IDC: Add folder containing DLL to search path for dependencies.

IDC crashes when attempting to register a ActiveQt COM DLL as
post-build event, if the DLL depends on other DLL(s) in the same
folder. The reason for this is because IDC loads the DLL using
LoadLibrary, which does NOT add the folder containing the DLL to
the search path when loading dependencies.

This patch fixes this problem by introducing the
LOAD_LIBRARY_SEARCH_DLL_LOAD_DIR flag to LoadLibraryEx and
expanding the input path to become fully qualified.

Change-Id: If41609d48842567984013b1f3f2b00b0a93d5960
Task-number: QTBUG-48586
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>

1 files changed, 24 insertions, 4 deletions

diff --git a/src/tools/idc/main.cpp b/src/tools/idc/main.cpp
index 6f00477..563b544 100644
--- a/src/tools/idc/main.cpp
+++ b/src/tools/idc/main.cpp
@@ -170,13 +170,31 @@ static bool attachTypeLibrary(const QString &applicationName, int resource, cons
     return true;
 }
 
+// Manually add defines that are missing from pre-VS2012 compilers
+#ifndef LOAD_LIBRARY_SEARCH_DLL_LOAD_DIR
+#  define LOAD_LIBRARY_SEARCH_DLL_LOAD_DIR 0x00000100
+#endif
+#ifndef LOAD_LIBRARY_SEARCH_DEFAULT_DIRS
+#  define LOAD_LIBRARY_SEARCH_DEFAULT_DIRS 0x00001000
+#endif
+
+static HMODULE loadLibraryQt(const QString &input)
+{
+    if (QSysInfo::windowsVersion() < QSysInfo::WV_VISTA)
+        return LoadLibrary((const wchar_t *)input.utf16()); // fallback for Windows XP and older
+
+    // Load DLL with the folder containing the DLL temporarily added to the search path when loading dependencies
+    return LoadLibraryEx((const wchar_t *)input.utf16(), NULL,
+                         LOAD_LIBRARY_SEARCH_DLL_LOAD_DIR | LOAD_LIBRARY_SEARCH_DEFAULT_DIRS);
+}
+
 static bool registerServer(const QString &input)
 {
     bool ok = false;
     if (hasExeExtension(input)) {
         ok = runWithQtInEnvironment(quotePath(input) + QLatin1String(" -regserver"));
     } else {
-        HMODULE hdll = LoadLibrary((const wchar_t *)input.utf16());
+        HMODULE hdll = loadLibraryQt(input);
         if (!hdll) {
             fprintf(stderr, "Couldn't load library file %s\n", (const char*)input.toLocal8Bit().data());
             return false;
@@ -198,7 +216,7 @@ static bool unregisterServer(const QString &input)
     if (hasExeExtension(input)) {
         ok = runWithQtInEnvironment(quotePath(input) + QLatin1String(" -unregserver"));
     } else {
-        HMODULE hdll = LoadLibrary((const wchar_t *)input.utf16());
+        HMODULE hdll = loadLibraryQt(input);
         if (!hdll) {
             fprintf(stderr, "Couldn't load library file %s\n", (const char*)input.toLocal8Bit().data());
             return false;
@@ -222,7 +240,7 @@ static HRESULT dumpIdl(const QString &input, const QString &idlfile, const QStri
         if (runWithQtInEnvironment(quotePath(input) + QLatin1String(" -dumpidl ") + idlfile + QLatin1String(" -version ") + version))
             res = S_OK;
     } else {
-        HMODULE hdll = LoadLibrary((const wchar_t *)input.utf16());
+        HMODULE hdll = loadLibraryQt(input);
         if (!hdll) {
             fprintf(stderr, "Couldn't load library file %s\n", (const char*)input.toLocal8Bit().data());
             return 3;
@@ -297,6 +315,9 @@ int runIdc(int argc, char **argv)
         } else {
             input = QLatin1String(argv[i]);
             input = input.trimmed();
+            // LoadLibraryEx requires a fully qualified path when used together with LOAD_LIBRARY_SEARCH_DLL_LOAD_DIR
+            input = QFileInfo(input).absoluteFilePath();
+            input = QDir::toNativeSeparators(input);
         }
         i++;
     }
@@ -317,7 +338,6 @@ int runIdc(int argc, char **argv)
         fprintf(stderr, "No interface definition file and no type library file specified!\n");
         return 3;
     }
-    input = QDir::toNativeSeparators(input);
     if (!tlbfile.isEmpty()) {
         tlbfile = QDir::toNativeSeparators(tlbfile);
         QFile file(tlbfile);