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#
#	File:     zipread.icn
#
#	Subject:  Procedures for reading files from ZIP archives
#
#	Author:   Gregg M. Townsend
#
#	Date:     March 5, 2000
#
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#
#   This file is in the public domain.
#
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#
#	These Unix procedures read files from ZIP format archives by
#	opening pipes to the "unzip" utility.  It is assumed that
#	"unzip" is in the shell search path.
#
#	iszip(zname) succeeds if zname is a ZIP archive.
#	zipdir(zname) opens a ZIP archive directory.
#	zipfile(zname, fname) opens a member of a ZIP archive.
#
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#
#	iszip(zname) succeeds if the named file appears to be
#	a ZIP format archive file.
#
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#
#	zipdir(zname) returns a pipe from which the members of the
#	ZIP archive can be read, one per line, as if reading a
#	directory.  It is assumed that zname is a ZIP archive.
#
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#
#	zipfile(zname, fname) returns a pipe from which the
#	file fname within the ZIP archive zname can be read.
#	It is assumed that zname and fname are valid.
#
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#
#   Requires: UNIX with "unzip" utility.
#
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#  iszip(zname) -- succeed if zname is a ZIP archive file

procedure iszip(fname)		#: check for ZIP archive
   local f, s

   f := open(fname, "ru") | fail
   s := reads(f, 4)
   close(f)
   return s === "PK\03\04"
end



#  zipdir(zname) -- returns a file representing the ZIP directory

procedure zipdir(zname)			#: open ZIP directory
   return open("unzip -l " || zname || " | sed -n 's/.*:..   //p'", "rp")
end



#  zipfile(zname, fname) -- open file fname inside archive zname

procedure zipfile(zname, fname)		#: open member of ZIP archive
   return open("unzip -p " || zname || " " || fname, "rp")
end