add gup-git-tree builder

README.md

@@ -63,6 +63,16 @@ from within a build script. So you may wish to place it in
 its own directory to avoid accidentally adding other scripts
 to `$PATH`.
 
+# Bundled builders
+
+Gup includes some generic builder scripts (in [./builders][]), which are
+typically installed alongside `gup`. These are intended to be used as builders
+in a `Gupfile` (prefixed with `!`). They are provided as-is, and will not
+necessarily be as portable or as stable as gup itself. If you bundle `gup` into
+your project, you should also include any scripts you make use of (you can
+place them next to the `gup` binary, as gup will automatically add its
+directory to your `$PATH` when building).
+
 ----
 
 ### Python version requirements

builders/gup-git-tree

@@ -0,0 +1,71 @@
+#!/usr/bin/env python
+# Export the current stash (or a specific revision) as a .tgz archive
+from __future__ import print_function
+
+import os, sys, subprocess, shutil
+from optparse import OptionParser
+
+def resolve_commit(rev):
+	return subprocess.check_output(['git', 'rev-parse', 'HEAD']).strip()
+
+def get_commit(cwd, rev):
+	if rev is not None:
+		return resolve_commit(rev)
+
+	env = os.environ.copy()
+	env['GIT_AUTHOR_NAME'] = 'nobody'
+	env['GIT_AUTHOR_EMAIL'] = 'nobody@example.org'
+	env['GIT_AUTHOR_DATE'] = '1970-01-01T00:00:00Z'
+	env['GIT_COMMITTER_NAME'] = 'nobody'
+	env['GIT_COMMITTER_EMAIL'] = 'nobody@example.org'
+	env['GIT_COMMITTER_DATE'] ='1970-01-01T00:00:00Z'
+	out = subprocess.check_output(['git', 'stash', 'create'], env=env).strip()
+	if out == '':
+		return resolve_commit('HEAD')
+	else:
+		return out
+
+def get_current_tar_commit(path):
+	gunzip = subprocess.Popen(['gunzip', '-c', path], stdout = subprocess.PIPE)
+	get_tar_commit = subprocess.Popen(['git', 'get-tar-commit-id'], stdin=gunzip.stdout)
+	current_commit, _ = get_tar_commit.communicate()
+	if not all([status == 0 for status in [ gunzip.wait(), get_tar_commit.wait() ]]):
+		print("WARN: unable to determine commit of existing file: %s" % (path,), file=sys.stderr)
+		return None
+	else:
+		return current_commit.strip()
+
+def export_commit(commit, dest, target, cwd):
+	subprocess.check_call(['gup', '--always'])
+	checksum_proc = subprocess.Popen(['gup', '--contents'], stdin=subprocess.PIPE)
+	checksum_proc.communicate(commit)
+	assert checksum_proc.wait() == 0, "gup --contents failed"
+
+	if os.path.exists(target):
+		current_commit = get_current_tar_commit(target)
+		if current_commit == commit:
+			# Don't regenerate archive; we just end up with the same contents but different mtimes
+			# (https://blog.lnx.cx/2015/05/15/getting-consistent-fingerprints-from-git-archive/)
+			shutil.copyfile(target, dest)
+		else:
+			with open(dest, 'w') as dest_f:
+				subprocess.check_call(['git', 'archive', commit, '--format=tar.gz', '--prefix=git-export/'], stdout=dest_f, cwd=cwd)
+
+def main():
+	try:
+		p = OptionParser()
+		p.add_option('--rev', help='export specific commit')
+		opts, args = p.parse_args()
+		dest, target = args
+
+		dest_dir = os.path.dirname(dest) or '.'
+		git_root = subprocess.check_output(['git', 'rev-parse', '--show-toplevel'], cwd=dest_dir).strip()
+		commit = get_commit(cwd=git_root, rev=opts.rev)
+		export_commit(commit, dest, target, cwd=git_root)
+	except KeyboardInterrupt:
+		sys.exit(1)
+	except subprocess.CalledProcessError as e:
+		print(str(e), file=sys.stderr)
+		sys.exit(1)
+
+main()

nix/gup-ocaml.nix

@@ -44,6 +44,7 @@ stdenv.mkDerivation {
   installPhase = ''
     mkdir -p $out
     cp -r ocaml/bin $out/bin
+    cp builders/* $out/bin
     cp -r share $out/share
   '';
 }

nix/gup-python.nix

@@ -28,5 +28,6 @@ stdenv.mkDerivation {
   installPhase = ''
     mkdir $out
     cp -r python/bin $out/bin
+    cp builders/* $out/bin/
   '';
 }