[Installer] Name only the payload programs installed in the directory (#7684)

The running-instance lookup named every process whose image path began with the
install directory, subfolders included. Installing into a folder that holds
another application in a subfolder therefore reported that application as
holding the previous version, and nothing the guard offers could clear it: the
close asks cockatrice.exe only, and the end answer refuses anything that is not
a payload program. Both answers were no-ops, so the update could only abort and
tell the user to close a program that was never touching the files.

Name only the programs the payload installs, and only when the image lies in the
install directory itself. A program below the directory that really does hold a
payload file is still named by the Restart Manager lookup, which is the lookup
for that question.

The Windows probe check now covers a payload-named program in a subfolder and a
program the payload does not install; both have to come back as nothing.

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

tools/installer-holder-probe/payload_paths.cpp

@@ -0,0 +1,52 @@
+#include "payload_paths.h"
+
+#include <algorithm>
+#include <cstddef>
+#include <iterator>
+
+namespace
+{
+/// The payload programs, by image name. A process running one of these is what the guard
+/// exists to name, so askingProcessIds() stops its walk up the parent chain at one.
+constexpr const wchar_t *PAYLOAD_PROGRAMS[] = {L"cockatrice.exe", L"oracle.exe", L"servatrice.exe"};
+
+/// Compares two file names the way the file system does, without a locale.
+///
+/// Only the names above are ever compared against, and all of them are ASCII, so folding
+/// the ASCII letters is the whole answer. The Windows ordinal comparison is not used here
+/// on purpose: this file is compiled into a test that runs everywhere, and the question
+/// "is this image a program the payload installs?" must be answerable without Windows.
+bool equalsIgnoringAsciiCase(const std::wstring &left, const std::wstring &right)
+{
+    if (left.size() != right.size()) {
+        return false;
+    }
+    return std::equal(left.begin(), left.end(), right.begin(), [](wchar_t a, wchar_t b) {
+        const wchar_t foldedA = a >= L'A' && a <= L'Z' ? static_cast<wchar_t>(a - L'A' + L'a') : a;
+        const wchar_t foldedB = b >= L'A' && b <= L'Z' ? static_cast<wchar_t>(b - L'A' + L'a') : b;
+        return foldedA == foldedB;
+    });
+}
+} // namespace
+
+std::wstring fileNameOf(const std::wstring &path)
+{
+    const std::size_t separator = path.find_last_of(L"\\/");
+    return separator == std::wstring::npos ? path : path.substr(separator + 1);
+}
+
+std::wstring parentDirectoryOf(const std::wstring &path)
+{
+    const std::size_t separator = path.find_last_of(L"\\/");
+    return separator == std::wstring::npos ? std::wstring() : path.substr(0, separator);
+}
+
+bool isPayloadProgram(const std::wstring &imageName)
+{
+    for (const wchar_t *program : PAYLOAD_PROGRAMS) {
+        if (equalsIgnoringAsciiCase(imageName, program)) {
+            return true;
+        }
+    }
+    return false;
+}