/* * 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 1.2 2001/09/14 01:44:12 zlaski Exp $ */ #include "tclInt.h" #include <fcntl.h> #ifdef HAVE_EXEC_AOUT_H # include <sys/exec_aout.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_ ((char * symbol)); /* * Prototypes for procedures referenced only in this file: */ static int FindLibraries _ANSI_ARGS_((Tcl_Interp * interp, char * fileName, Tcl_DString * buf)); static void UnlinkSymbolTable _ANSI_ARGS_((void)); /* *---------------------------------------------------------------------- * * TclLoadFile -- * * 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 interp->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. * * * 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 TclLoadFile(interp, fileName, sym1, sym2, proc1Ptr, proc2Ptr) 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. */ { 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 */ DictFn dictionary; /* Dictionary function in the load 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(fileName, &linkCommandBuf); Tcl_DStringAppend (&linkCommandBuf, " -A ", -1); Tcl_DStringAppend (&linkCommandBuf, inputSymbolTable, -1); Tcl_DStringAppend (&linkCommandBuf, " -N -T XXXXXXXX ", -1); Tcl_DStringAppend (&linkCommandBuf, fileName, -1); Tcl_DStringAppend (&linkCommandBuf, " ", -1); if (FindLibraries (interp, fileName, &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 */ #if defined(__mips) || defined(mips) status = lseek (relocatedFd, N_TXTOFF (relocatedHead.ex_f, relocatedHead.ex_o), SEEK_SET); #else status = lseek (relocatedFd, 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); /* Look up the entry points in the load module's dictionary. */ dictionary = (DictFn) startAddress; *proc1Ptr = dictionary (sym1); *proc2Ptr = dictionary (sym2); return TCL_OK; } /* *------------------------------------------------------------------------ * * 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 interp->result. The -l and -L flags * are concatenated onto the dynamic string `buf'. * *------------------------------------------------------------------------ */ static int FindLibraries (interp, fileName, buf) Tcl_Interp * interp; /* Used for error reporting */ char * fileName; /* Name of the load module */ Tcl_DString * buf; /* Buffer where the -l an -L flags */ { FILE * f; /* The load module */ int c; /* Byte from the load module */ char * p; /* Open the load module */ if ((f = fopen (fileName, "rb")) == 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; } /* *---------------------------------------------------------------------- * * 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. */ { char *p, *q, *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); if (islower(UCHAR(*r))) { *r = (char) toupper(UCHAR(*r)); } while (*(++r)) { if (isupper(UCHAR(*r))) { *r = (char) tolower(UCHAR(*r)); } } return 1; }