[Installer] Stop calling the payload free while an executable is locked

The guard answered "nothing is holding the payload" from two lookups that can
both miss a running instance: Restart Manager does not reliably report a
program's own image or the modules it mapped, and the image path of a process
running under another account cannot be read from the probe at all. A user log
showed exactly that: the first guard passed while cockatrice.exe was running
from the directory, the old uninstaller silently skipped the file it could not
delete, and the update aborted half an uninstall later with "cancelled by user"
after a close attempt the running window ignored.

Ask the file itself. A running image is opened without write sharing, so the
write open replacing it needs is refused with ERROR_SHARING_VIOLATION for as
long as the program runs, while a file that is merely being read still accepts
it. When neither lookup named anybody and a payload executable refuses that
open, the probe answers that the file is in use and that the program holding it
could not be identified - the guard's "could not confirm" dialog, whose Retry
works once the user has closed it - instead of passing the payload as free.

Only the payload executables are tested, not every file the purge removes: a
locked executable proves a program is running and a mapped DLL belongs to a
running executable, while a locked DLL or qt.conf can be the asking process
itself, which is the loop the guard already had. The open is retried once after
300 ms, and only for the files that refused, so a scanner holding a file for a
moment cannot stop an install for nothing.

The Windows probe check now covers that answer: a payload executable held by
the asking process, so that it cannot be named, has to come back as in use
rather than as free.

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

.ci/compile.sh

@@ -559,6 +559,29 @@ Start-Sleep -Seconds 120
     }
     if ($self.Code -ne 0) { throw "expected exit 0 when the asking process is the only holder, got $($self.Code) : $($self.Output)" }
     if ($self.Output -match "pid\s+$PID\b") { throw "the lookup named the process that started it: $($self.Output)" }
+
+    # A payload executable that refuses to be replaced is running, whether or not this probe
+    # may name it: the Restart Manager does not report every mapping, and the image path of a
+    # process under another account cannot be read from here, so both process lookups can
+    # come back empty while the program is still there. Held here by the asking process, so
+    # that it cannot be named - the answer has to be "could not name it", never "nothing is
+    # holding it", which is what sent an update into an uninstall that could only fail
+    # halfway. Exit 3 is the code the guard answers by asking the user to close it and retry.
+    $image = Join-Path $dir "oracle.exe"
+    [IO.File]::WriteAllText($image, "x")
+    $handle = [IO.File]::Open($image, "Open", "ReadWrite", "None")
+    try {
+        $unnameable = Invoke-Probe $dir
+    } finally {
+        $handle.Dispose()
+    }
+    if ($unnameable.Code -ne 3) {
+        throw "expected exit 3 for a payload executable that is in use but cannot be named, got $($unnameable.Code) : $($unnameable.Output)"
+    }
+    if ($unnameable.Output -notmatch "oracle\.exe is in use") {
+        throw "the answer did not name the executable it could not replace: $($unnameable.Output)"
+    }
+
     $empty = Join-Path $dir "empty"
     New-Item -ItemType Directory -Force $empty | Out-Null
     $nothing = Invoke-Probe $empty
@@ -623,7 +646,7 @@ Start-Sleep -Seconds 120
     if ($ignored.Code -ne 0) {
         throw "expected exit 0 for a program the payload does not install, got $($ignored.Code) : $($ignored.Output)"
     }
-    Write-Host "holder lookup named pid $($holder.Id) for a file another process holds, named nothing for a file only the asking process holds, named nothing for an empty directory, named pid $($running.Id) for a payload program running from the directory, and named nothing for a payload program in a folder below it or for a program the payload does not install"
+    Write-Host "holder lookup named pid $($holder.Id) for a file another process holds, named nothing for a file only the asking process holds, reported a payload executable it could not name as in use instead of free, named nothing for an empty directory, named pid $($running.Id) for a payload program running from the directory, and named nothing for a payload program in a folder below it or for a program the payload does not install"
 } finally {
     Remove-Item -Recurse -Force $dir -ErrorAction SilentlyContinue
 }