lib/json.c

   1 /*
   2  * Copyright (c) 2009, 2010, 2011, 2012, 2014 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18
  19 #include "json.h"
  20
  21 #include <ctype.h>
  22 #include <errno.h>
  23 #include <float.h>
  24 #include <limits.h>
  25 #include <string.h>
  26
  27 #include "dynamic-string.h"
  28 #include "hash.h"
  29 #include "shash.h"
  30 #include "unicode.h"
  31 #include "util.h"
  32
  33 /* The type of a JSON token. */
  34 enum json_token_type {
  35     T_EOF = 0,
  36     T_BEGIN_ARRAY = '[',
  37     T_END_ARRAY = ']',
  38     T_BEGIN_OBJECT = '{',
  39     T_END_OBJECT = '}',
  40     T_NAME_SEPARATOR = ':',
  41     T_VALUE_SEPARATOR = ',',
  42     T_FALSE = UCHAR_MAX + 1,
  43     T_NULL,
  44     T_TRUE,
  45     T_INTEGER,
  46     T_REAL,
  47     T_STRING
  48 };
  49
  50 /* A JSON token.
  51  *
  52  * RFC 4627 doesn't define a lexical structure for JSON but I believe this to
  53  * be compliant with the standard.
  54  */
  55 struct json_token {
  56     enum json_token_type type;
  57     union {
  58         double real;
  59         long long int integer;
  60         const char *string;
  61     } u;
  62 };
  63
  64 enum json_lex_state {
  65     JSON_LEX_START,             /* Not inside a token. */
  66     JSON_LEX_NUMBER,            /* Reading a number. */
  67     JSON_LEX_KEYWORD,           /* Reading a keyword. */
  68     JSON_LEX_STRING,            /* Reading a quoted string. */
  69     JSON_LEX_ESCAPE             /* In a quoted string just after a "\". */
  70 };
  71
  72 enum json_parse_state {
  73     JSON_PARSE_START,           /* Beginning of input. */
  74     JSON_PARSE_END,             /* End of input. */
  75
  76     /* Objects. */
  77     JSON_PARSE_OBJECT_INIT,     /* Expecting '}' or an object name. */
  78     JSON_PARSE_OBJECT_NAME,     /* Expecting an object name. */
  79     JSON_PARSE_OBJECT_COLON,    /* Expecting ':'. */
  80     JSON_PARSE_OBJECT_VALUE,    /* Expecting an object value. */
  81     JSON_PARSE_OBJECT_NEXT,     /* Expecting ',' or '}'. */
  82
  83     /* Arrays. */
  84     JSON_PARSE_ARRAY_INIT,      /* Expecting ']' or a value. */
  85     JSON_PARSE_ARRAY_VALUE,     /* Expecting a value. */
  86     JSON_PARSE_ARRAY_NEXT       /* Expecting ',' or ']'. */
  87 };
  88
  89 struct json_parser_node {
  90     struct json *json;
  91 };
  92
  93 /* A JSON parser. */
  94 struct json_parser {
  95     int flags;
  96
  97     /* Lexical analysis. */
  98     enum json_lex_state lex_state;
  99     struct ds buffer;           /* Buffer for accumulating token text. */
 100     int line_number;
 101     int column_number;
 102     int byte_number;
 103
 104     /* Parsing. */
 105     enum json_parse_state parse_state;
 106 #define JSON_MAX_HEIGHT 1000
 107     struct json_parser_node *stack;
 108     size_t height, allocated_height;
 109     char *member_name;
 110
 111     /* Parse status. */
 112     bool done;
 113     char *error;                /* Error message, if any, null if none yet. */
 114 };
 115
 116 static struct json *json_create(enum json_type type);
 117 static void json_parser_input(struct json_parser *, struct json_token *);
 118
 119 static void json_error(struct json_parser *p, const char *format, ...)
 120     PRINTF_FORMAT(2, 3);
 121 \f
 122 const char *
 123 json_type_to_string(enum json_type type)
 124 {
 125     switch (type) {
 126     case JSON_NULL:
 127         return "null";
 128
 129     case JSON_FALSE:
 130         return "false";
 131
 132     case JSON_TRUE:
 133         return "true";
 134
 135     case JSON_OBJECT:
 136         return "object";
 137
 138     case JSON_ARRAY:
 139         return "array";
 140
 141     case JSON_INTEGER:
 142     case JSON_REAL:
 143         return "number";
 144
 145     case JSON_STRING:
 146         return "string";
 147
 148     case JSON_N_TYPES:
 149     default:
 150         return "<invalid>";
 151     }
 152 }
 153 \f
 154 /* Functions for manipulating struct json. */
 155
 156 struct json *
 157 json_null_create(void)
 158 {
 159     return json_create(JSON_NULL);
 160 }
 161
 162 struct json *
 163 json_boolean_create(bool b)
 164 {
 165     return json_create(b ? JSON_TRUE : JSON_FALSE);
 166 }
 167
 168 struct json *
 169 json_string_create_nocopy(char *s)
 170 {
 171     struct json *json = json_create(JSON_STRING);
 172     json->u.string = s;
 173     return json;
 174 }
 175
 176 struct json *
 177 json_string_create(const char *s)
 178 {
 179     return json_string_create_nocopy(xstrdup(s));
 180 }
 181
 182 struct json *
 183 json_array_create_empty(void)
 184 {
 185     struct json *json = json_create(JSON_ARRAY);
 186     json->u.array.elems = NULL;
 187     json->u.array.n = 0;
 188     json->u.array.n_allocated = 0;
 189     return json;
 190 }
 191
 192 void
 193 json_array_add(struct json *array_, struct json *element)
 194 {
 195     struct json_array *array = json_array(array_);
 196     if (array->n >= array->n_allocated) {
 197         array->elems = x2nrealloc(array->elems, &array->n_allocated,
 198                                   sizeof *array->elems);
 199     }
 200     array->elems[array->n++] = element;
 201 }
 202
 203 void
 204 json_array_trim(struct json *array_)
 205 {
 206     struct json_array *array = json_array(array_);
 207     if (array->n < array->n_allocated){
 208         array->n_allocated = array->n;
 209         array->elems = xrealloc(array->elems, array->n * sizeof *array->elems);
 210     }
 211 }
 212
 213 struct json *
 214 json_array_create(struct json **elements, size_t n)
 215 {
 216     struct json *json = json_create(JSON_ARRAY);
 217     json->u.array.elems = elements;
 218     json->u.array.n = n;
 219     json->u.array.n_allocated = n;
 220     return json;
 221 }
 222
 223 struct json *
 224 json_array_create_1(struct json *elem0)
 225 {
 226     struct json **elems = xmalloc(sizeof *elems);
 227     elems[0] = elem0;
 228     return json_array_create(elems, 1);
 229 }
 230
 231 struct json *
 232 json_array_create_2(struct json *elem0, struct json *elem1)
 233 {
 234     struct json **elems = xmalloc(2 * sizeof *elems);
 235     elems[0] = elem0;
 236     elems[1] = elem1;
 237     return json_array_create(elems, 2);
 238 }
 239
 240 struct json *
 241 json_array_create_3(struct json *elem0, struct json *elem1, struct json *elem2)
 242 {
 243     struct json **elems = xmalloc(3 * sizeof *elems);
 244     elems[0] = elem0;
 245     elems[1] = elem1;
 246     elems[2] = elem2;
 247     return json_array_create(elems, 3);
 248 }
 249
 250 struct json *
 251 json_object_create(void)
 252 {
 253     struct json *json = json_create(JSON_OBJECT);
 254     json->u.object = xmalloc(sizeof *json->u.object);
 255     shash_init(json->u.object);
 256     return json;
 257 }
 258
 259 struct json *
 260 json_integer_create(long long int integer)
 261 {
 262     struct json *json = json_create(JSON_INTEGER);
 263     json->u.integer = integer;
 264     return json;
 265 }
 266
 267 struct json *
 268 json_real_create(double real)
 269 {
 270     struct json *json = json_create(JSON_REAL);
 271     json->u.real = real;
 272     return json;
 273 }
 274
 275 void
 276 json_object_put(struct json *json, const char *name, struct json *value)
 277 {
 278     json_destroy(shash_replace(json->u.object, name, value));
 279 }
 280
 281 void
 282 json_object_put_string(struct json *json, const char *name, const char *value)
 283 {
 284     json_object_put(json, name, json_string_create(value));
 285 }
 286
 287 const char *
 288 json_string(const struct json *json)
 289 {
 290     ovs_assert(json->type == JSON_STRING);
 291     return json->u.string;
 292 }
 293
 294 struct json_array *
 295 json_array(const struct json *json)
 296 {
 297     ovs_assert(json->type == JSON_ARRAY);
 298     return CONST_CAST(struct json_array *, &json->u.array);
 299 }
 300
 301 struct shash *
 302 json_object(const struct json *json)
 303 {
 304     ovs_assert(json->type == JSON_OBJECT);
 305     return CONST_CAST(struct shash *, json->u.object);
 306 }
 307
 308 bool
 309 json_boolean(const struct json *json)
 310 {
 311     ovs_assert(json->type == JSON_TRUE || json->type == JSON_FALSE);
 312     return json->type == JSON_TRUE;
 313 }
 314
 315 double
 316 json_real(const struct json *json)
 317 {
 318     ovs_assert(json->type == JSON_REAL || json->type == JSON_INTEGER);
 319     return json->type == JSON_REAL ? json->u.real : json->u.integer;
 320 }
 321
 322 int64_t
 323 json_integer(const struct json *json)
 324 {
 325     ovs_assert(json->type == JSON_INTEGER);
 326     return json->u.integer;
 327 }
 328 \f
 329 static void json_destroy_object(struct shash *object);
 330 static void json_destroy_array(struct json_array *array);
 331
 332 /* Frees 'json' and everything it points to, recursively. */
 333 void
 334 json_destroy(struct json *json)
 335 {
 336     if (json) {
 337         switch (json->type) {
 338         case JSON_OBJECT:
 339             json_destroy_object(json->u.object);
 340             break;
 341
 342         case JSON_ARRAY:
 343             json_destroy_array(&json->u.array);
 344             break;
 345
 346         case JSON_STRING:
 347             free(json->u.string);
 348             break;
 349
 350         case JSON_NULL:
 351         case JSON_FALSE:
 352         case JSON_TRUE:
 353         case JSON_INTEGER:
 354         case JSON_REAL:
 355             break;
 356
 357         case JSON_N_TYPES:
 358             OVS_NOT_REACHED();
 359         }
 360         free(json);
 361     }
 362 }
 363
 364 static void
 365 json_destroy_object(struct shash *object)
 366 {
 367     struct shash_node *node, *next;
 368
 369     SHASH_FOR_EACH_SAFE (node, next, object) {
 370         struct json *value = node->data;
 371
 372         json_destroy(value);
 373         shash_delete(object, node);
 374     }
 375     shash_destroy(object);
 376     free(object);
 377 }
 378
 379 static void
 380 json_destroy_array(struct json_array *array)
 381 {
 382     size_t i;
 383
 384     for (i = 0; i < array->n; i++) {
 385         json_destroy(array->elems[i]);
 386     }
 387     free(array->elems);
 388 }
 389 \f
 390 static struct json *json_clone_object(const struct shash *object);
 391 static struct json *json_clone_array(const struct json_array *array);
 392
 393 /* Returns a deep copy of 'json'. */
 394 struct json *
 395 json_clone(const struct json *json)
 396 {
 397     switch (json->type) {
 398     case JSON_OBJECT:
 399         return json_clone_object(json->u.object);
 400
 401     case JSON_ARRAY:
 402         return json_clone_array(&json->u.array);
 403
 404     case JSON_STRING:
 405         return json_string_create(json->u.string);
 406
 407     case JSON_NULL:
 408     case JSON_FALSE:
 409     case JSON_TRUE:
 410         return json_create(json->type);
 411
 412     case JSON_INTEGER:
 413         return json_integer_create(json->u.integer);
 414
 415     case JSON_REAL:
 416         return json_real_create(json->u.real);
 417
 418     case JSON_N_TYPES:
 419     default:
 420         OVS_NOT_REACHED();
 421     }
 422 }
 423
 424 static struct json *
 425 json_clone_object(const struct shash *object)
 426 {
 427     struct shash_node *node;
 428     struct json *json;
 429
 430     json = json_object_create();
 431     SHASH_FOR_EACH (node, object) {
 432         struct json *value = node->data;
 433         json_object_put(json, node->name, json_clone(value));
 434     }
 435     return json;
 436 }
 437
 438 static struct json *
 439 json_clone_array(const struct json_array *array)
 440 {
 441     struct json **elems;
 442     size_t i;
 443
 444     elems = xmalloc(array->n * sizeof *elems);
 445     for (i = 0; i < array->n; i++) {
 446         elems[i] = json_clone(array->elems[i]);
 447     }
 448     return json_array_create(elems, array->n);
 449 }
 450 \f
 451 static size_t
 452 json_hash_object(const struct shash *object, size_t basis)
 453 {
 454     const struct shash_node **nodes;
 455     size_t n, i;
 456
 457     nodes = shash_sort(object);
 458     n = shash_count(object);
 459     for (i = 0; i < n; i++) {
 460         const struct shash_node *node = nodes[i];
 461         basis = hash_string(node->name, basis);
 462         basis = json_hash(node->data, basis);
 463     }
 464     free(nodes);
 465     return basis;
 466 }
 467
 468 static size_t
 469 json_hash_array(const struct json_array *array, size_t basis)
 470 {
 471     size_t i;
 472
 473     basis = hash_int(array->n, basis);
 474     for (i = 0; i < array->n; i++) {
 475         basis = json_hash(array->elems[i], basis);
 476     }
 477     return basis;
 478 }
 479
 480 size_t
 481 json_hash(const struct json *json, size_t basis)
 482 {
 483     switch (json->type) {
 484     case JSON_OBJECT:
 485         return json_hash_object(json->u.object, basis);
 486
 487     case JSON_ARRAY:
 488         return json_hash_array(&json->u.array, basis);
 489
 490     case JSON_STRING:
 491         return hash_string(json->u.string, basis);
 492
 493     case JSON_NULL:
 494     case JSON_FALSE:
 495     case JSON_TRUE:
 496         return hash_int(json->type << 8, basis);
 497
 498     case JSON_INTEGER:
 499         return hash_int(json->u.integer, basis);
 500
 501     case JSON_REAL:
 502         return hash_double(json->u.real, basis);
 503
 504     case JSON_N_TYPES:
 505     default:
 506         OVS_NOT_REACHED();
 507     }
 508 }
 509
 510 static bool
 511 json_equal_object(const struct shash *a, const struct shash *b)
 512 {
 513     struct shash_node *a_node;
 514
 515     if (shash_count(a) != shash_count(b)) {
 516         return false;
 517     }
 518
 519     SHASH_FOR_EACH (a_node, a) {
 520         struct shash_node *b_node = shash_find(b, a_node->name);
 521         if (!b_node || !json_equal(a_node->data, b_node->data)) {
 522             return false;
 523         }
 524     }
 525
 526     return true;
 527 }
 528
 529 static bool
 530 json_equal_array(const struct json_array *a, const struct json_array *b)
 531 {
 532     size_t i;
 533
 534     if (a->n != b->n) {
 535         return false;
 536     }
 537
 538     for (i = 0; i < a->n; i++) {
 539         if (!json_equal(a->elems[i], b->elems[i])) {
 540             return false;
 541         }
 542     }
 543
 544     return true;
 545 }
 546
 547 bool
 548 json_equal(const struct json *a, const struct json *b)
 549 {
 550     if (a->type != b->type) {
 551         return false;
 552     }
 553
 554     switch (a->type) {
 555     case JSON_OBJECT:
 556         return json_equal_object(a->u.object, b->u.object);
 557
 558     case JSON_ARRAY:
 559         return json_equal_array(&a->u.array, &b->u.array);
 560
 561     case JSON_STRING:
 562         return !strcmp(a->u.string, b->u.string);
 563
 564     case JSON_NULL:
 565     case JSON_FALSE:
 566     case JSON_TRUE:
 567         return true;
 568
 569     case JSON_INTEGER:
 570         return a->u.integer == b->u.integer;
 571
 572     case JSON_REAL:
 573         return a->u.real == b->u.real;
 574
 575     case JSON_N_TYPES:
 576     default:
 577         OVS_NOT_REACHED();
 578     }
 579 }
 580 \f
 581 /* Lexical analysis. */
 582
 583 static void
 584 json_lex_keyword(struct json_parser *p)
 585 {
 586     struct json_token token;
 587     const char *s;
 588
 589     s = ds_cstr(&p->buffer);
 590     if (!strcmp(s, "false")) {
 591         token.type = T_FALSE;
 592     } else if (!strcmp(s, "true")) {
 593         token.type = T_TRUE;
 594     } else if (!strcmp(s, "null")) {
 595         token.type = T_NULL;
 596     } else {
 597         json_error(p, "invalid keyword '%s'", s);
 598         return;
 599     }
 600     json_parser_input(p, &token);
 601 }
 602
 603 static void
 604 json_lex_number(struct json_parser *p)
 605 {
 606     const char *cp = ds_cstr(&p->buffer);
 607     unsigned long long int significand = 0;
 608     struct json_token token;
 609     bool imprecise = false;
 610     bool negative = false;
 611     int pow10 = 0;
 612
 613     /* Leading minus sign. */
 614     if (*cp == '-') {
 615         negative = true;
 616         cp++;
 617     }
 618
 619     /* At least one integer digit, but 0 may not be used as a leading digit for
 620      * a longer number. */
 621     significand = 0;
 622     if (*cp == '0') {
 623         cp++;
 624         if (isdigit((unsigned char) *cp)) {
 625             json_error(p, "leading zeros not allowed");
 626             return;
 627         }
 628     } else if (isdigit((unsigned char) *cp)) {
 629         do {
 630             if (significand <= ULLONG_MAX / 10) {
 631                 significand = significand * 10 + (*cp - '0');
 632             } else {
 633                 pow10++;
 634                 if (*cp != '0') {
 635                     imprecise = true;
 636                 }
 637             }
 638             cp++;
 639         } while (isdigit((unsigned char) *cp));
 640     } else {
 641         json_error(p, "'-' must be followed by digit");
 642         return;
 643     }
 644
 645     /* Optional fraction. */
 646     if (*cp == '.') {
 647         cp++;
 648         if (!isdigit((unsigned char) *cp)) {
 649             json_error(p, "decimal point must be followed by digit");
 650             return;
 651         }
 652         do {
 653             if (significand <= ULLONG_MAX / 10) {
 654                 significand = significand * 10 + (*cp - '0');
 655                 pow10--;
 656             } else if (*cp != '0') {
 657                 imprecise = true;
 658             }
 659             cp++;
 660         } while (isdigit((unsigned char) *cp));
 661     }
 662
 663     /* Optional exponent. */
 664     if (*cp == 'e' || *cp == 'E') {
 665         bool negative_exponent = false;
 666         int exponent;
 667
 668         cp++;
 669         if (*cp == '+') {
 670             cp++;
 671         } else if (*cp == '-') {
 672             negative_exponent = true;
 673             cp++;
 674         }
 675
 676         if (!isdigit((unsigned char) *cp)) {
 677             json_error(p, "exponent must contain at least one digit");
 678             return;
 679         }
 680
 681         exponent = 0;
 682         do {
 683             if (exponent >= INT_MAX / 10) {
 684                 json_error(p, "exponent outside valid range");
 685                 return;
 686             }
 687             exponent = exponent * 10 + (*cp - '0');
 688             cp++;
 689         } while (isdigit((unsigned char) *cp));
 690
 691         if (negative_exponent) {
 692             pow10 -= exponent;
 693         } else {
 694             pow10 += exponent;
 695         }
 696     }
 697
 698     if (*cp != '\0') {
 699         json_error(p, "syntax error in number");
 700         return;
 701     }
 702
 703     /* Figure out number.
 704      *
 705      * We suppress negative zeros as a matter of policy. */
 706     if (!significand) {
 707         token.type = T_INTEGER;
 708         token.u.integer = 0;
 709         json_parser_input(p, &token);
 710         return;
 711     }
 712
 713     if (!imprecise) {
 714         while (pow10 > 0 && significand < ULLONG_MAX / 10) {
 715             significand *= 10;
 716             pow10--;
 717         }
 718         while (pow10 < 0 && significand % 10 == 0) {
 719             significand /= 10;
 720             pow10++;
 721         }
 722         if (pow10 == 0
 723             && significand <= (negative
 724                                ? (unsigned long long int) LLONG_MAX + 1
 725                                : LLONG_MAX)) {
 726             token.type = T_INTEGER;
 727             token.u.integer = negative ? -significand : significand;
 728             json_parser_input(p, &token);
 729             return;
 730         }
 731     }
 732
 733     token.type = T_REAL;
 734     if (!str_to_double(ds_cstr(&p->buffer), &token.u.real)) {
 735         json_error(p, "number outside valid range");
 736         return;
 737     }
 738     /* Suppress negative zero. */
 739     if (token.u.real == 0) {
 740         token.u.real = 0;
 741     }
 742     json_parser_input(p, &token);
 743 }
 744
 745 static const char *
 746 json_lex_4hex(const char *cp, const char *end, int *valuep)
 747 {
 748     unsigned int value;
 749
 750     if (cp + 4 > end) {
 751         return "quoted string ends within \\u escape";
 752     }
 753
 754     value = hexits_value(cp, 4, NULL);
 755     if (value == UINT_MAX) {
 756         return "malformed \\u escape";
 757     }
 758     if (!value) {
 759         return "null bytes not supported in quoted strings";
 760     }
 761     *valuep = value;
 762     return NULL;
 763 }
 764
 765 static const char *
 766 json_lex_unicode(const char *cp, const char *end, struct ds *out)
 767 {
 768     const char *error;
 769     int c0, c1;
 770
 771     error = json_lex_4hex(cp, end, &c0);
 772     if (error) {
 773         ds_clear(out);
 774         ds_put_cstr(out, error);
 775         return NULL;
 776     }
 777     cp += 4;
 778     if (!uc_is_leading_surrogate(c0)) {
 779         ds_put_utf8(out, c0);
 780         return cp;
 781     }
 782
 783     if (cp + 2 > end || *cp++ != '\\' || *cp++ != 'u') {
 784         ds_clear(out);
 785         ds_put_cstr(out, "malformed escaped surrogate pair");
 786         return NULL;
 787     }
 788
 789     error = json_lex_4hex(cp, end, &c1);
 790     if (error) {
 791         ds_clear(out);
 792         ds_put_cstr(out, error);
 793         return NULL;
 794     }
 795     cp += 4;
 796     if (!uc_is_trailing_surrogate(c1)) {
 797         ds_clear(out);
 798         ds_put_cstr(out, "second half of escaped surrogate pair is not "
 799                     "trailing surrogate");
 800         return NULL;
 801     }
 802
 803     ds_put_utf8(out, utf16_decode_surrogate_pair(c0, c1));
 804     return cp;
 805 }
 806
 807 bool
 808 json_string_unescape(const char *in, size_t in_len, char **outp)
 809 {
 810     const char *end = in + in_len;
 811     bool ok = false;
 812     struct ds out;
 813
 814     ds_init(&out);
 815     ds_reserve(&out, in_len);
 816     while (in < end) {
 817         if (*in == '"') {
 818             ds_clear(&out);
 819             ds_put_cstr(&out, "quoted string may not include unescaped \"");
 820             goto exit;
 821         }
 822         if (*in != '\\') {
 823             ds_put_char(&out, *in++);
 824             continue;
 825         }
 826
 827         in++;
 828         if (in >= end) {
 829             /* The JSON parser will never trigger this message, because its
 830              * lexer will never pass in a string that ends in a single
 831              * backslash, but json_string_unescape() has other callers that
 832              * are not as careful.*/
 833             ds_put_cstr(&out, "quoted string may not end with backslash");
 834             goto exit;
 835         }
 836         switch (*in++) {
 837         case '"': case '\\': case '/':
 838             ds_put_char(&out, in[-1]);
 839             break;
 840
 841         case 'b':
 842             ds_put_char(&out, '\b');
 843             break;
 844
 845         case 'f':
 846             ds_put_char(&out, '\f');
 847             break;
 848
 849         case 'n':
 850             ds_put_char(&out, '\n');
 851             break;
 852
 853         case 'r':
 854             ds_put_char(&out, '\r');
 855             break;
 856
 857         case 't':
 858             ds_put_char(&out, '\t');
 859             break;
 860
 861         case 'u':
 862             in = json_lex_unicode(in, end, &out);
 863             if (!in) {
 864                 goto exit;
 865             }
 866             break;
 867
 868         default:
 869             ds_clear(&out);
 870             ds_put_format(&out, "bad escape \\%c", in[-1]);
 871             goto exit;
 872         }
 873     }
 874     ok = true;
 875
 876 exit:
 877     *outp = ds_cstr(&out);
 878     return ok;
 879 }
 880
 881 static void
 882 json_parser_input_string(struct json_parser *p, const char *s)
 883 {
 884     struct json_token token;
 885
 886     token.type = T_STRING;
 887     token.u.string = s;
 888     json_parser_input(p, &token);
 889 }
 890
 891 static void
 892 json_lex_string(struct json_parser *p)
 893 {
 894     const char *raw = ds_cstr(&p->buffer);
 895     if (!strchr(raw, '\\')) {
 896         json_parser_input_string(p, raw);
 897     } else {
 898         char *cooked;
 899
 900         if (json_string_unescape(raw, strlen(raw), &cooked)) {
 901             json_parser_input_string(p, cooked);
 902         } else {
 903             json_error(p, "%s", cooked);
 904         }
 905
 906         free(cooked);
 907     }
 908 }
 909
 910 static bool
 911 json_lex_input(struct json_parser *p, unsigned char c)
 912 {
 913     struct json_token token;
 914
 915     switch (p->lex_state) {
 916     case JSON_LEX_START:
 917         switch (c) {
 918         case ' ': case '\t': case '\n': case '\r':
 919             /* Nothing to do. */
 920             return true;
 921
 922         case 'a': case 'b': case 'c': case 'd': case 'e':
 923         case 'f': case 'g': case 'h': case 'i': case 'j':
 924         case 'k': case 'l': case 'm': case 'n': case 'o':
 925         case 'p': case 'q': case 'r': case 's': case 't':
 926         case 'u': case 'v': case 'w': case 'x': case 'y':
 927         case 'z':
 928             p->lex_state = JSON_LEX_KEYWORD;
 929             break;
 930
 931         case '[': case '{': case ']': case '}': case ':': case ',':
 932             token.type = c;
 933             json_parser_input(p, &token);
 934             return true;
 935
 936         case '-':
 937         case '0': case '1': case '2': case '3': case '4':
 938         case '5': case '6': case '7': case '8': case '9':
 939             p->lex_state = JSON_LEX_NUMBER;
 940             break;
 941
 942         case '"':
 943             p->lex_state = JSON_LEX_STRING;
 944             return true;
 945
 946         default:
 947             if (isprint(c)) {
 948                 json_error(p, "invalid character '%c'", c);
 949             } else {
 950                 json_error(p, "invalid character U+%04x", c);
 951             }
 952             return true;
 953         }
 954         break;
 955
 956     case JSON_LEX_KEYWORD:
 957         if (!isalpha((unsigned char) c)) {
 958             json_lex_keyword(p);
 959             return false;
 960         }
 961         break;
 962
 963     case JSON_LEX_NUMBER:
 964         if (!strchr(".0123456789eE-+", c)) {
 965             json_lex_number(p);
 966             return false;
 967         }
 968         break;
 969
 970     case JSON_LEX_STRING:
 971         if (c == '\\') {
 972             p->lex_state = JSON_LEX_ESCAPE;
 973         } else if (c == '"') {
 974             json_lex_string(p);
 975             return true;
 976         } else if (c < 0x20) {
 977             json_error(p, "U+%04X must be escaped in quoted string", c);
 978             return true;
 979         }
 980         break;
 981
 982     case JSON_LEX_ESCAPE:
 983         p->lex_state = JSON_LEX_STRING;
 984         break;
 985
 986     default:
 987         abort();
 988     }
 989     ds_put_char(&p->buffer, c);
 990     return true;
 991 }
 992 \f
 993 /* Parsing. */
 994
 995 /* Parses 'string' as a JSON object or array and returns a newly allocated
 996  * 'struct json'.  The caller must free the returned structure with
 997  * json_destroy() when it is no longer needed.
 998  *
 999  * 'string' must be encoded in UTF-8.
1000  *
1001  * If 'string' is valid JSON, then the returned 'struct json' will be either an
1002  * object (JSON_OBJECT) or an array (JSON_ARRAY).
1003  *
1004  * If 'string' is not valid JSON, then the returned 'struct json' will be a
1005  * string (JSON_STRING) that describes the particular error encountered during
1006  * parsing.  (This is an acceptable means of error reporting because at its top
1007  * level JSON must be either an object or an array; a bare string is not
1008  * valid.) */
1009 struct json *
1010 json_from_string(const char *string)
1011 {
1012     struct json_parser *p = json_parser_create(JSPF_TRAILER);
1013     json_parser_feed(p, string, strlen(string));
1014     return json_parser_finish(p);
1015 }
1016
1017 /* Reads the file named 'file_name', parses its contents as a JSON object or
1018  * array, and returns a newly allocated 'struct json'.  The caller must free
1019  * the returned structure with json_destroy() when it is no longer needed.
1020  *
1021  * The file must be encoded in UTF-8.
1022  *
1023  * See json_from_string() for return value semantics.
1024  */
1025 struct json *
1026 json_from_file(const char *file_name)
1027 {
1028     struct json *json;
1029     FILE *stream;
1030
1031     stream = fopen(file_name, "r");
1032     if (!stream) {
1033         return json_string_create_nocopy(
1034             xasprintf("error opening \"%s\": %s", file_name,
1035                       ovs_strerror(errno)));
1036     }
1037     json = json_from_stream(stream);
1038     fclose(stream);
1039
1040     return json;
1041 }
1042
1043 /* Parses the contents of 'stream' as a JSON object or array, and returns a
1044  * newly allocated 'struct json'.  The caller must free the returned structure
1045  * with json_destroy() when it is no longer needed.
1046  *
1047  * The file must be encoded in UTF-8.
1048  *
1049  * See json_from_string() for return value semantics.
1050  */
1051 struct json *
1052 json_from_stream(FILE *stream)
1053 {
1054     struct json_parser *p;
1055     struct json *json;
1056
1057     p = json_parser_create(JSPF_TRAILER);
1058     for (;;) {
1059         char buffer[BUFSIZ];
1060         size_t n;
1061
1062         n = fread(buffer, 1, sizeof buffer, stream);
1063         if (!n || json_parser_feed(p, buffer, n) != n) {
1064             break;
1065         }
1066     }
1067     json = json_parser_finish(p);
1068
1069     if (ferror(stream)) {
1070         json_destroy(json);
1071         json = json_string_create_nocopy(
1072             xasprintf("error reading JSON stream: %s", ovs_strerror(errno)));
1073     }
1074
1075     return json;
1076 }
1077
1078 struct json_parser *
1079 json_parser_create(int flags)
1080 {
1081     struct json_parser *p = xzalloc(sizeof *p);
1082     p->flags = flags;
1083     return p;
1084 }
1085
1086 size_t
1087 json_parser_feed(struct json_parser *p, const char *input, size_t n)
1088 {
1089     size_t i;
1090     for (i = 0; !p->done && i < n; ) {
1091         if (json_lex_input(p, input[i])) {
1092             p->byte_number++;
1093             if (input[i] == '\n') {
1094                 p->column_number = 0;
1095                 p->line_number++;
1096             } else {
1097                 p->column_number++;
1098             }
1099             i++;
1100         }
1101     }
1102     return i;
1103 }
1104
1105 bool
1106 json_parser_is_done(const struct json_parser *p)
1107 {
1108     return p->done;
1109 }
1110
1111 struct json *
1112 json_parser_finish(struct json_parser *p)
1113 {
1114     struct json *json;
1115
1116     switch (p->lex_state) {
1117     case JSON_LEX_START:
1118         break;
1119
1120     case JSON_LEX_STRING:
1121     case JSON_LEX_ESCAPE:
1122         json_error(p, "unexpected end of input in quoted string");
1123         break;
1124
1125     case JSON_LEX_NUMBER:
1126     case JSON_LEX_KEYWORD:
1127         json_lex_input(p, ' ');
1128         break;
1129     }
1130
1131     if (p->parse_state == JSON_PARSE_START) {
1132         json_error(p, "empty input stream");
1133     } else if (p->parse_state != JSON_PARSE_END) {
1134         json_error(p, "unexpected end of input");
1135     }
1136
1137     if (!p->error) {
1138         ovs_assert(p->height == 1);
1139         ovs_assert(p->stack[0].json != NULL);
1140         json = p->stack[--p->height].json;
1141     } else {
1142         json = json_string_create_nocopy(p->error);
1143         p->error = NULL;
1144     }
1145
1146     json_parser_abort(p);
1147
1148     return json;
1149 }
1150
1151 void
1152 json_parser_abort(struct json_parser *p)
1153 {
1154     if (p) {
1155         ds_destroy(&p->buffer);
1156         if (p->height) {
1157             json_destroy(p->stack[0].json);
1158         }
1159         free(p->stack);
1160         free(p->member_name);
1161         free(p->error);
1162         free(p);
1163     }
1164 }
1165
1166 static struct json_parser_node *
1167 json_parser_top(struct json_parser *p)
1168 {
1169     return &p->stack[p->height - 1];
1170 }
1171
1172 static void
1173 json_parser_put_value(struct json_parser *p, struct json *value)
1174 {
1175     struct json_parser_node *node = json_parser_top(p);
1176     if (node->json->type == JSON_OBJECT) {
1177         json_object_put(node->json, p->member_name, value);
1178         free(p->member_name);
1179         p->member_name = NULL;
1180     } else if (node->json->type == JSON_ARRAY) {
1181         json_array_add(node->json, value);
1182     } else {
1183         OVS_NOT_REACHED();
1184     }
1185 }
1186
1187 static void
1188 json_parser_push(struct json_parser *p,
1189                  struct json *new_json, enum json_parse_state new_state)
1190 {
1191     if (p->height < JSON_MAX_HEIGHT) {
1192         struct json_parser_node *node;
1193
1194         if (p->height >= p->allocated_height) {
1195             p->stack = x2nrealloc(p->stack, &p->allocated_height,
1196                                   sizeof *p->stack);
1197         }
1198
1199         if (p->height > 0) {
1200             json_parser_put_value(p, new_json);
1201         }
1202
1203         node = &p->stack[p->height++];
1204         node->json = new_json;
1205         p->parse_state = new_state;
1206     } else {
1207         json_destroy(new_json);
1208         json_error(p, "input exceeds maximum nesting depth %d",
1209                    JSON_MAX_HEIGHT);
1210     }
1211 }
1212
1213 static void
1214 json_parser_push_object(struct json_parser *p)
1215 {
1216     json_parser_push(p, json_object_create(), JSON_PARSE_OBJECT_INIT);
1217 }
1218
1219 static void
1220 json_parser_push_array(struct json_parser *p)
1221 {
1222     json_parser_push(p, json_array_create_empty(), JSON_PARSE_ARRAY_INIT);
1223 }
1224
1225 static void
1226 json_parse_value(struct json_parser *p, struct json_token *token,
1227                  enum json_parse_state next_state)
1228 {
1229     struct json *value;
1230
1231     switch (token->type) {
1232     case T_FALSE:
1233         value = json_boolean_create(false);
1234         break;
1235
1236     case T_NULL:
1237         value = json_null_create();
1238         break;
1239
1240     case T_TRUE:
1241         value = json_boolean_create(true);
1242         break;
1243
1244     case '{':
1245         json_parser_push_object(p);
1246         return;
1247
1248     case '[':
1249         json_parser_push_array(p);
1250         return;
1251
1252     case T_INTEGER:
1253         value = json_integer_create(token->u.integer);
1254         break;
1255
1256     case T_REAL:
1257         value = json_real_create(token->u.real);
1258         break;
1259
1260     case T_STRING:
1261         value = json_string_create(token->u.string);
1262         break;
1263
1264     case T_EOF:
1265     case '}':
1266     case ']':
1267     case ':':
1268     case ',':
1269     default:
1270         json_error(p, "syntax error expecting value");
1271         return;
1272     }
1273
1274     json_parser_put_value(p, value);
1275     p->parse_state = next_state;
1276 }
1277
1278 static void
1279 json_parser_pop(struct json_parser *p)
1280 {
1281     struct json_parser_node *node;
1282
1283     /* Conserve memory. */
1284     node = json_parser_top(p);
1285     if (node->json->type == JSON_ARRAY) {
1286         json_array_trim(node->json);
1287     }
1288
1289     /* Pop off the top-of-stack. */
1290     if (p->height == 1) {
1291         p->parse_state = JSON_PARSE_END;
1292         if (!(p->flags & JSPF_TRAILER)) {
1293             p->done = true;
1294         }
1295     } else {
1296         p->height--;
1297         node = json_parser_top(p);
1298         if (node->json->type == JSON_ARRAY) {
1299             p->parse_state = JSON_PARSE_ARRAY_NEXT;
1300         } else if (node->json->type == JSON_OBJECT) {
1301             p->parse_state = JSON_PARSE_OBJECT_NEXT;
1302         } else {
1303             OVS_NOT_REACHED();
1304         }
1305     }
1306 }
1307
1308 static void
1309 json_parser_input(struct json_parser *p, struct json_token *token)
1310 {
1311     switch (p->parse_state) {
1312     case JSON_PARSE_START:
1313         if (token->type == '{') {
1314             json_parser_push_object(p);
1315         } else if (token->type == '[') {
1316             json_parser_push_array(p);
1317         } else {
1318             json_error(p, "syntax error at beginning of input");
1319         }
1320         break;
1321
1322     case JSON_PARSE_END:
1323         json_error(p, "trailing garbage at end of input");
1324         break;
1325
1326     case JSON_PARSE_OBJECT_INIT:
1327         if (token->type == '}') {
1328             json_parser_pop(p);
1329             break;
1330         }
1331         /* Fall through. */
1332     case JSON_PARSE_OBJECT_NAME:
1333         if (token->type == T_STRING) {
1334             p->member_name = xstrdup(token->u.string);
1335             p->parse_state = JSON_PARSE_OBJECT_COLON;
1336         } else {
1337             json_error(p, "syntax error parsing object expecting string");
1338         }
1339         break;
1340
1341     case JSON_PARSE_OBJECT_COLON:
1342         if (token->type == ':') {
1343             p->parse_state = JSON_PARSE_OBJECT_VALUE;
1344         } else {
1345             json_error(p, "syntax error parsing object expecting ':'");
1346         }
1347         break;
1348
1349     case JSON_PARSE_OBJECT_VALUE:
1350         json_parse_value(p, token, JSON_PARSE_OBJECT_NEXT);
1351         break;
1352
1353     case JSON_PARSE_OBJECT_NEXT:
1354         if (token->type == ',') {
1355             p->parse_state = JSON_PARSE_OBJECT_NAME;
1356         } else if (token->type == '}') {
1357             json_parser_pop(p);
1358         } else {
1359             json_error(p, "syntax error expecting '}' or ','");
1360         }
1361         break;
1362
1363     case JSON_PARSE_ARRAY_INIT:
1364         if (token->type == ']') {
1365             json_parser_pop(p);
1366             break;
1367         }
1368         /* Fall through. */
1369     case JSON_PARSE_ARRAY_VALUE:
1370         json_parse_value(p, token, JSON_PARSE_ARRAY_NEXT);
1371         break;
1372
1373     case JSON_PARSE_ARRAY_NEXT:
1374         if (token->type == ',') {
1375             p->parse_state = JSON_PARSE_ARRAY_VALUE;
1376         } else if (token->type == ']') {
1377             json_parser_pop(p);
1378         } else {
1379             json_error(p, "syntax error expecting ']' or ','");
1380         }
1381         break;
1382
1383     default:
1384         abort();
1385     }
1386
1387     p->lex_state = JSON_LEX_START;
1388     ds_clear(&p->buffer);
1389 }
1390
1391 static struct json *
1392 json_create(enum json_type type)
1393 {
1394     struct json *json = xmalloc(sizeof *json);
1395     json->type = type;
1396     return json;
1397 }
1398
1399 static void
1400 json_error(struct json_parser *p, const char *format, ...)
1401 {
1402     if (!p->error) {
1403         struct ds msg;
1404         va_list args;
1405
1406         ds_init(&msg);
1407         ds_put_format(&msg, "line %d, column %d, byte %d: ",
1408                       p->line_number, p->column_number, p->byte_number);
1409         va_start(args, format);
1410         ds_put_format_valist(&msg, format, args);
1411         va_end(args);
1412
1413         p->error = ds_steal_cstr(&msg);
1414
1415         p->done = true;
1416     }
1417 }
1418 \f
1419 #define SPACES_PER_LEVEL 2
1420
1421 struct json_serializer {
1422     struct ds *ds;
1423     int depth;
1424     int flags;
1425 };
1426
1427 static void json_serialize(const struct json *, struct json_serializer *);
1428 static void json_serialize_object(const struct shash *object,
1429                                   struct json_serializer *);
1430 static void json_serialize_array(const struct json_array *,
1431                                  struct json_serializer *);
1432 static void json_serialize_string(const char *, struct ds *);
1433
1434 /* Converts 'json' to a string in JSON format, encoded in UTF-8, and returns
1435  * that string.  The caller is responsible for freeing the returned string,
1436  * with free(), when it is no longer needed.
1437  *
1438  * If 'flags' contains JSSF_PRETTY, the output is pretty-printed with each
1439  * nesting level introducing an additional indentation.  Otherwise, the
1440  * returned string does not contain any new-line characters.
1441  *
1442  * If 'flags' contains JSSF_SORT, members of objects in the output are sorted
1443  * in bytewise lexicographic order for reproducibility.  Otherwise, members of
1444  * objects are output in an indeterminate order.
1445  *
1446  * The returned string is valid JSON only if 'json' represents an array or an
1447  * object, since a bare literal does not satisfy the JSON grammar. */
1448 char *
1449 json_to_string(const struct json *json, int flags)
1450 {
1451     struct ds ds;
1452
1453     ds_init(&ds);
1454     json_to_ds(json, flags, &ds);
1455     return ds_steal_cstr(&ds);
1456 }
1457
1458 /* Same as json_to_string(), but the output is appended to 'ds'. */
1459 void
1460 json_to_ds(const struct json *json, int flags, struct ds *ds)
1461 {
1462     struct json_serializer s;
1463
1464     s.ds = ds;
1465     s.depth = 0;
1466     s.flags = flags;
1467     json_serialize(json, &s);
1468 }
1469
1470 static void
1471 json_serialize(const struct json *json, struct json_serializer *s)
1472 {
1473     struct ds *ds = s->ds;
1474
1475     switch (json->type) {
1476     case JSON_NULL:
1477         ds_put_cstr(ds, "null");
1478         break;
1479
1480     case JSON_FALSE:
1481         ds_put_cstr(ds, "false");
1482         break;
1483
1484     case JSON_TRUE:
1485         ds_put_cstr(ds, "true");
1486         break;
1487
1488     case JSON_OBJECT:
1489         json_serialize_object(json->u.object, s);
1490         break;
1491
1492     case JSON_ARRAY:
1493         json_serialize_array(&json->u.array, s);
1494         break;
1495
1496     case JSON_INTEGER:
1497         ds_put_format(ds, "%lld", json->u.integer);
1498         break;
1499
1500     case JSON_REAL:
1501         ds_put_format(ds, "%.*g", DBL_DIG, json->u.real);
1502         break;
1503
1504     case JSON_STRING:
1505         json_serialize_string(json->u.string, ds);
1506         break;
1507
1508     case JSON_N_TYPES:
1509     default:
1510         OVS_NOT_REACHED();
1511     }
1512 }
1513
1514 static void
1515 indent_line(struct json_serializer *s)
1516 {
1517     if (s->flags & JSSF_PRETTY) {
1518         ds_put_char(s->ds, '\n');
1519         ds_put_char_multiple(s->ds, ' ', SPACES_PER_LEVEL * s->depth);
1520     }
1521 }
1522
1523 static void
1524 json_serialize_object_member(size_t i, const struct shash_node *node,
1525                              struct json_serializer *s)
1526 {
1527     struct ds *ds = s->ds;
1528
1529     if (i) {
1530         ds_put_char(ds, ',');
1531         indent_line(s);
1532     }
1533
1534     json_serialize_string(node->name, ds);
1535     ds_put_char(ds, ':');
1536     if (s->flags & JSSF_PRETTY) {
1537         ds_put_char(ds, ' ');
1538     }
1539     json_serialize(node->data, s);
1540 }
1541
1542 static void
1543 json_serialize_object(const struct shash *object, struct json_serializer *s)
1544 {
1545     struct ds *ds = s->ds;
1546
1547     ds_put_char(ds, '{');
1548
1549     s->depth++;
1550     indent_line(s);
1551
1552     if (s->flags & JSSF_SORT) {
1553         const struct shash_node **nodes;
1554         size_t n, i;
1555
1556         nodes = shash_sort(object);
1557         n = shash_count(object);
1558         for (i = 0; i < n; i++) {
1559             json_serialize_object_member(i, nodes[i], s);
1560         }
1561         free(nodes);
1562     } else {
1563         struct shash_node *node;
1564         size_t i;
1565
1566         i = 0;
1567         SHASH_FOR_EACH (node, object) {
1568             json_serialize_object_member(i++, node, s);
1569         }
1570     }
1571
1572     ds_put_char(ds, '}');
1573     s->depth--;
1574 }
1575
1576 static void
1577 json_serialize_array(const struct json_array *array, struct json_serializer *s)
1578 {
1579     struct ds *ds = s->ds;
1580     size_t i;
1581
1582     ds_put_char(ds, '[');
1583     s->depth++;
1584
1585     if (array->n > 0) {
1586         indent_line(s);
1587
1588         for (i = 0; i < array->n; i++) {
1589             if (i) {
1590                 ds_put_char(ds, ',');
1591                 indent_line(s);
1592             }
1593             json_serialize(array->elems[i], s);
1594         }
1595     }
1596
1597     s->depth--;
1598     ds_put_char(ds, ']');
1599 }
1600
1601 static void
1602 json_serialize_string(const char *string, struct ds *ds)
1603 {
1604     uint8_t c;
1605
1606     ds_put_char(ds, '"');
1607     while ((c = *string++) != '\0') {
1608         switch (c) {
1609         case '"':
1610             ds_put_cstr(ds, "\\\"");
1611             break;
1612
1613         case '\\':
1614             ds_put_cstr(ds, "\\\\");
1615             break;
1616
1617         case '\b':
1618             ds_put_cstr(ds, "\\b");
1619             break;
1620
1621         case '\f':
1622             ds_put_cstr(ds, "\\f");
1623             break;
1624
1625         case '\n':
1626             ds_put_cstr(ds, "\\n");
1627             break;
1628
1629         case '\r':
1630             ds_put_cstr(ds, "\\r");
1631             break;
1632
1633         case '\t':
1634             ds_put_cstr(ds, "\\t");
1635             break;
1636
1637         default:
1638             if (c >= 32) {
1639                 ds_put_char(ds, c);
1640             } else {
1641                 ds_put_format(ds, "\\u%04x", c);
1642             }
1643             break;
1644         }
1645     }
1646     ds_put_char(ds, '"');
1647 }