# 2010 January 7
#
# The author disclaims copyright to this source code. In place of
# a legal notice, here is a blessing:
#
# May you do good and not evil.
# May you find forgiveness for yourself and forgive others.
# May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements utility functions for SQLite library.
#
# This file attempts to restore the header of a journal.
# This may be useful for rolling-back the last committed
# transaction from a recovered journal.
#
package require sqlite3
set parm_error 0
set fix_chksums 0
set dump_pages 0
set db_name ""
for {set i 0} {$i<$argc} {incr i} {
if {[lindex $argv $i] == "-fix_chksums"} {
set fix_chksums -1
} elseif {[lindex $argv $i] == "-dump_pages"} {
set dump_pages -1
} elseif {$db_name == ""} {
set db_name [lindex $argv $i]
set jrnl_name $db_name-journal
} else {
set parm_error -1
}
}
if {$parm_error || $db_name == ""} {
puts "USAGE: restore_jrnl.tcl \[-fix_chksums\] \[-dump_pages\] db_name"
puts "Example: restore_jrnl.tcl foo.sqlite"
return
}
# is there a way to determine this?
set sectsz 512
# Copy file $from into $to
#
proc copy_file {from to} {
file copy -force $from $to
}
# Execute some SQL
#
proc catchsql {sql} {
set rc [catch {uplevel [list db eval $sql]} msg]
list $rc $msg
}
# Perform a test
#
proc do_test {name cmd expected} {
puts -nonewline "$name ..."
set res [uplevel $cmd]
if {$res eq $expected} {
puts Ok
} else {
puts Error
puts " Got: $res"
puts " Expected: $expected"
}
}
# Calc checksum nonce from journal page data.
#
proc calc_nonce {jrnl_pgno} {
global sectsz
global db_pgsz
global jrnl_name
set jrnl_pg_offset [expr $sectsz+((4+$db_pgsz+4)*$jrnl_pgno)]
set nonce [hexio_get_int [hexio_read $jrnl_name [expr $jrnl_pg_offset+4+$db_pgsz] 4]]
for {set i [expr $db_pgsz-200]} {$i>0} {set i [expr $i-200]} {
set byte [hexio_get_int [hexio_read $jrnl_name [expr $jrnl_pg_offset+4+$i] 1]]
set nonce [expr $nonce-$byte]
}
return $nonce
}
# Calc checksum from journal page data.
#
proc calc_chksum {jrnl_pgno} {
global sectsz
global db_pgsz
global jrnl_name
global nonce
set jrnl_pg_offset [expr $sectsz+((4+$db_pgsz+4)*$jrnl_pgno)]
set chksum $nonce
for {set i [expr $db_pgsz-200]} {$i>0} {set i [expr $i-200]} {
set byte [hexio_get_int [hexio_read $jrnl_name [expr $jrnl_pg_offset+4+$i] 1]]
set chksum [expr $chksum+$byte]
}
return $chksum
}
# Print journal page data in hex dump form
#
proc dump_jrnl_page {jrnl_pgno} {
global sectsz
global db_pgsz
global jrnl_name
# print a header block for the page
puts [string repeat "-" 79]
set jrnl_pg_offset [expr $sectsz+((4+$db_pgsz+4)*$jrnl_pgno)]
set db_pgno [hexio_get_int [hexio_read $jrnl_name [expr $jrnl_pg_offset] 4]]
set chksum [hexio_get_int [hexio_read $jrnl_name [expr $jrnl_pg_offset+4+$db_pgsz] 4]]
set nonce [calc_nonce $jrnl_pgno]
puts [ format {jrnl_pg_offset: %08x (%d) jrnl_pgno: %d db_pgno: %d} \
$jrnl_pg_offset $jrnl_pg_offset \
$jrnl_pgno $db_pgno]
puts [ format {nonce: %08x chksum: %08x} \
$nonce $chksum]
# now hex dump the data
# This is derived from the Tcler's WIKI
set fid [open $jrnl_name r]
fconfigure $fid -translation binary -encoding binary
seek $fid [expr $jrnl_pg_offset+4]
set data [read $fid $db_pgsz]
close $fid
for {set addr 0} {$addr<$db_pgsz} {set addr [expr $addr+16]} {
# get 16 bytes of data
set s [string range $data $addr [expr $addr+16]]
# Convert the data to hex and to characters.
binary scan $s H*@0a* hex ascii
# Replace non-printing characters in the data.
regsub -all -- {[^[:graph:] ]} $ascii {.} ascii
# Split the 16 bytes into two 8-byte chunks
regexp -- {(.{16})(.{0,16})} $hex -> hex1 hex2
# Convert the hex to pairs of hex digits
regsub -all -- {..} $hex1 {& } hex1
regsub -all -- {..} $hex2 {& } hex2
# Print the hex and ascii data
puts [ format {%08x %-24s %-24s %-16s} \
$addr $hex1 $hex2 $ascii ]
}
}
# Setup for the tests. Make a backup copy of the files.
#
if [file exist $db_name.org] {
puts "ERROR: during back-up: $db_name.org exists already."
return;
}
if [file exist $jrnl_name.org] {
puts "ERROR: during back-up: $jrnl_name.org exists already."
return
}
copy_file $db_name $db_name.org
copy_file $jrnl_name $jrnl_name.org
set db_fsize [file size $db_name]
set db_pgsz [hexio_get_int [hexio_read $db_name 16 2]]
set db_npage [expr {$db_fsize / $db_pgsz}]
set jrnl_fsize [file size $jrnl_name]
set jrnl_npage [expr {($jrnl_fsize - $sectsz) / (4 + $db_pgsz + 4)}]
# calculate checksum nonce for first page
set nonce [calc_nonce 0]
# verify all the pages in the journal use the same nonce
for {set i 1} {$i<$jrnl_npage} {incr i} {
set tnonce [calc_nonce $i]
if {$tnonce != $nonce} {
puts "WARNING: different nonces: 0=$nonce $i=$tnonce"
if {$fix_chksums } {
set jrnl_pg_offset [expr $sectsz+((4+$db_pgsz+4)*$i)]
set tchksum [calc_chksum $i]
hexio_write $jrnl_name [expr $jrnl_pg_offset+4+$db_pgsz] [format %08x $tchksum]
puts "INFO: fixing chksum: $i=$tchksum"
}
}
}
# verify all the page numbers in the journal
for {set i 0} {$i<$jrnl_npage} {incr i} {
set jrnl_pg_offset [expr $sectsz+((4+$db_pgsz+4)*$i)]
set db_pgno [hexio_get_int [hexio_read $jrnl_name $jrnl_pg_offset 4]]
if {$db_pgno < 1} {
puts "WARNING: page number < 1: $i=$db_pgno"
}
if {$db_pgno >= $db_npage} {
puts "WARNING: page number >= $db_npage: $i=$db_pgno"
}
}
# dump page data
if {$dump_pages} {
for {set i 0} {$i<$jrnl_npage} {incr i} {
dump_jrnl_page $i
}
}
# write the 8 byte magic string
hexio_write $jrnl_name 0 d9d505f920a163d7
# write -1 for number of records
hexio_write $jrnl_name 8 ffffffff
# write 00 for checksum nonce
hexio_write $jrnl_name 12 [format %08x $nonce]
# write page count
hexio_write $jrnl_name 16 [format %08x $db_npage]
# write sector size
hexio_write $jrnl_name 20 [format %08x $sectsz]
# write page size
hexio_write $jrnl_name 24 [format %08x $db_pgsz]
# check the integrity of the database with the patched journal
sqlite3 db $db_name
do_test restore_jrnl-1.0 {
catchsql {PRAGMA integrity_check}
} {0 ok}
db close