/* 

 * tclLoadAout.c --

 *

 *	This procedure provides a version of the TclLoadFile that

 *	provides pseudo-static linking using version-7 compatible

 *	a.out files described in either sys/exec.h or sys/a.out.h.

 *

 * Copyright (c) 1995, by General Electric Company. All rights reserved.

 *

 * See the file "license.terms" for information on usage and redistribution

 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.

 *

 * This work was supported in part by the ARPA Manufacturing Automation

 * and Design Engineering (MADE) Initiative through ARPA contract

 * F33615-94-C-4400.

 *

 * RCS: @(#) $Id: tclLoadAout.c,v 1.14 2002/10/10 12:25:53 vincentdarley Exp $

 */

#include "tclInt.h"

#include <fcntl.h>

#ifdef HAVE_EXEC_AOUT_H

#   include <sys/exec_aout.h>

#endif

#ifdef HAVE_UNISTD_H

#   include <unistd.h>

#else

#   include "../compat/unistd.h"

#endif

/*

 * Some systems describe the a.out header in sys/exec.h, and some in

 * a.out.h.

 */

#ifdef USE_SYS_EXEC_H

#include <sys/exec.h>

#endif

#ifdef USE_A_OUT_H

#include <a.out.h>

#endif

#ifdef USE_SYS_EXEC_AOUT_H

#include <sys/exec_aout.h>

#define a_magic a_midmag

#endif

/*

 * TCL_LOADSHIM is the amount by which to shim the break when loading

 */

#ifndef TCL_LOADSHIM

#define TCL_LOADSHIM 0x4000L

#endif

/*

 * TCL_LOADALIGN must be a power of 2, and is the alignment to which

 * to force the origin of load modules

 */

#ifndef TCL_LOADALIGN

#define TCL_LOADALIGN 0x4000L

#endif

/*

 * TCL_LOADMAX is the maximum size of a load module, and is used as

 * a sanity check when loading

 */

#ifndef TCL_LOADMAX

#define TCL_LOADMAX 2000000L

#endif

/*

 * Kernel calls that appear to be missing from the system .h files:

 */

extern char * brk _ANSI_ARGS_((char *));

extern char * sbrk _ANSI_ARGS_((size_t));

/*

 * The static variable SymbolTableFile contains the file name where the

 * result of the last link was stored.  The file is kept because doing so

 * allows one load module to use the symbols defined in another.

 */

static char * SymbolTableFile = NULL;

/*

 * Type of the dictionary function that begins each load module.

 */

typedef Tcl_PackageInitProc * (* DictFn) _ANSI_ARGS_ ((CONST char * symbol));

/*

 * Prototypes for procedures referenced only in this file:

 */

static int FindLibraries _ANSI_ARGS_((Tcl_Interp * interp, Tcl_Obj * pathPtr,

				      Tcl_DString * buf));

static void UnlinkSymbolTable _ANSI_ARGS_((void));

/*

 *----------------------------------------------------------------------

 *

 * 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.

 *

 *

 * Bugs:

 *	This function does not attempt to handle the case where the

 *	BSS segment is not executable.  It will therefore fail on

 *	Encore Multimax, Pyramid 90x, and similar machines.  The

 *	reason is that the mprotect() kernel call, which would

 *	otherwise be employed to mark the newly-loaded text segment

 *	executable, results in a system crash on BSD/386.

 *

 *	In an effort to make it fast, this function eschews the

 *	technique of linking the load module once, reading its header

 *	to determine its size, allocating memory for it, and linking

 *	it again.  Instead, it `shims out' memory allocation by

 *	placing the module TCL_LOADSHIM bytes beyond the break,

 *	and assuming that any malloc() calls required to run the

 *	linker will not advance the break beyond that point.  If

 *	the break is advanced beyonnd that point, the load will

 *	fail with an `inconsistent memory allocation' error.

 *	It perhaps ought to retry the link, but the failure has

 *	not been observed in two years of daily use of this function.

 *----------------------------------------------------------------------

 */

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). */

    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. */

{

    char * inputSymbolTable;	/* Name of the file containing the 

				 * symbol table from the last link. */

    Tcl_DString linkCommandBuf;	/* Command to do the run-time relocation

				 * of the module.*/

    char * linkCommand;

    char relocatedFileName [L_tmpnam];

				/* Name of the file holding the relocated */

				/* text of the module */

    int relocatedFd;		/* File descriptor of the file holding

				 * relocated text */

    struct exec relocatedHead;	/* Header of the relocated text */

    unsigned long relocatedSize;/* Size of the relocated text */

    char * startAddress;	/* Starting address of the module */

    int status;			/* Status return from Tcl_ calls */

    char * p;

    /* Find the file that contains the symbols for the run-time link. */

    if (SymbolTableFile != NULL) {

	inputSymbolTable = SymbolTableFile;

    } else if (tclExecutableName == NULL) {

	Tcl_SetResult (interp, "can't find the tclsh executable", TCL_STATIC);

	return TCL_ERROR;

    } else {

	inputSymbolTable = tclExecutableName;

    }

    /* Construct the `ld' command that builds the relocated module */

    tmpnam (relocatedFileName);

    Tcl_DStringInit (&linkCommandBuf);

    Tcl_DStringAppend (&linkCommandBuf, "exec ld -o ", -1);

    Tcl_DStringAppend (&linkCommandBuf, relocatedFileName, -1);

#if defined(__mips) || defined(mips)

    Tcl_DStringAppend (&linkCommandBuf, " -G 0 ", -1);

#endif

    Tcl_DStringAppend (&linkCommandBuf, " -u TclLoadDictionary_", -1);

    TclGuessPackageName(Tcl_GetString(pathPtr), &linkCommandBuf);

    Tcl_DStringAppend (&linkCommandBuf, " -A ", -1);

    Tcl_DStringAppend (&linkCommandBuf, inputSymbolTable, -1);

    Tcl_DStringAppend (&linkCommandBuf, " -N -T XXXXXXXX ", -1);

    Tcl_DStringAppend (&linkCommandBuf, Tcl_GetString(pathPtr), -1);

    Tcl_DStringAppend (&linkCommandBuf, " ", -1);

    if (FindLibraries (interp, pathPtr, &linkCommandBuf) != TCL_OK) {

	Tcl_DStringFree (&linkCommandBuf);

	return TCL_ERROR;

    }

    linkCommand = Tcl_DStringValue (&linkCommandBuf);

    /* Determine the starting address, and plug it into the command */

    startAddress = (char *) (((unsigned long) sbrk (0)

			      + TCL_LOADSHIM + TCL_LOADALIGN - 1)

			     & (- TCL_LOADALIGN));

    p = strstr (linkCommand, "-T") + 3;

    sprintf (p, "%08lx", (long) startAddress);

    p [8] = ' ';

    /* Run the linker */

    status = Tcl_Eval (interp, linkCommand);

    Tcl_DStringFree (&linkCommandBuf);

    if (status != 0) {

	return TCL_ERROR;

    }

    /* Open the linker's result file and read the header */

    relocatedFd = open (relocatedFileName, O_RDONLY);

    if (relocatedFd < 0) {

	goto ioError;

    }

    status= read (relocatedFd, (char *) & relocatedHead, sizeof relocatedHead);

    if (status < sizeof relocatedHead) {

	goto ioError;

    }

    /* Check the magic number */

    if (relocatedHead.a_magic != OMAGIC) {

	Tcl_AppendResult (interp, "bad magic number in intermediate file \"",

			  relocatedFileName, "\"", (char *) NULL);

	goto failure;

    }

    /* Make sure that memory allocation is still consistent */

    if ((unsigned long) sbrk (0) > (unsigned long) startAddress) {

	Tcl_SetResult (interp, "can't load, memory allocation is inconsistent.",

		       TCL_STATIC);

	goto failure;

    }

    /* Make sure that the relocated module's size is reasonable */

    relocatedSize = relocatedHead.a_text + relocatedHead.a_data

      + relocatedHead.a_bss;

    if (relocatedSize > TCL_LOADMAX) {

	Tcl_SetResult (interp, "module too big to load", TCL_STATIC);

	goto failure;

    }

    /* Advance the break to protect the loaded module */

    (void) brk (startAddress + relocatedSize);

    /*

     * Seek to the start of the module's text.

     *

     * Note that this does not really work with large files (i.e. where

     * lseek64 exists and is different to lseek), but anyone trying to

     * dynamically load a binary that is larger than what can fit in

     * addressable memory is in trouble anyway...

     */

#if defined(__mips) || defined(mips)

    status = lseek (relocatedFd,

		    (off_t) N_TXTOFF (relocatedHead.ex_f, relocatedHead.ex_o),

		    SEEK_SET);

#else

    status = lseek (relocatedFd, (off_t) N_TXTOFF (relocatedHead), SEEK_SET);

#endif

    if (status < 0) {

	goto ioError;

    }

    /* Read in the module's text and data */

    relocatedSize = relocatedHead.a_text + relocatedHead.a_data;

    if (read (relocatedFd, startAddress, relocatedSize) < relocatedSize) {

	brk (startAddress);

      ioError:

	Tcl_AppendResult (interp, "error on intermediate file \"",

			  relocatedFileName, "\": ", Tcl_PosixError (interp),

			  (char *) NULL);

      failure:

	(void) unlink (relocatedFileName);

	return TCL_ERROR;

    }

    /* Close the intermediate file. */

    (void) close (relocatedFd);

    /* Arrange things so that intermediate symbol tables eventually get

    * deleted. */

    if (SymbolTableFile != NULL) {

	UnlinkSymbolTable ();

    } else {

	atexit (UnlinkSymbolTable);

    }

    SymbolTableFile = ckalloc (strlen (relocatedFileName) + 1);

    strcpy (SymbolTableFile, relocatedFileName);

    *loadHandle = startAddress;

    return TCL_OK;

}

/*

 *----------------------------------------------------------------------

 *

 * TclpFindSymbol --

 *

 *	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.

 *

 *----------------------------------------------------------------------

 */

Tcl_PackageInitProc*

TclpFindSymbol(interp, loadHandle, symbol) 

    Tcl_Interp *interp;

    Tcl_LoadHandle loadHandle;

    CONST char *symbol;

{

    /* Look up the entry point in the load module's dictionary. */

    DictFn dictionary = (DictFn) loadHandle;

    return (Tcl_PackageInitProc*) dictionary(sym1);

}

/*

 *------------------------------------------------------------------------

 *

 * FindLibraries --

 *

 *	Find the libraries needed to link a load module at run time.

 *

 * Results:

 *	A standard Tcl completion code.  If an error occurs,

 *	an error message is left in the interp's result.  The -l and -L

 *	flags are concatenated onto the dynamic string `buf'.

 *

 *------------------------------------------------------------------------

 */

static int

FindLibraries (interp, pathPtr, buf)

    Tcl_Interp * interp;	/* Used for error reporting */

    Tcl_Obj * pathPtr;		/* Name of the load module */

    Tcl_DString * buf;		/* Buffer where the -l an -L flags */

{

    FILE * f;			/* The load module */

    int c = 0;			/* Byte from the load module */

    char * p;

    CONST char *native;

    char *fileName = Tcl_GetString(pathPtr);

    /* Open the load module */

    native = Tcl_FSGetNativePath(pathPtr);

    f = fopen(native, "rb");				/* INTL: Native. */

    if (f == NULL) {

	Tcl_AppendResult (interp, "couldn't open \"", fileName, "\": ",

			  Tcl_PosixError (interp), (char *) NULL);

	return TCL_ERROR;

    }

    /* Search for the library list in the load module */

    p = "@LIBS: ";

    while (*p != '\0' && (c = getc (f)) != EOF) {

	if (c == *p) {

	    ++p;

	}

	else {

	    p = "@LIBS: ";

	    if (c == *p) {

		++p;

	    }

	}

    }

    /* No library list -- this must be an ill-formed module */

    if (c == EOF) {

	Tcl_AppendResult (interp, "File \"", fileName,

			  "\" is not a Tcl load module.", (char *) NULL);

	(void) fclose (f);

	return TCL_ERROR;

    }

    /* Accumulate the library list */

    while ((c = getc (f)) != '\0' && c != EOF) {

	char cc = c;

	Tcl_DStringAppend (buf, &cc, 1);

    }

    (void) fclose (f);

    if (c == EOF) {

	Tcl_AppendResult (interp, "Library directory in \"", fileName,

			  "\" ends prematurely.", (char *) NULL);

	return TCL_ERROR;

    }

    return TCL_OK;

}

/*

 *------------------------------------------------------------------------

 *

 * UnlinkSymbolTable --

 *

 *	Remove the symbol table file from the last dynamic link.

 *

 * Results:

 *	None.

 *

 * Side effects:

 *	The symbol table file from the last dynamic link is removed.

 *	This function is called when (a) a new symbol table is present

 *	because another dynamic link is complete, or (b) the process

 *	is exiting.

 *------------------------------------------------------------------------

 */

static void

UnlinkSymbolTable ()

{

    (void) unlink (SymbolTableFile);

    ckfree (SymbolTableFile);

    SymbolTableFile = NULL;

}

/*

 *----------------------------------------------------------------------

 *

 * 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:

 *	Does nothing.  Can anything be done?

 *

 *----------------------------------------------------------------------

 */

void

TclpUnloadFile(loadHandle)

    Tcl_LoadHandle loadHandle;	/* loadHandle returned by a previous call

				 * to TclpDlopen().  The loadHandle is 

				 * a token that represents the loaded 

				 * file. */

{

}

/*

 *----------------------------------------------------------------------

 *

 * 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. */

{

    CONST char *p, *q;

    char *r;

    if ((q = strrchr(fileName,'/'))) {

	q++;

    } else {

	q = fileName;

    }

    if (!strncmp(q,"lib",3)) {

	q+=3;

    }

    p = q;

    while ((*p) && (*p != '.') && ((*p<'0') || (*p>'9'))) {

	p++;

    }

    if ((p>q+2) && !strncmp(p-2,"_G0.",4)) {

	p-=2;

    }

    if (p<q) {

	return 0;

    }

    Tcl_DStringAppend(bufPtr,q, p-q);

    r = Tcl_DStringValue(bufPtr);

    r += strlen(r) - (p-q);

    /*

     * Capitalize the string and then recompute the length.

     */

    Tcl_UtfToTitle(r);

    Tcl_DStringSetLength(bufPtr, strlen(Tcl_DStringValue(bufPtr)));

    return 1;

}