Binpkg: add chpathtool support for prefix

This uses a python-based chpathtool implementation which is intended to
be compatible with the C-based implemenation that the prefix branch
uses.

1 files changed, 182 insertions, 0 deletions

diff --git a/bin/chpathtool.py b/bin/chpathtool.py
new file mode 100755
index 000000000..d0d49cb6d
--- /dev/null
+++ b/bin/chpathtool.py
@@ -0,0 +1,182 @@
+#!/usr/bin/python
+# Copyright 2011 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+import io
+import optparse
+import os
+import stat
+import sys
+
+CONTENT_ENCODING = "utf_8"
+FS_ENCODING = "utf_8"
+
+try:
+	import magic
+except ImportError:
+	magic = None
+else:
+	try:
+		magic.MIME_TYPE
+	except AttributeError:
+		# magic module seems to be broken
+		magic = None
+
+class IsTextFile(object):
+
+	def __init__(self):
+		if magic is not None:
+			self._call = self._is_text_magic
+			self._m = magic.open(magic.MIME_TYPE)
+			self._m.load()
+		else:
+			self._call = self._is_text_encoding
+			self._encoding = CONTENT_ENCODING
+
+	def __call__(self, filename):
+		"""
+		Returns True if the given file is a text file, and False otherwise.
+		"""
+		return self._call(filename)
+
+	def _is_text_magic(self, filename):
+		mime_type = self._m.file(filename)
+		return mime_type.startswith("text/")
+
+	def _is_text_encoding(self, filename):
+		try:
+			for line in io.open(filename, mode='r', encoding=self._encoding):
+				pass
+		except UnicodeDecodeError:
+			return False
+		return True
+
+def chpath_inplace(filename, is_text_file, old, new):
+	"""
+	Returns True if any modifications were made, and False otherwise.
+	"""
+
+	modified = False
+	orig_stat = os.lstat(filename)
+	try:
+		f = io.open(filename, buffering=0, mode='r+b')
+	except IOError:
+		try:
+			orig_mode = stat.S_IMODE(os.lstat(filename).st_mode)
+		except OSError as e:
+			sys.stderr.write("%s: %s\n" % (e, filename))
+			return
+		temp_mode = 0o200 | orig_mode
+		os.chmod(filename, temp_mode)
+		try:
+			f = io.open(filename, buffering=0, mode='r+b')
+		finally:
+			os.chmod(filename, orig_mode)
+
+	len_old = len(old)
+	len_new = len(new)
+	matched_byte_count = 0
+	while True:
+		in_byte = f.read(1)
+
+		if not in_byte:
+			break
+
+		if in_byte == old[matched_byte_count]:
+			matched_byte_count += 1
+			if matched_byte_count == len_old:
+				modified = True
+				matched_byte_count = 0
+				end_position = f.tell()
+				start_position = end_position - len_old
+				if not is_text_file:
+					# search backwards for leading slashes written by
+					# a previous invocation of this tool
+					num_to_write = len_old
+					f.seek(start_position - 1)
+					while True:
+						if f.read(1) != b'/':
+							break
+						num_to_write += 1
+						f.seek(f.tell() - 2)
+
+					# pad with as many leading slashes as necessary
+					while num_to_write > len_new:
+						f.write(b'/')
+						num_to_write -= 1
+					f.write(new)
+				else:
+					remainder = f.read()
+					f.seek(start_position)
+					f.write(new)
+					if remainder:
+						f.write(remainder)
+						f.truncate()
+						f.seek(start_position + len_new)
+		elif matched_byte_count > 0:
+			# back up an try to start a new match after
+			# the first byte of the previous partial match
+			f.seek(f.tell() - matched_byte_count)
+			matched_byte_count = 0
+
+	f.close()
+	if modified:
+		orig_mtime = orig_stat[stat.ST_MTIME]
+		os.utime(filename, (orig_mtime, orig_mtime))
+	return modified
+
+def chpath_inplace_symlink(filename, st, old, new):
+	target = os.readlink(filename)
+	if target.startswith(old):
+		new_target = new + target[len(old):]
+		os.unlink(filename)
+		os.symlink(new_target, filename)
+		os.lchown(filename, st.st_uid, st.st_gid)
+
+def main(argv):
+
+	usage = "%s [options] <location> <old> <new>" % (os.path.basename(argv[0],))
+	parser = optparse.OptionParser(usage=usage)
+	options, args = parser.parse_args(argv[1:])
+
+	if len(args) != 3:
+		parser.error("3 args required, got %s" % (len(args),))
+
+	location, old, new = args
+
+	is_text_file = IsTextFile()
+
+	if not isinstance(location, bytes):
+		location = location.encode(FS_ENCODING)
+	if not isinstance(old, bytes):
+		old = old.encode(FS_ENCODING)
+	if not isinstance(new, bytes):
+		new = new.encode(FS_ENCODING)
+
+	st = os.lstat(location)
+
+	if stat.S_ISDIR(st.st_mode):
+		for parent, dirs, files in os.walk(location):
+			for filename in files:
+				filename = os.path.join(parent, filename)
+				try:
+					st = os.lstat(filename)
+				except OSError:
+					pass
+				else:
+					if stat.S_ISREG(st.st_mode):
+						chpath_inplace(filename,
+							is_text_file(filename), old, new)
+					elif stat.S_ISLNK(st.st_mode):
+						chpath_inplace_symlink(filename, st, old, new)
+
+	elif stat.S_ISREG(st.st_mode):
+		chpath_inplace(location,
+			is_text_file(location), old, new)
+	elif stat.S_ISLNK(st.st_mode):
+		chpath_inplace_symlink(location, st, old, new)
+
+	return os.EX_OK
+
+if __name__ == "__main__":
+	sys.exit(main(sys.argv))