sexp-format.c

   1 /* sexp-format.c
   2  *
   3  * Writing s-expressions.
   4  */
   5
   6 /* nettle, low-level cryptographics library
   7  *
   8  * Copyright (C) 2002 Niels Möller
   9  *
  10  * The nettle library is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU Lesser General Public License as published by
  12  * the Free Software Foundation; either version 2.1 of the License, or (at your
  13  * option) any later version.
  14  *
  15  * The nettle library is distributed in the hope that it will be useful, but
  16  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  17  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  18  * License for more details.
  19  *
  20  * You should have received a copy of the GNU Lesser General Public License
  21  * along with the nettle library; see the file COPYING.LIB.  If not, write to
  22  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  23  * MA 02111-1301, USA.
  24  */
  25
  26 #if HAVE_CONFIG_H
  27 # include "config.h"
  28 #endif
  29
  30 #include <assert.h>
  31 #include <stdarg.h>
  32 #include <stdio.h>
  33 #include <stdlib.h>
  34 #include <string.h>
  35
  36 #include "sexp.h"
  37 #include "buffer.h"
  38
  39 #include "bignum.h"
  40
  41 static unsigned
  42 format_prefix(struct nettle_buffer *buffer,
  43               unsigned length)
  44 {
  45   unsigned digit = 1;
  46   unsigned prefix_length = 1;
  47
  48   for (;;)
  49     {
  50       unsigned next = digit * 10;
  51       if (next > length)
  52         break;
  53
  54       prefix_length++;
  55       digit = next;
  56     }
  57
  58   if (buffer)
  59     {
  60       for (; digit; length %= digit, digit /= 10)
  61         if (!NETTLE_BUFFER_PUTC(buffer, '0' + length / digit))
  62           return 0;
  63
  64       if (!NETTLE_BUFFER_PUTC(buffer, ':'))
  65         return 0;
  66     }
  67
  68   return prefix_length + 1;
  69 }
  70
  71 static unsigned
  72 format_string(struct nettle_buffer *buffer,
  73               unsigned length, const uint8_t *s)
  74 {
  75   unsigned prefix_length = format_prefix(buffer, length);
  76   if (!prefix_length)
  77     return 0;
  78
  79   if (buffer && !nettle_buffer_write(buffer, length, s))
  80     return 0;
  81
  82   return prefix_length + length;
  83 }
  84
  85 unsigned
  86 sexp_vformat(struct nettle_buffer *buffer, const char *format, va_list args)
  87 {
  88   unsigned nesting = 0;
  89   unsigned done = 0;
  90
  91   for (;;)
  92     switch (*format++)
  93       {
  94       default:
  95         {
  96           const char *start = format - 1;
  97           unsigned length = 1 + strcspn(format, "()% \t");
  98           unsigned output_length = format_string(buffer, length, start);
  99           if (!output_length)
 100             return 0;
 101
 102           done += output_length;
 103           format = start + length;
 104
 105           break;
 106         }
 107       case ' ': case '\t':
 108         break;
 109
 110       case '\0':
 111         assert(!nesting);
 112
 113         return done;
 114
 115       case '(':
 116         if (buffer && !NETTLE_BUFFER_PUTC(buffer, '('))
 117           return 0;
 118
 119         done++;
 120         nesting++;
 121         break;
 122
 123       case ')':
 124         assert (nesting);
 125         if (buffer && !NETTLE_BUFFER_PUTC(buffer, ')'))
 126           return 0;
 127
 128         done++;
 129         nesting--;
 130         break;
 131
 132       case '%':
 133         {
 134           int nul_flag = 0;
 135
 136           if (*format == '0')
 137             {
 138               format++;
 139               nul_flag = 1;
 140             }
 141           switch (*format++)
 142             {
 143             default:
 144               abort();
 145
 146             case '(':
 147             case ')':
 148               /* Allow unbalanced parenthesis */
 149               if (buffer && !NETTLE_BUFFER_PUTC(buffer, format[-1]))
 150                 return 0;
 151               done++;
 152               break;
 153
 154             case 's':
 155               {
 156                 const char *s;
 157                 unsigned length;
 158                 unsigned output_length;
 159
 160                 if (nul_flag)
 161                   {
 162                     s = va_arg(args, const char *);
 163                     length = strlen(s);
 164                   }
 165                 else
 166                   {
 167                     length = va_arg(args, unsigned);
 168                     s = va_arg(args, const char *);
 169                   }
 170
 171                 output_length = format_string(buffer, length, s);
 172                 if (!output_length)
 173                   return 0;
 174
 175                 done += output_length;
 176                 break;
 177               }
 178             case 't':
 179               {
 180                 const char *s;
 181                 unsigned length;
 182                 unsigned output_length;
 183
 184                 if (nul_flag)
 185                   {
 186                     s = va_arg(args, const char *);
 187                     if (!s)
 188                       break;
 189
 190                     length = strlen(s);
 191                   }
 192                 else
 193                   {
 194                     length = va_arg(args, unsigned);
 195                     s = va_arg(args, const char *);
 196                     if (!s)
 197                       break;
 198                   }
 199
 200                 if (buffer && !NETTLE_BUFFER_PUTC(buffer, '['))
 201                   return 0;
 202                 done++;
 203
 204                 output_length = format_string(buffer, length, s);
 205
 206                 if (!output_length)
 207                   return 0;
 208
 209                 done += output_length;
 210
 211                 if (buffer && !NETTLE_BUFFER_PUTC(buffer, ']'))
 212                   return 0;
 213                 done++;
 214
 215                 break;
 216               }
 217
 218             case 'l':
 219               {
 220                 const char *s;
 221                 unsigned length;
 222
 223                 if (nul_flag)
 224                   {
 225                     s = va_arg(args, const char *);
 226                     length = strlen(s);
 227                   }
 228                 else
 229                   {
 230                     length = va_arg(args, unsigned);
 231                     s = va_arg(args, const char *);
 232                   }
 233
 234                 if (buffer && !nettle_buffer_write(buffer, length, s))
 235                   return 0;
 236
 237                 done += length;
 238                 break;
 239               }
 240             case 'i':
 241               {
 242                 uint32_t x = va_arg(args, uint32_t);
 243                 unsigned length;
 244
 245                 if (x < 0x80)
 246                   length = 1;
 247                 else if (x < 0x8000L)
 248                   length = 2;
 249                 else if (x < 0x800000L)
 250                   length = 3;
 251                 else if (x < 0x80000000L)
 252                   length = 4;
 253                 else
 254                   length = 5;
 255
 256                 if (buffer && !(NETTLE_BUFFER_PUTC(buffer, '0' + length)
 257                                 && NETTLE_BUFFER_PUTC(buffer, ':')))
 258                   return 0;
 259
 260                 done += (2 + length);
 261
 262                 if (buffer)
 263                   switch(length)
 264                     {
 265                     case 5:
 266                       /* Leading byte needed for the sign. */
 267                       if (!NETTLE_BUFFER_PUTC(buffer, 0))
 268                         return 0;
 269                       /* Fall through */
 270                     case 4:
 271                       if (!NETTLE_BUFFER_PUTC(buffer, x >> 24))
 272                         return 0;
 273                       /* Fall through */
 274                     case 3:
 275                       if (!NETTLE_BUFFER_PUTC(buffer, (x >> 16) & 0xff))
 276                         return 0;
 277                       /* Fall through */
 278                     case 2:
 279                       if (!NETTLE_BUFFER_PUTC(buffer, (x >> 8) & 0xff))
 280                         return 0;
 281                       /* Fall through */
 282                     case 1:
 283                       if (!NETTLE_BUFFER_PUTC(buffer, x & 0xff))
 284                         return 0;
 285                       break;
 286                     default:
 287                       abort();
 288                     }
 289                 break;
 290               }
 291             case 'b':
 292               {
 293                 const MP_INT *n = va_arg(args, const MP_INT *);
 294                 unsigned length;
 295                 unsigned prefix_length;
 296
 297                 length = nettle_mpz_sizeinbase_256_s(n);
 298                 prefix_length = format_prefix(buffer, length);
 299                 if (!prefix_length)
 300                   return 0;
 301
 302                 done += prefix_length;
 303
 304                 if (buffer)
 305                   {
 306                     uint8_t *space = nettle_buffer_space(buffer, length);
 307                     if (!space)
 308                       return 0;
 309
 310                     nettle_mpz_get_str_256(length, space, n);
 311                   }
 312
 313                 done += length;
 314
 315                 break;
 316               }
 317             }
 318         }
 319       }
 320 }
 321
 322 unsigned
 323 sexp_format(struct nettle_buffer *buffer, const char *format, ...)
 324 {
 325   va_list args;
 326   unsigned done;
 327
 328   va_start(args, format);
 329   done = sexp_vformat(buffer, format, args);
 330   va_end(args);
 331
 332   return done;
 333 }