#!/usr/bin/python
#
import os,shutil,sys,time

def extract(fname,member,outdir):
	if not os.path.isdir(outdir):
		os.mkdir(outdir)
	(i1,o1)=os.popen2(['ar','p',fname,member])
	i1.close()
	(i2,o2)=os.popen2(['tar','-xzf','-','-C',outdir])
	o2.close()
	shutil.copyfileobj(o1,i2)
	o1.close()
	i2.close()
def targz(srcdir):
	tmp=os.getcwd()
	os.chdir(srcdir)
	# symlink at the end
	f=os.popen("(find . '!' -type l -print0;find . -type l -print0)|tar --null -cf - -T - --no-recursion|gzip -9c","r")
	out=f.read()
	f.close()
	os.chdir(tmp)
	return out

class ArFile:
	def __init__(self,fname):
		self.off=0
		self.f=file(fname,'w')
		self.write("!<arch>\n")
	def close(self):
		self.f.close()
	def write(self,val):
		self.off+=len(val)
		self.f.write(val)
	def align(self):
		if self.off&1:
			self.write("\n")
	def writemember(self,name,t,value):
		self.write("%-16s%-12d0     0     100644  %-10d`\n%s"%(name,t,len(value),value))
		self.align()

if len(sys.argv)==3 and sys.argv[1]=='-x':
	fname=sys.argv[2]
	extract(fname,'control.tar.gz','control')
	extract(fname,'data.tar.gz','data')
elif len(sys.argv)==3 and sys.argv[1]=='-c':
	#ar crsv bah.deb debian-binary control.tar.gz data.tar.gz
	fname=sys.argv[2]
	f=ArFile(fname)
	# according to dpkg/dpkg-deb/build.c
	t=int(time.time())
	f.writemember("debian-binary",t,"2.0\n")
	f.writemember("control.tar.gz",t,targz("control"))
	f.writemember("data.tar.gz",t,targz("data"))
	f.close()
else:
	print """Name: debalter - a .deb alteration tool

debalter is a simple tools that can be used to manipulate .deb
files with a simplier interface than dpkg-deb.

Usage:
debalter -x file.deb
  will uncompress the debian archive in the current directory
  creating two sub-directories, "control" and "data".

debalter -c file.deb
  will create a debian archive from the sub-directories "control" and "data"
  found in the current directory

"""