sunrpc/xdr_rec.c

   1 /*
   2  * Sun RPC is a product of Sun Microsystems, Inc. and is provided for
   3  * unrestricted use provided that this legend is included on all tape
   4  * media and as a part of the software program in whole or part.  Users
   5  * may copy or modify Sun RPC without charge, but are not authorized
   6  * to license or distribute it to anyone else except as part of a product or
   7  * program developed by the user.
   8  *
   9  * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
  10  * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
  11  * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
  12  *
  13  * Sun RPC is provided with no support and without any obligation on the
  14  * part of Sun Microsystems, Inc. to assist in its use, correction,
  15  * modification or enhancement.
  16  *
  17  * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
  18  * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC
  19  * OR ANY PART THEREOF.
  20  *
  21  * In no event will Sun Microsystems, Inc. be liable for any lost revenue
  22  * or profits or other special, indirect and consequential damages, even if
  23  * Sun has been advised of the possibility of such damages.
  24  *
  25  * Sun Microsystems, Inc.
  26  * 2550 Garcia Avenue
  27  * Mountain View, California  94043
  28  */
  29
  30 /*
  31  * xdr_rec.c, Implements TCP/IP based XDR streams with a "record marking"
  32  * layer above tcp (for rpc's use).
  33  *
  34  * Copyright (C) 1984, Sun Microsystems, Inc.
  35  *
  36  * These routines interface XDRSTREAMS to a tcp/ip connection.
  37  * There is a record marking layer between the xdr stream
  38  * and the tcp transport level.  A record is composed on one or more
  39  * record fragments.  A record fragment is a thirty-two bit header followed
  40  * by n bytes of data, where n is contained in the header.  The header
  41  * is represented as a htonl(u_long).  The high order bit encodes
  42  * whether or not the fragment is the last fragment of the record
  43  * (1 => fragment is last, 0 => more fragments to follow.
  44  * The other 31 bits encode the byte length of the fragment.
  45  */
  46
  47 #include <stdio.h>
  48 #include <string.h>
  49 #include <unistd.h>
  50 #include <rpc/rpc.h>
  51 #include <libintl.h>
  52
  53 #ifdef USE_IN_LIBIO
  54 # include <libio/iolibio.h>
  55 # define fputs(s, f) _IO_fputs (s, f)
  56 #endif
  57
  58 static bool_t xdrrec_getlong (XDR *, long *);
  59 static bool_t xdrrec_putlong (XDR *, const long *);
  60 static bool_t xdrrec_getbytes (XDR *, caddr_t, u_int);
  61 static bool_t xdrrec_putbytes (XDR *, const char *, u_int);
  62 static u_int xdrrec_getpos (const XDR *);
  63 static bool_t xdrrec_setpos (XDR *, u_int);
  64 static int32_t *xdrrec_inline (XDR *, int);
  65 static void xdrrec_destroy (XDR *);
  66 static bool_t xdrrec_getint32 (XDR *, int32_t *);
  67 static bool_t xdrrec_putint32 (XDR *, const int32_t *);
  68
  69 static const struct xdr_ops xdrrec_ops =
  70 {
  71   xdrrec_getlong,
  72   xdrrec_putlong,
  73   xdrrec_getbytes,
  74   xdrrec_putbytes,
  75   xdrrec_getpos,
  76   xdrrec_setpos,
  77   xdrrec_inline,
  78   xdrrec_destroy,
  79   xdrrec_getint32,
  80   xdrrec_putint32
  81 };
  82
  83 /*
  84  * A record is composed of one or more record fragments.
  85  * A record fragment is a two-byte header followed by zero to
  86  * 2**32-1 bytes.  The header is treated as a long unsigned and is
  87  * encode/decoded to the network via htonl/ntohl.  The low order 31 bits
  88  * are a byte count of the fragment.  The highest order bit is a boolean:
  89  * 1 => this fragment is the last fragment of the record,
  90  * 0 => this fragment is followed by more fragment(s).
  91  *
  92  * The fragment/record machinery is not general;  it is constructed to
  93  * meet the needs of xdr and rpc based on tcp.
  94  */
  95
  96 #define LAST_FRAG (1UL << 31)
  97
  98 typedef struct rec_strm
  99   {
 100     caddr_t tcp_handle;
 101     caddr_t the_buffer;
 102     /*
 103      * out-going bits
 104      */
 105     int (*writeit) (char *, char *, int);
 106     caddr_t out_base;           /* output buffer (points to frag header) */
 107     caddr_t out_finger;         /* next output position */
 108     caddr_t out_boundry;        /* data cannot up to this address */
 109     u_int32_t *frag_header;     /* beginning of curren fragment */
 110     bool_t frag_sent;           /* true if buffer sent in middle of record */
 111     /*
 112      * in-coming bits
 113      */
 114     int (*readit) (char *, char *, int);
 115     u_long in_size;             /* fixed size of the input buffer */
 116     caddr_t in_base;
 117     caddr_t in_finger;          /* location of next byte to be had */
 118     caddr_t in_boundry;         /* can read up to this location */
 119     long fbtbc;                 /* fragment bytes to be consumed */
 120     bool_t last_frag;
 121     u_int sendsize;
 122     u_int recvsize;
 123   }
 124 RECSTREAM;
 125
 126 static u_int fix_buf_size (u_int) internal_function;
 127 static bool_t skip_input_bytes (RECSTREAM *, long) internal_function;
 128 static bool_t flush_out (RECSTREAM *, bool_t) internal_function;
 129 static bool_t set_input_fragment (RECSTREAM *) internal_function;
 130 static bool_t get_input_bytes (RECSTREAM *, caddr_t, int) internal_function;
 131
 132 /*
 133  * Create an xdr handle for xdrrec
 134  * xdrrec_create fills in xdrs.  Sendsize and recvsize are
 135  * send and recv buffer sizes (0 => use default).
 136  * tcp_handle is an opaque handle that is passed as the first parameter to
 137  * the procedures readit and writeit.  Readit and writeit are read and
 138  * write respectively.   They are like the system
 139  * calls expect that they take an opaque handle rather than an fd.
 140  */
 141 void
 142 xdrrec_create (XDR *xdrs, u_int sendsize,
 143                u_int recvsize, caddr_t tcp_handle,
 144                int (*readit) (char *, char *, int),
 145                int (*writeit) (char *, char *, int))
 146 {
 147   RECSTREAM *rstrm = (RECSTREAM *) mem_alloc (sizeof (RECSTREAM));
 148   caddr_t tmp;
 149
 150   if (rstrm == NULL)
 151     {
 152       (void) fputs (_("xdrrec_create: out of memory\n"), stderr);
 153       /*
 154        *  This is bad.  Should rework xdrrec_create to
 155        *  return a handle, and in this case return NULL
 156        */
 157       return;
 158     }
 159   /*
 160    * adjust sizes and allocate buffer quad byte aligned
 161    */
 162   rstrm->sendsize = sendsize = fix_buf_size (sendsize);
 163   rstrm->recvsize = recvsize = fix_buf_size (recvsize);
 164   rstrm->the_buffer = mem_alloc (sendsize + recvsize + BYTES_PER_XDR_UNIT);
 165   if (rstrm->the_buffer == NULL)
 166     {
 167       (void) fputs (_("xdrrec_create: out of memory\n"), stderr);
 168       return;
 169     }
 170   tmp = rstrm->the_buffer;
 171   if ((size_t)tmp % BYTES_PER_XDR_UNIT)
 172     tmp += BYTES_PER_XDR_UNIT - (size_t)tmp % BYTES_PER_XDR_UNIT;
 173   rstrm->out_base = tmp;
 174   rstrm->in_base = tmp + sendsize;
 175   /*
 176    * now the rest ...
 177    */
 178   /* We have to add the const since the `struct xdr_ops' in `struct XDR'
 179      is not `const'.  */
 180   xdrs->x_ops = (struct xdr_ops *) &xdrrec_ops;
 181   xdrs->x_private = (caddr_t) rstrm;
 182   rstrm->tcp_handle = tcp_handle;
 183   rstrm->readit = readit;
 184   rstrm->writeit = writeit;
 185   rstrm->out_finger = rstrm->out_boundry = rstrm->out_base;
 186   rstrm->frag_header = (u_int32_t *) rstrm->out_base;
 187   rstrm->out_finger += 4;
 188   rstrm->out_boundry += sendsize;
 189   rstrm->frag_sent = FALSE;
 190   rstrm->in_size = recvsize;
 191   rstrm->in_boundry = rstrm->in_base;
 192   rstrm->in_finger = (rstrm->in_boundry += recvsize);
 193   rstrm->fbtbc = 0;
 194   rstrm->last_frag = TRUE;
 195 }
 196
 197
 198 /*
 199  * The routines defined below are the xdr ops which will go into the
 200  * xdr handle filled in by xdrrec_create.
 201  */
 202
 203 static bool_t
 204 xdrrec_getlong (XDR *xdrs, long *lp)
 205 {
 206   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 207   int32_t *buflp = (int32_t *) rstrm->in_finger;
 208   int32_t mylong;
 209
 210   /* first try the inline, fast case */
 211   if (rstrm->fbtbc >= BYTES_PER_XDR_UNIT &&
 212       rstrm->in_boundry - (char *) buflp >= BYTES_PER_XDR_UNIT)
 213     {
 214       *lp = (int32_t) ntohl (*buflp);
 215       rstrm->fbtbc -= BYTES_PER_XDR_UNIT;
 216       rstrm->in_finger += BYTES_PER_XDR_UNIT;
 217     }
 218   else
 219     {
 220       if (!xdrrec_getbytes (xdrs, (caddr_t) & mylong,
 221                             BYTES_PER_XDR_UNIT))
 222         return FALSE;
 223       *lp = (int32_t) ntohl (mylong);
 224     }
 225   return TRUE;
 226 }
 227
 228 static bool_t
 229 xdrrec_putlong (XDR *xdrs, const long *lp)
 230 {
 231   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 232   int32_t *dest_lp = (int32_t *) rstrm->out_finger;
 233
 234   if ((rstrm->out_finger += BYTES_PER_XDR_UNIT) > rstrm->out_boundry)
 235     {
 236       /*
 237        * this case should almost never happen so the code is
 238        * inefficient
 239        */
 240       rstrm->out_finger -= BYTES_PER_XDR_UNIT;
 241       rstrm->frag_sent = TRUE;
 242       if (!flush_out (rstrm, FALSE))
 243         return FALSE;
 244       dest_lp = (int32_t *) rstrm->out_finger;
 245       rstrm->out_finger += BYTES_PER_XDR_UNIT;
 246     }
 247   *dest_lp = htonl (*lp);
 248   return TRUE;
 249 }
 250
 251 static bool_t      /* must manage buffers, fragments, and records */
 252 xdrrec_getbytes (XDR *xdrs, caddr_t addr, u_int len)
 253 {
 254   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 255   u_int current;
 256
 257   while (len > 0)
 258     {
 259       current = rstrm->fbtbc;
 260       if (current == 0)
 261         {
 262           if (rstrm->last_frag)
 263             return FALSE;
 264           if (!set_input_fragment (rstrm))
 265             return FALSE;
 266           continue;
 267         }
 268       current = (len < current) ? len : current;
 269       if (!get_input_bytes (rstrm, addr, current))
 270         return FALSE;
 271       addr += current;
 272       rstrm->fbtbc -= current;
 273       len -= current;
 274     }
 275   return TRUE;
 276 }
 277
 278 static bool_t
 279 xdrrec_putbytes (XDR *xdrs, const char *addr, u_int len)
 280 {
 281   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 282   u_int current;
 283
 284   while (len > 0)
 285     {
 286       current = rstrm->out_boundry - rstrm->out_finger;
 287       current = (len < current) ? len : current;
 288       bcopy (addr, rstrm->out_finger, current);
 289       rstrm->out_finger += current;
 290       addr += current;
 291       len -= current;
 292       if (rstrm->out_finger == rstrm->out_boundry)
 293         {
 294           rstrm->frag_sent = TRUE;
 295           if (!flush_out (rstrm, FALSE))
 296             return FALSE;
 297         }
 298     }
 299   return TRUE;
 300 }
 301
 302 static u_int
 303 xdrrec_getpos (const XDR *xdrs)
 304 {
 305   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 306   long pos;
 307
 308   pos = __lseek ((int) rstrm->tcp_handle, (long) 0, 1);
 309   if (pos != -1)
 310     switch (xdrs->x_op)
 311       {
 312
 313       case XDR_ENCODE:
 314         pos += rstrm->out_finger - rstrm->out_base;
 315         break;
 316
 317       case XDR_DECODE:
 318         pos -= rstrm->in_boundry - rstrm->in_finger;
 319         break;
 320
 321       default:
 322         pos = (u_int) - 1;
 323         break;
 324       }
 325   return (u_int) pos;
 326 }
 327
 328 static bool_t
 329 xdrrec_setpos (XDR *xdrs, u_int pos)
 330 {
 331   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 332   u_int currpos = xdrrec_getpos (xdrs);
 333   int delta = currpos - pos;
 334   caddr_t newpos;
 335
 336   if ((int) currpos != -1)
 337     switch (xdrs->x_op)
 338       {
 339
 340       case XDR_ENCODE:
 341         newpos = rstrm->out_finger - delta;
 342         if (newpos > (caddr_t) rstrm->frag_header &&
 343             newpos < rstrm->out_boundry)
 344           {
 345             rstrm->out_finger = newpos;
 346             return TRUE;
 347           }
 348         break;
 349
 350       case XDR_DECODE:
 351         newpos = rstrm->in_finger - delta;
 352         if ((delta < (int) (rstrm->fbtbc)) &&
 353             (newpos <= rstrm->in_boundry) &&
 354             (newpos >= rstrm->in_base))
 355           {
 356             rstrm->in_finger = newpos;
 357             rstrm->fbtbc -= delta;
 358             return TRUE;
 359           }
 360         break;
 361
 362       default:
 363         break;
 364       }
 365   return FALSE;
 366 }
 367
 368 static int32_t *
 369 xdrrec_inline (XDR *xdrs, int len)
 370 {
 371   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 372   int32_t *buf = NULL;
 373
 374   switch (xdrs->x_op)
 375     {
 376
 377     case XDR_ENCODE:
 378       if ((rstrm->out_finger + len) <= rstrm->out_boundry)
 379         {
 380           buf = (int32_t *) rstrm->out_finger;
 381           rstrm->out_finger += len;
 382         }
 383       break;
 384
 385     case XDR_DECODE:
 386       if ((len <= rstrm->fbtbc) &&
 387           ((rstrm->in_finger + len) <= rstrm->in_boundry))
 388         {
 389           buf = (int32_t *) rstrm->in_finger;
 390           rstrm->fbtbc -= len;
 391           rstrm->in_finger += len;
 392         }
 393       break;
 394
 395     default:
 396       break;
 397     }
 398   return buf;
 399 }
 400
 401 static void
 402 xdrrec_destroy (XDR *xdrs)
 403 {
 404   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 405
 406   mem_free (rstrm->the_buffer,
 407             rstrm->sendsize + rstrm->recvsize + BYTES_PER_XDR_UNIT);
 408   mem_free ((caddr_t) rstrm, sizeof (RECSTREAM));
 409 }
 410
 411 static bool_t
 412 xdrrec_getint32 (XDR *xdrs, int32_t *ip)
 413 {
 414   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 415   int32_t *bufip = (int32_t *) rstrm->in_finger;
 416   int32_t mylong;
 417
 418   /* first try the inline, fast case */
 419   if (rstrm->fbtbc >= BYTES_PER_XDR_UNIT &&
 420       rstrm->in_boundry - (char *) bufip >= BYTES_PER_XDR_UNIT)
 421     {
 422       *ip = ntohl (*bufip);
 423       rstrm->fbtbc -= BYTES_PER_XDR_UNIT;
 424       rstrm->in_finger += BYTES_PER_XDR_UNIT;
 425     }
 426   else
 427     {
 428       if (!xdrrec_getbytes (xdrs, (caddr_t) &mylong,
 429                             BYTES_PER_XDR_UNIT))
 430         return FALSE;
 431       *ip = ntohl (mylong);
 432     }
 433   return TRUE;
 434 }
 435
 436 static bool_t
 437 xdrrec_putint32 (XDR *xdrs, const int32_t *ip)
 438 {
 439   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 440   int32_t *dest_ip = (int32_t *) rstrm->out_finger;
 441
 442   if ((rstrm->out_finger += BYTES_PER_XDR_UNIT) > rstrm->out_boundry)
 443     {
 444       /*
 445        * this case should almost never happen so the code is
 446        * inefficient
 447        */
 448       rstrm->out_finger -= BYTES_PER_XDR_UNIT;
 449       rstrm->frag_sent = TRUE;
 450       if (!flush_out (rstrm, FALSE))
 451         return FALSE;
 452       dest_ip = (int32_t *) rstrm->out_finger;
 453       rstrm->out_finger += BYTES_PER_XDR_UNIT;
 454     }
 455   *dest_ip = htonl (*ip);
 456   return TRUE;
 457 }
 458
 459 /*
 460  * Exported routines to manage xdr records
 461  */
 462
 463 /*
 464  * Before reading (deserializing from the stream, one should always call
 465  * this procedure to guarantee proper record alignment.
 466  */
 467 bool_t
 468 xdrrec_skiprecord (xdrs)
 469      XDR *xdrs;
 470 {
 471   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 472
 473   while (rstrm->fbtbc > 0 || (!rstrm->last_frag))
 474     {
 475       if (!skip_input_bytes (rstrm, rstrm->fbtbc))
 476         return FALSE;
 477       rstrm->fbtbc = 0;
 478       if ((!rstrm->last_frag) && (!set_input_fragment (rstrm)))
 479         return FALSE;
 480     }
 481   rstrm->last_frag = FALSE;
 482   return TRUE;
 483 }
 484
 485 /*
 486  * Lookahead function.
 487  * Returns TRUE iff there is no more input in the buffer
 488  * after consuming the rest of the current record.
 489  */
 490 bool_t
 491 xdrrec_eof (xdrs)
 492      XDR *xdrs;
 493 {
 494   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 495
 496   while (rstrm->fbtbc > 0 || (!rstrm->last_frag))
 497     {
 498       if (!skip_input_bytes (rstrm, rstrm->fbtbc))
 499         return TRUE;
 500       rstrm->fbtbc = 0;
 501       if ((!rstrm->last_frag) && (!set_input_fragment (rstrm)))
 502         return TRUE;
 503     }
 504   if (rstrm->in_finger == rstrm->in_boundry)
 505     return TRUE;
 506   return FALSE;
 507 }
 508
 509 /*
 510  * The client must tell the package when an end-of-record has occurred.
 511  * The second parameter tells whether the record should be flushed to the
 512  * (output) tcp stream.  (This lets the package support batched or
 513  * pipelined procedure calls.)  TRUE => immediate flush to tcp connection.
 514  */
 515 bool_t
 516 xdrrec_endofrecord (xdrs, sendnow)
 517      XDR *xdrs;
 518      bool_t sendnow;
 519 {
 520   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 521   u_long len;           /* fragment length */
 522
 523   if (sendnow || rstrm->frag_sent
 524       || rstrm->out_finger + BYTES_PER_XDR_UNIT >= rstrm->out_boundry)
 525     {
 526       rstrm->frag_sent = FALSE;
 527       return flush_out (rstrm, TRUE);
 528     }
 529   len = (rstrm->out_finger - (char *) rstrm->frag_header
 530          - BYTES_PER_XDR_UNIT);
 531   *rstrm->frag_header = htonl ((u_long) len | LAST_FRAG);
 532   rstrm->frag_header = (u_int32_t *) rstrm->out_finger;
 533   rstrm->out_finger += BYTES_PER_XDR_UNIT;
 534   return TRUE;
 535 }
 536
 537
 538 /*
 539  * Internal useful routines
 540  */
 541 static bool_t
 542 internal_function
 543 flush_out (RECSTREAM *rstrm, bool_t eor)
 544 {
 545   u_long eormask = (eor == TRUE) ? LAST_FRAG : 0;
 546   u_long len = (rstrm->out_finger - (char *) rstrm->frag_header
 547                 - BYTES_PER_XDR_UNIT);
 548
 549   *rstrm->frag_header = htonl (len | eormask);
 550   len = rstrm->out_finger - rstrm->out_base;
 551   if ((*(rstrm->writeit)) (rstrm->tcp_handle, rstrm->out_base, (int) len)
 552       != (int) len)
 553     return FALSE;
 554   rstrm->frag_header = (u_int32_t *) rstrm->out_base;
 555   rstrm->out_finger = (caddr_t) rstrm->out_base + BYTES_PER_XDR_UNIT;
 556   return TRUE;
 557 }
 558
 559 static bool_t   /* knows nothing about records!  Only about input buffers */
 560 fill_input_buf (RECSTREAM *rstrm)
 561 {
 562   caddr_t where;
 563   size_t i;
 564   int len;
 565
 566   where = rstrm->in_base;
 567   i = (size_t) rstrm->in_boundry % BYTES_PER_XDR_UNIT;
 568   where += i;
 569   len = rstrm->in_size - i;
 570   if ((len = (*(rstrm->readit)) (rstrm->tcp_handle, where, len)) == -1)
 571     return FALSE;
 572   rstrm->in_finger = where;
 573   where += len;
 574   rstrm->in_boundry = where;
 575   return TRUE;
 576 }
 577
 578 static bool_t   /* knows nothing about records!  Only about input buffers */
 579 internal_function
 580 get_input_bytes (RECSTREAM *rstrm, caddr_t addr, int len)
 581 {
 582   int current;
 583
 584   while (len > 0)
 585     {
 586       current = rstrm->in_boundry - rstrm->in_finger;
 587       if (current == 0)
 588         {
 589           if (!fill_input_buf (rstrm))
 590             return FALSE;
 591           continue;
 592         }
 593       current = (len < current) ? len : current;
 594       bcopy (rstrm->in_finger, addr, current);
 595       rstrm->in_finger += current;
 596       addr += current;
 597       len -= current;
 598     }
 599   return TRUE;
 600 }
 601
 602 static bool_t /* next two bytes of the input stream are treated as a header */
 603 internal_function
 604 set_input_fragment (RECSTREAM *rstrm)
 605 {
 606   u_long header;
 607
 608   if (! get_input_bytes (rstrm, (caddr_t)&header, BYTES_PER_XDR_UNIT))
 609     return FALSE;
 610   header = ntohl (header);
 611   rstrm->last_frag = ((header & LAST_FRAG) == 0) ? FALSE : TRUE;
 612   /*
 613    * Sanity check. Try not to accept wildly incorrect
 614    * record sizes. Unfortunately, the only record size
 615    * we can positively identify as being 'wildly incorrect'
 616    * is zero.  Ridiculously large record sizes may look wrong,
 617    * but we don't have any way to be certain that they aren't
 618    * what the client actually intended to send us.
 619    */
 620   if ((header & (~LAST_FRAG)) == 0)
 621     return FALSE;
 622   rstrm->fbtbc = header & ~LAST_FRAG;
 623   return TRUE;
 624 }
 625
 626 static bool_t   /* consumes input bytes; knows nothing about records! */
 627 internal_function
 628 skip_input_bytes (RECSTREAM *rstrm, long cnt)
 629 {
 630   int current;
 631
 632   while (cnt > 0)
 633     {
 634       current = rstrm->in_boundry - rstrm->in_finger;
 635       if (current == 0)
 636         {
 637           if (!fill_input_buf (rstrm))
 638             return FALSE;
 639           continue;
 640         }
 641       current = (cnt < current) ? cnt : current;
 642       rstrm->in_finger += current;
 643       cnt -= current;
 644     }
 645   return TRUE;
 646 }
 647
 648 static u_int
 649 internal_function
 650 fix_buf_size (u_int s)
 651 {
 652   if (s < 100)
 653     s = 4000;
 654   return RNDUP (s);
 655 }