1 files changed, 76 insertions, 0 deletions
diff --git a/winsup/cygwin/autoload.h b/winsup/cygwin/autoload.h
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+++ b/winsup/cygwin/autoload.h
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+/* autoload.h: Define functions for auto-loading symbols from a DLL.
+
+   Copyright 1999 Cygnus Solutions.
+
+   Written by Christopher Faylor <cgf@cygnus.com>
+
+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. */
+
+#define LoadDLLinitfunc(dllname) \
+HANDLE NO_COPY dllname ## _handle = NULL; \
+static int dllname ## _init () __asm__ (#dllname "_init") __attribute__ ((unused)); \
+static int dllname ## _init ()
+
+#define LoadDLLinitnow(dllname) \
+  ({__asm__ ("movl $cygwin_dll_func_load, " #dllname "_init_holder"); dllname##_init ();})
+
+#define _LoadDLLinitnow(dllname) \
+  __asm__ ("movl $cygwin_dll_func_load, " #dllname "_init_holder"); \
+  __asm__ ("call " #dllname "_init"); \
+
+#define LoadDLLinit(dllname) \
+  __asm__ (".section .data_cygwin_nocopy,\"w\""); \
+  __asm__ (#dllname "_init_holder: .long " #dllname "_init_and_load"); \
+  __asm__ (".text"); \
+  __asm__ (#dllname "_init_and_load:"); \
+  _LoadDLLinitnow (dllname); \
+  __asm__ ("jmp cygwin_dll_func_load");
+
+
+/* Macro for defining "auto-load" functions.
+ * Note that this is self-modifying code *gasp*.
+ * The first invocation of a routine will trigger the loading of
+ * the DLL.  This will then be followed by the discovery of
+ * the procedure's entry point, which is placed into the location
+ * pointed to by the stack pointer.  This code then changes
+ * the "call" operand which invoked it to a "jmp" which will
+ * transfer directly to the DLL function on the next invocation.
+ *
+ * Subsequent calls to routines whose transfer address has not been
+ * determined will skip the "load the dll" step, starting at the
+ * "discovery of the DLL" step.
+ *
+ * So, immediately following the the call to one of the above routines
+ * we have:
+ *  foojmp (4 bytes) 	 Pointer to a word containing the routine used
+ *			 to eventually invokethe function.  Initially
+ *			 points to an init function which loads the
+ *			 DLL, gets the processes load address,
+ *			 changes the contents here to point to the
+ *			 function address, and changes the call *(%eax)
+ *			 to a jmp %eax.  If the initialization has been
+ *			 done, only the load part is done.
+ *  DLL handle (4 bytes) The handle to use when loading the DLL.
+ *  func name (n bytes)	 asciz string containing the name of the function
+ *			 to be loaded.
+ */
+
+#define LoadDLLfunc(name, mangled, dllname) \
+__asm__ (".section .data_cygwin_nocopy,\"w\""); \
+__asm__ (".global _" #mangled); \
+__asm__ (".global _win32_" #mangled); \
+__asm__ (".align 8"); \
+__asm__ ("_" #mangled ":"); \
+__asm__ ("_win32_" #mangled ":"); \
+__asm__ ("movl (" #name "jump),%eax"); \
+__asm__ ("call *(%eax)"); \
+__asm__ (#name "jump: .long " #dllname "_init_holder"); \
+__asm__ (" .long _" #dllname "_handle"); \
+__asm__ (".asciz \"" #name "\""); \
+__asm__ (".text");
+
+extern "C" void cygwin_dll_func_load () __asm__ ("cygwin_dll_func_load");