}" || fail=1
-		"${LZIPRECOVER}" -df copy.lz || fail=1
-		cmp "${in}" copy || fail=1
-		printf .
-		"${LZIPRECOVER}" -m -o copy.lz "${j}" "${i}" || fail=1
-		"${LZIPRECOVER}" -df copy.lz || fail=1
-		cmp "${in}" copy || fail=1
+		"${LZIPRECOVER}" -mf -o copy.lz "${i}" "${j}" || fail=1
+		cmp "${in_lz}" copy.lz || fail=1
+		"${LZIPRECOVER}" -mf -o copy.lz "${j}" "${i}" || fail=1
+		cmp "${in_lz}" copy.lz || fail=1
 		printf .
 	done
 done
 
-"${LZIPRECOVER}" -m -o copy.lz "${bad3_lz}" "${bad4_lz}" "${bad5_lz}" || fail=1
-"${LZIPRECOVER}" -df copy.lz || fail=1
-cmp "${in}" copy || fail=1
+"${LZIPRECOVER}" -mf -o copy.lz "${bad3_lz}" "${bad4_lz}" "${bad5_lz}" || fail=1
+cmp "${in_lz}" copy.lz || fail=1
 printf .
-"${LZIPRECOVER}" -m -o copy.lz "${bad4_lz}" "${bad5_lz}" "${bad3_lz}" || fail=1
-"${LZIPRECOVER}" -df copy.lz || fail=1
-cmp "${in}" copy || fail=1
+"${LZIPRECOVER}" -mf -o copy.lz "${bad3_lz}" "${bad5_lz}" "${bad4_lz}" || fail=1
+cmp "${in_lz}" copy.lz || fail=1
 printf .
-"${LZIPRECOVER}" -m -o copy.lz "${bad5_lz}" "${bad3_lz}" "${bad4_lz}" || fail=1
-"${LZIPRECOVER}" -df copy.lz || fail=1
-cmp "${in}" copy || fail=1
+"${LZIPRECOVER}" -mf -o copy.lz "${bad4_lz}" "${bad3_lz}" "${bad5_lz}" || fail=1
+cmp "${in_lz}" copy.lz || fail=1
 printf .
-
-"${LZIPRECOVER}" -R "${in_lz}" || fail=1
+"${LZIPRECOVER}" -mf -o copy.lz "${bad4_lz}" "${bad5_lz}" "${bad3_lz}" || fail=1
+cmp "${in_lz}" copy.lz || fail=1
+printf .
+"${LZIPRECOVER}" -mf -o copy.lz "${bad5_lz}" "${bad3_lz}" "${bad4_lz}" || fail=1
+cmp "${in_lz}" copy.lz || fail=1
+printf .
+"${LZIPRECOVER}" -mf -o copy.lz "${bad5_lz}" "${bad4_lz}" "${bad3_lz}" || fail=1
+cmp "${in_lz}" copy.lz || fail=1
 printf .
+
+rm -f copy.lz
+"${LZIPRECOVER}" -R -o copy.lz "${fox5_lz}" || fail=1
+if [ $? = 0 ] && [ ! -e copy.lz ] ; then printf . ; else fail=1 ; printf - ; fi
 "${LZIPRECOVER}" -R -o copy.lz "${bad2_lz}" -q
-if [ $? != 2 ] ; then fail=1 ; printf - ; else printf . ; fi
-"${LZIPRECOVER}" -R -o copy.lz "${bad1_lz}" || fail=1
-"${LZIPRECOVER}" -df copy.lz || fail=1
-cmp "${in}" copy || fail=1
+if [ $? = 2 ] && [ ! -e copy.lz ] ; then printf . ; else fail=1 ; printf - ; fi
+"${LZIPRECOVER}" -Rf -o copy.lz "${f5b1_lz}" || fail=1
+cmp "${fox5_lz}" copy.lz || fail=1
+printf .
+"${LZIPRECOVER}" -Rf -o copy.lz "${bad1_lz}" || fail=1
+cmp "${in_lz}" copy.lz || fail=1
 printf .
 
 cat "${in_lz}" "${in_lz}" "${in_lz}" > copy || framework_failure
diff --git a/testsuite/fox5_bad.lz b/testsuite/fox5.lz
index 8bfd314..3472f64 100644
--- a/testsuite/fox5_bad.lz
+++ b/testsuite/fox5.lz
diff --git a/testsuite/fox5_bad1.lz b/testsuite/fox5_bad1.lz
new file mode 100644
index 0000000..a3b5658
--- /dev/null
+++ b/testsuite/fox5_bad1.lz
diff --git a/testsuite/fox5_bad.txt b/testsuite/fox5_bad1.txt
index 813a71f..14e5367 100644
--- a/testsuite/fox5_bad.txt
+++ b/testsuite/fox5_bad1.txt
@@ -1,4 +1,4 @@
 The quick brown fox jumps over the lazy dog.
 The quick brown fox jumps over the lazy dog.
-The quick brown fox c††zzzzzzzzzzzzzzzzzzzzzzThe quick brown fox jumps over the lazy dog.
+The quick brown fox c††zzzzzzzzzzzzzzzzzzzzzzVhe quick brown fox jumps over the lazy dog.
 The quick brown fox jumps over the lazy dog.
diff --git a/testsuite/fox5_bad2.lz b/testsuite/fox5_bad2.lz
new file mode 100644
index 0000000..9993ea7
--- /dev/null
+++ b/testsuite/fox5_bad2.lz
diff --git a/testsuite/fox5_bad3.lz b/testsuite/fox5_bad3.lz
new file mode 100644
index 0000000..ef58e47
--- /dev/null
+++ b/testsuite/fox5_bad3.lz
diff --git a/testsuite/fox5_bad4.lz b/testsuite/fox5_bad4.lz
new file mode 100644
index 0000000..0474bb9
--- /dev/null
+++ b/testsuite/fox5_bad4.lz
diff --git a/testsuite/fox5_bad5.lz b/testsuite/fox5_bad5.lz
new file mode 100644
index 0000000..6ec2740
--- /dev/null
+++ b/testsuite/fox5_bad5.lz
diff --git a/testsuite/test.txt.lz b/testsuite/test.txt.lz
new file mode 100644
index 0000000..4db881a
--- /dev/null
+++ b/testsuite/test.txt.lz
diff --git a/testsuite/test_bad1.lz b/testsuite/test_bad1.lz
index 0b84883..687c8a1 100644
--- a/testsuite/test_bad1.lz
+++ b/testsuite/test_bad1.lz
diff --git a/testsuite/test_bad2.lz b/testsuite/test_bad2.lz
index cce6a3c..c8ac08c 100644
--- a/testsuite/test_bad2.lz
+++ b/testsuite/test_bad2.lz
diff --git a/testsuite/test_bad3.lz b/testsuite/test_bad3.lz
index a1676bb..3ed8936 100644
--- a/testsuite/test_bad3.lz
+++ b/testsuite/test_bad3.lz
diff --git a/testsuite/test_bad4.lz b/testsuite/test_bad4.lz
index a8f89a3..c912871 100644
--- a/testsuite/test_bad4.lz
+++ b/testsuite/test_bad4.lz
diff --git a/testsuite/test_bad5.lz b/testsuite/test_bad5.lz
index 73e0142..7c70365 100644
--- a/testsuite/test_bad5.lz
+++ b/testsuite/test_bad5.lz
diff --git a/testsuite/test_v0.lz b/testsuite/test_v0.lz
deleted file mode 100644
index a09b1e8..0000000
--- a/testsuite/test_v0.lz
+++ /dev/null
diff --git a/testsuite/test_v1.lz b/testsuite/test_v1.lz
deleted file mode 100644
index f1c79eb..0000000
--- a/testsuite/test_v1.lz
+++ /dev/null
diff --git a/testsuite/unzcrash.cc b/testsuite/unzcrash.cc
index abf61bb..24defa6 100644
--- a/testsuite/unzcrash.cc
+++ b/testsuite/unzcrash.cc
@@ -58,11 +58,11 @@ void show_help()
                "  -h, --help                 display this help and exit\n"
                "  -V, --version              output version information and exit\n"
                "  -b, --bits=<range>         test N-bit errors instead of full byte\n"
-               "  -p, --position=<bytes>     first byte position to test\n"
+               "  -p, --position=<bytes>     first byte position to test [default 0]\n"
                "  -q, --quiet                suppress all messages\n"
-               "  -s, --size=<bytes>         number of byte positions to test\n"
+               "  -s, --size=<bytes>         number of byte positions to test [all]\n"
                "  -v, --verbose              be verbose (a 2nd -v gives more)\n"
-               "Examples of <range>:  1  1,2,3  1-4  1,3-5,8\n"
+               "Examples of <range>:  1  1,2,3  1-4  1,3-5,8  1-3,5-8\n"
                "\nReport bugs to lzip-bug@nongnu.org\n"
                "Lzip home page: http://www.nongnu.org/lzip/lzip.html\n" );
   }
@@ -109,8 +109,8 @@ unsigned long long getnum( const char * const ptr,
                            const unsigned long long llimit,
                            const unsigned long long ulimit )
   {
-  errno = 0;
   char * tail;
+  errno = 0;
   unsigned long long result = strtoull( ptr, &tail, 0 );
   if( tail == ptr )
     {
@@ -172,7 +172,7 @@ public:
   bool includes( const int i ) const
     { return ( i >= 1 && i <= 8 && data[i-1] ); }
 
-  // Recognized formats: 1 1,2,3 1-4 1,3-5,8
+  // Recognized formats: 1 1,2,3 1-4 1,3-5,8 1-3,5-8
   bool parse( const char * p )
     {
     for( int i = 0; i < 8; ++i ) data[i] = false;