RFR: 8282862: AwtWindow::SetIconData leaks old icon handles if an exception is detected [v6]

[Phil Race]

On Fri, 17 Jan 2025 18:22:57 GMT, Rajat Mahajan <rmahajan at openjdk.org> wrote:

>> **Issue:** 
>> AwtWindow::SetIconData leaks the old icon handles in hOldIcon and hOldIconSm if CreateIconFromRaster raises an exception. Additionally, an exception is checked only after the first call to CreateIconFromRaster.
>> 
>> **Solution:**
>> I have added the exception handling code to take care that the handles are properly destroyed and not leaked.
>> 
>> **Testing:**
>> I have tested the code to make sure there are no regressions caused by this.
>
> Rajat Mahajan has updated the pull request incrementally with one additional commit since the last revision:
> 
>   check using not equal to NULL to match the rest of the code in the function

Although this leak is extremely unlikely, leaks of GDI resources can bring even a modern windows system to its knees in a matter of seconds ..

src/java.desktop/windows/native/libawt/windows/awt_Window.cpp line 2115:

> 2113:     HICON hNewIcon = NULL;
> 2114:     HICON hNewIconSm = NULL;
> 2115: 

I presume we know for sure there's no exception pending when we enter ?
Looking at the only caller, it seems probable.

src/java.desktop/windows/native/libawt/windows/awt_Window.cpp line 2147:

> 2145:     HICON hOldIcon = NULL;
> 2146:     HICON hOldIconSm = NULL;
> 2147:     if ((m_hIcon != NULL) && !m_iconInherited) {

I am not sure why the check for NULL is needed .. but it is OK.

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Marked as reviewed by prr (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/22932#pullrequestreview-2560101616
PR Review Comment: https://git.openjdk.org/jdk/pull/22932#discussion_r1920838476
PR Review Comment: https://git.openjdk.org/jdk/pull/22932#discussion_r1920839867