Add filename to attachment streams.

src/Messages/Attachments/TSAttachmentStream.h

@@ -14,7 +14,7 @@ NS_ASSUME_NONNULL_BEGIN
 @interface TSAttachmentStream : TSAttachment
 
 - (instancetype)init NS_UNAVAILABLE;
-- (instancetype)initWithContentType:(NSString *)contentType NS_DESIGNATED_INITIALIZER;
+- (instancetype)initWithContentType:(NSString *)contentType filename:(NSString *)filename NS_DESIGNATED_INITIALIZER;
 - (instancetype)initWithPointer:(TSAttachmentPointer *)pointer NS_DESIGNATED_INITIALIZER;
 
 // Though now required, `digest` may be null for pre-existing records or from

src/Messages/Attachments/TSAttachmentStream.m

@@ -12,7 +12,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 @implementation TSAttachmentStream
 
-- (instancetype)initWithContentType:(NSString *)contentType
+- (instancetype)initWithContentType:(NSString *)contentType filename:(NSString *)filename
 {
     self = [super initWithContentType:contentType];
     if (!self) {
@@ -24,6 +24,7 @@ NS_ASSUME_NONNULL_BEGIN
     // state, but this constructor is used only for new outgoing
     // attachments which haven't been uploaded yet.
     _isUploaded = NO;
+    _filename = filename;
 
     return self;
 }

src/Messages/OWSMessageSender.m

@@ -516,7 +516,8 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
     NSData *dataCopy = (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(10, 0) ? data : [data copy]);
 
     dispatch_async([OWSDispatch attachmentsQueue], ^{
-        TSAttachmentStream *attachmentStream = [[TSAttachmentStream alloc] initWithContentType:contentType];
+        TSAttachmentStream *attachmentStream =
+            [[TSAttachmentStream alloc] initWithContentType:contentType filename:filename];
 
         NSError *error;
         [attachmentStream writeData:dataCopy error:&error];