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/* autoload.h: Define functions for auto-loading symbols from a DLL.
Copyright 1999, 2000 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 invoke the function. Initially
* points to an init function which loads the
* DLL, gets the process's 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.
* flag (4 bytes) If "TRUE" then it is not a fatal error if this
* function cannot be found. Instead, error is set
* to ERROR_PROC_NOT_FOUND and 0 is returned.
* func name (n bytes) asciz string containing the name of the function
* to be loaded.
*/
#define LoadDLLmangle(name, n) #name "@" #n
#define LoadDLLfunc(name, n, dllname) LoadDLLfuncEx (name, n, dllname, 0)
#define LoadDLLfuncEx(name, n, dllname, notimp) \
__asm__ (".section .data_cygwin_nocopy,\"w\""); \
__asm__ (".global _" LoadDLLmangle (name, n)); \
__asm__ (".global _win32_" LoadDLLmangle (name, n)); \
__asm__ (".align 8"); \
__asm__ ("_" LoadDLLmangle (name, n) ":"); \
__asm__ ("_win32_" LoadDLLmangle (name, n) ":"); \
__asm__ ("movl (" #name "jump),%eax"); \
__asm__ ("call *(%eax)"); \
__asm__ (#name "jump: .long " #dllname "_init_holder"); \
__asm__ (" .long _" #dllname "_handle"); \
__asm__ (" .long " #n "+" #notimp); \
__asm__ (".asciz \"" #name "\""); \
__asm__ (".text"); \
extern "C" void cygwin_dll_func_load () __asm__ ("cygwin_dll_func_load");
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