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This bug is due to the fact, applications are restarted before extension
defaults are loaded.
To reproduce, choose any preference and set the values like:
system default:
pref("prefkey",systemvalue);
extension default:
pref("prefkey", extensiondefault);
user pref:
user_pref("prefkey", systemvalue);
Next, trigger application behaviour similar to upgrade by removing compreg.dat
from profile and start the application.
Result:
User sees extensiondefault after upgrade, because the user_pref has been
eliminated ... which is definitly not what the user expects because he explicitly
had *systemvalue* set before the upgrade.
Evaluation:
The bug happens because restart is performed *before* extension defaults have been
loaded and the prefapi.cpp always eliminate user preference if the user preference
is equal to the actual default (which happens to be extensiondefault normally - so
no reset, but is systemvalue during restart).
Fix:
1. savePrefs should not try to be smart ... this patch removes the heuristic that guesses
whether a setting can be eliminated or not; it should be sufficient to only eliminate
prefs in hashPrefs.
2. This patch prevents hashPrefs from eliminating the user pref in case we are in
*startup* ... unfortunately no such state info exists, which lets us guess that
we are in startup for the previously not dealt case: !set_default &&
!pref_ValueChanged(pref->defaultPref, value, type) && !PREF_HAS_USER_VALUE(pref).
If is the case we explicitly remember that this setting is a user-pref ...
even though it might be temporarily equal to the default pref.
---
modules/libpref/src/prefapi.cpp | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)
Index: modules/libpref/src/prefapi.cpp
===================================================================
--- modules/libpref/src/prefapi.cpp
+++ modules/libpref/src/prefapi.cpp
@@ -324,23 +324,20 @@
if (!pref)
return PL_DHASH_NEXT;
nsCAutoString prefValue;
// where we're getting our pref from
PrefValue* sourcePref;
- if (PREF_HAS_USER_VALUE(pref) &&
- pref_ValueChanged(pref->defaultPref,
- pref->userPref,
- (PrefType) PREF_TYPE(pref)))
- sourcePref = &pref->userPref;
- else if (PREF_IS_LOCKED(pref))
+ if (PREF_IS_LOCKED(pref))
sourcePref = &pref->defaultPref;
+ else if (PREF_HAS_USER_VALUE(pref))
+ sourcePref = &pref->userPref;
else
// do not save default prefs that haven't changed
return PL_DHASH_NEXT;
// strings are in quotes!
if (pref->flags & PREF_STRING) {
prefValue = '\"';
str_escape(sourcePref->stringVal, prefValue);
@@ -742,16 +739,27 @@
Otherwise, set the user value only if it has changed */
if ( !pref_ValueChanged(pref->defaultPref, value, type) )
{
if (PREF_HAS_USER_VALUE(pref))
{
pref->flags &= ~PREF_USERSET;
if (!PREF_IS_LOCKED(pref))
valueChanged = PR_TRUE;
+ } else {
+ // this is tricky: we have !set_default ...
+ // thus we are setting a user pref; however the user
+ // pref set is same as *current default*; this normally
+ // means to un-set ... however since we have
+ // !PREF_HAS_USER_VALUE(pref) this can only be during
+ // startup
+ pref_SetValue(&pref->userPref, value, type);
+ pref->flags |= PREF_USERSET;
+ if (!PREF_IS_LOCKED(pref))
+ valueChanged = PR_TRUE;
}
}
else if ( !PREF_HAS_USER_VALUE(pref) ||
pref_ValueChanged(pref->userPref, value, type) )
{
pref_SetValue(&pref->userPref, value, type);
pref->flags |= PREF_USERSET;
if (!PREF_IS_LOCKED(pref))
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