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434 lines
12 KiB
C
434 lines
12 KiB
C
/*
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* tclLoadAout.c --
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*
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* This procedure provides a version of the TclLoadFile that
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* provides pseudo-static linking using version-7 compatible
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* a.out files described in either sys/exec.h or sys/a.out.h.
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*
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* Copyright (c) 1995, by General Electric Company. All rights reserved.
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*
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* See the file "license.terms" for information on usage and redistribution
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* of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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*
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* This work was supported in part by the ARPA Manufacturing Automation
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* and Design Engineering (MADE) Initiative through ARPA contract
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* F33615-94-C-4400.
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*
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* SCCS: @(#) tclLoadAout.c 1.7 96/02/15 11:58:53
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*/
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#include "tclInt.h"
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#include <fcntl.h>
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#ifdef HAVE_EXEC_AOUT_H
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# include <sys/exec_aout.h>
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#endif
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/*
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* Some systems describe the a.out header in sys/exec.h, and some in
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* a.out.h.
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*/
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#ifdef USE_SYS_EXEC_H
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#include <sys/exec.h>
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#endif
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#ifdef USE_A_OUT_H
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#include <a.out.h>
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#endif
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#ifdef USE_SYS_EXEC_AOUT_H
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#include <sys/exec_aout.h>
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#define a_magic a_midmag
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#endif
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/*
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* TCL_LOADSHIM is the amount by which to shim the break when loading
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*/
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#ifndef TCL_LOADSHIM
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#define TCL_LOADSHIM 0x4000L
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#endif
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/*
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* TCL_LOADALIGN must be a power of 2, and is the alignment to which
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* to force the origin of load modules
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*/
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#ifndef TCL_LOADALIGN
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#define TCL_LOADALIGN 0x4000L
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#endif
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/*
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* TCL_LOADMAX is the maximum size of a load module, and is used as
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* a sanity check when loading
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*/
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#ifndef TCL_LOADMAX
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#define TCL_LOADMAX 2000000L
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#endif
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/*
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* Kernel calls that appear to be missing from the system .h files:
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*/
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extern char * brk _ANSI_ARGS_((char *));
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extern char * sbrk _ANSI_ARGS_((size_t));
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/*
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* The static variable SymbolTableFile contains the file name where the
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* result of the last link was stored. The file is kept because doing so
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* allows one load module to use the symbols defined in another.
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*/
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static char * SymbolTableFile = NULL;
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/*
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* Type of the dictionary function that begins each load module.
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*/
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typedef Tcl_PackageInitProc * (* DictFn) _ANSI_ARGS_ ((char * symbol));
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/*
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* Prototypes for procedures referenced only in this file:
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*/
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static int FindLibraries _ANSI_ARGS_((Tcl_Interp * interp, char * fileName,
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Tcl_DString * buf));
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static void UnlinkSymbolTable _ANSI_ARGS_((void));
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/*
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*----------------------------------------------------------------------
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*
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* TclLoadFile --
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*
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* Dynamically loads a binary code file into memory and returns
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* the addresses of two procedures within that file, if they
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* are defined.
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*
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* Results:
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* A standard Tcl completion code. If an error occurs, an error
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* message is left in interp->result. *proc1Ptr and *proc2Ptr
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* are filled in with the addresses of the symbols given by
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* *sym1 and *sym2, or NULL if those symbols can't be found.
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*
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* Side effects:
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* New code suddenly appears in memory.
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*
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*
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* Bugs:
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* This function does not attempt to handle the case where the
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* BSS segment is not executable. It will therefore fail on
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* Encore Multimax, Pyramid 90x, and similar machines. The
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* reason is that the mprotect() kernel call, which would
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* otherwise be employed to mark the newly-loaded text segment
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* executable, results in a system crash on BSD/386.
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*
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* In an effort to make it fast, this function eschews the
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* technique of linking the load module once, reading its header
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* to determine its size, allocating memory for it, and linking
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* it again. Instead, it `shims out' memory allocation by
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* placing the module TCL_LOADSHIM bytes beyond the break,
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* and assuming that any malloc() calls required to run the
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* linker will not advance the break beyond that point. If
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* the break is advanced beyonnd that point, the load will
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* fail with an `inconsistent memory allocation' error.
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* It perhaps ought to retry the link, but the failure has
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* not been observed in two years of daily use of this function.
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*----------------------------------------------------------------------
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*/
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int
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TclLoadFile(interp, fileName, sym1, sym2, proc1Ptr, proc2Ptr)
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Tcl_Interp *interp; /* Used for error reporting. */
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char *fileName; /* Name of the file containing the desired
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* code. */
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char *sym1, *sym2; /* Names of two procedures to look up in
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* the file's symbol table. */
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Tcl_PackageInitProc **proc1Ptr, **proc2Ptr;
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/* Where to return the addresses corresponding
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* to sym1 and sym2. */
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{
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char * inputSymbolTable; /* Name of the file containing the
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* symbol table from the last link. */
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Tcl_DString linkCommandBuf; /* Command to do the run-time relocation
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* of the module.*/
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char * linkCommand;
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char relocatedFileName [L_tmpnam];
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/* Name of the file holding the relocated */
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/* text of the module */
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int relocatedFd; /* File descriptor of the file holding
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* relocated text */
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struct exec relocatedHead; /* Header of the relocated text */
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unsigned long relocatedSize; /* Size of the relocated text */
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char * startAddress; /* Starting address of the module */
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DictFn dictionary; /* Dictionary function in the load module */
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int status; /* Status return from Tcl_ calls */
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char * p;
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/* Find the file that contains the symbols for the run-time link. */
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if (SymbolTableFile != NULL) {
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inputSymbolTable = SymbolTableFile;
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} else if (tclExecutableName == NULL) {
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Tcl_SetResult (interp, "can't find the tclsh executable", TCL_STATIC);
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return TCL_ERROR;
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} else {
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inputSymbolTable = tclExecutableName;
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}
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/* Construct the `ld' command that builds the relocated module */
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tmpnam (relocatedFileName);
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Tcl_DStringInit (&linkCommandBuf);
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Tcl_DStringAppend (&linkCommandBuf, "exec ld -o ", -1);
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Tcl_DStringAppend (&linkCommandBuf, relocatedFileName, -1);
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#if defined(__mips) || defined(mips)
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Tcl_DStringAppend (&linkCommandBuf, " -G 0 ", -1);
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#endif
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Tcl_DStringAppend (&linkCommandBuf, " -A ", -1);
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Tcl_DStringAppend (&linkCommandBuf, inputSymbolTable, -1);
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Tcl_DStringAppend (&linkCommandBuf, " -N -T XXXXXXXX ", -1);
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Tcl_DStringAppend (&linkCommandBuf, fileName, -1);
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Tcl_DStringAppend (&linkCommandBuf, " ", -1);
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if (FindLibraries (interp, fileName, &linkCommandBuf) != TCL_OK) {
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Tcl_DStringFree (&linkCommandBuf);
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return TCL_ERROR;
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}
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linkCommand = Tcl_DStringValue (&linkCommandBuf);
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/* Determine the starting address, and plug it into the command */
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startAddress = (char *) (((unsigned long) sbrk (0)
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+ TCL_LOADSHIM + TCL_LOADALIGN - 1)
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& (- TCL_LOADALIGN));
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p = strstr (linkCommand, "-T") + 3;
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sprintf (p, "%08lx", (long) startAddress);
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p [8] = ' ';
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/* Run the linker */
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status = Tcl_Eval (interp, linkCommand);
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Tcl_DStringFree (&linkCommandBuf);
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if (status != 0) {
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return TCL_ERROR;
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}
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/* Open the linker's result file and read the header */
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relocatedFd = open (relocatedFileName, O_RDONLY);
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if (relocatedFd < 0) {
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goto ioError;
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}
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status= read (relocatedFd, (char *) & relocatedHead, sizeof relocatedHead);
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if (status < sizeof relocatedHead) {
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goto ioError;
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}
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/* Check the magic number */
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if (relocatedHead.a_magic != OMAGIC) {
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Tcl_AppendResult (interp, "bad magic number in intermediate file \"",
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relocatedFileName, "\"", (char *) NULL);
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goto failure;
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}
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/* Make sure that memory allocation is still consistent */
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if ((unsigned long) sbrk (0) > (unsigned long) startAddress) {
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Tcl_SetResult (interp, "can't load, memory allocation is inconsistent.",
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TCL_STATIC);
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goto failure;
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}
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/* Make sure that the relocated module's size is reasonable */
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relocatedSize = relocatedHead.a_text + relocatedHead.a_data
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+ relocatedHead.a_bss;
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if (relocatedSize > TCL_LOADMAX) {
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Tcl_SetResult (interp, "module too big to load", TCL_STATIC);
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goto failure;
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}
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/* Advance the break to protect the loaded module */
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(void) brk (startAddress + relocatedSize);
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/* Seek to the start of the module's text */
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#if defined(__mips) || defined(mips)
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status = lseek (relocatedFd,
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N_TXTOFF (relocatedHead.ex_f, relocatedHead.ex_o),
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SEEK_SET);
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#else
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status = lseek (relocatedFd, N_TXTOFF (relocatedHead), SEEK_SET);
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#endif
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if (status < 0) {
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goto ioError;
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}
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/* Read in the module's text and data */
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relocatedSize = relocatedHead.a_text + relocatedHead.a_data;
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if (read (relocatedFd, startAddress, relocatedSize) < relocatedSize) {
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brk (startAddress);
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ioError:
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Tcl_AppendResult (interp, "error on intermediate file \"",
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relocatedFileName, "\": ", Tcl_PosixError (interp),
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(char *) NULL);
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failure:
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(void) unlink (relocatedFileName);
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return TCL_ERROR;
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}
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/* Close the intermediate file. */
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(void) close (relocatedFd);
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/* Arrange things so that intermediate symbol tables eventually get
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* deleted. */
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if (SymbolTableFile != NULL) {
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UnlinkSymbolTable ();
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} else {
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atexit (UnlinkSymbolTable);
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}
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SymbolTableFile = ckalloc (strlen (relocatedFileName) + 1);
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strcpy (SymbolTableFile, relocatedFileName);
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/* Look up the entry points in the load module's dictionary. */
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dictionary = (DictFn) startAddress;
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*proc1Ptr = dictionary (sym1);
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*proc2Ptr = dictionary (sym2);
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return TCL_OK;
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}
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/*
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*------------------------------------------------------------------------
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*
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* FindLibraries --
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*
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* Find the libraries needed to link a load module at run time.
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*
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* Results:
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* A standard Tcl completion code. If an error occurs,
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* an error message is left in interp->result. The -l and -L flags
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* are concatenated onto the dynamic string `buf'.
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*
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*------------------------------------------------------------------------
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*/
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static int
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FindLibraries (interp, fileName, buf)
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Tcl_Interp * interp; /* Used for error reporting */
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char * fileName; /* Name of the load module */
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Tcl_DString * buf; /* Buffer where the -l an -L flags */
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{
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FILE * f; /* The load module */
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int c; /* Byte from the load module */
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char * p;
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/* Open the load module */
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if ((f = fopen (fileName, "rb")) == NULL) {
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Tcl_AppendResult (interp, "couldn't open \"", fileName, "\": ",
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Tcl_PosixError (interp), (char *) NULL);
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return TCL_ERROR;
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}
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/* Search for the library list in the load module */
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p = "@LIBS: ";
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while (*p != '\0' && (c = getc (f)) != EOF) {
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if (c == *p) {
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++p;
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}
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else {
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p = "@LIBS: ";
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if (c == *p) {
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++p;
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}
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}
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}
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/* No library list -- this must be an ill-formed module */
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if (c == EOF) {
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Tcl_AppendResult (interp, "File \"", fileName,
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"\" is not a Tcl load module.", (char *) NULL);
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(void) fclose (f);
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return TCL_ERROR;
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}
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/* Accumulate the library list */
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while ((c = getc (f)) != '\0' && c != EOF) {
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char cc = c;
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Tcl_DStringAppend (buf, &cc, 1);
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}
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(void) fclose (f);
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if (c == EOF) {
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Tcl_AppendResult (interp, "Library directory in \"", fileName,
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"\" ends prematurely.", (char *) NULL);
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return TCL_ERROR;
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}
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return TCL_OK;
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}
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/*
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*------------------------------------------------------------------------
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*
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* UnlinkSymbolTable --
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*
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* Remove the symbol table file from the last dynamic link.
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*
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* Results:
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* None.
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*
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* Side effects:
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* The symbol table file from the last dynamic link is removed.
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* This function is called when (a) a new symbol table is present
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* because another dynamic link is complete, or (b) the process
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* is exiting.
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*------------------------------------------------------------------------
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*/
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static void
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UnlinkSymbolTable ()
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{
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(void) unlink (SymbolTableFile);
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ckfree (SymbolTableFile);
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SymbolTableFile = NULL;
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}
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/*
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*----------------------------------------------------------------------
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*
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* TclGuessPackageName --
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*
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* If the "load" command is invoked without providing a package
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* name, this procedure is invoked to try to figure it out.
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*
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* Results:
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* Always returns 0 to indicate that we couldn't figure out a
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* package name; generic code will then try to guess the package
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* from the file name. A return value of 1 would have meant that
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* we figured out the package name and put it in bufPtr.
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*
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* Side effects:
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* None.
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*
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*----------------------------------------------------------------------
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*/
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int
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TclGuessPackageName(fileName, bufPtr)
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char *fileName; /* Name of file containing package (already
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* translated to local form if needed). */
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Tcl_DString *bufPtr; /* Initialized empty dstring. Append
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* package name to this if possible. */
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{
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return 0;
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}
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