tool/restore_jrnl.tcl

   1 # 2010 January 7
   2 #
   3 # The author disclaims copyright to this source code.  In place of
   4 # a legal notice, here is a blessing:
   5 #
   6 #    May you do good and not evil.
   7 #    May you find forgiveness for yourself and forgive others.
   8 #    May you share freely, never taking more than you give.
   9 #
  10 #***********************************************************************
  11 # This file implements utility functions for SQLite library.
  12 #
  13 # This file attempts to restore the header of a journal.
  14 # This may be useful for rolling-back the last committed
  15 # transaction from a recovered journal.
  16 #
  17
  18 package require sqlite3
  19
  20 set parm_error 0
  21 set fix_chksums 0
  22 set dump_pages 0
  23 set db_name ""
  24
  25 for {set i 0} {$i<$argc} {incr i} {
  26   if {[lindex $argv $i] == "-fix_chksums"} {
  27     set fix_chksums -1
  28   } elseif {[lindex $argv $i] == "-dump_pages"} {
  29     set dump_pages -1
  30   } elseif {$db_name == ""} {
  31     set db_name [lindex $argv $i]
  32     set jrnl_name $db_name-journal
  33   } else {
  34     set parm_error -1
  35   }
  36 }
  37 if {$parm_error || $db_name == ""} {
  38   puts "USAGE: restore_jrnl.tcl \[-fix_chksums\] \[-dump_pages\] db_name"
  39   puts "Example: restore_jrnl.tcl foo.sqlite"
  40   return
  41 }
  42
  43 # is there a way to determine this?
  44 set sectsz 512
  45
  46 # Copy file $from into $to
  47 #
  48 proc copy_file {from to} {
  49   file copy -force $from $to
  50 }
  51
  52 # Execute some SQL
  53 #
  54 proc catchsql {sql} {
  55   set rc [catch {uplevel [list db eval $sql]} msg]
  56   list $rc $msg
  57 }
  58
  59 # Perform a test
  60 #
  61 proc do_test {name cmd expected} {
  62   puts -nonewline "$name ..."
  63   set res [uplevel $cmd]
  64   if {$res eq $expected} {
  65     puts Ok
  66   } else {
  67     puts Error
  68     puts "  Got: $res"
  69     puts "  Expected: $expected"
  70   }
  71 }
  72
  73 # Calc checksum nonce from journal page data.
  74 #
  75 proc calc_nonce {jrnl_pgno} {
  76   global sectsz
  77   global db_pgsz
  78   global jrnl_name
  79   set jrnl_pg_offset [expr $sectsz+((4+$db_pgsz+4)*$jrnl_pgno)]
  80   set nonce [hexio_get_int [hexio_read $jrnl_name [expr $jrnl_pg_offset+4+$db_pgsz] 4]]
  81   for {set i [expr $db_pgsz-200]} {$i>0} {set i [expr $i-200]} {
  82     set byte [hexio_get_int [hexio_read $jrnl_name [expr $jrnl_pg_offset+4+$i] 1]]
  83     set nonce [expr $nonce-$byte]
  84   }
  85   return $nonce
  86 }
  87
  88 # Calc checksum from journal page data.
  89 #
  90 proc calc_chksum {jrnl_pgno} {
  91   global sectsz
  92   global db_pgsz
  93   global jrnl_name
  94   global nonce
  95   set jrnl_pg_offset [expr $sectsz+((4+$db_pgsz+4)*$jrnl_pgno)]
  96   set chksum $nonce
  97   for {set i [expr $db_pgsz-200]} {$i>0} {set i [expr $i-200]} {
  98     set byte [hexio_get_int [hexio_read $jrnl_name [expr $jrnl_pg_offset+4+$i] 1]]
  99     set chksum [expr $chksum+$byte]
 100   }
 101   return $chksum
 102 }
 103
 104 # Print journal page data in hex dump form
 105 #
 106 proc dump_jrnl_page {jrnl_pgno} {
 107   global sectsz
 108   global db_pgsz
 109   global jrnl_name
 110
 111   # print a header block for the page
 112   puts [string repeat "-" 79]
 113   set jrnl_pg_offset [expr $sectsz+((4+$db_pgsz+4)*$jrnl_pgno)]
 114   set db_pgno [hexio_get_int [hexio_read $jrnl_name [expr $jrnl_pg_offset] 4]]
 115   set chksum [hexio_get_int [hexio_read $jrnl_name [expr $jrnl_pg_offset+4+$db_pgsz] 4]]
 116   set nonce [calc_nonce $jrnl_pgno]
 117   puts [ format {jrnl_pg_offset: %08x (%d)  jrnl_pgno: %d  db_pgno: %d} \
 118       $jrnl_pg_offset $jrnl_pg_offset \
 119       $jrnl_pgno $db_pgno]
 120   puts [ format {nonce: %08x chksum: %08x} \
 121       $nonce $chksum]
 122
 123   # now hex dump the data
 124   # This is derived from the Tcler's WIKI
 125   set fid [open $jrnl_name r]
 126   fconfigure $fid -translation binary -encoding binary
 127   seek $fid [expr $jrnl_pg_offset+4]
 128   set data [read $fid $db_pgsz]
 129   close $fid
 130   for {set addr 0} {$addr<$db_pgsz} {set addr [expr $addr+16]} {
 131     # get 16 bytes of data
 132     set s [string range $data $addr [expr $addr+16]]
 133
 134     # Convert the data to hex and to characters.
 135     binary scan $s H*@0a* hex ascii
 136
 137     # Replace non-printing characters in the data.
 138     regsub -all -- {[^[:graph:] ]} $ascii {.} ascii
 139
 140     # Split the 16 bytes into two 8-byte chunks
 141     regexp -- {(.{16})(.{0,16})} $hex -> hex1 hex2
 142
 143     # Convert the hex to pairs of hex digits
 144     regsub -all -- {..} $hex1 {& } hex1
 145     regsub -all -- {..} $hex2 {& } hex2
 146
 147     # Print the hex and ascii data
 148     puts [ format {%08x %-24s %-24s %-16s} \
 149         $addr $hex1 $hex2 $ascii ]
 150   }
 151 }
 152
 153 # Setup for the tests.  Make a backup copy of the files.
 154 #
 155 if [file exist $db_name.org] {
 156   puts "ERROR: during back-up: $db_name.org exists already."
 157   return;
 158 }
 159 if [file exist $jrnl_name.org] {
 160   puts "ERROR: during back-up: $jrnl_name.org exists already."
 161   return
 162 }
 163 copy_file $db_name $db_name.org
 164 copy_file $jrnl_name $jrnl_name.org
 165
 166 set db_fsize [file size $db_name]
 167 set db_pgsz [hexio_get_int [hexio_read $db_name 16 2]]
 168 set db_npage [expr {$db_fsize / $db_pgsz}]
 169
 170 set jrnl_fsize [file size $jrnl_name]
 171 set jrnl_npage [expr {($jrnl_fsize - $sectsz) / (4 + $db_pgsz + 4)}]
 172
 173 # calculate checksum nonce for first page
 174 set nonce [calc_nonce 0]
 175
 176 # verify all the pages in the journal use the same nonce
 177 for {set i 1} {$i<$jrnl_npage} {incr i} {
 178   set tnonce [calc_nonce $i]
 179   if {$tnonce != $nonce} {
 180     puts "WARNING: different nonces: 0=$nonce $i=$tnonce"
 181     if {$fix_chksums } {
 182       set jrnl_pg_offset [expr $sectsz+((4+$db_pgsz+4)*$i)]
 183       set tchksum [calc_chksum $i]
 184       hexio_write $jrnl_name [expr $jrnl_pg_offset+4+$db_pgsz] [format %08x $tchksum]
 185       puts "INFO: fixing chksum: $i=$tchksum"
 186     }
 187   }
 188 }
 189
 190 # verify all the page numbers in the journal
 191 for {set i 0} {$i<$jrnl_npage} {incr i} {
 192   set jrnl_pg_offset [expr $sectsz+((4+$db_pgsz+4)*$i)]
 193   set db_pgno [hexio_get_int [hexio_read $jrnl_name $jrnl_pg_offset 4]]
 194   if {$db_pgno < 1} {
 195     puts "WARNING: page number < 1: $i=$db_pgno"
 196   }
 197   if {$db_pgno >= $db_npage} {
 198     puts "WARNING: page number >= $db_npage: $i=$db_pgno"
 199   }
 200 }
 201
 202 # dump page data
 203 if {$dump_pages} {
 204   for {set i 0} {$i<$jrnl_npage} {incr i} {
 205     dump_jrnl_page $i
 206   }
 207 }
 208
 209 # write the 8 byte magic string
 210 hexio_write $jrnl_name 0 d9d505f920a163d7
 211
 212 # write -1 for number of records
 213 hexio_write $jrnl_name 8 ffffffff
 214
 215 # write 00 for checksum nonce
 216 hexio_write $jrnl_name 12 [format %08x $nonce]
 217
 218 # write page count
 219 hexio_write $jrnl_name 16 [format %08x $db_npage]
 220
 221 # write sector size
 222 hexio_write $jrnl_name 20 [format %08x $sectsz]
 223
 224 # write page size
 225 hexio_write $jrnl_name 24 [format %08x $db_pgsz]
 226
 227 # check the integrity of the database with the patched journal
 228 sqlite3 db $db_name
 229 do_test restore_jrnl-1.0 {
 230   catchsql {PRAGMA integrity_check}
 231 } {0 ok}
 232 db close
 233