Improve log cleanup on launch

Signal/src/AppDelegate.m

@@ -1267,7 +1267,7 @@ static void uncaughtExceptionHandler(NSException *exception)
     [SignalApp.shared ensureRootViewController:launchStartedAt];
 
     dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0),
-        ^{ [DebugLogger.shared removeObsoleteDebugLogs]; });
+        ^{ [DebugLogger.shared postLaunchLogCleanup]; });
 }
 
 - (void)registrationStateDidChange

SignalMessaging/utils/DebugLogger.h

@@ -22,7 +22,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (void)wipeLogs;
 
-- (void)removeObsoleteDebugLogs;
+- (void)postLaunchLogCleanup;
 
 - (NSArray<NSString *> *)allLogFilePaths;
 

SignalMessaging/utils/DebugLogger.m

@@ -9,6 +9,7 @@
 #import <CocoaLumberjack/DDTTYLogger.h>
 #import <SignalCoreKit/NSDate+OWS.h>
 #import <SignalServiceKit/AppContext.h>
+#import <SignalServiceKit/AppVersion.h>
 #import <SignalServiceKit/OWSFileSystem.h>
 #import <SignalServiceKit/SignalServiceKit-Swift.h>
 #import <SignalServiceKit/TestAppContext.h>
@@ -229,6 +230,21 @@ const NSUInteger kMaxDebugLogFileSize = 1024 * 1024 * 3;
     }
 }
 
+static NSString *const kLastCleanupVersionKey = @"kLastCleanupVersionKey";
+static NSString *const kFirstValidLogVersion = @"5.35.1.2";
+- (void)postLaunchLogCleanup
+{
+    NSString *lastCleanupVersion = [CurrentAppContext().appUserDefaults stringForKey:kLastCleanupVersionKey] ?: @"0";
+
+    if ([AppVersion compareAppVersion:lastCleanupVersion with:kFirstValidLogVersion] == NSOrderedAscending) {
+        [self wipeLogs];
+        OWSLogWarn(@"Wiped logs. (%@ < %@)", lastCleanupVersion, kFirstValidLogVersion);
+    }
+    [self removeObsoleteDebugLogs];
+
+    [CurrentAppContext().appUserDefaults setObject:AppVersion.shared.currentAppVersion4 forKey:kLastCleanupVersionKey];
+}
+
 @end
 
 #pragma mark -

SignalServiceKit/src/Util/AppVersion.h

@@ -55,6 +55,8 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (BOOL)isFirstLaunch;
 
++ (NSComparisonResult)compareAppVersion:(NSString *)lhs with:(NSString *)rhs;
+
 @end
 
 NS_ASSUME_NONNULL_END

SignalServiceKit/src/Util/AppVersion.m

@@ -215,6 +215,29 @@ NSString *const kNSUserDefaults_LastCompletedLaunchAppVersion_NSE
     return self.firstAppVersion != nil;
 }
 
++ (NSComparisonResult)compareAppVersion:(NSString *)lhs with:(NSString *)rhs
+{
+    // It might be nice to have a first-class version struct that's comparable, but it's not important right now.
+    NSArray<NSString *> *lhsComponents = [lhs componentsSeparatedByString:@"."];
+    NSArray<NSString *> *rhsComponents = [rhs componentsSeparatedByString:@"."];
+
+    NSUInteger largestIdx = MAX(lhsComponents.count, rhsComponents.count);
+    for (NSInteger idx = 0; idx < largestIdx; idx++) {
+        // If we run off the end of an array, we'll assume zero for the component segment
+        NSString *lhsComponentString = (idx < lhsComponents.count) ? lhsComponents[idx] : nil;
+        NSString *rhsComponentString = (idx < rhsComponents.count) ? rhsComponents[idx] : nil;
+        NSInteger lhsComponent = [lhsComponentString integerValue];
+        NSInteger rhsComponent = [rhsComponentString integerValue];
+
+        if (lhsComponent != rhsComponent) {
+            return (lhsComponent < rhsComponent) ? NSOrderedAscending : NSOrderedDescending;
+        }
+    }
+
+    // If we get here, the versions are effectively equal
+    return NSOrderedSame;
+}
+
 @end
 
 NS_ASSUME_NONNULL_END