# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@octobus.net>
# Date 1589048707 -7200
# Node ID 35bb67427f63abeb02be76238ab79afbe1ded034
# Parent  c5574408254acb8ccab87f760b4324bf724c18bc
manifest-cache: ignore IOError while writing

If the wcache directory is non writable for some reason (eg: belong to root).
Trying to write to it currently crash Mercurial. Instead we ignore the error and
skip writing that cache.

We should probably improve the user experience of multiple users interacting
with the same repository. However this is not an adventure for stable.

Differential Revision: https://phab.mercurial-scm.org/D8512

diff -r c5574408254a -r 35bb67427f63 mercurial/manifest.py
--- a/mercurial/manifest.py	Wed May 06 11:40:17 2020 -0700
+++ b/mercurial/manifest.py	Sat May 09 20:25:07 2020 +0200
@@ -1455,18 +1455,29 @@
         if not self._dirty or self._opener is None:
             return
         # rotate backwards to the first used node
-        with self._opener(
-            self._file, b'w', atomictemp=True, checkambig=True
-        ) as fp:
-            node = self._head.prev
-            while True:
-                if node.key in self._cache:
-                    fp.write(node.key)
-                    fp.write(struct.pack(b'>L', len(node.value)))
-                    fp.write(node.value)
-                if node is self._head:
-                    break
-                node = node.prev
+        try:
+            with self._opener(
+                self._file, b'w', atomictemp=True, checkambig=True
+            ) as fp:
+                node = self._head.prev
+                while True:
+                    if node.key in self._cache:
+                        fp.write(node.key)
+                        fp.write(struct.pack(b'>L', len(node.value)))
+                        fp.write(node.value)
+                    if node is self._head:
+                        break
+                    node = node.prev
+        except IOError:
+            # We could not write the cache (eg: permission error)
+            # the content can be missing.
+            #
+            # We could try harder and see if we could recreate a wcache
+            # directory were we coudl write too.
+            #
+            # XXX the error pass silently, having some way to issue an error
+            # log `ui.log` would be nice.
+            pass
 
     def __len__(self):
         if not self._read: