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Commit 8d199518 authored by Songchun Fan's avatar Songchun Fan
Browse files

[SettingsProvider] clean up if a setting failed to be serialized 

Previously, if a setting is partially serialized with an error, the code
doesn't clean it up but proceeds to the next setting. This can cause
parsing errors on the next reboot. This CL captures such error and
deletes the problematic setting before trying again to persist the rest
of the settings. This makes sure that the final file doesn't contain any
partially serialized settings.

BUG: 295555884
Test: manually forcing a setting write to parially fail
Change-Id: I13337d9cbd325c0b6f9e526b3dc44bd4d03e3bd0
parent 2ba72c06

packages/SettingsProvider/src/com/android/providers/settings/SettingsState.java

+23 −8
Original line number Diff line number Diff line
@@ -845,6 +845,7 @@ final class SettingsState { 


    private void doWriteState() {

        boolean wroteState = false;

        String settingFailedToBePersisted = null;

        final int version;

        final ArrayMap<String, Setting> settings;

        final ArrayMap<String, String> namespaceBannedHashes;
@@ -895,8 +896,14 @@ final class SettingsState { 
                            }

                        }

                    } catch (IOException ex) {

                        Slog.e(LOG_TAG, "[SKIPPED PERSISTING]" + setting.getName()

                        Slog.e(LOG_TAG, "[ABORT PERSISTING]" + setting.getName()

                                + " due to error writing to disk", ex);

                        // A setting failed to be written. Abort the serialization to avoid leaving

                        // a partially serialized setting on disk, which can cause parsing errors.

                        // Note down the problematic setting, so that we can delete it before trying

                        // again to persist the rest of the settings.

                        settingFailedToBePersisted = setting.getName();

                        throw ex;

                    }

                }

                serializer.endTag(null, TAG_SETTINGS);
@@ -922,14 +929,14 @@ final class SettingsState { 
                    Slog.i(LOG_TAG, "[PERSIST END]");

                }

            } catch (Throwable t) {

                Slog.wtf(LOG_TAG, "Failed to write settings, restoring backup", t);

                Slog.wtf(LOG_TAG, "Failed to write settings, restoring old file", t);

                if (t instanceof IOException) {

                    if (t.getMessage().contains("Couldn't create directory")) {

                        if (DEBUG) {

                            // we failed to create a directory, so log the permissions and existence

                            // state for the settings file and directory

                            logSettingsDirectoryInformation(destination.getBaseFile());

                        }

                    if (t.getMessage().contains("Couldn't create directory")) {

                        // attempt to create the directory with Files.createDirectories, which

                        // throws more informative errors than File.mkdirs.

                        Path parentPath = destination.getBaseFile().getParentFile().toPath();
@@ -950,7 +957,15 @@ final class SettingsState { 
            }

        }



        if (wroteState) {

        if (!wroteState) {

            if (settingFailedToBePersisted != null) {

                synchronized (mLock) {

                    // Delete the problematic setting. This will schedule a write as well.

                    deleteSettingLocked(settingFailedToBePersisted);

                }

            }

        } else {

            // success

            synchronized (mLock) {

                addHistoricalOperationLocked(HISTORICAL_OPERATION_PERSIST, null);

            }