rainyl
Disable native calls if an object is disposed.
Describe the bug
Stepping through harmless code crashes the application.
To Reproduce
Just try the following code. Place a breakpoint on the first line and hit F10 to execute the code line by line until you reach (or try to reach) the third line:
final image = cv.Mat.zeros(600, 800, cv.MatType.CV_8UC3);
image.dispose();
print('After dispose().');
Immediately after executing image.dispose(), using F10 on Visual Studio Code, the application crashes:
F/libc (25616): Fatal signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x381c30bec81 in tid 25701 (1.ui), pid 25616 (ple.application)
*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
Build fingerprint: 'motorola/sabahl_ge/sabahl:13/TLAS33.105-285-6/105-285-6:user/release-keys'
Revision: '0'
ABI: 'arm64'
Timestamp: 2025-03-09 19:36:01.551311735+0100
Process uptime: 53s
Cmdline: com.example.application
pid: 25616, tid: 25701, name: 1.ui >>> com.example.application <<<
uid: 10266
signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x00000381c30bec81
x0 00000381c30bec81 x1 0000007500000000 x2 00000381c30bec81 x3 000000000000501a
x4 000000750000a4b1 x5 0000000000000000 x6 000000750b786f41 x7 0000000000000002
x8 00000381c30bec81 x9 00000074eb32fd88 x10 00000076e55718a0 x11 00000000ffffffff
x12 0000000000000000 x13 0000000000000000 x14 00000075007ca010 x15 000000776b858d40
x16 00000074ec425760 x17 00000074eb32fdac x18 000000776b078000 x19 000000776b858d40
x20 00000381c30bec81 x21 b4000076c9da1000 x22 0000007500008081 x23 000000750ba1d4d9
x24 00000074eb32fd88 x25 000000776b679000 x26 b4000076c9da1000 x27 000000750c1f0290
x28 0000000800000075 x29 000000776b858d30
lr 00000074eb32fda0 sp 000000776b858d10 pc 00000074eb32fdb8 pst 0000000020000000
backtrace:
#00 pc 000000000072fdb8 /data/app/~~8SwqNWiuFj86YZNj7aD4nw==/com.example.application-IfBt3mdq7GiPdmPK4aHc9w==/base.apk!libdartcv.so (cv::Mat::type() const+12) (BuildId: e01ba305a24c6a1dd51663920c3735f6f30ee3d1)
#01 pc 000000000072fd9c /data/app/~~8SwqNWiuFj86YZNj7aD4nw==/com.example.application-IfBt3mdq7GiPdmPK4aHc9w==/base.apk!libdartcv.so (cv_Mat_type+20) (BuildId: e01ba305a24c6a1dd51663920c3735f6f30ee3d1)
#02 pc 00000000000075a4 [anon:dart-code]
Lost connection to device.
Exited.
I am getting the same problem using valid JPEG bytes with the following code:
final image = cv.imdecode(jpegBytes, cv.IMREAD_UNCHANGED);
image.dispose();
With the code above, I am getting a similar native stack trace ((cv::Mat::type() const+12) and (cv_Mat_type+20)).
Expected behavior
No crash.
Desktop (please complete the following information):
- OS: Windows 11 24H2
Smartphone (please complete the following information):
- Device: Android 13
- ABI Version: arm64-v8a
This can be reproduced when running natively on Windows, too.
Using Flutter 3.27.3 (also tried 3.27.4), Visual Studio Code 1.98, Dart/Flutter extensions 3.106.
I have an idea about what might be happening. When launching a debug session the VS Variables window is automatically expanded and the contents of the 'image' variable is displayed. After dispose() has been called, accessing the various getters causes a crash. Would it be possible for you to disable all native calls on an instance after dispose has been called? This seems a lot of hassle but this would be the only way to prevent crashes while debugging.
I have an idea about what might be happening. When launching a debug session the VS Variables window is automatically expanded and the contents of the 'image' variable is displayed. After dispose() has been called, accessing the various getters causes a crash.
Exactly.
Would it be possible for you to disable all native calls on an instance after dispose has been called? This seems a lot of hassle but this would be the only way to prevent crashes while debugging.
Sounds possible but I have no idea how to implement it. Adding a new flag and checking whether an instance is disposed may works but some overheads will be introduced.
For now, you can check whether it's in debug mode and dispose it if not
final image = ...;
// do some process
if (!kDebugMode){
image.dispose();
}
It doesn't solve you problem but much better and keeps the same behavior in release mode.
