Fix most nullability issues

Author: tiennou

ObjectiveGit/GTBlob.h

@@ -104,8 +104,8 @@ NS_ASSUME_NONNULL_BEGIN
 - (git_blob *)git_blob __attribute__((objc_returns_inner_pointer));
 
 - (git_off_t)size;
-- (NSString *)content;
-- (NSData * _Nullable)data;
+- (NSString * _Nullable)content;
+- (NSData *)data;
 
 /// Attempts to apply the filter list for `path` to the blob.
 ///

ObjectiveGit/GTBranch.m

@@ -179,14 +179,21 @@ - (BOOL)rename:(NSString *)name force:(BOOL)force error:(NSError **)error {
 		return NO;
 	}
 
-	_reference = [[GTReference alloc] initWithGitReference:git_ref repository:self.repository];
+	GTReference *renamedRef = [[GTReference alloc] initWithGitReference:git_ref repository:self.repository];
+	NSAssert(renamedRef, @"Unable to allocate renamed ref");
+	_reference = renamedRef;
 
 	return YES;
 }
 
 - (GTBranch *)trackingBranchWithError:(NSError **)error success:(BOOL *)success {
+	BOOL underSuccess = NO;
+	if (success == NULL) {
+		success = &underSuccess;
+	}
+
 	if (self.branchType == GTBranchTypeRemote) {
-		if (success != NULL) *success = YES;
+		*success = YES;
 		return self;
 	}
 
@@ -195,25 +202,32 @@ - (GTBranch *)trackingBranchWithError:(NSError **)error success:(BOOL *)success
 
 	// GIT_ENOTFOUND means no tracking branch found.
 	if (gitError == GIT_ENOTFOUND) {
-		if (success != NULL) *success = YES;
+		*success = YES;
 		return nil;
 	}
 
 	if (gitError != GIT_OK) {
-		if (success != NULL) *success = NO;
+		*success = NO;
 		if (error != NULL) *error = [NSError git_errorFor:gitError description:@"Failed to create reference to tracking branch from %@", self];
 		return nil;
 	}
 
 	if (trackingRef == NULL) {
-		if (success != NULL) *success = NO;
+		*success = NO;
 		if (error != NULL) *error = [NSError git_errorFor:gitError description:@"Got a NULL remote ref for %@", self];
 		return nil;
 	}
 
-	if (success != NULL) *success = YES;
+	GTReference *upsteamRef = [[GTReference alloc] initWithGitReference:trackingRef repository:self.repository];
+	if (upsteamRef == nil) {
+		*success = NO;
+		if (error != NULL) *error = [NSError git_errorFor:GIT_ERROR description:@"Failed to allocate upstream ref"];
+		return nil;
+	}
+
+	*success = YES;
 
-	return [[self class] branchWithReference:[[GTReference alloc] initWithGitReference:trackingRef repository:self.repository]];
+	return [[self class] branchWithReference:upsteamRef];
 }
 
 - (BOOL)updateTrackingBranch:(GTBranch *)trackingBranch error:(NSError **)error {

ObjectiveGit/GTCheckoutOptions.h

@@ -87,13 +87,13 @@ typedef NS_OPTIONS(NSInteger, GTCheckoutNotifyFlags) {
 @property (assign) GTCheckoutStrategyType strategy;
 
 /// The checkout progress block that was passed in.
-@property (copy) void (^progressBlock)(NSString *path, NSUInteger completedSteps, NSUInteger totalSteps);
+@property (copy, nullable) void (^progressBlock)(NSString *path, NSUInteger completedSteps, NSUInteger totalSteps);
 
 /// The notification flags currently enabled.
 @property (assign) GTCheckoutNotifyFlags notifyFlags;
 
 /// The checkout notification block that was passed in.
-@property (copy) int (^notifyBlock)(GTCheckoutNotifyFlags why, NSString *path, GTDiffFile *baseline, GTDiffFile *target, GTDiffFile *workdir);
+@property (copy, nullable) int (^notifyBlock)(GTCheckoutNotifyFlags why, NSString *path, GTDiffFile *baseline, GTDiffFile *target, GTDiffFile *workdir);
 
 /// An array of strings used to restrict what will be checked out.
 @property (copy) NSArray <NSString *> *pathSpecs;

ObjectiveGit/GTConfiguration.m

@@ -134,10 +134,12 @@ - (NSArray *)remotes {
 	NSMutableArray *remotes = [NSMutableArray arrayWithCapacity:names.count];
 	for (size_t i = 0; i < names.count; i++) {
 		const char *name = names.strings[i];
-		git_remote *remote = NULL;
+		git_remote *git_remote = NULL;
 
-		if (git_remote_lookup(&remote, repository.git_repository, name) == 0) {
-			[remotes addObject:[[GTRemote alloc] initWithGitRemote:remote inRepository:repository]];
+		if (git_remote_lookup(&git_remote, repository.git_repository, name) == 0) {
+			GTRemote *remote = [[GTRemote alloc] initWithGitRemote:git_remote inRepository:repository];
+			if (remote)
+				[remotes addObject:remote];
 		}
 	}
 

ObjectiveGit/GTDiffDelta.h

@@ -63,10 +63,10 @@ NS_ASSUME_NONNULL_BEGIN
 @property (nonatomic, assign, readonly) GTDiffFileFlag flags;
 
 /// The file to the "left" of the diff.
-@property (nonatomic, readonly, copy) GTDiffFile *oldFile;
+@property (nonatomic, readonly, copy) GTDiffFile * _Nullable oldFile;
 
 /// The file to the "right" of the diff.
-@property (nonatomic, readonly, copy) GTDiffFile *newFile __attribute__((ns_returns_not_retained));
+@property (nonatomic, readonly, copy) GTDiffFile * _Nullable newFile __attribute__((ns_returns_not_retained));
 
 /// The type of change that this delta represents.
 ///

ObjectiveGit/GTDiffHunk.m

@@ -47,7 +47,9 @@ - (instancetype)initWithPatch:(GTDiffPatch *)patch hunkIndex:(NSUInteger)hunkInd
 
 	_patch = patch;
 	_hunkIndex = hunkIndex;
-	_header = [[[NSString alloc] initWithBytes:self.git_hunk->header length:self.git_hunk->header_len encoding:NSUTF8StringEncoding] stringByTrimmingCharactersInSet:NSCharacterSet.newlineCharacterSet];
+	NSString *hunkHeader = [[[NSString alloc] initWithBytes:self.git_hunk->header length:self.git_hunk->header_len encoding:NSUTF8StringEncoding] stringByTrimmingCharactersInSet:NSCharacterSet.newlineCharacterSet];
+	NSAssert(hunkHeader != nil, @"Failed to build hunk header");
+	_header = hunkHeader;
 
 	return self;
 }

ObjectiveGit/GTEnumerator.m

@@ -259,7 +259,8 @@ - (NSUInteger)countRemainingObjects:(NSError **)error {
 #pragma mark NSEnumerator
 
 - (NSArray *)allObjects {
-	return [self allObjectsWithError:NULL];
+	NSArray *objects = [self allObjectsWithError:NULL];
+	return objects ? objects : [NSArray array];
 }
 
 - (id)nextObject {

ObjectiveGit/GTFilter.m

@@ -96,7 +96,9 @@ static void GTFilterShutdown(git_filter *filter) {
 
 static int GTFilterCheck(git_filter *filter, void **payload, const git_filter_source *src, const char **attr_values) {
 	GTFilter *self = GTFiltersGitFilterToRegisteredFilters[[NSValue valueWithPointer:filter]];
-	BOOL accept = self.checkBlock(payload, [[GTFilterSource alloc] initWithGitFilterSource:src], attr_values);
+	GTFilterSource *source = [[GTFilterSource alloc] initWithGitFilterSource:src];
+	NSCAssert(source != nil, @"Unexpected nil filter source");
+	BOOL accept = self.checkBlock(payload, source, attr_values);
 	return accept ? 0 : GIT_PASSTHROUGH;
 }
 

ObjectiveGit/GTIndex.m

@@ -278,7 +278,9 @@ - (GTTree *)writeTreeToRepository:(GTRepository *)repository error:(NSError **)e
 - (NSArray *)entries {
 	NSMutableArray *entries = [NSMutableArray arrayWithCapacity:self.entryCount];
 	for (NSUInteger i = 0; i < self.entryCount; i++) {
-		[entries addObject:[self entryAtIndex:i]];
+		GTIndexEntry *entry = [self entryAtIndex:i];
+		if (entry)
+			[entries addObject:entry];
 	}
 
 	return entries;

ObjectiveGit/GTOID.h

@@ -16,7 +16,7 @@ NS_ASSUME_NONNULL_BEGIN
 @interface GTOID : NSObject <NSCopying>
 
 /// The SHA pointed to by the OID.
-@property (nonatomic, readonly, copy) NSString * _Nullable SHA;
+@property (nonatomic, readonly, copy) NSString *SHA;
 
 /// Is the OID all zero? This usually indicates that the object has not been
 /// inserted into the ODB yet.