Python/marshal.c

   1
   2 /* Write Python objects to files and read them back.
   3    This is intended for writing and reading compiled Python code only;
   4    a true persistent storage facility would be much harder, since
   5    it would have to take circular links and sharing into account. */
   6
   7 #include "Python.h"
   8 #include "longintrepr.h"
   9 #include "compile.h"
  10 #include "marshal.h"
  11
  12 /* High water mark to determine when the marshalled object is dangerously deep
  13  * and risks coring the interpreter.  When the object stack gets this deep,
  14  * raise an exception instead of continuing.
  15  */
  16 #define MAX_MARSHAL_STACK_DEPTH 5000
  17
  18 #define TYPE_NULL       '0'
  19 #define TYPE_NONE       'N'
  20 #define TYPE_STOPITER   'S'
  21 #define TYPE_ELLIPSIS   '.'
  22 #define TYPE_INT        'i'
  23 #define TYPE_INT64      'I'
  24 #define TYPE_FLOAT      'f'
  25 #define TYPE_COMPLEX    'x'
  26 #define TYPE_LONG       'l'
  27 #define TYPE_STRING     's'
  28 #define TYPE_TUPLE      '('
  29 #define TYPE_LIST       '['
  30 #define TYPE_DICT       '{'
  31 #define TYPE_CODE       'c'
  32 #define TYPE_UNICODE    'u'
  33 #define TYPE_UNKNOWN    '?'
  34
  35 typedef struct {
  36         FILE *fp;
  37         int error;
  38         int depth;
  39         /* If fp == NULL, the following are valid: */
  40         PyObject *str;
  41         char *ptr;
  42         char *end;
  43 } WFILE;
  44
  45 #define w_byte(c, p) if (((p)->fp)) putc((c), (p)->fp); \
  46                       else if ((p)->ptr != (p)->end) *(p)->ptr++ = (c); \
  47                            else w_more(c, p)
  48
  49 static void
  50 w_more(int c, WFILE *p)
  51 {
  52         int size, newsize;
  53         if (p->str == NULL)
  54                 return; /* An error already occurred */
  55         size = PyString_Size(p->str);
  56         newsize = size + 1024;
  57         if (_PyString_Resize(&p->str, newsize) != 0) {
  58                 p->ptr = p->end = NULL;
  59         }
  60         else {
  61                 p->ptr = PyString_AS_STRING((PyStringObject *)p->str) + size;
  62                 p->end =
  63                         PyString_AS_STRING((PyStringObject *)p->str) + newsize;
  64                 *p->ptr++ = Py_SAFE_DOWNCAST(c, int, char);
  65         }
  66 }
  67
  68 static void
  69 w_string(char *s, int n, WFILE *p)
  70 {
  71         if (p->fp != NULL) {
  72                 fwrite(s, 1, n, p->fp);
  73         }
  74         else {
  75                 while (--n >= 0) {
  76                         w_byte(*s, p);
  77                         s++;
  78                 }
  79         }
  80 }
  81
  82 static void
  83 w_short(int x, WFILE *p)
  84 {
  85         w_byte( x      & 0xff, p);
  86         w_byte((x>> 8) & 0xff, p);
  87 }
  88
  89 static void
  90 w_long(long x, WFILE *p)
  91 {
  92         w_byte((int)( x      & 0xff), p);
  93         w_byte((int)((x>> 8) & 0xff), p);
  94         w_byte((int)((x>>16) & 0xff), p);
  95         w_byte((int)((x>>24) & 0xff), p);
  96 }
  97
  98 #if SIZEOF_LONG > 4
  99 static void
 100 w_long64(long x, WFILE *p)
 101 {
 102         w_long(x, p);
 103         w_long(x>>32, p);
 104 }
 105 #endif
 106
 107 static void
 108 w_object(PyObject *v, WFILE *p)
 109 {
 110         int i, n;
 111         PyBufferProcs *pb;
 112
 113         p->depth++;
 114
 115         if (p->depth > MAX_MARSHAL_STACK_DEPTH) {
 116                 p->error = 2;
 117         }
 118         else if (v == NULL) {
 119                 w_byte(TYPE_NULL, p);
 120         }
 121         else if (v == Py_None) {
 122                 w_byte(TYPE_NONE, p);
 123         }
 124         else if (v == PyExc_StopIteration) {
 125                 w_byte(TYPE_STOPITER, p);
 126         }
 127         else if (v == Py_Ellipsis) {
 128                 w_byte(TYPE_ELLIPSIS, p);
 129         }
 130         else if (PyInt_Check(v)) {
 131                 long x = PyInt_AS_LONG((PyIntObject *)v);
 132 #if SIZEOF_LONG > 4
 133                 long y = Py_ARITHMETIC_RIGHT_SHIFT(long, x, 31);
 134                 if (y && y != -1) {
 135                         w_byte(TYPE_INT64, p);
 136                         w_long64(x, p);
 137                 }
 138                 else
 139 #endif
 140                         {
 141                         w_byte(TYPE_INT, p);
 142                         w_long(x, p);
 143                 }
 144         }
 145         else if (PyLong_Check(v)) {
 146                 PyLongObject *ob = (PyLongObject *)v;
 147                 w_byte(TYPE_LONG, p);
 148                 n = ob->ob_size;
 149                 w_long((long)n, p);
 150                 if (n < 0)
 151                         n = -n;
 152                 for (i = 0; i < n; i++)
 153                         w_short(ob->ob_digit[i], p);
 154         }
 155         else if (PyFloat_Check(v)) {
 156                 char buf[256]; /* Plenty to format any double */
 157                 PyFloat_AsReprString(buf, (PyFloatObject *)v);
 158                 n = strlen(buf);
 159                 w_byte(TYPE_FLOAT, p);
 160                 w_byte(n, p);
 161                 w_string(buf, n, p);
 162         }
 163 #ifndef WITHOUT_COMPLEX
 164         else if (PyComplex_Check(v)) {
 165                 char buf[256]; /* Plenty to format any double */
 166                 PyFloatObject *temp;
 167                 w_byte(TYPE_COMPLEX, p);
 168                 temp = (PyFloatObject*)PyFloat_FromDouble(
 169                         PyComplex_RealAsDouble(v));
 170                 PyFloat_AsReprString(buf, temp);
 171                 Py_DECREF(temp);
 172                 n = strlen(buf);
 173                 w_byte(n, p);
 174                 w_string(buf, n, p);
 175                 temp = (PyFloatObject*)PyFloat_FromDouble(
 176                         PyComplex_ImagAsDouble(v));
 177                 PyFloat_AsReprString(buf, temp);
 178                 Py_DECREF(temp);
 179                 n = strlen(buf);
 180                 w_byte(n, p);
 181                 w_string(buf, n, p);
 182         }
 183 #endif
 184         else if (PyString_Check(v)) {
 185                 w_byte(TYPE_STRING, p);
 186                 n = PyString_GET_SIZE(v);
 187                 w_long((long)n, p);
 188                 w_string(PyString_AS_STRING(v), n, p);
 189         }
 190         else if (PyUnicode_Check(v)) {
 191                 PyObject *utf8;
 192                 utf8 = PyUnicode_AsUTF8String(v);
 193                 if (utf8 == NULL) {
 194                         p->depth--;
 195                         p->error = 1;
 196                         return;
 197                 }
 198                 w_byte(TYPE_UNICODE, p);
 199                 n = PyString_GET_SIZE(utf8);
 200                 w_long((long)n, p);
 201                 w_string(PyString_AS_STRING(utf8), n, p);
 202                 Py_DECREF(utf8);
 203         }
 204         else if (PyTuple_Check(v)) {
 205                 w_byte(TYPE_TUPLE, p);
 206                 n = PyTuple_Size(v);
 207                 w_long((long)n, p);
 208                 for (i = 0; i < n; i++) {
 209                         w_object(PyTuple_GET_ITEM(v, i), p);
 210                 }
 211         }
 212         else if (PyList_Check(v)) {
 213                 w_byte(TYPE_LIST, p);
 214                 n = PyList_GET_SIZE(v);
 215                 w_long((long)n, p);
 216                 for (i = 0; i < n; i++) {
 217                         w_object(PyList_GET_ITEM(v, i), p);
 218                 }
 219         }
 220         else if (PyDict_Check(v)) {
 221                 int pos;
 222                 PyObject *key, *value;
 223                 w_byte(TYPE_DICT, p);
 224                 /* This one is NULL object terminated! */
 225                 pos = 0;
 226                 while (PyDict_Next(v, &pos, &key, &value)) {
 227                         w_object(key, p);
 228                         w_object(value, p);
 229                 }
 230                 w_object((PyObject *)NULL, p);
 231         }
 232         else if (PyCode_Check(v)) {
 233                 PyCodeObject *co = (PyCodeObject *)v;
 234                 w_byte(TYPE_CODE, p);
 235                 w_short(co->co_argcount, p);
 236                 w_short(co->co_nlocals, p);
 237                 w_short(co->co_stacksize, p);
 238                 w_short(co->co_flags, p);
 239                 w_object(co->co_code, p);
 240                 w_object(co->co_consts, p);
 241                 w_object(co->co_names, p);
 242                 w_object(co->co_varnames, p);
 243                 w_object(co->co_freevars, p);
 244                 w_object(co->co_cellvars, p);
 245                 w_object(co->co_filename, p);
 246                 w_object(co->co_name, p);
 247                 w_short(co->co_firstlineno, p);
 248                 w_object(co->co_lnotab, p);
 249         }
 250         else if ((pb = v->ob_type->tp_as_buffer) != NULL &&
 251                  pb->bf_getsegcount != NULL &&
 252                  pb->bf_getreadbuffer != NULL &&
 253                  (*pb->bf_getsegcount)(v, NULL) == 1)
 254         {
 255                 /* Write unknown buffer-style objects as a string */
 256                 char *s;
 257                 w_byte(TYPE_STRING, p);
 258                 n = (*pb->bf_getreadbuffer)(v, 0, (void **)&s);
 259                 w_long((long)n, p);
 260                 w_string(s, n, p);
 261         }
 262         else {
 263                 w_byte(TYPE_UNKNOWN, p);
 264                 p->error = 1;
 265         }
 266
 267         p->depth--;
 268 }
 269
 270 void
 271 PyMarshal_WriteLongToFile(long x, FILE *fp)
 272 {
 273         WFILE wf;
 274         wf.fp = fp;
 275         wf.error = 0;
 276         wf.depth = 0;
 277         w_long(x, &wf);
 278 }
 279
 280 void
 281 PyMarshal_WriteObjectToFile(PyObject *x, FILE *fp)
 282 {
 283         WFILE wf;
 284         wf.fp = fp;
 285         wf.error = 0;
 286         wf.depth = 0;
 287         w_object(x, &wf);
 288 }
 289
 290 typedef WFILE RFILE; /* Same struct with different invariants */
 291
 292 #define rs_byte(p) (((p)->ptr != (p)->end) ? (unsigned char)*(p)->ptr++ : EOF)
 293
 294 #define r_byte(p) ((p)->fp ? getc((p)->fp) : rs_byte(p))
 295
 296 static int
 297 r_string(char *s, int n, RFILE *p)
 298 {
 299         if (p->fp != NULL)
 300                 return fread(s, 1, n, p->fp);
 301         if (p->end - p->ptr < n)
 302                 n = p->end - p->ptr;
 303         memcpy(s, p->ptr, n);
 304         p->ptr += n;
 305         return n;
 306 }
 307
 308 static int
 309 r_short(RFILE *p)
 310 {
 311         register short x;
 312         x = r_byte(p);
 313         x |= r_byte(p) << 8;
 314         /* Sign-extension, in case short greater than 16 bits */
 315         x |= -(x & 0x8000);
 316         return x;
 317 }
 318
 319 static long
 320 r_long(RFILE *p)
 321 {
 322         register long x;
 323         register FILE *fp = p->fp;
 324         if (fp) {
 325                 x = getc(fp);
 326                 x |= (long)getc(fp) << 8;
 327                 x |= (long)getc(fp) << 16;
 328                 x |= (long)getc(fp) << 24;
 329         }
 330         else {
 331                 x = rs_byte(p);
 332                 x |= (long)rs_byte(p) << 8;
 333                 x |= (long)rs_byte(p) << 16;
 334                 x |= (long)rs_byte(p) << 24;
 335         }
 336 #if SIZEOF_LONG > 4
 337         /* Sign extension for 64-bit machines */
 338         x |= -(x & 0x80000000L);
 339 #endif
 340         return x;
 341 }
 342
 343 static long
 344 r_long64(RFILE *p)
 345 {
 346         register long x;
 347         x = r_long(p);
 348 #if SIZEOF_LONG > 4
 349         x = (x & 0xFFFFFFFFL) | (r_long(p) << 32);
 350 #else
 351         if (r_long(p) != 0) {
 352                 PyObject *f = PySys_GetObject("stderr");
 353                 if (f != NULL)
 354                         (void) PyFile_WriteString(
 355                             "Warning: un-marshal 64-bit int in 32-bit mode\n",
 356                             f);
 357         }
 358 #endif
 359         return x;
 360 }
 361
 362 static PyObject *
 363 r_object(RFILE *p)
 364 {
 365         PyObject *v, *v2;
 366         long i, n;
 367         int type = r_byte(p);
 368
 369         switch (type) {
 370
 371         case EOF:
 372                 PyErr_SetString(PyExc_EOFError,
 373                                 "EOF read where object expected");
 374                 return NULL;
 375
 376         case TYPE_NULL:
 377                 return NULL;
 378
 379         case TYPE_NONE:
 380                 Py_INCREF(Py_None);
 381                 return Py_None;
 382
 383         case TYPE_STOPITER:
 384                 Py_INCREF(PyExc_StopIteration);
 385                 return PyExc_StopIteration;
 386
 387         case TYPE_ELLIPSIS:
 388                 Py_INCREF(Py_Ellipsis);
 389                 return Py_Ellipsis;
 390
 391         case TYPE_INT:
 392                 return PyInt_FromLong(r_long(p));
 393
 394         case TYPE_INT64:
 395                 return PyInt_FromLong(r_long64(p));
 396
 397         case TYPE_LONG:
 398                 {
 399                         int size;
 400                         PyLongObject *ob;
 401                         n = r_long(p);
 402                         size = n<0 ? -n : n;
 403                         ob = _PyLong_New(size);
 404                         if (ob == NULL)
 405                                 return NULL;
 406                         ob->ob_size = n;
 407                         for (i = 0; i < size; i++)
 408                                 ob->ob_digit[i] = r_short(p);
 409                         return (PyObject *)ob;
 410                 }
 411
 412         case TYPE_FLOAT:
 413                 {
 414                         char buf[256];
 415                         double dx;
 416                         n = r_byte(p);
 417                         if (r_string(buf, (int)n, p) != n) {
 418                                 PyErr_SetString(PyExc_EOFError,
 419                                         "EOF read where object expected");
 420                                 return NULL;
 421                         }
 422                         buf[n] = '\0';
 423                         PyFPE_START_PROTECT("atof", return 0)
 424                         dx = atof(buf);
 425                         PyFPE_END_PROTECT(dx)
 426                         return PyFloat_FromDouble(dx);
 427                 }
 428
 429 #ifndef WITHOUT_COMPLEX
 430         case TYPE_COMPLEX:
 431                 {
 432                         char buf[256];
 433                         Py_complex c;
 434                         n = r_byte(p);
 435                         if (r_string(buf, (int)n, p) != n) {
 436                                 PyErr_SetString(PyExc_EOFError,
 437                                         "EOF read where object expected");
 438                                 return NULL;
 439                         }
 440                         buf[n] = '\0';
 441                         PyFPE_START_PROTECT("atof", return 0)
 442                         c.real = atof(buf);
 443                         PyFPE_END_PROTECT(c)
 444                         n = r_byte(p);
 445                         if (r_string(buf, (int)n, p) != n) {
 446                                 PyErr_SetString(PyExc_EOFError,
 447                                         "EOF read where object expected");
 448                                 return NULL;
 449                         }
 450                         buf[n] = '\0';
 451                         PyFPE_START_PROTECT("atof", return 0)
 452                         c.imag = atof(buf);
 453                         PyFPE_END_PROTECT(c)
 454                         return PyComplex_FromCComplex(c);
 455                 }
 456 #endif
 457
 458         case TYPE_STRING:
 459                 n = r_long(p);
 460                 if (n < 0) {
 461                         PyErr_SetString(PyExc_ValueError, "bad marshal data");
 462                         return NULL;
 463                 }
 464                 v = PyString_FromStringAndSize((char *)NULL, n);
 465                 if (v != NULL) {
 466                         if (r_string(PyString_AS_STRING(v), (int)n, p) != n) {
 467                                 Py_DECREF(v);
 468                                 v = NULL;
 469                                 PyErr_SetString(PyExc_EOFError,
 470                                         "EOF read where object expected");
 471                         }
 472                 }
 473                 return v;
 474
 475         case TYPE_UNICODE:
 476             {
 477                 char *buffer;
 478
 479                 n = r_long(p);
 480                 if (n < 0) {
 481                         PyErr_SetString(PyExc_ValueError, "bad marshal data");
 482                         return NULL;
 483                 }
 484                 buffer = PyMem_NEW(char, n);
 485                 if (buffer == NULL)
 486                         return PyErr_NoMemory();
 487                 if (r_string(buffer, (int)n, p) != n) {
 488                         PyMem_DEL(buffer);
 489                         PyErr_SetString(PyExc_EOFError,
 490                                 "EOF read where object expected");
 491                         return NULL;
 492                 }
 493                 v = PyUnicode_DecodeUTF8(buffer, n, NULL);
 494                 PyMem_DEL(buffer);
 495                 return v;
 496             }
 497
 498         case TYPE_TUPLE:
 499                 n = r_long(p);
 500                 if (n < 0) {
 501                         PyErr_SetString(PyExc_ValueError, "bad marshal data");
 502                         return NULL;
 503                 }
 504                 v = PyTuple_New((int)n);
 505                 if (v == NULL)
 506                         return v;
 507                 for (i = 0; i < n; i++) {
 508                         v2 = r_object(p);
 509                         if ( v2 == NULL ) {
 510                                 Py_DECREF(v);
 511                                 v = NULL;
 512                                 break;
 513                         }
 514                         PyTuple_SET_ITEM(v, (int)i, v2);
 515                 }
 516                 return v;
 517
 518         case TYPE_LIST:
 519                 n = r_long(p);
 520                 if (n < 0) {
 521                         PyErr_SetString(PyExc_ValueError, "bad marshal data");
 522                         return NULL;
 523                 }
 524                 v = PyList_New((int)n);
 525                 if (v == NULL)
 526                         return v;
 527                 for (i = 0; i < n; i++) {
 528                         v2 = r_object(p);
 529                         if ( v2 == NULL ) {
 530                                 Py_DECREF(v);
 531                                 v = NULL;
 532                                 break;
 533                         }
 534                         PyList_SetItem(v, (int)i, v2);
 535                 }
 536                 return v;
 537
 538         case TYPE_DICT:
 539                 v = PyDict_New();
 540                 if (v == NULL)
 541                         return NULL;
 542                 for (;;) {
 543                         PyObject *key, *val;
 544                         key = r_object(p);
 545                         if (key == NULL)
 546                                 break; /* XXX Assume TYPE_NULL, not an error */
 547                         val = r_object(p);
 548                         if (val != NULL)
 549                                 PyDict_SetItem(v, key, val);
 550                         Py_DECREF(key);
 551                         Py_XDECREF(val);
 552                 }
 553                 return v;
 554
 555         case TYPE_CODE:
 556                 {
 557                         int argcount = r_short(p);
 558                         int nlocals = r_short(p);
 559                         int stacksize = r_short(p);
 560                         int flags = r_short(p);
 561                         PyObject *code = NULL;
 562                         PyObject *consts = NULL;
 563                         PyObject *names = NULL;
 564                         PyObject *varnames = NULL;
 565                         PyObject *freevars = NULL;
 566                         PyObject *cellvars = NULL;
 567                         PyObject *filename = NULL;
 568                         PyObject *name = NULL;
 569                         int firstlineno = 0;
 570                         PyObject *lnotab = NULL;
 571
 572                         code = r_object(p);
 573                         if (code) consts = r_object(p);
 574                         if (consts) names = r_object(p);
 575                         if (names) varnames = r_object(p);
 576                         if (varnames) freevars = r_object(p);
 577                         if (freevars) cellvars = r_object(p);
 578                         if (cellvars) filename = r_object(p);
 579                         if (filename) name = r_object(p);
 580                         if (name) {
 581                                 firstlineno = r_short(p);
 582                                 lnotab = r_object(p);
 583                         }
 584
 585                         if (!PyErr_Occurred()) {
 586                                 v = (PyObject *) PyCode_New(
 587                                         argcount, nlocals, stacksize, flags,
 588                                         code, consts, names, varnames,
 589                                         freevars, cellvars, filename, name,
 590                                         firstlineno, lnotab);
 591                         }
 592                         else
 593                                 v = NULL;
 594                         Py_XDECREF(code);
 595                         Py_XDECREF(consts);
 596                         Py_XDECREF(names);
 597                         Py_XDECREF(varnames);
 598                         Py_XDECREF(freevars);
 599                         Py_XDECREF(cellvars);
 600                         Py_XDECREF(filename);
 601                         Py_XDECREF(name);
 602                         Py_XDECREF(lnotab);
 603
 604                 }
 605                 return v;
 606
 607         default:
 608                 /* Bogus data got written, which isn't ideal.
 609                    This will let you keep working and recover. */
 610                 PyErr_SetString(PyExc_ValueError, "bad marshal data");
 611                 return NULL;
 612
 613         }
 614 }
 615
 616 long
 617 PyMarshal_ReadLongFromFile(FILE *fp)
 618 {
 619         RFILE rf;
 620         rf.fp = fp;
 621         return r_long(&rf);
 622 }
 623
 624 #ifdef HAVE_FSTAT
 625 /* Return size of file in bytes; < 0 if unknown. */
 626 static off_t
 627 getfilesize(FILE *fp)
 628 {
 629         struct stat st;
 630         if (fstat(fileno(fp), &st) != 0)
 631                 return -1;
 632         else
 633                 return st.st_size;
 634 }
 635 #endif
 636
 637 /* If we can get the size of the file up-front, and it's reasonably small,
 638  * read it in one gulp and delegate to ...FromString() instead.  Much quicker
 639  * than reading a byte at a time from file; speeds .pyc imports.
 640  * CAUTION:  since this may read the entire remainder of the file, don't
 641  * call it unless you know you're done with the file.
 642  */
 643 PyObject *
 644 PyMarshal_ReadLastObjectFromFile(FILE *fp)
 645 {
 646 /* 75% of 2.1's .pyc files can exploit SMALL_FILE_LIMIT.
 647  * REASONABLE_FILE_LIMIT is by defn something big enough for Tkinter.pyc.
 648  */
 649 #define SMALL_FILE_LIMIT (1L << 14)
 650 #define REASONABLE_FILE_LIMIT (1L << 18)
 651 #ifdef HAVE_FSTAT
 652         off_t filesize;
 653 #endif
 654         if (PyErr_Occurred()) {
 655                 fprintf(stderr, "XXX rd_object called with exception set\n");
 656                 return NULL;
 657         }
 658 #ifdef HAVE_FSTAT
 659         filesize = getfilesize(fp);
 660         if (filesize > 0) {
 661                 char buf[SMALL_FILE_LIMIT];
 662                 char* pBuf = NULL;
 663                 if (filesize <= SMALL_FILE_LIMIT)
 664                         pBuf = buf;
 665                 else if (filesize <= REASONABLE_FILE_LIMIT)
 666                         pBuf = (char *)PyMem_MALLOC(filesize);
 667                 if (pBuf != NULL) {
 668                         PyObject* v;
 669                         size_t n = fread(pBuf, 1, filesize, fp);
 670                         v = PyMarshal_ReadObjectFromString(pBuf, n);
 671                         if (pBuf != buf)
 672                                 PyMem_FREE(pBuf);
 673                         return v;
 674                 }
 675
 676         }
 677 #endif
 678         /* We don't have fstat, or we do but the file is larger than
 679          * REASONABLE_FILE_LIMIT or malloc failed -- read a byte at a time.
 680          */
 681         return PyMarshal_ReadObjectFromFile(fp);
 682
 683 #undef SMALL_FILE_LIMIT
 684 #undef REASONABLE_FILE_LIMIT
 685 }
 686
 687 PyObject *
 688 PyMarshal_ReadObjectFromFile(FILE *fp)
 689 {
 690         RFILE rf;
 691         if (PyErr_Occurred()) {
 692                 fprintf(stderr, "XXX rd_object called with exception set\n");
 693                 return NULL;
 694         }
 695         rf.fp = fp;
 696         return r_object(&rf);
 697 }
 698
 699 PyObject *
 700 PyMarshal_ReadObjectFromString(char *str, int len)
 701 {
 702         RFILE rf;
 703         if (PyErr_Occurred()) {
 704                 fprintf(stderr, "XXX rds_object called with exception set\n");
 705                 return NULL;
 706         }
 707         rf.fp = NULL;
 708         rf.str = NULL;
 709         rf.ptr = str;
 710         rf.end = str + len;
 711         return r_object(&rf);
 712 }
 713
 714 PyObject *
 715 PyMarshal_WriteObjectToString(PyObject *x) /* wrs_object() */
 716 {
 717         WFILE wf;
 718         wf.fp = NULL;
 719         wf.str = PyString_FromStringAndSize((char *)NULL, 50);
 720         if (wf.str == NULL)
 721                 return NULL;
 722         wf.ptr = PyString_AS_STRING((PyStringObject *)wf.str);
 723         wf.end = wf.ptr + PyString_Size(wf.str);
 724         wf.error = 0;
 725         wf.depth = 0;
 726         w_object(x, &wf);
 727         if (wf.str != NULL)
 728                 _PyString_Resize(&wf.str,
 729                     (int) (wf.ptr -
 730                            PyString_AS_STRING((PyStringObject *)wf.str)));
 731         if (wf.error) {
 732                 Py_XDECREF(wf.str);
 733                 PyErr_SetString(PyExc_ValueError,
 734                                 (wf.error==1)?"unmarshallable object"
 735                                 :"object too deeply nested to marshal");
 736                 return NULL;
 737         }
 738         return wf.str;
 739 }
 740
 741 /* And an interface for Python programs... */
 742
 743 static PyObject *
 744 marshal_dump(PyObject *self, PyObject *args)
 745 {
 746         WFILE wf;
 747         PyObject *x;
 748         PyObject *f;
 749         if (!PyArg_ParseTuple(args, "OO:dump", &x, &f))
 750                 return NULL;
 751         if (!PyFile_Check(f)) {
 752                 PyErr_SetString(PyExc_TypeError,
 753                                 "marshal.dump() 2nd arg must be file");
 754                 return NULL;
 755         }
 756         wf.fp = PyFile_AsFile(f);
 757         wf.str = NULL;
 758         wf.ptr = wf.end = NULL;
 759         wf.error = 0;
 760         wf.depth = 0;
 761         w_object(x, &wf);
 762         if (wf.error) {
 763                 PyErr_SetString(PyExc_ValueError,
 764                                 (wf.error==1)?"unmarshallable object"
 765                                 :"object too deeply nested to marshal");
 766                 return NULL;
 767         }
 768         Py_INCREF(Py_None);
 769         return Py_None;
 770 }
 771
 772 static PyObject *
 773 marshal_load(PyObject *self, PyObject *args)
 774 {
 775         RFILE rf;
 776         PyObject *f;
 777         PyObject *v;
 778         if (!PyArg_ParseTuple(args, "O:load", &f))
 779                 return NULL;
 780         if (!PyFile_Check(f)) {
 781                 PyErr_SetString(PyExc_TypeError,
 782                                 "marshal.load() arg must be file");
 783                 return NULL;
 784         }
 785         rf.fp = PyFile_AsFile(f);
 786         rf.str = NULL;
 787         rf.ptr = rf.end = NULL;
 788         PyErr_Clear();
 789         v = r_object(&rf);
 790         if (PyErr_Occurred()) {
 791                 Py_XDECREF(v);
 792                 v = NULL;
 793         }
 794         return v;
 795 }
 796
 797 static PyObject *
 798 marshal_dumps(PyObject *self, PyObject *args)
 799 {
 800         PyObject *x;
 801         if (!PyArg_ParseTuple(args, "O:dumps", &x))
 802                 return NULL;
 803         return PyMarshal_WriteObjectToString(x);
 804 }
 805
 806 static PyObject *
 807 marshal_loads(PyObject *self, PyObject *args)
 808 {
 809         RFILE rf;
 810         PyObject *v;
 811         char *s;
 812         int n;
 813         if (!PyArg_ParseTuple(args, "s#:loads", &s, &n))
 814                 return NULL;
 815         rf.fp = NULL;
 816         rf.str = args;
 817         rf.ptr = s;
 818         rf.end = s + n;
 819         PyErr_Clear();
 820         v = r_object(&rf);
 821         if (PyErr_Occurred()) {
 822                 Py_XDECREF(v);
 823                 v = NULL;
 824         }
 825         return v;
 826 }
 827
 828 static PyMethodDef marshal_methods[] = {
 829         {"dump",        marshal_dump,   1},
 830         {"load",        marshal_load,   1},
 831         {"dumps",       marshal_dumps,  1},
 832         {"loads",       marshal_loads,  1},
 833         {NULL,          NULL}           /* sentinel */
 834 };
 835
 836 void
 837 PyMarshal_Init(void)
 838 {
 839         (void) Py_InitModule("marshal", marshal_methods);
 840 }