/* 
 * tclLoadDyld.c --
 *
 *     This procedure provides a version of the TclLoadFile that
 *     works with Apple's dyld dynamic loading.  This file
 *     provided by Wilfredo Sanchez (wsanchez@apple.com).
 *     This works on Mac OS X.
 *
 * Copyright (c) 1995 Apple Computer, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclLoadDyld.c,v 1.9 2002/07/17 20:00:46 vincentdarley Exp $
 */

#include "tclInt.h"
#include "tclPort.h"
#include <mach-o/dyld.h>

/*
 *----------------------------------------------------------------------
 *
 * TclpLoadFile --
 *
 *     Dynamically loads a binary code file into memory and returns
 *     the addresses of two procedures within that file, if they
 *     are defined.
 *
 * Results:
 *     A standard Tcl completion code.  If an error occurs, an error
 *     message is left in the interpreter's result.  *proc1Ptr and *proc2Ptr
 *     are filled in with the addresses of the symbols given by
 *     *sym1 and *sym2, or NULL if those symbols can't be found.
 *
 * Side effects:
 *     New code suddenly appears in memory.
 *
 *----------------------------------------------------------------------
 */

int
TclpDlopen(interp, pathPtr, loadHandle, unloadProcPtr)
    Tcl_Interp *interp;		/* Used for error reporting. */
    Tcl_Obj *pathPtr;		/* Name of the file containing the desired
				 * code (UTF-8). */
    TclLoadHandle *loadHandle;	/* Filled with token for dynamically loaded
				 * file which will be passed back to 
				 * (*unloadProcPtr)() to unload the file. */
    Tcl_FSUnloadFileProc **unloadProcPtr;	
				/* Filled with address of Tcl_FSUnloadFileProc
				 * function which should be used for
				 * this file. */
{
    const struct mach_header *dyld_lib;
    char *native;

    native = Tcl_FSGetNativePath(pathPtr);
    dyld_lib = NSAddImage(native, 
        NSADDIMAGE_OPTION_WITH_SEARCHING | 
        NSADDIMAGE_OPTION_RETURN_ON_ERROR);
    
    if (!dyld_lib) {
        NSLinkEditErrors editError;
        char *name, *msg;
        NSLinkEditError(&editError, &errno, &name, &msg);
        Tcl_AppendResult(interp, msg, (char *) NULL);
        return TCL_ERROR;
    }
    *loadHandle = (TclLoadHandle)dyld_lib;
    *unloadProcPtr = &TclpUnloadFile;
    return TCL_OK;
}

Tcl_PackageInitProc*
TclpFindSymbol(interp, loadHandle, symbol) 
    Tcl_Interp *interp;
    TclLoadHandle loadHandle;
    CONST char *symbol;
{
    NSSymbol nsSymbol;
    CONST char *native;
    Tcl_DString newName, ds;
    Tcl_PackageInitProc* proc = NULL;
    const struct mach_header *dyld_lib = (mach_header *)loadHandle;
    /* 
     * dyld adds an underscore to the beginning of symbol names.
     */

    native = Tcl_UtfToExternalDString(NULL, symbol, -1, &ds);
    Tcl_DStringInit(&newName);
    Tcl_DStringAppend(&newName, "_", 1);
    native = Tcl_DStringAppend(&newName, native, -1);
    nsSymbol = NSLookupSymbolInImage(dyld_lib, native, 
	NSLOOKUPSYMBOLINIMAGE_OPTION_BIND_NOW | 
	NSLOOKUPSYMBOLINIMAGE_OPTION_RETURN_ON_ERROR);
    if(nsSymbol) {
	proc = NSAddressOfSymbol(nsSymbol);
	/* *clientDataPtr = NSModuleForSymbol(nsSymbol); */
    }
    Tcl_DStringFree(&newName);
    Tcl_DStringFree(&ds);
    
    return proc;
}

/*
 *----------------------------------------------------------------------
 *
 * TclpUnloadFile --
 *
 *     Unloads a dynamically loaded binary code file from memory.
 *     Code pointers in the formerly loaded file are no longer valid
 *     after calling this function.
 *
 * Results:
 *     None.
 *
 * Side effects:
 *     Code dissapears from memory.
 *     Note that this is a no-op on older (OpenStep) versions of dyld.
 *
 *----------------------------------------------------------------------
 */

void
TclpUnloadFile(clientData)
    ClientData clientData;	/* ClientData returned by a previous call
				 * to TclpLoadFile().  The clientData is 
				 * a token that represents the loaded 
				 * file. */
{
    NSUnLinkModule(clientData, FALSE);
}

/*
 *----------------------------------------------------------------------
 *
 * TclGuessPackageName --
 *
 *     If the "load" command is invoked without providing a package
 *     name, this procedure is invoked to try to figure it out.
 *
 * Results:
 *     Always returns 0 to indicate that we couldn't figure out a
 *     package name;  generic code will then try to guess the package
 *     from the file name.  A return value of 1 would have meant that
 *     we figured out the package name and put it in bufPtr.
 *
 * Side effects:
 *     None.
 *
 *----------------------------------------------------------------------
 */

int
TclGuessPackageName(fileName, bufPtr)
    CONST char *fileName;      /* Name of file containing package (already
				* translated to local form if needed). */
    Tcl_DString *bufPtr;       /* Initialized empty dstring.  Append
				* package name to this if possible. */
{
    return 0;
}