rename src/make_dafsa.py to src/psl-make-dafsa, add documentation

I've talked to the good people on #debian-bootstrap who would be most
affected by the possible build-dep cycle, and i think the simplest
approach is actually to split out make_dafsa.py into its own
architecture-independent package.

I'm thinking i'll call the package psl-make-dafsa, and in the course of
shipping it, i'll place src/make_dafsa.py as /usr/bin/psl-make-dafsa.

This is because:

 * debian discourages scripts on the $PATH from having language-specific
   suffixes like .py:

    https://lintian.debian.org/tags/script-with-language-extension.html

 * "-" appears to be a more common delimiter in command names than "_":

    0 dkg@alice:~$ for x in - _; do printf "%s: %d " "$x" $(ls -1 ${PATH//:/ } | grep -c "$x"); done; echo
    -: 1235 _: 368
    0 dkg@alice:~$

 * i'd prefer to prefix the command with "psl-" since it really is
   producing and interpreting PSL-specific data structures.

Accepting this patch would mean i'd have fewer changes to make in the
debian packaging, and would allow other distributors to take a similar
approach if they want to.

README.md

@@ -78,7 +78,7 @@ representation of strings. Here we use it to reduce the whole PSL to about 32k i
 
 Generate `psl.dafsa` from `list/public_suffix_list.dat`
 
-	$ src/make_dafsa.py --output-format=binary --input-format=psl list/public_suffix_list.dat psl.dafsa
+	$ src/psl-make-dafsa --output-format=binary --input-format=psl list/public_suffix_list.dat psl.dafsa
 
 Test the result (example)
 
@@ -90,7 +90,7 @@ License
 Libpsl is made available under the terms of the MIT license.<br>
 See the LICENSE file that accompanies this distribution for the full text of the license.
 
-src/make_dafsa.py and src/lookup_string_in_fixed_set.c are licensed under the term written in
+src/psl-make-dafsa and src/lookup_string_in_fixed_set.c are licensed under the term written in
 src/LICENSE.chromium.
 
 Building from git

configure.ac

@@ -72,7 +72,7 @@ AS_IF([ test "$enable_man" != no ], [
   AC_MSG_RESULT([no])
 ])
 
-# src/make_dafsa.py needs python 2.7+
+# src/psl-make-dafsa needs python 2.7+
 AM_PATH_PYTHON([2.7])
 
 PKG_PROG_PKG_CONFIG

src/LICENSE.chromium

@@ -1,5 +1,5 @@
 * The following License is for the source code files
-  make_dafsa.py and lookup_string_in_fixed_set.c.
+  psl-make-dafsa and lookup_string_in_fixed_set.c.
 
 // Copyright 2015 The Chromium Authors. All rights reserved.
 //

src/Makefile.am

@@ -22,7 +22,7 @@ endif
 
 noinst_PROGRAMS = psl2c
 psl2c_SOURCES = psl2c.c lookup_string_in_fixed_set.c
-psl2c_CPPFLAGS = -I$(top_srcdir)/include -DMAKE_DAFSA=\"$(top_srcdir)/src/make_dafsa.py\"
+psl2c_CPPFLAGS = -I$(top_srcdir)/include -DMAKE_DAFSA=\"$(top_srcdir)/src/psl-make-dafsa\"
 if BUILTIN_GENERATOR_LIBICU
   psl2c_LDADD = -licuuc
 endif
@@ -38,4 +38,4 @@ endif
 suffixes_dafsa.c: $(PSL_FILE) psl2c$(EXEEXT)
 	./psl2c$(EXEEXT) "$(PSL_FILE)" suffixes_dafsa.c
 
-EXTRA_DIST = make_dafsa.py LICENSE.chromium
+EXTRA_DIST = psl-make-dafsa LICENSE.chromium

src/lookup_string_in_fixed_set.c

@@ -118,14 +118,14 @@ static int GetReturnValue(const unsigned char* offset,
  *  Looks up the string |key| with length |key_length| in a fixed set of
  * strings. The set of strings must be known at compile time. It is converted to
  * a graph structure named a DAFSA (Deterministic Acyclic Finite State
- * Automaton) by the script make_dafsa.py during compilation. This permits
+ * Automaton) by the script psl-make-dafsa during compilation. This permits
- * efficient (in time and space) lookup. The graph generated by make_dafsa.py
+ * efficient (in time and space) lookup. The graph generated by psl-make-dafsa
  * takes the form of a constant byte array which should be supplied via the
  * |graph| and |length| parameters.  The return value is kDafsaNotFound,
  * kDafsaFound, or a bitmap consisting of one or more of kDafsaExceptionRule,
  * kDafsaWildcardRule and kDafsaPrivateRule ORed together.
  * 
- * Lookup a domain key in a byte array generated by make_dafsa.py.
+ * Lookup a domain key in a byte array generated by psl-make-dafsa.
  */
 
 /* prototype to skip warning with -Wmissing-prototypes */

src/psl-make-dafsa

@@ -418,7 +418,7 @@ def encode(dafsa):
 def to_cxx(data):
   """Generates C++ code from a list of encoded bytes."""
   text = '/* This file is generated. DO NOT EDIT!\n\n'
-  text += 'The byte array encodes effective tld names. See make_dafsa.py for'
+  text += 'The byte array encodes effective tld names. See psl-make-dafsa source for'
   text += ' documentation.'
   text += '*/\n\n'
   text += 'static const unsigned char kDafsa[%s] = {\n' % len(data)

src/psl-make-dafsa.1

@@ -0,0 +1,36 @@
+.TH PSL "1" "July 2016" "psl 0.13.0" "User Commands"
+.SH NAME
+psl-make-dafsa \- generate a compact and optimized DAFSA from a Public Suffix List 
+.SH SYNOPSIS
+.B psl-make-dafsa
+[\fI\,options\/\fR] \fIinfile\fR \fIoutfile\fR
+.SH DESCRIPTION
+\fBpsl-make-dafsa\fR produces C/C++ code or an
+architecture-independent binary object that represents a Deterministic
+Acyclic Finite State Automaton (DAFSA) from a textual representation
+of a Public Suffix List.  Input and output files must be specified on
+the command line.
+
+This compact representation enables optimized queries of the list,
+saving both time and space when compared to searches of human-readable
+representations.
+.SH OPTIONS
+The format of the data read and written by \fBpsl-make-dafsa\fR
+depends on options passed to it.
+.br
+.TP
+\fB\-\-input\-format=\fR[\fIpsl2c\fR|\fIpsl\fR]
+\fBpsl2c\fR: (default) input is C code generated by libpsl/psl2c
+.br
+\fBpsl\fR: input is standard textual Public Suffix List file
+.TP
+\fB\-\-output\-format=\fR[\fIcxx\fR|\fIbinary\fR]
+\fBcxx\fR: (default) output is C/C++ code
+.br
+\fBbinary\fR: output is an architecture-independent binary format
+.SH SEE ALSO
+.IR https://publicsuffix.org/ ", " https://github.com/rockdaboot/libpsl
+.SH COPYRIGHT
+\fBpsl-make-dafsa\fR was originally part of the Chromium project, and
+has been modified by Tim Ruehsen and Daniel Kahn Gillmor.  The code
+and its documentation is governed by a BSD-style license.