diff mercurial/util.py @ 41289:593f6359681d

update: fix edge-case with update.atomic-file and read-only files

We used to create the tempfile with the original file mode. That means
creating a read-only tempfile when the original file is read-only, which crash
if we need to write on the tempfile.

The file in the working directory ends up being writable with and without the
atomic update config, so the behavior is the same.

--- a/mercurial/util.py	Wed Jan 16 16:49:15 2019 -0800
+++ b/mercurial/util.py	Thu Jan 10 14:57:01 2019 +0100
@@ -2045,7 +2045,7 @@
     function if need.'''
     return path.split(pycompat.ossep)
 
-def mktempcopy(name, emptyok=False, createmode=None):
+def mktempcopy(name, emptyok=False, createmode=None, enforcewritable=False):
     """Create a temporary file with the same contents from name
 
     The permission bits are copied from the original file.
@@ -2061,7 +2061,8 @@
     # Temporary files are created with mode 0600, which is usually not
     # what we want.  If the original file already exists, just copy
     # its mode.  Otherwise, manually obey umask.
-    copymode(name, temp, createmode)
+    copymode(name, temp, createmode, enforcewritable)
+
     if emptyok:
         return temp
     try:
@@ -2204,7 +2205,9 @@
     def __init__(self, name, mode='w+b', createmode=None, checkambig=False):
         self.__name = name      # permanent name
         self._tempname = mktempcopy(name, emptyok=('w' in mode),
-                                    createmode=createmode)
+                                    createmode=createmode,
+                                    enforcewritable=('w' in mode))
+
         self._fp = posixfile(self._tempname, mode)
         self._checkambig = checkambig