* loadlib.h: New header implementing safe LoadLibrary calls.

Include throughout files using LoadLibrary function.
	* cygcheck.cc (dump_sysinfo): Retrieve kernel32.dll handle via
	GetModuleHandle, rather than using LoadLibrary.
	* cygpath.cc (get_long_name): Ditto.
	(do_sysfolders): Append .dll suffix in LoadLibrary call.
	* ldh.cc (WinMain): Use LoadLibraryExW with DONT_RESOLVE_DLL_REFERENCES
	to avoid loading malicious library code.
	* locale.cc (print_locale_with_codeset): Change way to retrieve
	kernel32.dll path.

winsup/utils/loadlib.h

@@ -0,0 +1,59 @@
+/* loadlib.h
+
+   Copyright 2010 Red Hat, Inc.
+
+   This file is part of Cygwin.
+
+   This software is a copyrighted work licensed under the terms of the
+   Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
+   details. */
+
+#ifndef _LOADLIB_H
+#define _LOADLIB_H
+
+#include <windows.h>
+#include <wchar.h>
+
+/* Load all system libs from the windows system directory by prepending the
+   full path.  This doesn't work for loadling cygwin1.dll.  For this case,
+   instead of prepending the path, make sure that the CWD is removed from
+   the DLL search path, if possible (XP SP1++, Vista++). */
+static HMODULE
+_load_sys_library (const wchar_t *dll)
+{
+  static BOOL (*set_dll_directory)(LPCWSTR);
+  static WCHAR sysdir[MAX_PATH];
+  static UINT sysdir_len;
+
+  WCHAR dllpath[MAX_PATH];
+
+  if (!sysdir_len)
+    {
+      sysdir_len = GetSystemDirectoryW (sysdir, MAX_PATH);
+      sysdir[sysdir_len++] = L'\\';
+      sysdir[sysdir_len] = L'\0';
+    }
+  if (!set_dll_directory)
+    {
+      HMODULE k32 = GetModuleHandleW (L"kernel32.dll");
+      if (k32)
+      	set_dll_directory = (BOOL (*)(LPCWSTR))
+		     GetProcAddress (k32, "SetDllDirectoryW");
+      if (!set_dll_directory)
+	set_dll_directory = (BOOL (*)(LPCWSTR)) -1;
+      else
+      	set_dll_directory (L"");
+    }
+
+  if (wcscmp (dll, L"cygwin1.dll") == 0)
+    return LoadLibraryExW (L"cygwin1.dll", NULL, LOAD_WITH_ALTERED_SEARCH_PATH);
+    
+  wcscpy (dllpath, sysdir);
+  wcscpy (dllpath + sysdir_len, dll);
+  return LoadLibraryExW (dllpath, NULL, LOAD_WITH_ALTERED_SEARCH_PATH);
+}
+
+#define LoadLibraryW(d)	_load_sys_library(d)
+#define LoadLibraryA(d)	_load_sys_library(L##d)
+
+#endif /* _LOADLIB_H */