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Bug 5375 - [PATCH] WGI: Fix HSTRING memory leak.
Summary: [PATCH] WGI: Fix HSTRING memory leak.
Status: RESOLVED FIXED
Alias: None
Product: SDL
Classification: Unclassified
Component: joystick (show other bugs)
Version: 2.0.13
Hardware: All Windows 10
: P2 normal
Assignee: Sam Lantinga
QA Contact: Sam Lantinga
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2020-12-01 23:49 UTC by Joel Linn
Modified: 2020-12-10 04:29 UTC (History)
0 users

See Also:

Attachments
Release the HSTRING to fix memleak. (2.46 KB, patch)
2020-12-01 23:49 UTC, Joel Linn 		Details | Diff
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Description Joel Linn 2020-12-01 23:49:42 UTC 
Created attachment 4551 [details]
Release the HSTRING to fix memleak.

I might be wrong about this one since the documentation on the WinRT C interface is pretty much non-existent.

However I am pretty certain the property-getter transfers ownership of the HSTRING to the caller or rather increments the reference count. Anyways, we shall release the HSTRING.
Comment 1 Sam Lantinga 2020-12-09 14:28:36 UTC 
I'm not sure about this one, so I'm going to wait to include it until after 2.0.14 release.
Comment 2 Joel Linn 2020-12-09 23:31:38 UTC 
TLDR; https://godbolt.org/z/43fd8G

Let's deduce this from C++ reference code:

https://docs.microsoft.com/en-us/cpp/cppcx/wrl/how-to-activate-and-use-a-windows-runtime-component-using-wrl?view=msvc-160
At the bottom of the page there is this snippet:
```
int wmain()
{
    /* ... more code ... */

    // Get the domain part of the URI.
    HString domainName;
    hr = uri->get_Domain(domainName.GetAddressOf());
    if (FAILED(hr))
    {
        return PrintError(__LINE__, hr);
    }

    // Print the domain name and return.
    wprintf_s(L"Domain name: %s\n", domainName.GetRawBuffer(nullptr));

    // All smart pointers and RAII objects go out of scope here.
}
```

`HString` is defined in `corewrappers.h` and the call chain for the destructor is:
`~HString() -> Release() -> ::WindowsDeleteString()`

QED
Comment 3 Sam Lantinga 2020-12-10 04:29:24 UTC 
Sold!
https://hg.libsdl.org/SDL/rev/e4681c33144e

Thanks for researching this. :)