[gentoo-portage-dev] [PATCH v2] egencache: stable use.local.desc mtime for rsync (bug 557192)

[Zac Medico]

Preserve mtime when the md5sum is identical.

X-Gentoo-Bug: 557192
X-Gentoo-Bug-url: https://bugs.gentoo.org/show_bug.cgi?id=557192
---
[PATCH v2] ensures exact integer mtime when there is not an existing file, for
consistency with the mtime preservation code.

 bin/egencache | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/bin/egencache b/bin/egencache
index 5c00248..4f4c715 100755
--- a/bin/egencache
+++ b/bin/egencache
@@ -7,6 +7,7 @@ from __future__ import print_function, unicode_literals
 
 import platform
 import signal
+import stat
 import sys
 # This block ensures that ^C interrupts are handled quietly.
 try:
@@ -487,6 +488,8 @@ class GenUseLocalDesc(object):
 	def run(self):
 		repo_path = self._portdb.porttrees[0]
 		ops = {'<':0, '<=':1, '=':2, '>=':3, '>':4}
+		prev_mtime = None
+		prev_md5 = None
 
 		if self._output is None or self._output != '-':
 			if self._output is None:
@@ -500,6 +503,12 @@ class GenUseLocalDesc(object):
 				desc_path = self._output
 
 			try:
+				prev_md5 = portage.checksum.perform_md5(desc_path)
+				prev_mtime = os.stat(desc_path)[stat.ST_MTIME]
+			except (portage.exception.FileNotFound, OSError):
+				pass
+
+			try:
 				if self._preserve_comments:
 					# Probe in binary mode, in order to avoid
 					# potential character encoding issues.
@@ -651,6 +660,17 @@ class GenUseLocalDesc(object):
 						output.write('%s:%s - %s\n' % (cp, flag, resdesc))
 
 		output.close()
+		if (prev_mtime is not None and
+			prev_md5 == portage.checksum.perform_md5(desc_path)):
+			# Preserve mtime for rsync.
+			mtime = prev_mtime
+		else:
+			# For portability, and consistency with the mtime preservation
+			# code, set mtime to an exact integer value.
+			mtime = int(time.time())
+
+		os.utime(desc_path, (mtime, mtime))
+
 
 if sys.hexversion < 0x3000000:
 	_filename_base = unicode
-- 
2.4.6