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Diffstat (limited to 'examples/scripts/dd-ex.sh')
| -rw-r--r-- | examples/scripts/dd-ex.sh | 476 |
1 files changed, 476 insertions, 0 deletions
diff --git a/examples/scripts/dd-ex.sh b/examples/scripts/dd-ex.sh new file mode 100644 index 0000000..fafc83f --- /dev/null +++ b/examples/scripts/dd-ex.sh @@ -0,0 +1,476 @@ +#!/bin/sh + +# this is a line editor using only /bin/sh, /bin/dd and /bin/rm + +# /bin/rm is not really required, but it is nice to clean up temporary files + +PATH= +dd=/bin/dd +rm=/bin/rm + +# temporary files we might need +tmp=/tmp/silly.$$ +ed=/tmp/ed.$$ +trap "$rm -f $tmp $tmp.1 $tmp.2 $tmp.3 $tmp.4 $tmp.5 $tmp.6 $ed.a $ed.b $ed.c; exit" 0 1 2 3 + +# from now on, no more rm - the above trap is enough +unset rm + +# we do interesting things with IFS, but better save it... +saveIFS="$IFS" + +# in case "echo" is not a shell builtin... + +Echo () { +case "$1" in + -n) shift + $dd of=$tmp 2>/dev/null <<EOF +$@ +EOF + IFS="+" + set `$dd if=$tmp bs=1 of=/dev/null skip=1 2>&1` + IFS="$saveIFS" + $dd if=$tmp bs=1 count=$1 2>/dev/null + ;; + *) $dd 2>/dev/null <<EOF +$@ +EOF + ;; +esac +} + +# this is used to generate garbage files + +true () { + return 0 +} + +false () { + return 1 +} + +zero () { + ( trap 'go=false' 13 + go=true + while $go + do + $dd "if=$0" + case "$?" in + 0) ;; + *) go=false ;; + esac + done + ) 2>/dev/null +} + +# arithmetic using dd! + +# add variable n1 n2 n3... +# assigns n1+n2+n3+... to variable + +add () { + result="$1" + shift + $dd if=/dev/null of=$tmp bs=1 2>/dev/null + for n in "$@" + do + case "$n" in + 0) ;; + *) zero | $dd of=$tmp.1 bs=1 "count=$n" 2>/dev/null + ( $dd if=$tmp; $dd if=$tmp.1 ) 2>/dev/null | $dd of=$tmp.2 2>/dev/null + $dd if=$tmp.2 of=$tmp 2>/dev/null + ;; + esac + done + IFS="+" + set `$dd if=$tmp bs=1 of=/dev/null 2>&1` + IFS="$saveIFS" + eval $result='$1' +} + +# subtract variable n1 n2 +# subtracts n2 from n1, assigns result to variable + +subtract () { + result="$1" + zero | $dd of=$tmp bs=1 "count=$2" 2>/dev/null + IFS="+" + set `$dd if=$tmp bs=1 of=/dev/null "skip=$3" 2>&1` + IFS="$saveIFS" + case "$1" in + dd*) set 0 ;; + esac + eval $result='$1' +} + +# multiply variable n1 n2 +# variable = n1 * n2 + +multiply () { + result="$1" + zero | $dd "bs=$2" of=$tmp "count=$3" 2>/dev/null + IFS="+" + set `$dd if=$tmp bs=1 of=/dev/null 2>&1` + IFS="$saveIFS" + eval $result='$1' +} + +# divide variable n1 n2 +# variable = int( n1 / n2 ) + +divide () { + result="$1" + zero | $dd bs=1 of=$tmp "count=$2" 2>/dev/null + IFS="+" + set `$dd if=$tmp "bs=$3" of=/dev/null 2>&1` + IFS="$saveIFS" + eval $result='$1' +} + +# compare variable n1 n2 sets variable to lt if n1<n2, gt if n1>n2, eq if n1==n2 + +compare () { + res="$1" + n1="$2" + n2="$3" + subtract somename "$n1" "$n2" + case "$somename" in + 0) ;; + *) eval $res=gt; return; + esac + subtract somename "$n2" "$n1" + case "$somename" in + 0) ;; + *) eval $res=lt; return; + esac + eval $res=eq +} + +# lt n1 n2 returns true if n1 < n2 + +lt () { + n1="$1" + n2="$2" + subtract somename "$n2" "$n1" + case "$somename" in + 0) return 1 ;; + esac + return 0 +} + +# le n1 n2 returns true if n1 <= n2 + +le () { + n1="$1" + n2="$2" + subtract somename "$n1" "$n2" + case "$somename" in + 0) return 0 ;; + esac + return 1 +} + +# gt n1 n2 returns true if n1 > n2 + +gt () { + n1="$1" + n2="$2" + subtract somename "$n1" "$n2" + case "$somename" in + 0) return 1 ;; + esac + return 0 +} + +# ge n1 n2 returns true if n1 >= n2 + +ge () { + n1="$1" + n2="$2" + subtract somename "$n2" "$n1" + case "$somename" in + 0) return 0 ;; + esac + return 1 +} + +# useful functions for the line editor + +# open a file - copy it to the buffers + +open () { + file="$1" + set `$dd "if=$file" of=/dev/null 2>&1` + case "$1" in + dd*) return 1 + esac + # copy the first line to $ed.c + go=true + len=0 + while $go + do + case "`$dd "if=$file" bs=1 skip=$len count=1 2>/dev/null`" in + ?*) go=true ;; + *) go=false ;; + esac + add len 1 $len + done + # now $len is the length of the first line (including newline) + $dd "if=$file" bs=1 count=$len of=$ed.c 2>/dev/null + $dd "if=$file" bs=1 skip=$len of=$ed.b 2>/dev/null + $dd if=/dev/null of=$ed.a 2>/dev/null + lineno=1 +} + +# save a file - copy the buffers to the file + +save () { + # make a backup copy of the original + $dd "if=$1" "of=$1.bak" 2>/dev/null + # and save + ( $dd if=$ed.a; $dd if=$ed.c; $dd if=$ed.b ) > "$1" 2>/dev/null +} + +# replace n1 n2 bla replaces n2 chars of current line, starting n1-th + +replace () { + $dd if=$ed.c of=$tmp.1 bs=1 "count=$1" 2>/dev/null + ( $dd if=$ed.c "skip=$1" bs=1 | $dd of=$tmp.2 bs=1 "skip=$2" ) 2>/dev/null + shift + shift + ( $dd if=$tmp.1; Echo -n "$@"; $dd if=$tmp.2 ) > $tmp.3 2>/dev/null + $dd if=$tmp.3 of=$ed.c 2>/dev/null +} + +# rstring n s bla +# replace the n-th occurence of s with bla + +rstring () { + n="$1" + shift; + # first we have to find it - this is fun! + # we have $tmp.4 => text before string, $tmp.5 => text after + $dd if=/dev/null of=$tmp.4 2>/dev/null + $dd if=$ed.c of=$tmp.5 2>/dev/null + string="$1" + shift + $dd of=$tmp.6 2>/dev/null <<EOF +$@ +EOF + while : + do + case "`$dd if=$tmp.5 2>/dev/null`" in + $string*) + if lt $n 2 + then + # now we want to replace the string + Echo -n "$@" > $tmp.2 + Echo -n "$string" > $tmp.1 + IFS="+" + set `$dd bs=1 if=$tmp.1 of=/dev/null 2>&1` + IFS="$saveIFS" + slen=$1 + IFS="+" + ( $dd if=$tmp.4; $dd if=$tmp.2; $dd if=$tmp.5 bs=1 skip=$slen ) \ + 2>/dev/null > $tmp + $dd if=$tmp of=$ed.c 2>/dev/null + return 0 + else + subtract n $n 1 + ( $dd if=$tmp.4; $dd if=$tmp.5 bs=1 count=1 ) > $tmp 2>/dev/null + $dd if=$tmp of=$tmp.4 2>/dev/null + # and remove it from $tmp.5 + $dd if=$tmp.5 of=$tmp bs=1 skip=1 2>/dev/null + $dd if=$tmp of=$tmp.5 2>/dev/null + fi + ;; + ?*) # add one more byte... + ( $dd if=$tmp.4; $dd if=$tmp.5 bs=1 count=1 ) > $tmp 2>/dev/null + $dd if=$tmp of=$tmp.4 2>/dev/null + # and remove it from $tmp.5 + $dd if=$tmp.5 of=$tmp bs=1 skip=1 2>/dev/null + $dd if=$tmp of=$tmp.5 2>/dev/null + ;; + *) # not found + return 1 + ;; + esac + done +} + +# skip to next line +next () { + add l $lineno 1 + ( $dd if=$ed.a; $dd if=$ed.c ) 2>/dev/null > $tmp.3 + $dd if=$ed.b of=$tmp.4 2>/dev/null + open $tmp.4 + $dd if=$tmp.3 of=$ed.a 2>/dev/null + lineno=$l +} + +# delete current line +delete () { + l=$lineno + $dd if=$ed.a 2>/dev/null > $tmp.1 + $dd if=$ed.b of=$tmp.2 2>/dev/null + open $tmp.2 + $dd if=$tmp.1 of=$ed.a 2>/dev/null + lineno=$l +} + +# insert before current line (without changing current) +insert () { + ( $dd if=$ed.a; Echo "$@" ) 2>/dev/null > $tmp.1 + $dd if=$tmp.1 of=$ed.a 2>/dev/null + add lineno $lineno 1 +} + +# previous line +prev () { + case "$lineno" in + 1) ;; + *) subtract lineno $lineno 1 + # read last line of $ed.a + IFS='+' + set `$dd if=$ed.a of=/dev/null bs=1 2>&1` + IFS="$saveIFS" + size=$1 + # empty? + case "$size" in + 0) return ;; + esac + subtract size $size 1 + # skip final newline + case "$size" in + 0) ;; + *) subtract size1 $size 1 + case "`$dd if=$ed.a bs=1 skip=$size count=1 2>/dev/null`" in + ?*) ;; + *) size=$size1 ;; + esac + ;; + esac + go=true + while $go + do + case "$size" in + 0) go=false ;; + *) case "`$dd if=$ed.a bs=1 skip=$size count=1 2>/dev/null`" in + ?*) go=true; subtract size $size 1 ;; + *) go=false; add size $size 1 ;; + esac + ;; + esac + done + # now $size is the size of the first n-1 lines + # add $ed.c to $ed.b + ( $dd if=$ed.c; $dd if=$ed.b ) 2>/dev/null > $tmp.5 + $dd if=$tmp.5 of=$ed.b 2>/dev/null + # move line to ed.c + case "$size" in + 0) $dd if=$ed.a of=$ed.c 2>/dev/null + $dd if=/dev/null of=$tmp.5 2>/dev/null + ;; + *) $dd if=$ed.a of=$ed.c bs=1 skip=$size 2>/dev/null + $dd if=$ed.a of=$tmp.5 bs=1 count=$size 2>/dev/null + ;; + esac + # move rest to ed.a + $dd if=$tmp.5 of=$ed.a 2>/dev/null + ;; + esac +} + +# goes to a given line +goto () { + rl="$1" + compare bla "$rl" $lineno + case "$bla" in + eq) return + ;; + gt) while gt "$rl" $lineno + do + next + done + ;; + lt) while lt "$rl" $lineno + do + prev + done + ;; + esac +} + +lineout () { + Echo -n "$lineno: " + $dd if=$ed.c 2>/dev/null +} + +state=closed +name= +autoprint=true + +while true +do + Echo -n '> ' + read cmd arg + case "$cmd:$state" in + open:open) Echo "There is a file open already" ;; + open:*) if open "$arg" + then state=open; name="$arg"; $autoprint + else Echo "Cannot open $arg" + fi + ;; + new:open) Echo "There is a file open already" ;; + new:*) open "$arg" + state=open + name="$arg" + $autoprint + ;; + close:changed) Echo "Use 'discard' or 'save'" ;; + close:closed) Echo "Closed already" ;; + close:*) state=closed ;; + save:closed) Echo "There isn't a file to save" ;; + save:*) case "$arg" in + ?*) save "$arg" ;; + *) save "$name" ;; + esac + state=open + ;; + discard:changed) Echo "Your problem!"; state=closed ;; + discard:*) state=closed ;; + print:closed) Echo "No current file" ;; + print:*) lineout ;; + goto:closed) Echo "No current file" ;; + goto:*) goto "$arg"; $autoprint ;; + next:closed) Echo "No current file" ;; + next:*) next; $autoprint ;; + prev:closed) Echo "No current file" ;; + prev:*) prev; $autoprint ;; + name:closed) Echo "No current file" ;; + name:*) name="$arg" ;; + replace:closed) Echo "No current file" ;; + replace:*) if rstring 1 $arg + then state=changed; $autoprint + else Echo "Not found" + fi + ;; + nreplace:closed) Echo "No current file" ;; + nreplace:*) if rstring $arg + then state=changed; $autoprint + else Echo "Not found" + fi + ;; + delete:closed) Echo "No current file" ;; + delete:*) delete; state=changed; $autoprint ;; + insert:closed) Echo "No current file" ;; + insert:*) insert "$arg"; prev; state=changed; $autoprint ;; + quit:changed) Echo "Use 'save' or 'discard'" ;; + quit:*) Echo "bye"; exit;; + autoprint:*) autoprint="lineout" ;; + noprint:*) autoprint="" ;; + :*) ;; + *) Echo "Command not understood" ;; + esac +done + |