Add Python support library for remote helpers

This patch introduces parts of a Python package called
"git_remote_helpers" containing the building blocks for
remote helpers written in Python.

No actual remote helpers are part of this patch, this patch only
includes the common basics needed to start writing such helpers.

The patch includes the necessary Makefile additions to build and
install the git_remote_helpers Python package along with the rest of
Git.

This patch is based on Johan Herland's git_remote_cvs patch and
has been improved by the following contributions:
- David Aguilar: Lots of Python coding style fixes
- David Aguilar: DESTDIR support in Makefile

Cc: David Aguilar <davvid@gmail.com>
Cc: Johan Herland <johan@herland.net>
Signed-off-by: NSverre Rabbelier <srabbelier@gmail.com>
Signed-off-by: NJohan Herland <johan@herland.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Makefile

@@ -1398,6 +1398,9 @@ ifndef NO_TCLTK
 endif
 ifndef NO_PERL
 	$(QUIET_SUBDIR0)perl $(QUIET_SUBDIR1) PERL_PATH='$(PERL_PATH_SQ)' prefix='$(prefix_SQ)' all
+endif
+ifndef NO_PYTHON
+	$(QUIET_SUBDIR0)git_remote_helpers $(QUIET_SUBDIR1) PYTHON_PATH='$(PYTHON_PATH_SQ)' prefix='$(prefix_SQ)' all
 endif
 	$(QUIET_SUBDIR0)templates $(QUIET_SUBDIR1)
 
@@ -1517,6 +1520,35 @@ $(patsubst %.perl,%,$(SCRIPT_PERL)) git-instaweb: % : unimplemented.sh
 	mv $@+ $@
 endif # NO_PERL
 
+ifndef NO_PYTHON
+$(patsubst %.py,%,$(SCRIPT_PYTHON)): GIT-CFLAGS
+$(patsubst %.py,%,$(SCRIPT_PYTHON)): % : %.py
+	$(QUIET_GEN)$(RM) $@ $@+ && \
+	INSTLIBDIR=`MAKEFLAGS= $(MAKE) -C git_remote_helpers -s \
+		--no-print-directory prefix='$(prefix_SQ)' DESTDIR='$(DESTDIR_SQ)' \
+		instlibdir` && \
+	sed -e '1{' \
+	    -e '	s|#!.*python|#!$(PYTHON_PATH_SQ)|' \
+	    -e '}' \
+	    -e 's|^import sys.*|&; \\\
+	           import os; \\\
+	           sys.path[0] = os.environ.has_key("GITPYTHONLIB") and \\\
+	                         os.environ["GITPYTHONLIB"] or \\\
+	                         "@@INSTLIBDIR@@"|' \
+	    -e 's|@@INSTLIBDIR@@|'"$$INSTLIBDIR"'|g' \
+	    $@.py >$@+ && \
+	chmod +x $@+ && \
+	mv $@+ $@
+else # NO_PYTHON
+$(patsubst %.py,%,$(SCRIPT_PYTHON)): % : unimplemented.sh
+	$(QUIET_GEN)$(RM) $@ $@+ && \
+	sed -e '1s|#!.*/sh|#!$(SHELL_PATH_SQ)|' \
+	    -e 's|@@REASON@@|NO_PYTHON=$(NO_PYTHON)|g' \
+	    unimplemented.sh >$@+ && \
+	chmod +x $@+ && \
+	mv $@+ $@
+endif # NO_PYTHON
+
 configure: configure.ac
 	$(QUIET_GEN)$(RM) $@ $<+ && \
 	sed -e 's/@@GIT_VERSION@@/$(GIT_VERSION)/g' \
@@ -1741,6 +1773,9 @@ install: all
 ifndef NO_PERL
 	$(MAKE) -C perl prefix='$(prefix_SQ)' DESTDIR='$(DESTDIR_SQ)' install
 endif
+ifndef NO_PYTHON
+	$(MAKE) -C git_remote_helpers prefix='$(prefix_SQ)' DESTDIR='$(DESTDIR_SQ)' install
+endif
 ifndef NO_TCLTK
 	$(MAKE) -C gitk-git install
 	$(MAKE) -C git-gui gitexecdir='$(gitexec_instdir_SQ)' install
@@ -1854,6 +1889,9 @@ clean:
 ifndef NO_PERL
 	$(RM) gitweb/gitweb.cgi
 	$(MAKE) -C perl clean
+endif
+ifndef NO_PYTHON
+	$(MAKE) -C git_remote_helpers clean
 endif
 	$(MAKE) -C templates/ clean
 	$(MAKE) -C t/ clean

git_remote_helpers/.gitignore

+/build
+/dist

git_remote_helpers/Makefile

+#
+# Makefile for the git_remote_helpers python support modules
+#
+pysetupfile:=setup.py
+
+# Shell quote (do not use $(call) to accommodate ancient setups);
+DESTDIR_SQ = $(subst ','\'',$(DESTDIR))
+
+ifndef PYTHON_PATH
+	PYTHON_PATH = /usr/bin/python
+endif
+ifndef prefix
+	prefix = $(HOME)
+endif
+ifndef V
+	QUIET = @
+	QUIETSETUP = --quiet
+endif
+
+PYLIBDIR=$(shell $(PYTHON_PATH) -c \
+	 "import sys; \
+	 print 'lib/python%i.%i/site-packages' % sys.version_info[:2]")
+
+all: $(pysetupfile)
+	$(QUIET)$(PYTHON_PATH) $(pysetupfile) $(QUIETSETUP) build
+
+install: $(pysetupfile)
+	$(PYTHON_PATH) $(pysetupfile) install --prefix $(DESTDIR_SQ)$(prefix)
+
+instlibdir: $(pysetupfile)
+	@echo "$(DESTDIR_SQ)$(prefix)/$(PYLIBDIR)"
+
+clean:
+	$(QUIET)$(PYTHON_PATH) $(pysetupfile) $(QUIETSETUP) clean -a
+	$(RM) *.pyo *.pyc

git_remote_helpers/__init__.py

+#!/usr/bin/env python
+
+"""Support library package for git remote helpers.
+
+Git remote helpers are helper commands that interfaces with a non-git
+repository to provide automatic import of non-git history into a Git
+repository.
+
+This package provides the support library needed by these helpers..
+The following modules are included:
+
+- git.git - Interaction with Git repositories
+
+- util - General utility functionality use by the other modules in
+         this package, and also used directly by the helpers.
+"""

git_remote_helpers/setup.py

+#!/usr/bin/env python
+
+"""Distutils build/install script for the git_remote_helpers package."""
+
+from distutils.core import setup
+
+setup(
+    name = 'git_remote_helpers',
+    version = '0.1.0',
+    description = 'Git remote helper program for non-git repositories',
+    license = 'GPLv2',
+    author = 'The Git Community',
+    author_email = 'git@vger.kernel.org',
+    url = 'http://www.git-scm.com/',
+    package_dir = {'git_remote_helpers': ''},
+    packages = ['git_remote_helpers', 'git_remote_helpers.git'],
+)

git_remote_helpers/util.py

+#!/usr/bin/env python
+
+"""Misc. useful functionality used by the rest of this package.
+
+This module provides common functionality used by the other modules in
+this package.
+
+"""
+
+import sys
+import os
+import subprocess
+
+
+# Whether or not to show debug messages
+DEBUG = False
+
+def notify(msg, *args):
+    """Print a message to stderr."""
+    print >> sys.stderr, msg % args
+
+def debug (msg, *args):
+    """Print a debug message to stderr when DEBUG is enabled."""
+    if DEBUG:
+        print >> sys.stderr, msg % args
+
+def error (msg, *args):
+    """Print an error message to stderr."""
+    print >> sys.stderr, "ERROR:", msg % args
+
+def warn(msg, *args):
+    """Print a warning message to stderr."""
+    print >> sys.stderr, "warning:", msg % args
+
+def die (msg, *args):
+    """Print as error message to stderr and exit the program."""
+    error(msg, *args)
+    sys.exit(1)
+
+
+class ProgressIndicator(object):
+
+    """Simple progress indicator.
+
+    Displayed as a spinning character by default, but can be customized
+    by passing custom messages that overrides the spinning character.
+
+    """
+
+    States = ("|", "/", "-", "\\")
+
+    def __init__ (self, prefix = "", f = sys.stdout):
+        """Create a new ProgressIndicator, bound to the given file object."""
+        self.n = 0  # Simple progress counter
+        self.f = f  # Progress is written to this file object
+        self.prev_len = 0  # Length of previous msg (to be overwritten)
+        self.prefix = prefix  # Prefix prepended to each progress message
+        self.prefix_lens = [] # Stack of prefix string lengths
+
+    def pushprefix (self, prefix):
+        """Append the given prefix onto the prefix stack."""
+        self.prefix_lens.append(len(self.prefix))
+        self.prefix += prefix
+
+    def popprefix (self):
+        """Remove the last prefix from the prefix stack."""
+        prev_len = self.prefix_lens.pop()
+        self.prefix = self.prefix[:prev_len]
+
+    def __call__ (self, msg = None, lf = False):
+        """Indicate progress, possibly with a custom message."""
+        if msg is None:
+            msg = self.States[self.n % len(self.States)]
+        msg = self.prefix + msg
+        print >> self.f, "\r%-*s" % (self.prev_len, msg),
+        self.prev_len = len(msg.expandtabs())
+        if lf:
+            print >> self.f
+            self.prev_len = 0
+        self.n += 1
+
+    def finish (self, msg = "done", noprefix = False):
+        """Finalize progress indication with the given message."""
+        if noprefix:
+            self.prefix = ""
+        self(msg, True)
+
+
+def start_command (args, cwd = None, shell = False, add_env = None,
+                   stdin = subprocess.PIPE, stdout = subprocess.PIPE,
+                   stderr = subprocess.PIPE):
+    """Start the given command, and return a subprocess object.
+
+    This provides a simpler interface to the subprocess module.
+
+    """
+    env = None
+    if add_env is not None:
+        env = os.environ.copy()
+        env.update(add_env)
+    return subprocess.Popen(args, bufsize = 1, stdin = stdin, stdout = stdout,
+                            stderr = stderr, cwd = cwd, shell = shell,
+                            env = env, universal_newlines = True)
+
+
+def run_command (args, cwd = None, shell = False, add_env = None,
+                 flag_error = True):
+    """Run the given command to completion, and return its results.
+
+    This provides a simpler interface to the subprocess module.
+
+    The results are formatted as a 3-tuple: (exit_code, output, errors)
+
+    If flag_error is enabled, Error messages will be produced if the
+    subprocess terminated with a non-zero exit code and/or stderr
+    output.
+
+    The other arguments are passed on to start_command().
+
+    """
+    process = start_command(args, cwd, shell, add_env)
+    (output, errors) = process.communicate()
+    exit_code = process.returncode
+    if flag_error and errors:
+        error("'%s' returned errors:\n---\n%s---", " ".join(args), errors)
+    if flag_error and exit_code:
+        error("'%s' returned exit code %i", " ".join(args), exit_code)
+    return (exit_code, output, errors)
+
+
+def file_reader_method (missing_ok = False):
+    """Decorator for simplifying reading of files.
+
+    If missing_ok is True, a failure to open a file for reading will
+    not raise the usual IOError, but instead the wrapped method will be
+    called with f == None.  The method must in this case properly
+    handle f == None.
+
+    """
+    def _wrap (method):
+        """Teach given method to handle both filenames and file objects.
+
+        The given method must take a file object as its second argument
+        (the first argument being 'self', of course).  This decorator
+        will take a filename given as the second argument and promote
+        it to a file object.
+
+        """
+        def _wrapped_method (self, filename, *args, **kwargs):
+            if isinstance(filename, file):
+                f = filename
+            else:
+                try:
+                    f = open(filename, 'r')
+                except IOError:
+                    if missing_ok:
+                        f = None
+                    else:
+                        raise
+            try:
+                return method(self, f, *args, **kwargs)
+            finally:
+                if not isinstance(filename, file) and f:
+                    f.close()
+        return _wrapped_method
+    return _wrap
+
+
+def file_writer_method (method):
+    """Decorator for simplifying writing of files.
+
+    Enables the given method to handle both filenames and file objects.
+
+    The given method must take a file object as its second argument
+    (the first argument being 'self', of course).  This decorator will
+    take a filename given as the second argument and promote it to a
+    file object.
+
+    """
+    def _new_method (self, filename, *args, **kwargs):
+        if isinstance(filename, file):
+            f = filename
+        else:
+            # Make sure the containing directory exists
+            parent_dir = os.path.dirname(filename)
+            if not os.path.isdir(parent_dir):
+                os.makedirs(parent_dir)
+            f = open(filename, 'w')
+        try:
+            return method(self, f, *args, **kwargs)
+        finally:
+            if not isinstance(filename, file):
+                f.close()
+    return _new_method

t/test-lib.sh

@@ -638,6 +638,15 @@ test -d ../templates/blt || {
 	error "You haven't built things yet, have you?"
 }
 
+if test -z "$GIT_TEST_INSTALLED"
+then
+	GITPYTHONLIB="$(pwd)/../git_remote_helpers/build/lib"
+	export GITPYTHONLIB
+	test -d ../git_remote_helpers/build || {
+		error "You haven't built git_remote_helpers yet, have you?"
+	}
+fi
+
 if ! test -x ../test-chmtime; then
 	echo >&2 'You need to build test-chmtime:'
 	echo >&2 'Run "make test-chmtime" in the source (toplevel) directory'