path: root/unix/tclLoadDl.c

/*
 * 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.
 */

#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_LOCAL flag doesn't exist on
 * some platforms; if it doesn't exist, set it to 0 so it has no effect.
 * See [Bug #3216070]
 */

#ifndef RTLD_NOW
#   define RTLD_NOW 1
#endif

#ifndef RTLD_LOCAL
#   define RTLD_LOCAL 0
#endif

/*
 * Static procedures defined within this file.
 */

static void *		FindSymbol(Tcl_Interp *interp,
			    Tcl_LoadHandle loadHandle, const char *symbol);
static void		UnloadFile(Tcl_LoadHandle loadHandle);

/*
 *---------------------------------------------------------------------------
 *
 * TclpDlopen --
 *
 *	Dynamically loads a binary code file into memory and returns a handle
 *	to the new code.
 *
 * Results:
 *	A standard Tcl completion code. If an error occurs, an error message
 *	is left in the interp's result.
 *
 * Side effects:
 *	New code suddenly appears in memory.
 *
 *---------------------------------------------------------------------------
 */

int
TclpDlopen(
    Tcl_Interp *interp,		/* Used for error reporting. */
    Tcl_Obj *pathPtr,		/* Name of the file containing the desired
				 * code (UTF-8). */
    Tcl_LoadHandle *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. */
{
    void *handle;
    Tcl_LoadHandle newHandle;
    const char *native;

    /*
     * First try the full path the user gave us. This is particularly
     * important if the cwd is inside a vfs, and we are trying to load using a
     * relative path.
     */

    native = Tcl_FSGetNativePath(pathPtr);
    /*
     * Use (RTLD_NOW|RTLD_LOCAL) always, see [Bug #3216070]
     */
    handle = dlopen(native, RTLD_NOW | RTLD_LOCAL);
    if (handle == NULL) {
	/*
	 * Let the OS loader examine the binary search path for whatever
	 * string the user gave us which hopefully refers to a file on the
	 * binary path.
	 */

	Tcl_DString ds;
	const char *fileName = Tcl_GetString(pathPtr);

	native = Tcl_UtfToExternalDString(NULL, fileName, -1, &ds);
	/*
	 * Use (RTLD_NOW|RTLD_LOCAL) always, see [Bug #3216070]
	 */
	handle = dlopen(native, RTLD_NOW | RTLD_LOCAL);
	Tcl_DStringFree(&ds);
    }

    if (handle == NULL) {
	/*
	 * Write the string to a variable first to work around a compiler bug
	 * in the Sun Forte 6 compiler. [Bug 1503729]
	 */

	const char *errorStr = dlerror();

	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		"couldn't load file \"%s\": %s",
		Tcl_GetString(pathPtr), errorStr));
	return TCL_ERROR;
    }
    newHandle = ckalloc(sizeof(*newHandle));
    newHandle->clientData = handle;
    newHandle->findSymbolProcPtr = &FindSymbol;
    newHandle->unloadFileProcPtr = &UnloadFile;
    *unloadProcPtr = &UnloadFile;
    *loadHandle = newHandle;

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * FindSymbol --
 *
 *	Looks up a symbol, by name, through a handle associated with a
 *	previously loaded piece of code (shared library).
 *
 * Results:
 *	Returns a pointer to the function associated with 'symbol' if it is
 *	found. Otherwise returns NULL and may leave an error message in the
 *	interp's result.
 *
 *----------------------------------------------------------------------
 */

static void *
FindSymbol(
    Tcl_Interp *interp,		/* Place to put error messages. */
    Tcl_LoadHandle loadHandle,	/* Value from TcpDlopen(). */
    const char *symbol)		/* Symbol to look up. */
{
    const char *native;		/* Name of the library to be loaded, in
				 * system encoding */
    Tcl_DString newName, ds;	/* Buffers for converting the name to
				 * system encoding and prepending an 
				 * underscore*/
    void *handle = (void *) loadHandle->clientData;
				/* Native handle to the loaded library */
    void *proc;			/* Address corresponding to the resolved
				 * symbol */

    /*
     * 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, symbol, -1, &ds);
    proc = dlsym(handle, native);	/* INTL: Native. */
    if (proc == NULL) {
	Tcl_DStringInit(&newName);
	TclDStringAppendLiteral(&newName, "_");
	native = Tcl_DStringAppend(&newName, native, -1);
	proc = dlsym(handle, native);	/* INTL: Native. */
	Tcl_DStringFree(&newName);
    }
    Tcl_DStringFree(&ds);
    if (proc == NULL && interp != NULL) {
	const char *errorStr = dlerror();

	if (!errorStr) {
	    errorStr = "unknown";
	}

	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		"cannot find symbol \"%s\": %s", symbol, errorStr));
	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "LOAD_SYMBOL", symbol,
		NULL);
    }
    return proc;
}

/*
 *----------------------------------------------------------------------
 *
 * UnloadFile --
 *
 *	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.
 *
 *----------------------------------------------------------------------
 */

static void
UnloadFile(
    Tcl_LoadHandle loadHandle)	/* loadHandle returned by a previous call to
				 * TclpDlopen(). The loadHandle is a token
				 * that represents the loaded file. */
{
    void *handle = loadHandle->clientData;

    dlclose(handle);
    ckfree(loadHandle);
}

/*
 *----------------------------------------------------------------------
 *
 * 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(
    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;
}

/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 4
 * fill-column: 78
 * End:
 */