/* 
 * tclLoadDl.c --
 *
 *	This procedure provides a version of the TclLoadFile that
 *	works with the "dlopen" and "dlsym" library procedures for
 *	dynamic loading.
 *
 * Copyright (c) 1995-1997 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) Id
 */

#include "tclInt.h"
#ifdef NO_DLFCN_H
#   include "../compat/dlfcn.h"
#else
#   include <dlfcn.h>
#endif

/*
 * In some systems, like SunOS 4.1.3, the RTLD_NOW flag isn't defined
 * and this argument to dlopen must always be 1.  The RTLD_GLOBAL
 * flag is needed on some systems (e.g. SCO and UnixWare) but doesn't
 * exist on others;  if it doesn't exist, set it to 0 so it has no effect.
 */

#ifndef RTLD_NOW
#   define RTLD_NOW 1
#endif

#ifndef RTLD_GLOBAL
#   define RTLD_GLOBAL 0
#endif

/*
 *---------------------------------------------------------------------------
 *
 * 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 interp'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
TclpLoadFile(interp, fileName, sym1, sym2, proc1Ptr, proc2Ptr, clientDataPtr)
    Tcl_Interp *interp;		/* Used for error reporting. */
    char *fileName;		/* Name of the file containing the desired
				 * code. */
    char *sym1, *sym2;		/* Names of two procedures to look up in
				 * the file's symbol table. */
    Tcl_PackageInitProc **proc1Ptr, **proc2Ptr;
				/* Where to return the addresses corresponding
				 * to sym1 and sym2. */
    ClientData *clientDataPtr;	/* Filled with token for dynamically loaded
				 * file which will be passed back to 
				 * TclpUnloadFile() to unload the file. */
{
    VOID *handle;
    Tcl_DString newName, ds;
    char *native;

    native = Tcl_UtfToExternalDString(NULL, fileName, -1, &ds);
    handle = dlopen(native, RTLD_NOW | RTLD_GLOBAL);	/* INTL: Native. */
    Tcl_DStringFree(&ds);
    
    *clientDataPtr = (ClientData) handle;
    
    if (handle == NULL) {
	Tcl_AppendResult(interp, "couldn't load file \"", fileName,
		"\": ", dlerror(), (char *) NULL);
	return TCL_ERROR;
    }

    /* 
     * Some platforms still add an underscore to the beginning of symbol
     * names.  If we can't find a name without an underscore, try again
     * with the underscore.
     */

    native = Tcl_UtfToExternalDString(NULL, sym1, -1, &ds);
    *proc1Ptr = (Tcl_PackageInitProc *) dlsym(handle,	/* INTL: Native. */
	    native);	
    if (*proc1Ptr == NULL) {
	Tcl_DStringInit(&newName);
	Tcl_DStringAppend(&newName, "_", 1);
	native = Tcl_DStringAppend(&newName, native, -1);
	*proc1Ptr = (Tcl_PackageInitProc *) dlsym(handle, /* INTL: Native. */
		native);
	Tcl_DStringFree(&newName);
    }
    Tcl_DStringFree(&ds);

    native = Tcl_UtfToExternalDString(NULL, sym2, -1, &ds);
    *proc2Ptr = (Tcl_PackageInitProc *) dlsym(handle,	/* INTL: Native. */
	    native);
    if (*proc2Ptr == NULL) {
	Tcl_DStringInit(&newName);
	Tcl_DStringAppend(&newName, "_", 1);
	native = Tcl_DStringAppend(&newName, native, -1);
	*proc2Ptr = (Tcl_PackageInitProc *) dlsym(handle, /* INTL: Native. */
		native);
	Tcl_DStringFree(&newName);
    }
    Tcl_DStringFree(&ds);
    
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * 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 removed from memory.
 *
 *----------------------------------------------------------------------
 */

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

    handle = (VOID *) clientData;
    dlclose(handle);
}

/*
 *----------------------------------------------------------------------
 *
 * 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)
    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;
}
