lib/vasnprintf.c

   1 /* vsprintf with automatic memory allocation.
   2    Copyright (C) 1999, 2002-2003 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License along
  15    with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* Tell glibc's <stdio.h> to provide a prototype for snprintf().
  19    This must come before <config.h> because <config.h> may include
  20    <features.h>, and once <features.h> has been included, it's too late.  */
  21 #ifndef _GNU_SOURCE
  22 # define _GNU_SOURCE    1
  23 #endif
  24
  25 #ifdef HAVE_CONFIG_H
  26 # include <config.h>
  27 #endif
  28 #include <alloca.h>
  29
  30 /* Specification.  */
  31 #include "vasnprintf.h"
  32
  33 #include <stdio.h>      /* snprintf(), sprintf() */
  34 #include <stdlib.h>     /* abort(), malloc(), realloc(), free() */
  35 #include <string.h>     /* memcpy(), strlen() */
  36 #include <errno.h>      /* errno */
  37 #include <limits.h>     /* CHAR_BIT */
  38 #include <float.h>      /* DBL_MAX_EXP, LDBL_MAX_EXP */
  39 #include "printf-parse.h"
  40
  41 /* For those losing systems which don't have 'alloca' we have to add
  42    some additional code emulating it.  */
  43 #ifdef HAVE_ALLOCA
  44 # define freea(p) /* nothing */
  45 #else
  46 # define alloca(n) malloc (n)
  47 # define freea(p) free (p)
  48 #endif
  49
  50 #ifdef HAVE_WCHAR_T
  51 # ifdef HAVE_WCSLEN
  52 #  define local_wcslen wcslen
  53 # else
  54    /* Solaris 2.5.1 has wcslen() in a separate library libw.so. To avoid
  55       a dependency towards this library, here is a local substitute.  */
  56 static size_t
  57 local_wcslen (const wchar_t *s)
  58 {
  59   const wchar_t *ptr;
  60
  61   for (ptr = s; *ptr != (wchar_t) 0; ptr++)
  62     ;
  63   return ptr - s;
  64 }
  65 # endif
  66 #endif
  67
  68 char *
  69 vasnprintf (char *resultbuf, size_t *lengthp, const char *format, va_list args)
  70 {
  71   char_directives d;
  72   arguments a;
  73
  74   if (printf_parse (format, &d, &a) < 0)
  75     {
  76       errno = EINVAL;
  77       return NULL;
  78     }
  79
  80 #define CLEANUP() \
  81   free (d.dir);                                                         \
  82   if (a.arg)                                                            \
  83     free (a.arg);
  84
  85   if (printf_fetchargs (args, &a) < 0)
  86     {
  87       CLEANUP ();
  88       errno = EINVAL;
  89       return NULL;
  90     }
  91
  92   {
  93     char *buf =
  94       (char *) alloca (7 + d.max_width_length + d.max_precision_length + 6);
  95     const char *cp;
  96     unsigned int i;
  97     char_directive *dp;
  98     /* Output string accumulator.  */
  99     char *result;
 100     size_t allocated;
 101     size_t length;
 102
 103     if (resultbuf != NULL)
 104       {
 105         result = resultbuf;
 106         allocated = *lengthp;
 107       }
 108     else
 109       {
 110         result = NULL;
 111         allocated = 0;
 112       }
 113     length = 0;
 114     /* Invariants:
 115        result is either == resultbuf or == NULL or malloc-allocated.
 116        If length > 0, then result != NULL.  */
 117
 118 #define ENSURE_ALLOCATION(needed) \
 119     if ((needed) > allocated)                                           \
 120       {                                                                 \
 121         char *memory;                                                   \
 122                                                                         \
 123         allocated = (allocated > 0 ? 2 * allocated : 12);               \
 124         if ((needed) > allocated)                                       \
 125           allocated = (needed);                                         \
 126         if (result == resultbuf || result == NULL)                      \
 127           memory = (char *) malloc (allocated);                         \
 128         else                                                            \
 129           memory = (char *) realloc (result, allocated);                \
 130                                                                         \
 131         if (memory == NULL)                                             \
 132           {                                                             \
 133             if (!(result == resultbuf || result == NULL))               \
 134               free (result);                                            \
 135             freea (buf);                                                \
 136             CLEANUP ();                                                 \
 137             errno = ENOMEM;                                             \
 138             return NULL;                                                \
 139           }                                                             \
 140         if (result == resultbuf && length > 0)                          \
 141           memcpy (memory, result, length);                              \
 142         result = memory;                                                \
 143       }
 144
 145     for (cp = format, i = 0, dp = &d.dir[0]; ; cp = dp->dir_end, i++, dp++)
 146       {
 147         if (cp != dp->dir_start)
 148           {
 149             size_t n = dp->dir_start - cp;
 150
 151             ENSURE_ALLOCATION (length + n);
 152             memcpy (result + length, cp, n);
 153             length += n;
 154           }
 155         if (i == d.count)
 156           break;
 157
 158         /* Execute a single directive.  */
 159         if (dp->conversion == '%')
 160           {
 161             if (!(dp->arg_index < 0))
 162               abort ();
 163             ENSURE_ALLOCATION (length + 1);
 164             result[length] = '%';
 165             length += 1;
 166           }
 167         else
 168           {
 169             if (!(dp->arg_index >= 0))
 170               abort ();
 171
 172             if (dp->conversion == 'n')
 173               {
 174                 switch (a.arg[dp->arg_index].type)
 175                   {
 176                   case TYPE_COUNT_SCHAR_POINTER:
 177                     *a.arg[dp->arg_index].a.a_count_schar_pointer = length;
 178                     break;
 179                   case TYPE_COUNT_SHORT_POINTER:
 180                     *a.arg[dp->arg_index].a.a_count_short_pointer = length;
 181                     break;
 182                   case TYPE_COUNT_INT_POINTER:
 183                     *a.arg[dp->arg_index].a.a_count_int_pointer = length;
 184                     break;
 185                   case TYPE_COUNT_LONGINT_POINTER:
 186                     *a.arg[dp->arg_index].a.a_count_longint_pointer = length;
 187                     break;
 188 #ifdef HAVE_LONG_LONG
 189                   case TYPE_COUNT_LONGLONGINT_POINTER:
 190                     *a.arg[dp->arg_index].a.a_count_longlongint_pointer = length;
 191                     break;
 192 #endif
 193                   default:
 194                     abort ();
 195                   }
 196               }
 197             else
 198               {
 199                 arg_type type = a.arg[dp->arg_index].type;
 200                 char *p;
 201                 unsigned int prefix_count;
 202                 int prefixes[2];
 203 #if !HAVE_SNPRINTF
 204                 unsigned int tmp_length;
 205                 char tmpbuf[700];
 206                 char *tmp;
 207
 208                 /* Allocate a temporary buffer of sufficient size for calling
 209                    sprintf.  */
 210                 {
 211                   unsigned int width;
 212                   unsigned int precision;
 213
 214                   width = 0;
 215                   if (dp->width_start != dp->width_end)
 216                     {
 217                       if (dp->width_arg_index >= 0)
 218                         {
 219                           int arg;
 220
 221                           if (!(a.arg[dp->width_arg_index].type == TYPE_INT))
 222                             abort ();
 223                           arg = a.arg[dp->width_arg_index].a.a_int;
 224                           width = (arg < 0 ? -arg : arg);
 225                         }
 226                       else
 227                         {
 228                           const char *digitp = dp->width_start;
 229
 230                           do
 231                             width = width * 10 + (*digitp++ - '0');
 232                           while (digitp != dp->width_end);
 233                         }
 234                     }
 235
 236                   precision = 6;
 237                   if (dp->precision_start != dp->precision_end)
 238                     {
 239                       if (dp->precision_arg_index >= 0)
 240                         {
 241                           int arg;
 242
 243                           if (!(a.arg[dp->precision_arg_index].type == TYPE_INT))
 244                             abort ();
 245                           arg = a.arg[dp->precision_arg_index].a.a_int;
 246                           precision = (arg < 0 ? 0 : arg);
 247                         }
 248                       else
 249                         {
 250                           const char *digitp = dp->precision_start + 1;
 251
 252                           precision = 0;
 253                           do
 254                             precision = precision * 10 + (*digitp++ - '0');
 255                           while (digitp != dp->precision_end);
 256                         }
 257                     }
 258
 259                   switch (dp->conversion)
 260                     {
 261
 262                     case 'd': case 'i': case 'u':
 263 # ifdef HAVE_LONG_LONG
 264                       if (type == TYPE_LONGLONGINT || type == TYPE_ULONGLONGINT)
 265                         tmp_length =
 266                           (unsigned int) (sizeof (unsigned long long) * CHAR_BIT
 267                                           * 0.30103 /* binary -> decimal */
 268                                           * 2 /* estimate for FLAG_GROUP */
 269                                          )
 270                           + 1 /* turn floor into ceil */
 271                           + 1; /* account for leading sign */
 272                       else
 273 # endif
 274                       if (type == TYPE_LONGINT || type == TYPE_ULONGINT)
 275                         tmp_length =
 276                           (unsigned int) (sizeof (unsigned long) * CHAR_BIT
 277                                           * 0.30103 /* binary -> decimal */
 278                                           * 2 /* estimate for FLAG_GROUP */
 279                                          )
 280                           + 1 /* turn floor into ceil */
 281                           + 1; /* account for leading sign */
 282                       else
 283                         tmp_length =
 284                           (unsigned int) (sizeof (unsigned int) * CHAR_BIT
 285                                           * 0.30103 /* binary -> decimal */
 286                                           * 2 /* estimate for FLAG_GROUP */
 287                                          )
 288                           + 1 /* turn floor into ceil */
 289                           + 1; /* account for leading sign */
 290                       break;
 291
 292                     case 'o':
 293 # ifdef HAVE_LONG_LONG
 294                       if (type == TYPE_LONGLONGINT || type == TYPE_ULONGLONGINT)
 295                         tmp_length =
 296                           (unsigned int) (sizeof (unsigned long long) * CHAR_BIT
 297                                           * 0.333334 /* binary -> octal */
 298                                          )
 299                           + 1 /* turn floor into ceil */
 300                           + 1; /* account for leading sign */
 301                       else
 302 # endif
 303                       if (type == TYPE_LONGINT || type == TYPE_ULONGINT)
 304                         tmp_length =
 305                           (unsigned int) (sizeof (unsigned long) * CHAR_BIT
 306                                           * 0.333334 /* binary -> octal */
 307                                          )
 308                           + 1 /* turn floor into ceil */
 309                           + 1; /* account for leading sign */
 310                       else
 311                         tmp_length =
 312                           (unsigned int) (sizeof (unsigned int) * CHAR_BIT
 313                                           * 0.333334 /* binary -> octal */
 314                                          )
 315                           + 1 /* turn floor into ceil */
 316                           + 1; /* account for leading sign */
 317                       break;
 318
 319                     case 'x': case 'X':
 320 # ifdef HAVE_LONG_LONG
 321                       if (type == TYPE_LONGLONGINT || type == TYPE_ULONGLONGINT)
 322                         tmp_length =
 323                           (unsigned int) (sizeof (unsigned long long) * CHAR_BIT
 324                                           * 0.25 /* binary -> hexadecimal */
 325                                          )
 326                           + 1 /* turn floor into ceil */
 327                           + 2; /* account for leading sign or alternate form */
 328                       else
 329 # endif
 330                       if (type == TYPE_LONGINT || type == TYPE_ULONGINT)
 331                         tmp_length =
 332                           (unsigned int) (sizeof (unsigned long) * CHAR_BIT
 333                                           * 0.25 /* binary -> hexadecimal */
 334                                          )
 335                           + 1 /* turn floor into ceil */
 336                           + 2; /* account for leading sign or alternate form */
 337                       else
 338                         tmp_length =
 339                           (unsigned int) (sizeof (unsigned int) * CHAR_BIT
 340                                           * 0.25 /* binary -> hexadecimal */
 341                                          )
 342                           + 1 /* turn floor into ceil */
 343                           + 2; /* account for leading sign or alternate form */
 344                       break;
 345
 346                     case 'f': case 'F':
 347 # ifdef HAVE_LONG_DOUBLE
 348                       if (type == TYPE_LONGDOUBLE)
 349                         tmp_length =
 350                           (unsigned int) (LDBL_MAX_EXP
 351                                           * 0.30103 /* binary -> decimal */
 352                                           * 2 /* estimate for FLAG_GROUP */
 353                                          )
 354                           + 1 /* turn floor into ceil */
 355                           + precision
 356                           + 10; /* sign, decimal point etc. */
 357                       else
 358 # endif
 359                         tmp_length =
 360                           (unsigned int) (DBL_MAX_EXP
 361                                           * 0.30103 /* binary -> decimal */
 362                                           * 2 /* estimate for FLAG_GROUP */
 363                                          )
 364                           + 1 /* turn floor into ceil */
 365                           + precision
 366                           + 10; /* sign, decimal point etc. */
 367                       break;
 368
 369                     case 'e': case 'E': case 'g': case 'G':
 370                     case 'a': case 'A':
 371                       tmp_length =
 372                         precision
 373                         + 12; /* sign, decimal point, exponent etc. */
 374                       break;
 375
 376                     case 'c':
 377 # ifdef HAVE_WINT_T
 378                       if (type == TYPE_WIDE_CHAR)
 379                         tmp_length = MB_CUR_MAX;
 380                       else
 381 # endif
 382                         tmp_length = 1;
 383                       break;
 384
 385                     case 's':
 386 # ifdef HAVE_WCHAR_T
 387                       if (type == TYPE_WIDE_STRING)
 388                         tmp_length =
 389                           local_wcslen (a.arg[dp->arg_index].a.a_wide_string)
 390                           * MB_CUR_MAX;
 391                       else
 392 # endif
 393                         tmp_length = strlen (a.arg[dp->arg_index].a.a_string);
 394                       break;
 395
 396                     case 'p':
 397                       tmp_length =
 398                         (unsigned int) (sizeof (void *) * CHAR_BIT
 399                                         * 0.25 /* binary -> hexadecimal */
 400                                        )
 401                           + 1 /* turn floor into ceil */
 402                           + 2; /* account for leading 0x */
 403                       break;
 404
 405                     default:
 406                       abort ();
 407                     }
 408
 409                   if (tmp_length < width)
 410                     tmp_length = width;
 411
 412                   tmp_length++; /* account for trailing NUL */
 413                 }
 414
 415                 if (tmp_length <= sizeof (tmpbuf))
 416                   tmp = tmpbuf;
 417                 else
 418                   {
 419                     tmp = (char *) malloc (tmp_length);
 420                     if (tmp == NULL)
 421                       {
 422                         /* Out of memory.  */
 423                         if (!(result == resultbuf || result == NULL))
 424                           free (result);
 425                         freea (buf);
 426                         CLEANUP ();
 427                         errno = ENOMEM;
 428                         return NULL;
 429                       }
 430                   }
 431 #endif
 432
 433                 /* Construct the format string for calling snprintf or
 434                    sprintf.  */
 435                 p = buf;
 436                 *p++ = '%';
 437                 if (dp->flags & FLAG_GROUP)
 438                   *p++ = '\'';
 439                 if (dp->flags & FLAG_LEFT)
 440                   *p++ = '-';
 441                 if (dp->flags & FLAG_SHOWSIGN)
 442                   *p++ = '+';
 443                 if (dp->flags & FLAG_SPACE)
 444                   *p++ = ' ';
 445                 if (dp->flags & FLAG_ALT)
 446                   *p++ = '#';
 447                 if (dp->flags & FLAG_ZERO)
 448                   *p++ = '0';
 449                 if (dp->width_start != dp->width_end)
 450                   {
 451                     size_t n = dp->width_end - dp->width_start;
 452                     memcpy (p, dp->width_start, n);
 453                     p += n;
 454                   }
 455                 if (dp->precision_start != dp->precision_end)
 456                   {
 457                     size_t n = dp->precision_end - dp->precision_start;
 458                     memcpy (p, dp->precision_start, n);
 459                     p += n;
 460                   }
 461
 462                 switch (type)
 463                   {
 464 #ifdef HAVE_LONG_LONG
 465                   case TYPE_LONGLONGINT:
 466                   case TYPE_ULONGLONGINT:
 467                     *p++ = 'l';
 468                     /*FALLTHROUGH*/
 469 #endif
 470                   case TYPE_LONGINT:
 471                   case TYPE_ULONGINT:
 472 #ifdef HAVE_WINT_T
 473                   case TYPE_WIDE_CHAR:
 474 #endif
 475 #ifdef HAVE_WCHAR_T
 476                   case TYPE_WIDE_STRING:
 477 #endif
 478                     *p++ = 'l';
 479                     break;
 480 #ifdef HAVE_LONG_DOUBLE
 481                   case TYPE_LONGDOUBLE:
 482                     *p++ = 'L';
 483                     break;
 484 #endif
 485                   default:
 486                     break;
 487                   }
 488                 *p = dp->conversion;
 489 #if HAVE_SNPRINTF
 490                 p[1] = '%';
 491                 p[2] = 'n';
 492                 p[3] = '\0';
 493 #else
 494                 p[1] = '\0';
 495 #endif
 496
 497                 /* Construct the arguments for calling snprintf or sprintf.  */
 498                 prefix_count = 0;
 499                 if (dp->width_arg_index >= 0)
 500                   {
 501                     if (!(a.arg[dp->width_arg_index].type == TYPE_INT))
 502                       abort ();
 503                     prefixes[prefix_count++] = a.arg[dp->width_arg_index].a.a_int;
 504                   }
 505                 if (dp->precision_arg_index >= 0)
 506                   {
 507                     if (!(a.arg[dp->precision_arg_index].type == TYPE_INT))
 508                       abort ();
 509                     prefixes[prefix_count++] = a.arg[dp->precision_arg_index].a.a_int;
 510                   }
 511
 512 #if HAVE_SNPRINTF
 513                 /* Prepare checking whether snprintf returns the count
 514                    via %n.  */
 515                 ENSURE_ALLOCATION (length + 1);
 516                 result[length] = '\0';
 517 #endif
 518
 519                 for (;;)
 520                   {
 521                     size_t maxlen;
 522                     int count;
 523                     int retcount;
 524
 525                     maxlen = allocated - length;
 526                     count = -1;
 527                     retcount = 0;
 528
 529 #if HAVE_SNPRINTF
 530 #define SNPRINTF_BUF(arg) \
 531                     switch (prefix_count)                                   \
 532                       {                                                     \
 533                       case 0:                                               \
 534                         retcount = snprintf (result + length, maxlen, buf,  \
 535                                              arg, &count);                  \
 536                         break;                                              \
 537                       case 1:                                               \
 538                         retcount = snprintf (result + length, maxlen, buf,  \
 539                                              prefixes[0], arg, &count);     \
 540                         break;                                              \
 541                       case 2:                                               \
 542                         retcount = snprintf (result + length, maxlen, buf,  \
 543                                              prefixes[0], prefixes[1], arg, \
 544                                              &count);                       \
 545                         break;                                              \
 546                       default:                                              \
 547                         abort ();                                           \
 548                       }
 549 #else
 550 #define SNPRINTF_BUF(arg) \
 551                     switch (prefix_count)                                   \
 552                       {                                                     \
 553                       case 0:                                               \
 554                         count = sprintf (tmp, buf, arg);                    \
 555                         break;                                              \
 556                       case 1:                                               \
 557                         count = sprintf (tmp, buf, prefixes[0], arg);       \
 558                         break;                                              \
 559                       case 2:                                               \
 560                         count = sprintf (tmp, buf, prefixes[0], prefixes[1],\
 561                                          arg);                              \
 562                         break;                                              \
 563                       default:                                              \
 564                         abort ();                                           \
 565                       }
 566 #endif
 567
 568                     switch (type)
 569                       {
 570                       case TYPE_SCHAR:
 571                         {
 572                           int arg = a.arg[dp->arg_index].a.a_schar;
 573                           SNPRINTF_BUF (arg);
 574                         }
 575                         break;
 576                       case TYPE_UCHAR:
 577                         {
 578                           unsigned int arg = a.arg[dp->arg_index].a.a_uchar;
 579                           SNPRINTF_BUF (arg);
 580                         }
 581                         break;
 582                       case TYPE_SHORT:
 583                         {
 584                           int arg = a.arg[dp->arg_index].a.a_short;
 585                           SNPRINTF_BUF (arg);
 586                         }
 587                         break;
 588                       case TYPE_USHORT:
 589                         {
 590                           unsigned int arg = a.arg[dp->arg_index].a.a_ushort;
 591                           SNPRINTF_BUF (arg);
 592                         }
 593                         break;
 594                       case TYPE_INT:
 595                         {
 596                           int arg = a.arg[dp->arg_index].a.a_int;
 597                           SNPRINTF_BUF (arg);
 598                         }
 599                         break;
 600                       case TYPE_UINT:
 601                         {
 602                           unsigned int arg = a.arg[dp->arg_index].a.a_uint;
 603                           SNPRINTF_BUF (arg);
 604                         }
 605                         break;
 606                       case TYPE_LONGINT:
 607                         {
 608                           long int arg = a.arg[dp->arg_index].a.a_longint;
 609                           SNPRINTF_BUF (arg);
 610                         }
 611                         break;
 612                       case TYPE_ULONGINT:
 613                         {
 614                           unsigned long int arg = a.arg[dp->arg_index].a.a_ulongint;
 615                           SNPRINTF_BUF (arg);
 616                         }
 617                         break;
 618 #ifdef HAVE_LONG_LONG
 619                       case TYPE_LONGLONGINT:
 620                         {
 621                           long long int arg = a.arg[dp->arg_index].a.a_longlongint;
 622                           SNPRINTF_BUF (arg);
 623                         }
 624                         break;
 625                       case TYPE_ULONGLONGINT:
 626                         {
 627                           unsigned long long int arg = a.arg[dp->arg_index].a.a_ulonglongint;
 628                           SNPRINTF_BUF (arg);
 629                         }
 630                         break;
 631 #endif
 632                       case TYPE_DOUBLE:
 633                         {
 634                           double arg = a.arg[dp->arg_index].a.a_double;
 635                           SNPRINTF_BUF (arg);
 636                         }
 637                         break;
 638 #ifdef HAVE_LONG_DOUBLE
 639                       case TYPE_LONGDOUBLE:
 640                         {
 641                           long double arg = a.arg[dp->arg_index].a.a_longdouble;
 642                           SNPRINTF_BUF (arg);
 643                         }
 644                         break;
 645 #endif
 646                       case TYPE_CHAR:
 647                         {
 648                           int arg = a.arg[dp->arg_index].a.a_char;
 649                           SNPRINTF_BUF (arg);
 650                         }
 651                         break;
 652 #ifdef HAVE_WINT_T
 653                       case TYPE_WIDE_CHAR:
 654                         {
 655                           wint_t arg = a.arg[dp->arg_index].a.a_wide_char;
 656                           SNPRINTF_BUF (arg);
 657                         }
 658                         break;
 659 #endif
 660                       case TYPE_STRING:
 661                         {
 662                           const char *arg = a.arg[dp->arg_index].a.a_string;
 663                           SNPRINTF_BUF (arg);
 664                         }
 665                         break;
 666 #ifdef HAVE_WCHAR_T
 667                       case TYPE_WIDE_STRING:
 668                         {
 669                           const wchar_t *arg = a.arg[dp->arg_index].a.a_wide_string;
 670                           SNPRINTF_BUF (arg);
 671                         }
 672                         break;
 673 #endif
 674                       case TYPE_POINTER:
 675                         {
 676                           void *arg = a.arg[dp->arg_index].a.a_pointer;
 677                           SNPRINTF_BUF (arg);
 678                         }
 679                         break;
 680                       default:
 681                         abort ();
 682                       }
 683
 684 #if HAVE_SNPRINTF
 685                     /* Portability: Not all implementations of snprintf()
 686                        are ISO C 99 compliant.  Determine the number of
 687                        bytes that snprintf() has produced or would have
 688                        produced.  */
 689                     if (count >= 0)
 690                       {
 691                         /* Verify that snprintf() has NUL-terminated its
 692                            result.  */
 693                         if (count < maxlen && result[length + count] != '\0')
 694                           abort ();
 695                         /* Portability hack.  */
 696                         if (retcount > count)
 697                           count = retcount;
 698                       }
 699                     else
 700                       {
 701                         /* snprintf() doesn't understand the '%n'
 702                            directive.  */
 703                         if (p[1] != '\0')
 704                           {
 705                             /* Don't use the '%n' directive; instead, look
 706                                at the snprintf() return value.  */
 707                             p[1] = '\0';
 708                             continue;
 709                           }
 710                         count = retcount;
 711                       }
 712 #endif
 713
 714                     /* Attempt to handle failure.  */
 715                     if (count < 0)
 716                       {
 717                         if (!(result == resultbuf || result == NULL))
 718                           free (result);
 719                         freea (buf);
 720                         CLEANUP ();
 721                         errno = EINVAL;
 722                         return NULL;
 723                       }
 724
 725 #if !HAVE_SNPRINTF
 726                     if (count >= tmp_length)
 727                       /* tmp_length was incorrectly calculated - fix the
 728                          code above!  */
 729                       abort ();
 730 #endif
 731
 732                     /* Make room for the result.  */
 733                     if (count >= maxlen)
 734                       {
 735                         /* Need at least count bytes.  But allocate
 736                            proportionally, to avoid looping eternally if
 737                            snprintf() reports a too small count.  */
 738                         size_t n = length + count;
 739
 740                         if (n < 2 * allocated)
 741                           n = 2 * allocated;
 742
 743                         ENSURE_ALLOCATION (n);
 744 #if HAVE_SNPRINTF
 745                         continue;
 746 #endif
 747                       }
 748
 749 #if HAVE_SNPRINTF
 750                     /* The snprintf() result did fit.  */
 751 #else
 752                     /* Append the sprintf() result.  */
 753                     memcpy (result + length, tmp, count);
 754                     if (tmp != tmpbuf)
 755                       free (tmp);
 756 #endif
 757
 758                     length += count;
 759                     break;
 760                   }
 761               }
 762           }
 763       }
 764
 765     /* Add the final NUL.  */
 766     ENSURE_ALLOCATION (length + 1);
 767     result[length] = '\0';
 768
 769     if (result != resultbuf && length + 1 < allocated)
 770       {
 771         /* Shrink the allocated memory if possible.  */
 772         char *memory;
 773
 774         memory = (char *) realloc (result, length + 1);
 775         if (memory != NULL)
 776           result = memory;
 777       }
 778
 779     freea (buf);
 780     CLEANUP ();
 781     *lengthp = length;
 782     return result;
 783   }
 784 }