320 lines
6.4 KiB
C
320 lines
6.4 KiB
C
/* $OpenBSD: json.c,v 1.9 2017/01/24 13:32:55 jsing Exp $ */
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/*
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* Copyright (c) 2016 Kristaps Dzonsons <kristaps@bsd.lv>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <assert.h>
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#include <err.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "jsmn.h"
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#include "main.h"
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struct jsmnp;
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/*
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* Objects consist of node pairs: the left-hand side (before the colon)
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* and the right-hand side---the data.
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*/
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struct jsmnp {
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struct jsmnn *lhs; /* left of colon */
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struct jsmnn *rhs; /* right of colon */
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};
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/*
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* Object for converting the JSMN token array into a tree.
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*/
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struct parse {
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struct jsmnn *nodes; /* all nodes */
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size_t cur; /* current number */
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size_t max; /* nodes in "nodes" */
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};
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/*
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* Recursive part for convertin a JSMN token array into a tree.
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* See "example/jsondump.c" for its construction (it's the same except
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* for how it handles allocation errors).
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*/
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static ssize_t
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build(struct parse *parse, struct jsmnn **np,
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jsmntok_t *t, const char *js, size_t sz)
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{
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size_t i, j;
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struct jsmnn *n;
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ssize_t tmp;
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if (sz == 0)
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return 0;
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assert(parse->cur < parse->max);
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n = *np = &parse->nodes[parse->cur++];
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n->p = parse;
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n->type = t->type;
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switch (t->type) {
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case JSMN_STRING:
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/* FALLTHROUGH */
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case JSMN_PRIMITIVE:
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n->fields = 1;
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n->d.str = strndup
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(js + t->start,
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t->end - t->start);
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if (n->d.str == NULL)
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break;
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return 1;
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case JSMN_OBJECT:
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n->fields = t->size;
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n->d.obj = calloc(n->fields,
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sizeof(struct jsmnp));
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if (n->d.obj == NULL)
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break;
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for (i = j = 0; i < (size_t)t->size; i++) {
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tmp = build(parse,
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&n->d.obj[i].lhs,
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t + 1 + j, js, sz - j);
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if (tmp < 0)
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break;
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j += tmp;
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tmp = build(parse,
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&n->d.obj[i].rhs,
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t + 1 + j, js, sz - j);
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if (tmp < 0)
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break;
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j += tmp;
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}
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if (i < (size_t)t->size)
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break;
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return j + 1;
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case JSMN_ARRAY:
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n->fields = t->size;
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n->d.array = calloc(n->fields,
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sizeof(struct jsmnn *));
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if (n->d.array == NULL)
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break;
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for (i = j = 0; i < (size_t)t->size; i++) {
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tmp = build(parse,
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&n->d.array[i],
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t + 1 + j, js, sz - j);
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if (tmp < 0)
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break;
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j += tmp;
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}
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if (i < (size_t)t->size)
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break;
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return j + 1;
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default:
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break;
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}
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return -1;
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}
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/*
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* Fully free up a parse sequence.
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* This handles all nodes sequentially, not recursively.
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*/
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static void
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jsmnparse_free(struct parse *p)
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{
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size_t i;
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if (p == NULL)
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return;
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for (i = 0; i < p->max; i++) {
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struct jsmnn *n = &p->nodes[i];
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switch (n->type) {
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case JSMN_ARRAY:
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free(n->d.array);
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break;
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case JSMN_OBJECT:
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free(n->d.obj);
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break;
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case JSMN_PRIMITIVE:
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free(n->d.str);
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break;
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case JSMN_STRING:
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free(n->d.str);
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break;
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case JSMN_UNDEFINED:
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break;
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}
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}
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free(p->nodes);
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free(p);
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}
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/*
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* Allocate a tree representation of "t".
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* This returns NULL on allocation failure or when sz is zero, in which
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* case all resources allocated along the way are freed already.
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*/
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static struct jsmnn *
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jsmntree_alloc(jsmntok_t *t, const char *js, size_t sz)
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{
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struct jsmnn *first;
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struct parse *p;
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if (sz == 0)
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return NULL;
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p = calloc(1, sizeof(struct parse));
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if (p == NULL)
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return NULL;
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p->max = sz;
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p->nodes = calloc(p->max, sizeof(struct jsmnn));
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if (p->nodes == NULL) {
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free(p);
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return NULL;
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}
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if (build(p, &first, t, js, sz) < 0) {
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jsmnparse_free(p);
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first = NULL;
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}
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return first;
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}
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/*
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* Call through to free parse contents.
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*/
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void
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json_free(struct jsmnn *first)
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{
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if (first != NULL)
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jsmnparse_free(first->p);
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}
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/*
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* Just check that the array object is in fact an object.
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*/
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struct jsmnn *
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json_getarrayobj(struct jsmnn *n)
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{
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return n->type != JSMN_OBJECT ? NULL : n;
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}
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/*
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* Extract an array from the returned JSON object, making sure that it's
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* the correct type.
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* Returns NULL on failure.
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*/
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struct jsmnn *
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json_getarray(struct jsmnn *n, const char *name)
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{
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size_t i;
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if (n->type != JSMN_OBJECT)
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return NULL;
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for (i = 0; i < n->fields; i++) {
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if (n->d.obj[i].lhs->type != JSMN_STRING &&
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n->d.obj[i].lhs->type != JSMN_PRIMITIVE)
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continue;
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else if (strcmp(name, n->d.obj[i].lhs->d.str))
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continue;
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break;
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}
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if (i == n->fields)
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return NULL;
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if (n->d.obj[i].rhs->type != JSMN_ARRAY)
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return NULL;
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return n->d.obj[i].rhs;
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}
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/*
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* Extract a single string from the returned JSON object, making sure
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* that it's the correct type.
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* Returns NULL on failure.
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*/
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char *
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json_getstr(struct jsmnn *n, const char *name)
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{
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size_t i;
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char *cp;
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if (n->type != JSMN_OBJECT)
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return NULL;
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for (i = 0; i < n->fields; i++) {
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if (n->d.obj[i].lhs->type != JSMN_STRING &&
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n->d.obj[i].lhs->type != JSMN_PRIMITIVE)
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continue;
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else if (strcmp(name, n->d.obj[i].lhs->d.str))
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continue;
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break;
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}
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if (i == n->fields)
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return NULL;
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if (n->d.obj[i].rhs->type != JSMN_STRING &&
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n->d.obj[i].rhs->type != JSMN_PRIMITIVE)
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return NULL;
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cp = strdup(n->d.obj[i].rhs->d.str);
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if (cp == NULL)
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warn("strdup");
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return cp;
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}
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/*
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* Parse an HTTP response body from a buffer of size "sz".
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* Returns an opaque pointer on success, otherwise NULL on error.
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*/
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struct jsmnn *
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json_parse(const char *buf, size_t sz)
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{
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struct jsmnn *n;
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jsmn_parser p;
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jsmntok_t *tok;
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int r;
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size_t tokcount;
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jsmn_init(&p);
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tokcount = 128;
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/* Do this until we don't need any more tokens. */
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again:
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tok = calloc(tokcount, sizeof(jsmntok_t));
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if (tok == NULL) {
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warn("calloc");
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return NULL;
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}
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/* Actually try to parse the JSON into the tokens. */
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r = jsmn_parse(&p, buf, sz, tok, tokcount);
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if (r < 0 && r == JSMN_ERROR_NOMEM) {
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tokcount *= 2;
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free(tok);
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goto again;
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} else if (r < 0) {
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warnx("jsmn_parse: %d", r);
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free(tok);
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return NULL;
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}
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/* Now parse the tokens into a tree. */
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n = jsmntree_alloc(tok, buf, r);
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free(tok);
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return n;
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}
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