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############################################################################
#
# File: press.icn
#
# Subject: Program to archive files
#
# Author: Robert J. Alexander
#
# Date: November 14, 1991
#
###########################################################################
#
# Besides being a useful file archiving utility, this program can be
# used to experiment with the LZW compression process, as it contains
# extensive tracing facilities that illustrate the process in detail.
#
# Compression can be turned off if faster archiving is desired.
#
# The LZW compression procedures in this program are general purpose
# and suitable for reuse in other programs.
#
############################################################################
#
# Instructions for use are summarized in "help" procedures that follow.
#
############################################################################
#
# Links: options, colmize, wildcard
#
############################################################################
link options, colmize, wildcard
procedure Usage(s)
/s := ""
stop("\nUsage:_
\n Compress: press -c <archive file> [<options>] [<file to compress>...]_
\n Archive: press -a <archive file> [<options>] [<file to archive>...]_
\n Extract: press -x <archive file> [<options>] [<file to extract>...]_
\n Print: press -p <archive file> [<options>] [<file to print>...]_
\n List: press -l <archive file> [<options>] [<file to list>...]_
\n Delete: press -d <archive file> [<options>] <file to delete>..._
\n_
\n Help: press (prints this message)_
\n More help:press -h (prints more details)_
\n_
\n -c perform compression into <archive file>_
\n -a add file(s) to <archive file> in uncompressed format_
\n -x extract (& decompress) file(s) from <archive file>_
\n -p extract (& decompress) from <archive file> to standard output_
\n -l list file names in <archive file>_
\n -d delete file(s) from <archive file>_
\n (produces new file -- old file saved with \".bak\" suffix)_
\n_
\n Options:_
\n -q work quietly_
\n -t text file(s) (retrieves with correct line end format)_
\n -n process all files in archive *except* specified files_
\n_
\n LZW Experimentor Options:_
\n -T produce detailed compression trace info (to standard error file)_
\n -S maximum compression string table size_
\n (for -c only -- default = 1024)_
\n"
,s)
end
procedure MoreHelp()
return "\n _
The archive (-a) option means to add the file without compression._
\n_
\n If no files are specified to extract, print, or list, then all files_
\n in the archive are used._
\n_
\n UNIX-style filename wildcard conventions can be used to express_
\n the archived file names for extract, print, list, and delete_
\n operations. Be sure to quote names containing wildcard characters_
\n so that they aren't expanded by the shell (if applicable)._
\n_
\n If a <file to compress> or <file to archive> is \"-\", or if no files_
\n are specified, standard input is archived._
\n_
\n If <archive file> for extract, print, or list is \"-\", standard input_
\n is the archive file._
\n_
\n If <archive file> for compress or archive is \"-\", archive is written_
\n to standard output._
\n_
\n New files archived to an existing archive file are always appended,_
\n deleting any previously archived version of the same file name._
\n_
\n Archive files can be simply concatenated to create their union._
\n However, if the same file exists in both archives, only the first_
\n in the resulting file will be able to be accessed._
\n_
\n If a \"compressed\" file turns out to be longer than the uncompressed_
\n file (rare but possible, usually for very short files), the file will_
\n automatically be archived in uncompressed format._
\n_
\n A default file name suffix of \".prx\" is assumed for <archive file>_
\n names that are specified without a suffix._
\n_
\n_
\n LZW \"internals\" option:_
\n_
\n If the specified maximum table size is positive, the string table is_
\n discarded when the maximum size is reached and rebuilt (usually the_
\n better choice). If negative, the original table is not discarded,_
\n which might produce better results in some circumstances. This_
\n option was provided primarily for experimentors._
\n"
end
#
# Global variables.
#
# Note: additional globals that contain option values are defined near
# Options(), below.
#
global inchars,outchars,tinchars,toutchars,lzw_recycles,
lzw_stringTable,rf,wf,magic,rline,wline
#
# Main procedure.
#
procedure main(arg)
local arcfile
#
# Initialize.
#
Options(arg)
inchars := outchars := tinchars := toutchars := lzw_recycles := 0
magic := "\^p\^r\^e\^s\^s\^i\^c\^n"
#
# Do requested operation.
#
arcfile :=
DefaultSuffix(\(compr | archive | extract | print | lister | deleter),
"prx") | Usage()
if \(compr | archive) then Archive(arcfile,arg)
else if \(extract | print) then Extract(arcfile,arg)
else if \lister then List(arcfile,arg)
else if \deleter then Delete(arcfile,arg)
return
end
#
# Option global variables.
#
global lzw_trace,maxTableSpecified,maxTableSize,print,quiet,tmode,WildMatch
global extract,compr,archive,lister,deleter
#
# Options() -- Handle command line options.
#
procedure Options(arg)
local opt,n,x
opt := options(arg,"hc:a:x:p:l:d:qtTS+n")
if \opt["h"] then Usage(MoreHelp())
extract := opt["x"]
print := opt["p"]
compr := opt["c"]
archive := opt["a"]
lister := opt["l"]
deleter := opt["d"]
quiet := opt["q"]
tmode := if \opt["t"] then "t" else "u"
WildMatch := if \opt["n"] then not_wild_match else whole_wild_match
lzw_trace := opt["T"]
maxTableSpecified := opt["S"]
maxTableSize := \maxTableSpecified | 1024 # 10 bits default
n := 0
every x := compr | archive | extract | print | lister | deleter do
if \x then n +:= 1
if n ~= 1 then Usage()
return
end
#
# Archive() -- Do archiving.
#
procedure Archive(arcfile,arg)
local fn,addr,realLen,maxT,length,addr2,deleteFiles,new_data_start
#
# Confirm options and open the archive file.
#
if *arg = 0 | WildMatch === not_wild_match then Usage()
if ("" | "-") ~== arcfile then {
if wf := open(arcfile,"ru") then {
if not (reads(wf,*magic) == magic) then {
stop("Invalid archive file ",arcfile)
}
close(wf)
}
wf := open(arcfile,"bu" | "wu") | stop("Can't open archive file ",arcfile)
if tmode == "t" then rline := "\n"
seek(wf,0)
if where(wf) = 1 then writes(wf,magic)
}
else {
wf := &output
arcfile := "stdout"
}
new_data_start := where(wf)
## if /quiet then
## write(&errout,"New data starting at byte ",new_data_start," of ",arcfile)
#
# Loop to process files on command line.
#
if *arg = 0 then arg := ["-"]
deleteFiles := []
every fn := !arg do {
if fn === arcfile then next
if /quiet then
writes(&errout,"File \"",fn,"\" -- ")
rf := if fn ~== "-" then open(fn,tmode) | &null else &input
if /rf then {
if /quiet then
write(&errout,"Can't open input file \"",fn,"\" -- skipped")
next
}
put(deleteFiles,fn)
WriteString(wf,Tail(fn))
addr := where(rf)
seek(rf,0)
realLen := where(rf) - 1
WriteInteger(wf,realLen)
seek(rf,addr)
if /quiet then
writes(&errout,"Length: ",realLen)
addr := where(wf)
WriteInteger(wf,0)
writes(wf,"\1") # write a compression version string
if \compr then {
WriteInteger(wf,maxTableSize)
maxT := Compress(R,W,maxTableSize)
length := outchars + 4
if /quiet then
writes(&errout," Compressed: ",length," ",
Percent(realLen - outchars,realLen))
}
#
# If compressed file is larger than original, just copy the original.
#
if \archive | length > realLen then {
if /quiet then
writes(&errout," -- Archived uncompressed")
seek(wf,addr + 4)
writes(wf,"\0") # write a zero version string for uncompressed
seek(rf,1)
CopyFile(rf,wf)
inchars := outchars := length := realLen
maxT := 0
lzw_stringTable := ""
}
if /quiet then
write(&errout)
close(rf)
addr2 := where(wf)
seek(wf,addr)
WriteInteger(wf,length)
seek(wf,addr2)
if /quiet then
Stats(maxT)
}
close(wf)
if /quiet then
if *arg > 1 then FinalStats()
Delete(arcfile,deleteFiles,new_data_start)
return
end
#
# Extract() -- Extract a file from the archive.
#
procedure Extract(arcfile,arg)
local fileSet,wfn,realLen,cmprLen,maxT,version,theArg
if \maxTableSpecified then Usage()
rf := OpenReadArchive(arcfile)
arcfile := rf[2]
rf := rf[1]
if *arg > 0 then fileSet := set(arg)
#
# Process input file.
#
while wfn := ReadString(rf) do {
(realLen := ReadInteger(rf) &
cmprLen := ReadInteger(rf) &
version := ord(reads(rf))) |
stop("Bad format in compressed file")
if /quiet then
writes(&errout,"File \"",wfn,"\" -- length: ",realLen,
" compressed: ",cmprLen," bytes -- ")
if /fileSet | WildMatch(theArg := !arg,wfn) then {
delete(\fileSet,theArg)
if not version = (0 | 1) then {
if /quiet then
write(&errout,"can't handle this compression type (",version,
") -- skipped")
seek(rf,where(rf) + cmprLen)
}
else {
if /quiet then
write(&errout,"extracted")
if /print then {
wf := open(wfn,"w" || tmode) | &null
if /wf then {
if /quiet then
write(&errout,"Can't open output file \"",wfn,
"\" -- quitting")
exit(1)
}
}
else wf := &output
if version = 1 then {
maxT := ReadInteger(rf) |
stop("Error in archive file format: ","table size missing")
Decompress(R,W,maxT)
}
else {
maxT := 0
CopyFile(rf,wf,cmprLen)
outchars := inchars := realLen
}
close(&output ~=== wf)
if /quiet then
Stats(maxT)
}
}
else {
if /quiet then
write(&errout,"skipped")
seek(rf,where(rf) + cmprLen)
}
}
close(rf)
FilesNotFound(fileSet)
return
end
#
# List() -- Skip through the archive, extracting info about files,
# then list in columns.
#
procedure List(arcfile,arg)
local fileSet,flist,wfn,realLen,cmprLen,version,theArg
if \maxTableSpecified then Usage()
rf := OpenReadArchive(arcfile)
arcfile := rf[2]
rf := rf[1]
write(&errout,"Archive file ",arcfile,":")
if *arg > 0 then fileSet := set(arg)
#
# Process input file.
#
flist := []
while wfn := ReadString(rf) do {
(realLen := ReadInteger(rf) &
cmprLen := ReadInteger(rf) &
version := ord(reads(rf))) |
stop("Bad format in compressed file")
if /fileSet | WildMatch(theArg := !arg,wfn) then {
delete(\fileSet,theArg)
put(flist,"\"" || wfn || "\" " || realLen || "->" || cmprLen)
tinchars +:= realLen
toutchars +:= cmprLen
}
seek(rf,where(rf) + cmprLen)
}
close(rf)
every write(&errout,colmize(sort(flist)))
FilesNotFound(fileSet)
FinalStats()
return
end
#
# Delete() -- Delete a file from the archive.
#
procedure Delete(arcfile,arg,new_data_start)
local workfn,workf,fileSet,wfn,realLen,cmprLen,bakfn,deletedFiles,
head,version,hdrLen,theArg
if *arg = 0 | (\deleter & \maxTableSpecified) then Usage()
rf := OpenReadArchive(arcfile)
arcfile := rf[2]
rf := rf[1]
workfn := Root(arcfile) || ".wrk"
workf := open(workfn,"wu") | stop("Can't open work file ",workfn)
writes(workf,magic)
fileSet := set(arg)
#
# Process input file.
#
deletedFiles := 0
head := if \deleter then "File" else "Replaced file"
while not (\new_data_start <= where(rf)) & wfn := ReadString(rf) do {
(realLen := ReadInteger(rf) &
cmprLen := ReadInteger(rf) &
version := ord(reads(rf))) |
stop("Bad format in compressed file")
if /quiet then
writes(&errout,head," \"",wfn,"\" -- length: ",realLen,
" compressed: ",cmprLen," bytes -- ")
if WildMatch(theArg := !arg,wfn) then {
deletedFiles +:= 1
delete(fileSet,theArg)
if /quiet then
write(&errout,"deleted")
seek(rf,where(rf) + cmprLen)
}
else {
if /quiet then
write(&errout,"kept")
hdrLen := *wfn + 10
seek(rf,where(rf) - hdrLen)
CopyFile(rf,workf,cmprLen + hdrLen)
}
}
if deletedFiles > 0 then {
CopyFile(rf,workf)
every close(workf | rf)
if (rf ~=== &input) then {
bakfn := Root(arcfile) || ".bak"
remove(bakfn)
rename(arcfile,bakfn) | stop("Couldn't rename ",arcfile," to ",bakfn)
}
rename(workfn,arcfile) | stop("Couldn't rename ",workfn," to ",arcfile)
}
else {
every close(workf | rf)
remove(workfn)
}
if \deleter then FilesNotFound(fileSet)
return
end
#
# OpenReadArchive() -- Open an archive for reading.
#
procedure OpenReadArchive(arcfile)
local rf
rf := if ("" | "-") ~== arcfile then
open(arcfile,"ru") | stop("Can't open archive file ",arcfile)
else {
arcfile := "stdin"
&input
}
if reads(rf,*magic) ~== magic then stop("Invalid archive file ",arcfile)
if tmode == "t" then wline := "\x0a"
return [rf,arcfile]
end
#
# FilesNotFound() -- List the files remaining in "fileSet".
#
procedure FilesNotFound(fileSet)
return if *\fileSet > 0 then {
write(&errout,"\nFiles not found:")
every write(&errout," ",colmize(sort(fileSet),78))
&null
}
end
#
# Stats() -- Print stats after a file.
#
procedure Stats(maxTableSize)
#
# Write statistics
#
if \lzw_trace then write(&errout,
" table size = ",*lzw_stringTable,"/",maxTableSize,
" (recycles: ",lzw_recycles,")")
tinchars +:= inchars
toutchars +:= outchars
inchars := outchars := lzw_recycles := 0
return
end
#
# FinalStats() -- Print final stats.
#
procedure FinalStats()
#
# Write final statistics
#
write(&errout,"\nTotals: ",
"\n input: ",tinchars,
"\n output: ",toutchars,
"\n compression: ",Percent(tinchars - toutchars,tinchars) | "",
"\n")
return
end
#
# WriteInteger() -- Write a 4-byte binary integer to "f".
#
procedure WriteInteger(f,i)
local s
s := ""
every 1 to 4 do {
s := char(i % 256) || s
i /:= 256
}
return writes(f,s)
end
#
# ReadInteger() -- Read a 4-byte binary integer from "f".
#
procedure ReadInteger(f)
local s,v
s := reads(f,4) | fail
if *s < 4 then
stop("Error in archive file format: ","bad integer")
v := 0
s ? while v := v * 256 + ord(move(1))
return v
end
#
# WriteString() -- Write a string preceded by a length byte to "f".
#
procedure WriteString(f,s)
return writes(f,char(*s),s)
end
#
# ReadString() -- Read a string preceded by a length byte from "f".
#
procedure ReadString(f)
local len,s
len := ord(reads(f)) | fail
s := reads(f,len)
if *s < len then
stop("Error in archive file format: ","bad string")
return s
end
#
# CopyFile() -- Copy a file.
#
procedure CopyFile(rf,wf,len)
local s
if /len then {
while writes(wf,s := reads(rf,1000))
}
else {
while len > 1000 & writes(wf,s := reads(rf,1000)) do len -:= *s
writes(wf,s := reads(rf,len)) & len -:= *s
}
return len
end
#
# Percent() -- Format a rational number "n"/"d" as a percentage.
#
procedure Percent(n,d)
local sign,whole,fraction
n / (0.0 ~= d) ? {
sign := ="-" | ""
whole := tab(find("."))
move(1)
fraction := tab(0)
}
return (\sign || ("0" ~== whole | "") ||
(if whole == "0" then integer else 1)(left(fraction,2,"0")) | "--") ||
"%"
end
#
# R() -- Read-a-character procedure.
#
procedure R()
local c
c := reads(rf) | fail
inchars +:= 1
if c === rline then c := "\x0a"
return c
end
#
# W() -- Write-characters procedure.
#
procedure W(s)
local i
every i := find(\wline,s) do s[i] := "\n"
outchars +:= *s
return writes(wf,s)
end
#
# Tail() -- Return the file name portion (minus the path) of a
# qualified file name.
#
procedure Tail(fn)
local i
i := 0
every i := upto('/\\:',fn)
return .fn[i + 1:0]
end
#
# Root() -- Return the root portion (minus the suffix) of a file name.
#
procedure Root(fn)
local i
i := 0
every i := find(".",fn)
return .fn[1:i]
end
procedure DefaultSuffix(fn,suf)
local i
return fn || "." || suf
end
############################################################################
#
# Compress() -- LZW compression
#
# Arguments:
#
# inproc a procedure that returns a single character from
# the input stream.
#
# outproc a procedure that writes a single character (its
# argument) to the output stream.
#
# maxTableSize the maximum size to which the string table
# is allowed to grow before something is done about it.
# If the size is positive, the table is discarded and
# a new one started. If negative, it is retained, but
# no new entries are added.
#
procedure Compress(inproc,outproc,maxTableSize)
local EOF,c,charTable,junk1,junk2,outcode,s,t,tossTable,x
#
# Initialize.
#
/maxTableSize := 1024 # default 10 "bits"
tossTable := maxTableSize
/lzw_recycles := 0
if maxTableSize < 0 then maxTableSize := -maxTableSize
charTable := table()
every c := !&cset do charTable[c] := ord(c)
EOF := charTable[*charTable] := *charTable # reserve code=256 for EOF
lzw_stringTable := copy(charTable)
#
# Compress the input stream.
#
s := inproc() | return maxTableSize
if \lzw_trace then {
write(&errout,"\nInput string\tOutput code\tNew table entry")
writes(&errout,"\"",image(s)[2:-1])
}
while c := inproc() do {
if \lzw_trace then
writes(&errout,image(c)[2:-1])
if \lzw_stringTable[t := s || c] then s := t
else {
Compress_output(outproc,junk2 := lzw_stringTable[s],
junk1 := *lzw_stringTable)
if *lzw_stringTable < maxTableSize then
lzw_stringTable[t] := *lzw_stringTable
else if tossTable >= 0 then {
lzw_stringTable := copy(charTable)
lzw_recycles +:= 1
}
if \lzw_trace then
writes(&errout,"\"\t\t",
image(char(*&cset > junk2) | junk2),
"(",junk1,")\t\t",lzw_stringTable[t]," = ",image(t),"\n\"")
s := c
}
}
Compress_output(outproc,junk2 := lzw_stringTable[s],
junk1 := *lzw_stringTable)
if *lzw_stringTable < maxTableSize then
{}
else if tossTable >= 0 then {
lzw_stringTable := copy(charTable)
lzw_recycles +:= 1
}
if \lzw_trace then
writes(&errout,"\"\t\t",
image(char(*&cset > junk2) | junk2),"(",junk1,")\n")
Compress_output(outproc,EOF,*lzw_stringTable)
if \lzw_trace then write(&errout,"\"\t\t",EOF)
Compress_output(outproc)
return maxTableSize
end
procedure Compress_output(outproc,code,stringTableSize)
local outcode
static max,bits,buffer,bufferbits,lastSize
#
# Initialize.
#
initial {
lastSize := 1000000
buffer := bufferbits := 0
}
#
# If this is "close" call, flush buffer and reinitialize.
#
if /code then {
outcode := &null
if bufferbits > 0 then
outproc(char(outcode := ishift(buffer,8 - bufferbits)))
lastSize := 1000000
buffer := bufferbits := 0
return outcode
}
#
# Expand output code size if necessary.
#
if stringTableSize < lastSize then {
max := 1
bits := 0
}
while stringTableSize > max do {
max *:= 2
bits +:= 1
}
lastSize := stringTableSize
#
# Merge new code into buffer.
#
buffer := ior(ishift(buffer,bits),code)
bufferbits +:= bits
#
# Output bits.
#
while bufferbits >= 8 do {
outproc(char(outcode := ishift(buffer,8 - bufferbits)))
buffer := ixor(buffer,ishift(outcode,bufferbits - 8))
bufferbits -:= 8
}
return outcode
end
############################################################################
#
# Decompress() -- LZW decompression of compressed stream created
# by Compress()
#
# Arguments:
#
# inproc a procedure that returns a single character from
# the input stream.
#
# outproc a procedure that writes a single character (its
# argument) to the output stream.
#
procedure Decompress(inproc,outproc,maxTableSize)
local EOF,c,charSize,code,i,new_code,old_strg,
strg,tossTable
#
# Initialize.
#
/maxTableSize := 1024 # default 10 "bits"
tossTable := maxTableSize
/lzw_recycles := 0
if maxTableSize < 0 then maxTableSize := -maxTableSize
maxTableSize -:= 1
lzw_stringTable := list(*&cset)
every i := 1 to *lzw_stringTable do lzw_stringTable[i] := char(i - 1)
put(lzw_stringTable,EOF := *lzw_stringTable) # reserve code=256 for EOF
charSize := *lzw_stringTable
if \lzw_trace then
write(&errout,"\nInput code\tOutput string\tNew table entry")
#
# Decompress the input stream.
#
while old_strg :=
lzw_stringTable[Decompress_read_code(inproc,
*lzw_stringTable,EOF) + 1] do {
if \lzw_trace then
write(&errout,image(old_strg),"(",*lzw_stringTable,")",
"\t",image(old_strg))
outproc(old_strg)
c := old_strg[1]
(while new_code := Decompress_read_code(inproc,
*lzw_stringTable + 1,EOF) do {
strg := lzw_stringTable[new_code + 1] | old_strg || c
outproc(strg)
c := strg[1]
if \lzw_trace then
write(&errout,image(char(*&cset > new_code) \ 1 | new_code),
"(",*lzw_stringTable + 1,")","\t",
image(strg),"\t\t",
*lzw_stringTable," = ",image(old_strg || c))
if *lzw_stringTable < maxTableSize then
put(lzw_stringTable,old_strg || c)
else if tossTable >= 0 then {
lzw_stringTable := lzw_stringTable[1:charSize + 1]
lzw_recycles +:= 1
break
}
old_strg := strg
}) | break # exit outer loop if this loop completed
}
Decompress_read_code()
return maxTableSize
end
procedure Decompress_read_code(inproc,stringTableSize,EOF)
local code
static max,bits,buffer,bufferbits,lastSize
#
# Initialize.
#
initial {
lastSize := 1000000
buffer := bufferbits := 0
}
#
# Reinitialize if called with no arguments.
#
if /inproc then {
lastSize := 1000000
buffer := bufferbits := 0
return
}
#
# Expand code size if necessary.
#
if stringTableSize < lastSize then {
max := 1
bits := 0
}
while stringTableSize > max do {
max *:= 2
bits +:= 1
}
#
# Read in more data if necessary.
#
while bufferbits < bits do {
buffer := ior(ishift(buffer,8),ord(inproc())) |
stop("Premature end of file")
bufferbits +:= 8
}
#
# Extract code from buffer and return.
#
code := ishift(buffer,bits - bufferbits)
buffer := ixor(buffer,ishift(code,bufferbits - bits))
bufferbits -:= bits
return EOF ~= code
end
procedure whole_wild_match(p,s)
return wild_match(p,s) > *s
end
procedure not_wild_match(p,s)
return not (wild_match(p,s) > *s)
end