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<div class="moz-cite-prefix">On 12/08/2022 15:43, Pedro Lamarão
wrote:<br>
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<blockquote type="cite" cite="mid:CAC8PkgHrkeduyYufh4Xcsk-Pg=6agXLyMbyX7=J6a1PzPU3aaQ@mail.gmail.com">
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<div>This is incorrect. WriteFile() indicates an
error, but GetLastError() returns 0 (= NO_ERROR).
Could it be that the debugger calls another Windows
API function between those two functions, resetting
the last error?</div>
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<div>In my project that's a major issue. Since the
software behaves incorrectly with the debugger, the
software can no longer be debugged. This doesn't
just affect it when debugging this particular piece
of code but anytime this code is run in a debugging
session.</div>
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<div>This would be a blocker for all applications of Windows
API functions via panama.</div>
<div>Windows Sockets has a similar mechanism called
WSAGetLastError.</div>
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<p>And JNI - I doubt there's anything Panama specific here (unless
proven otherwise).</p>
<p>So that it's clear - it's not that GetLastError fails in general.
It fails when a debugger is attached. As I explained, this could
be due to _which_ debugger is attached, or some existing issue
(predating Panama) in the way jdb/JPDA deal with some Windows
system calls.<br>
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<p>Maurizio<br>
</p>
<blockquote type="cite" cite="mid:CAC8PkgHrkeduyYufh4Xcsk-Pg=6agXLyMbyX7=J6a1PzPU3aaQ@mail.gmail.com">
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<div>As far as I know, GetLastError and WSAGetLastError are
getter-like functions for effectively thread local data.</div>
<div>It is safe to call Windows API functions from inside the
same process but another thread.</div>
<div>If some piece of software infrastructure has perturbed
your program, then it has called a Windows API function from
inside our program</div>
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<div>Is there something I'm not doing incorrectly? Or is
there a fix or workaround?<br>
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<div>Here's the Java code:</div>
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<pre style="background-color:rgb(43,43,43);color:rgb(169,183,198);font-family:"JetBrains Mono",monospace;font-size:9.8pt"><span style="color:rgb(204,120,50)">import </span>java.lang.foreign.*<span style="color:rgb(204,120,50)">;
</span><span style="color:rgb(204,120,50)">import </span>java.lang.invoke.MethodHandle<span style="color:rgb(204,120,50)">;
</span><span style="color:rgb(204,120,50)">
</span><span style="color:rgb(204,120,50)">import static </span>java.lang.foreign.MemoryAddress.<span style="color:rgb(152,118,170);font-style:italic">NULL</span><span style="color:rgb(204,120,50)">;
</span><span style="color:rgb(204,120,50)">import static </span>java.lang.foreign.ValueLayout.<span style="color:rgb(152,118,170);font-style:italic">ADDRESS</span><span style="color:rgb(204,120,50)">;
</span><span style="color:rgb(204,120,50)">import static </span>java.lang.foreign.ValueLayout.<span style="color:rgb(152,118,170);font-style:italic">JAVA_INT</span><span style="color:rgb(204,120,50)">;
</span><span style="color:rgb(204,120,50)">
</span><span style="color:rgb(204,120,50)">public class </span>WinApi {
<span style="color:rgb(204,120,50)">static final </span>MethodHandle <span style="color:rgb(152,118,170);font-style:italic">WriteFile$Func</span><span style="color:rgb(204,120,50)">;
</span><span style="color:rgb(204,120,50)"> static final </span>MethodHandle <span style="color:rgb(152,118,170);font-style:italic">GetLastError$Func</span><span style="color:rgb(204,120,50)">;
</span><span style="color:rgb(204,120,50)"> static final </span>MemoryAddress <span style="color:rgb(152,118,170);font-style:italic">INVALID_HANDLE_VALUE </span>= MemoryAddress.<span style="font-style:italic">ofLong</span>(-<span style="color:rgb(104,151,187)">1</span>)<span style="color:rgb(204,120,50)">;
</span><span style="color:rgb(204,120,50)">
</span><span style="color:rgb(204,120,50)"> static </span>{
<span style="color:rgb(204,120,50)">var </span>linker = Linker.<span style="font-style:italic">nativeLinker</span>()<span style="color:rgb(204,120,50)">;
</span><span style="color:rgb(204,120,50)"> var </span>lookup = SymbolLookup.<span style="font-style:italic">libraryLookup</span>(<span style="color:rgb(106,135,89)">"Kernel32"</span><span style="color:rgb(204,120,50)">, </span>MemorySession.<span style="font-style:italic">global</span>())<span style="color:rgb(204,120,50)">;
</span><span style="color:rgb(204,120,50)">
</span><span style="color:rgb(204,120,50)"> </span><span style="color:rgb(152,118,170);font-style:italic">WriteFile$Func </span>= linker.downcallHandle(
lookup.lookup(<span style="color:rgb(106,135,89)">"WriteFile"</span>).get()<span style="color:rgb(204,120,50)">,
</span><span style="color:rgb(204,120,50)"> </span>FunctionDescriptor.<span style="font-style:italic">of</span>(<span style="color:rgb(152,118,170);font-style:italic">JAVA_INT</span><span style="color:rgb(204,120,50)">, </span><span style="color:rgb(152,118,170);font-style:italic">ADDRESS</span><span style="color:rgb(204,120,50)">, </span><span style="color:rgb(152,118,170);font-style:italic">ADDRESS</span><span style="color:rgb(204,120,50)">, </span><span style="color:rgb(152,118,170);font-style:italic">JAVA_INT</span><span style="color:rgb(204,120,50)">, </span><span style="color:rgb(152,118,170);font-style:italic">ADDRESS</span><span style="color:rgb(204,120,50)">, </span><span style="color:rgb(152,118,170);font-style:italic">ADDRESS</span>)
)<span style="color:rgb(204,120,50)">;
</span><span style="color:rgb(204,120,50)"> </span><span style="color:rgb(152,118,170);font-style:italic">GetLastError$Func </span>= linker.downcallHandle(
lookup.lookup(<span style="color:rgb(106,135,89)">"GetLastError"</span>).get()<span style="color:rgb(204,120,50)">,
</span><span style="color:rgb(204,120,50)"> </span>FunctionDescriptor.<span style="font-style:italic">of</span>(<span style="color:rgb(152,118,170);font-style:italic">JAVA_INT</span>)
)<span style="color:rgb(204,120,50)">;
</span><span style="color:rgb(204,120,50)"> </span>}
<span style="color:rgb(204,120,50)">public static void </span><span style="color:rgb(255,198,109)">main</span>(String[] args) {
<span style="color:rgb(204,120,50)">var </span>res = <span style="font-style:italic">WriteFile</span>(<span style="color:rgb(152,118,170);font-style:italic">INVALID_HANDLE_VALUE</span><span style="color:rgb(204,120,50)">, </span><span style="color:rgb(152,118,170);font-style:italic">NULL</span><span style="color:rgb(204,120,50)">, </span><span style="color:rgb(104,151,187)">0</span><span style="color:rgb(204,120,50)">, </span><span style="color:rgb(152,118,170);font-style:italic">NULL</span><span style="color:rgb(204,120,50)">, </span><span style="color:rgb(152,118,170);font-style:italic">NULL</span>)<span style="color:rgb(204,120,50)">;
</span><span style="color:rgb(204,120,50)"> var </span>err = <span style="font-style:italic">GetLastError</span>()<span style="color:rgb(204,120,50)">;
</span><span style="color:rgb(204,120,50)"> </span>System.<span style="color:rgb(152,118,170);font-style:italic">out</span>.printf(<span style="color:rgb(106,135,89)">"WriteFile result: %d, GetLastError result: %d</span><span style="color:rgb(204,120,50)">\n</span><span style="color:rgb(106,135,89)">"</span><span style="color:rgb(204,120,50)">, </span>res<span style="color:rgb(204,120,50)">, </span>err)<span style="color:rgb(204,120,50)">;
</span><span style="color:rgb(204,120,50)"> </span>}
<span style="color:rgb(204,120,50)">static int </span><span style="color:rgb(255,198,109)">WriteFile</span>(MemoryAddress hFile<span style="color:rgb(204,120,50)">, </span>MemoryAddress lpBuffer<span style="color:rgb(204,120,50)">, int </span>nNumberOfBytesToWrite<span style="color:rgb(204,120,50)">,
</span><span style="color:rgb(204,120,50)"> </span>MemoryAddress lpNumberOfBytesWritten<span style="color:rgb(204,120,50)">, </span>MemoryAddress lpOverlapped) {
<span style="color:rgb(204,120,50)">try </span>{
<span style="color:rgb(204,120,50)">return </span>(<span style="color:rgb(204,120,50)">int</span>) <span style="color:rgb(152,118,170);font-style:italic">WriteFile$Func</span>.invokeExact((Addressable)hFile<span style="color:rgb(204,120,50)">, </span>(Addressable)lpBuffer<span style="color:rgb(204,120,50)">, </span>nNumberOfBytesToWrite<span style="color:rgb(204,120,50)">,
</span><span style="color:rgb(204,120,50)"> </span>(Addressable)lpNumberOfBytesWritten<span style="color:rgb(204,120,50)">, </span>(Addressable)lpOverlapped)<span style="color:rgb(204,120,50)">;
</span><span style="color:rgb(204,120,50)"> </span>} <span style="color:rgb(204,120,50)">catch </span>(Throwable e) {
<span style="color:rgb(204,120,50)">throw new </span>RuntimeException(e)<span style="color:rgb(204,120,50)">;
</span><span style="color:rgb(204,120,50)"> </span>}
}
<span style="color:rgb(204,120,50)">static int </span><span style="color:rgb(255,198,109)">GetLastError</span>() {
<span style="color:rgb(204,120,50)">try </span>{
<span style="color:rgb(204,120,50)">return </span>(<span style="color:rgb(204,120,50)">int</span>) <span style="color:rgb(152,118,170);font-style:italic">GetLastError$Func</span>.invokeExact()<span style="color:rgb(204,120,50)">;
</span><span style="color:rgb(204,120,50)"> </span>} <span style="color:rgb(204,120,50)">catch </span>(Throwable e) {
<span style="color:rgb(204,120,50)">throw new </span>RuntimeException(e)<span style="color:rgb(204,120,50)">;
</span><span style="color:rgb(204,120,50)"> </span>}
}
}</pre>
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<div>Cheers</div>
<div>Manuel</div>
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-- <br>
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<div>Pedro Lamarão</div>
<div><a href="https://www.prodist.com.br" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">https://www.prodist.com.br</a></div>
<div>Securing Critical Systems</div>
<div>Tel: +55 11 4380-6585</div>
<div><img src="https://ci3.googleusercontent.com/mail-sig/AIorK4wgjsxiTyEHhb40ITzhw-mChttfn1y6GautnhGEr5tVa82AzYOrJJ9lEh-34sfDfoCQkFlQ7oY" moz-do-not-send="true"><br>
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<div style="color:rgb(34,34,34)">
<p class="MsoNormal" style="margin-bottom:12pt"><span style="font-size:8pt;font-family:Arial,sans-serif;color:rgb(0,51,102)">Antes
de imprimir esta mensagem e seus anexos,
certifique-se que seja realmente necessário.<br>
</span><span style="font-size:8pt;font-family:Arial,sans-serif;color:rgb(0,51,102)" lang="EN-US">Proteger o meio ambiente é nosso dever.<br>
Before printing this e-mail or attachments, be sure
it is necessary.<br>
It is in our hands to protect the environment.</span></p>
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