From 113a57c7c759d4e9674cdea2428c8a028622c397 Mon Sep 17 00:00:00 2001
From: Evgeny Poberezkin <2769109+epoberezkin@users.noreply.github.com>
Date: Thu, 7 Sep 2023 22:43:51 +0100
Subject: [PATCH] ios: update chat_read_file (#3037)

---
 apps/ios/SimpleXChat/CryptoFile.swift | 25 +++++++++++++++----------
 apps/ios/SimpleXChat/SimpleX.h        | 11 ++++++-----
 2 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/apps/ios/SimpleXChat/CryptoFile.swift b/apps/ios/SimpleXChat/CryptoFile.swift
index d641464ee..dcb2be9ae 100644
--- a/apps/ios/SimpleXChat/CryptoFile.swift
+++ b/apps/ios/SimpleXChat/CryptoFile.swift
@@ -25,20 +25,25 @@ public func writeCryptoFile(path: String, data: Data) throws -> CryptoFileArgs {
     }
 }
 
-enum ReadFileResult: Decodable {
-    case result(fileSize: Int)
-    case error(readError: String)
-}
-
 public func readCryptoFile(path: String, cryptoArgs: CryptoFileArgs) throws -> Data {
     var cPath = path.cString(using: .utf8)!
     var cKey = cryptoArgs.fileKey.cString(using: .utf8)!
     var cNonce = cryptoArgs.fileNonce.cString(using: .utf8)!
-    let r = chat_read_file(&cPath, &cKey, &cNonce)!
-    let d = String.init(cString: r).data(using: .utf8)!
-    switch try jsonDecoder.decode(ReadFileResult.self, from: d) {
-    case let .error(err): throw RuntimeError(err)
-    case let .result(size): return Data(bytes: r.advanced(by: d.count + 1), count: size)
+    let ptr = chat_read_file(&cPath, &cKey, &cNonce)!
+    let status = UInt8(ptr.pointee)
+    switch status {
+    case 0: // ok
+        let dLen = Data(bytes: ptr.advanced(by: 1), count: 4)
+        let len = dLen.withUnsafeBytes { $0.load(as: UInt32.self) }
+        let d = Data(bytes: ptr.advanced(by: 5), count: Int(len))
+        free(ptr)
+        return d
+    case 1: // error
+        let err = String.init(cString: ptr)
+        free(ptr)
+        throw RuntimeError(err)
+    default:
+        throw RuntimeError("unexpected chat_read_file status: \(status)")
     }
 }
 
diff --git a/apps/ios/SimpleXChat/SimpleX.h b/apps/ios/SimpleXChat/SimpleX.h
index 55b44dee3..67c2fa728 100644
--- a/apps/ios/SimpleXChat/SimpleX.h
+++ b/apps/ios/SimpleXChat/SimpleX.h
@@ -26,16 +26,17 @@ extern char *chat_password_hash(char *pwd, char *salt);
 extern char *chat_encrypt_media(char *key, char *frame, int len);
 extern char *chat_decrypt_media(char *key, char *frame, int len);
 
-// chat_write_file returns NUL-terminated string with JSON of WriteFileResult
+// chat_write_file returns null-terminated string with JSON of WriteFileResult
 extern char *chat_write_file(char *path, char *data, int len);
 
 // chat_read_file returns a buffer with:
-// 1. NUL-terminated C string with JSON of ReadFileResult, followed by
-// 2. file data, the length is defined in ReadFileResult
+// result status (1 byte), then if
+//   status == 0 (success): buffer length (uint32, 4 bytes), buffer of specified length.
+//   status == 1 (error): null-terminated error message string.
 extern char *chat_read_file(char *path, char *key, char *nonce);
 
-// chat_encrypt_file returns NUL-terminated string with JSON of WriteFileResult
+// chat_encrypt_file returns null-terminated string with JSON of WriteFileResult
 extern char *chat_encrypt_file(char *fromPath, char *toPath);
 
-// chat_decrypt_file returns NUL-terminated string with the error message
+// chat_decrypt_file returns null-terminated string with the error message
 extern char *chat_decrypt_file(char *fromPath, char *key, char *nonce, char *toPath);