1/* 2 * tclLoadAout.c -- 3 * 4 * This procedure provides a version of the TclLoadFile that 5 * provides pseudo-static linking using version-7 compatible 6 * a.out files described in either sys/exec.h or sys/a.out.h. 7 * 8 * Copyright (c) 1995, by General Electric Company. All rights reserved. 9 * 10 * See the file "license.terms" for information on usage and redistribution 11 * of this file, and for a DISCLAIMER OF ALL WARRANTIES. 12 * 13 * This work was supported in part by the ARPA Manufacturing Automation 14 * and Design Engineering (MADE) Initiative through ARPA contract 15 * F33615-94-C-4400. 16 * 17 * RCS: @(#) $Id: tclLoadAout.c,v 1.14 2002/10/10 12:25:53 vincentdarley Exp $ 18 */ 19 20#include "tclInt.h" 21#include <fcntl.h> 22#ifdef HAVE_EXEC_AOUT_H 23# include <sys/exec_aout.h> 24#endif 25#ifdef HAVE_UNISTD_H 26# include <unistd.h> 27#else 28# include "../compat/unistd.h" 29#endif 30 31/* 32 * Some systems describe the a.out header in sys/exec.h, and some in 33 * a.out.h. 34 */ 35 36#ifdef USE_SYS_EXEC_H 37#include <sys/exec.h> 38#endif 39#ifdef USE_A_OUT_H 40#include <a.out.h> 41#endif 42#ifdef USE_SYS_EXEC_AOUT_H 43#include <sys/exec_aout.h> 44#define a_magic a_midmag 45#endif 46 47/* 48 * TCL_LOADSHIM is the amount by which to shim the break when loading 49 */ 50 51#ifndef TCL_LOADSHIM 52#define TCL_LOADSHIM 0x4000L 53#endif 54 55/* 56 * TCL_LOADALIGN must be a power of 2, and is the alignment to which 57 * to force the origin of load modules 58 */ 59 60#ifndef TCL_LOADALIGN 61#define TCL_LOADALIGN 0x4000L 62#endif 63 64/* 65 * TCL_LOADMAX is the maximum size of a load module, and is used as 66 * a sanity check when loading 67 */ 68 69#ifndef TCL_LOADMAX 70#define TCL_LOADMAX 2000000L 71#endif 72 73/* 74 * Kernel calls that appear to be missing from the system .h files: 75 */ 76 77extern char * brk _ANSI_ARGS_((char *)); 78extern char * sbrk _ANSI_ARGS_((size_t)); 79 80/* 81 * The static variable SymbolTableFile contains the file name where the 82 * result of the last link was stored. The file is kept because doing so 83 * allows one load module to use the symbols defined in another. 84 */ 85 86static char * SymbolTableFile = NULL; 87 88/* 89 * Type of the dictionary function that begins each load module. 90 */ 91 92typedef Tcl_PackageInitProc * (* DictFn) _ANSI_ARGS_ ((CONST char * symbol)); 93 94/* 95 * Prototypes for procedures referenced only in this file: 96 */ 97 98static int FindLibraries _ANSI_ARGS_((Tcl_Interp * interp, Tcl_Obj * pathPtr, 99 Tcl_DString * buf)); 100static void UnlinkSymbolTable _ANSI_ARGS_((void)); 101 102/* 103 *---------------------------------------------------------------------- 104 * 105 * TclpDlopen -- 106 * 107 * Dynamically loads a binary code file into memory and returns 108 * a handle to the new code. 109 * 110 * Results: 111 * A standard Tcl completion code. If an error occurs, an error 112 * message is left in the interp's result. 113 * 114 * Side effects: 115 * New code suddenly appears in memory. 116 * 117 * 118 * Bugs: 119 * This function does not attempt to handle the case where the 120 * BSS segment is not executable. It will therefore fail on 121 * Encore Multimax, Pyramid 90x, and similar machines. The 122 * reason is that the mprotect() kernel call, which would 123 * otherwise be employed to mark the newly-loaded text segment 124 * executable, results in a system crash on BSD/386. 125 * 126 * In an effort to make it fast, this function eschews the 127 * technique of linking the load module once, reading its header 128 * to determine its size, allocating memory for it, and linking 129 * it again. Instead, it `shims out' memory allocation by 130 * placing the module TCL_LOADSHIM bytes beyond the break, 131 * and assuming that any malloc() calls required to run the 132 * linker will not advance the break beyond that point. If 133 * the break is advanced beyonnd that point, the load will 134 * fail with an `inconsistent memory allocation' error. 135 * It perhaps ought to retry the link, but the failure has 136 * not been observed in two years of daily use of this function. 137 *---------------------------------------------------------------------- 138 */ 139 140int 141TclpDlopen(interp, pathPtr, loadHandle, unloadProcPtr) 142 Tcl_Interp *interp; /* Used for error reporting. */ 143 Tcl_Obj *pathPtr; /* Name of the file containing the desired 144 * code (UTF-8). */ 145 Tcl_LoadHandle *loadHandle; /* Filled with token for dynamically loaded 146 * file which will be passed back to 147 * (*unloadProcPtr)() to unload the file. */ 148 Tcl_FSUnloadFileProc **unloadProcPtr; 149 /* Filled with address of Tcl_FSUnloadFileProc 150 * function which should be used for 151 * this file. */ 152{ 153 char * inputSymbolTable; /* Name of the file containing the 154 * symbol table from the last link. */ 155 Tcl_DString linkCommandBuf; /* Command to do the run-time relocation 156 * of the module.*/ 157 char * linkCommand; 158 char relocatedFileName [L_tmpnam]; 159 /* Name of the file holding the relocated */ 160 /* text of the module */ 161 int relocatedFd; /* File descriptor of the file holding 162 * relocated text */ 163 struct exec relocatedHead; /* Header of the relocated text */ 164 unsigned long relocatedSize;/* Size of the relocated text */ 165 char * startAddress; /* Starting address of the module */ 166 int status; /* Status return from Tcl_ calls */ 167 char * p; 168 169 /* Find the file that contains the symbols for the run-time link. */ 170 171 if (SymbolTableFile != NULL) { 172 inputSymbolTable = SymbolTableFile; 173 } else if (tclExecutableName == NULL) { 174 Tcl_SetResult (interp, "can't find the tclsh executable", TCL_STATIC); 175 return TCL_ERROR; 176 } else { 177 inputSymbolTable = tclExecutableName; 178 } 179 180 /* Construct the `ld' command that builds the relocated module */ 181 182 tmpnam (relocatedFileName); 183 Tcl_DStringInit (&linkCommandBuf); 184 Tcl_DStringAppend (&linkCommandBuf, "exec ld -o ", -1); 185 Tcl_DStringAppend (&linkCommandBuf, relocatedFileName, -1); 186#if defined(__mips) || defined(mips) 187 Tcl_DStringAppend (&linkCommandBuf, " -G 0 ", -1); 188#endif 189 Tcl_DStringAppend (&linkCommandBuf, " -u TclLoadDictionary_", -1); 190 TclGuessPackageName(Tcl_GetString(pathPtr), &linkCommandBuf); 191 Tcl_DStringAppend (&linkCommandBuf, " -A ", -1); 192 Tcl_DStringAppend (&linkCommandBuf, inputSymbolTable, -1); 193 Tcl_DStringAppend (&linkCommandBuf, " -N -T XXXXXXXX ", -1); 194 Tcl_DStringAppend (&linkCommandBuf, Tcl_GetString(pathPtr), -1); 195 Tcl_DStringAppend (&linkCommandBuf, " ", -1); 196 197 if (FindLibraries (interp, pathPtr, &linkCommandBuf) != TCL_OK) { 198 Tcl_DStringFree (&linkCommandBuf); 199 return TCL_ERROR; 200 } 201 202 linkCommand = Tcl_DStringValue (&linkCommandBuf); 203 204 /* Determine the starting address, and plug it into the command */ 205 206 startAddress = (char *) (((unsigned long) sbrk (0) 207 + TCL_LOADSHIM + TCL_LOADALIGN - 1) 208 & (- TCL_LOADALIGN)); 209 p = strstr (linkCommand, "-T") + 3; 210 sprintf (p, "%08lx", (long) startAddress); 211 p [8] = ' '; 212 213 /* Run the linker */ 214 215 status = Tcl_Eval (interp, linkCommand); 216 Tcl_DStringFree (&linkCommandBuf); 217 if (status != 0) { 218 return TCL_ERROR; 219 } 220 221 /* Open the linker's result file and read the header */ 222 223 relocatedFd = open (relocatedFileName, O_RDONLY); 224 if (relocatedFd < 0) { 225 goto ioError; 226 } 227 status= read (relocatedFd, (char *) & relocatedHead, sizeof relocatedHead); 228 if (status < sizeof relocatedHead) { 229 goto ioError; 230 } 231 232 /* Check the magic number */ 233 234 if (relocatedHead.a_magic != OMAGIC) { 235 Tcl_AppendResult (interp, "bad magic number in intermediate file \"", 236 relocatedFileName, "\"", (char *) NULL); 237 goto failure; 238 } 239 240 /* Make sure that memory allocation is still consistent */ 241 242 if ((unsigned long) sbrk (0) > (unsigned long) startAddress) { 243 Tcl_SetResult (interp, "can't load, memory allocation is inconsistent.", 244 TCL_STATIC); 245 goto failure; 246 } 247 248 /* Make sure that the relocated module's size is reasonable */ 249 250 relocatedSize = relocatedHead.a_text + relocatedHead.a_data 251 + relocatedHead.a_bss; 252 if (relocatedSize > TCL_LOADMAX) { 253 Tcl_SetResult (interp, "module too big to load", TCL_STATIC); 254 goto failure; 255 } 256 257 /* Advance the break to protect the loaded module */ 258 259 (void) brk (startAddress + relocatedSize); 260 261 /* 262 * Seek to the start of the module's text. 263 * 264 * Note that this does not really work with large files (i.e. where 265 * lseek64 exists and is different to lseek), but anyone trying to 266 * dynamically load a binary that is larger than what can fit in 267 * addressable memory is in trouble anyway... 268 */ 269 270#if defined(__mips) || defined(mips) 271 status = lseek (relocatedFd, 272 (off_t) N_TXTOFF (relocatedHead.ex_f, relocatedHead.ex_o), 273 SEEK_SET); 274#else 275 status = lseek (relocatedFd, (off_t) N_TXTOFF (relocatedHead), SEEK_SET); 276#endif 277 if (status < 0) { 278 goto ioError; 279 } 280 281 /* Read in the module's text and data */ 282 283 relocatedSize = relocatedHead.a_text + relocatedHead.a_data; 284 if (read (relocatedFd, startAddress, relocatedSize) < relocatedSize) { 285 brk (startAddress); 286 ioError: 287 Tcl_AppendResult (interp, "error on intermediate file \"", 288 relocatedFileName, "\": ", Tcl_PosixError (interp), 289 (char *) NULL); 290 failure: 291 (void) unlink (relocatedFileName); 292 return TCL_ERROR; 293 } 294 295 /* Close the intermediate file. */ 296 297 (void) close (relocatedFd); 298 299 /* Arrange things so that intermediate symbol tables eventually get 300 * deleted. */ 301 302 if (SymbolTableFile != NULL) { 303 UnlinkSymbolTable (); 304 } else { 305 atexit (UnlinkSymbolTable); 306 } 307 SymbolTableFile = ckalloc (strlen (relocatedFileName) + 1); 308 strcpy (SymbolTableFile, relocatedFileName); 309 310 *loadHandle = startAddress; 311 return TCL_OK; 312} 313 314/* 315 *---------------------------------------------------------------------- 316 * 317 * TclpFindSymbol -- 318 * 319 * Looks up a symbol, by name, through a handle associated with 320 * a previously loaded piece of code (shared library). 321 * 322 * Results: 323 * Returns a pointer to the function associated with 'symbol' if 324 * it is found. Otherwise returns NULL and may leave an error 325 * message in the interp's result. 326 * 327 *---------------------------------------------------------------------- 328 */ 329Tcl_PackageInitProc* 330TclpFindSymbol(interp, loadHandle, symbol) 331 Tcl_Interp *interp; 332 Tcl_LoadHandle loadHandle; 333 CONST char *symbol; 334{ 335 /* Look up the entry point in the load module's dictionary. */ 336 DictFn dictionary = (DictFn) loadHandle; 337 return (Tcl_PackageInitProc*) dictionary(sym1); 338} 339 340 341/* 342 *------------------------------------------------------------------------ 343 * 344 * FindLibraries -- 345 * 346 * Find the libraries needed to link a load module at run time. 347 * 348 * Results: 349 * A standard Tcl completion code. If an error occurs, 350 * an error message is left in the interp's result. The -l and -L 351 * flags are concatenated onto the dynamic string `buf'. 352 * 353 *------------------------------------------------------------------------ 354 */ 355 356static int 357FindLibraries (interp, pathPtr, buf) 358 Tcl_Interp * interp; /* Used for error reporting */ 359 Tcl_Obj * pathPtr; /* Name of the load module */ 360 Tcl_DString * buf; /* Buffer where the -l an -L flags */ 361{ 362 FILE * f; /* The load module */ 363 int c = 0; /* Byte from the load module */ 364 char * p; 365 CONST char *native; 366 367 char *fileName = Tcl_GetString(pathPtr); 368 369 /* Open the load module */ 370 371 native = Tcl_FSGetNativePath(pathPtr); 372 f = fopen(native, "rb"); /* INTL: Native. */ 373 374 if (f == NULL) { 375 Tcl_AppendResult (interp, "couldn't open \"", fileName, "\": ", 376 Tcl_PosixError (interp), (char *) NULL); 377 return TCL_ERROR; 378 } 379 380 /* Search for the library list in the load module */ 381 382 p = "@LIBS: "; 383 while (*p != '\0' && (c = getc (f)) != EOF) { 384 if (c == *p) { 385 ++p; 386 } 387 else { 388 p = "@LIBS: "; 389 if (c == *p) { 390 ++p; 391 } 392 } 393 } 394 395 /* No library list -- this must be an ill-formed module */ 396 397 if (c == EOF) { 398 Tcl_AppendResult (interp, "File \"", fileName, 399 "\" is not a Tcl load module.", (char *) NULL); 400 (void) fclose (f); 401 return TCL_ERROR; 402 } 403 404 /* Accumulate the library list */ 405 406 while ((c = getc (f)) != '\0' && c != EOF) { 407 char cc = c; 408 Tcl_DStringAppend (buf, &cc, 1); 409 } 410 (void) fclose (f); 411 412 if (c == EOF) { 413 Tcl_AppendResult (interp, "Library directory in \"", fileName, 414 "\" ends prematurely.", (char *) NULL); 415 return TCL_ERROR; 416 } 417 418 return TCL_OK; 419} 420 421/* 422 *------------------------------------------------------------------------ 423 * 424 * UnlinkSymbolTable -- 425 * 426 * Remove the symbol table file from the last dynamic link. 427 * 428 * Results: 429 * None. 430 * 431 * Side effects: 432 * The symbol table file from the last dynamic link is removed. 433 * This function is called when (a) a new symbol table is present 434 * because another dynamic link is complete, or (b) the process 435 * is exiting. 436 *------------------------------------------------------------------------ 437 */ 438 439static void 440UnlinkSymbolTable () 441{ 442 (void) unlink (SymbolTableFile); 443 ckfree (SymbolTableFile); 444 SymbolTableFile = NULL; 445} 446 447/* 448 *---------------------------------------------------------------------- 449 * 450 * TclpUnloadFile -- 451 * 452 * Unloads a dynamically loaded binary code file from memory. 453 * Code pointers in the formerly loaded file are no longer valid 454 * after calling this function. 455 * 456 * Results: 457 * None. 458 * 459 * Side effects: 460 * Does nothing. Can anything be done? 461 * 462 *---------------------------------------------------------------------- 463 */ 464 465void 466TclpUnloadFile(loadHandle) 467 Tcl_LoadHandle loadHandle; /* loadHandle returned by a previous call 468 * to TclpDlopen(). The loadHandle is 469 * a token that represents the loaded 470 * file. */ 471{ 472} 473 474/* 475 *---------------------------------------------------------------------- 476 * 477 * TclGuessPackageName -- 478 * 479 * If the "load" command is invoked without providing a package 480 * name, this procedure is invoked to try to figure it out. 481 * 482 * Results: 483 * Always returns 0 to indicate that we couldn't figure out a 484 * package name; generic code will then try to guess the package 485 * from the file name. A return value of 1 would have meant that 486 * we figured out the package name and put it in bufPtr. 487 * 488 * Side effects: 489 * None. 490 * 491 *---------------------------------------------------------------------- 492 */ 493 494int 495TclGuessPackageName(fileName, bufPtr) 496 CONST char *fileName; /* Name of file containing package (already 497 * translated to local form if needed). */ 498 Tcl_DString *bufPtr; /* Initialized empty dstring. Append 499 * package name to this if possible. */ 500{ 501 CONST char *p, *q; 502 char *r; 503 504 if ((q = strrchr(fileName,'/'))) { 505 q++; 506 } else { 507 q = fileName; 508 } 509 if (!strncmp(q,"lib",3)) { 510 q+=3; 511 } 512 p = q; 513 while ((*p) && (*p != '.') && ((*p<'0') || (*p>'9'))) { 514 p++; 515 } 516 if ((p>q+2) && !strncmp(p-2,"_G0.",4)) { 517 p-=2; 518 } 519 if (p<q) { 520 return 0; 521 } 522 523 Tcl_DStringAppend(bufPtr,q, p-q); 524 525 r = Tcl_DStringValue(bufPtr); 526 r += strlen(r) - (p-q); 527 528 /* 529 * Capitalize the string and then recompute the length. 530 */ 531 532 Tcl_UtfToTitle(r); 533 Tcl_DStringSetLength(bufPtr, strlen(Tcl_DStringValue(bufPtr))); 534 535 return 1; 536} 537