| /* |
| * Lightweight Embedded JSON Parser |
| * |
| * Copyright (C) 2013 Andy Green <andy@warmcat.com> |
| * This code is licensed under LGPL 2.1 |
| * http://www.gnu.org/licenses/lgpl-2.1.html |
| */ |
| |
| #include <string.h> |
| #include "lejp.h" |
| |
| #include <stdio.h> |
| |
| /** |
| * lejp_construct - prepare a struct lejp_ctx for use |
| * |
| * @ctx: pointer to your struct lejp_ctx |
| * @callback: your user callback which will received parsed tokens |
| * @user: optional user data pointer untouched by lejp |
| * @paths: your array of name elements you are interested in |
| * @count_paths: ARRAY_SIZE() of @paths |
| * |
| * Prepares your context struct for use with lejp |
| */ |
| |
| void |
| lejp_construct(struct lejp_ctx *ctx, |
| char (*callback)(struct lejp_ctx *ctx, char reason), void *user, |
| const char * const *paths, unsigned char count_paths) |
| { |
| ctx->st[0].s = 0; |
| ctx->st[0].p = 0; |
| ctx->st[0].i = 0; |
| ctx->st[0].b = 0; |
| ctx->sp = 0; |
| ctx->ipos = 0; |
| ctx->ppos = 0; |
| ctx->path_match = 0; |
| ctx->path[0] = '\0'; |
| ctx->callback = callback; |
| ctx->user = user; |
| ctx->paths = paths; |
| ctx->count_paths = count_paths; |
| ctx->line = 1; |
| ctx->callback(ctx, LEJPCB_CONSTRUCTED); |
| } |
| |
| /** |
| * lejp_destruct - retire a previously constructed struct lejp_ctx |
| * |
| * @ctx: pointer to your struct lejp_ctx |
| * |
| * lejp does not perform any allocations, but since your user code might, this |
| * provides a one-time LEJPCB_DESTRUCTED callback at destruction time where |
| * you can clean up in your callback. |
| */ |
| |
| void |
| lejp_destruct(struct lejp_ctx *ctx) |
| { |
| /* no allocations... just let callback know what it happening */ |
| ctx->callback(ctx, LEJPCB_DESTRUCTED); |
| } |
| |
| /** |
| * lejp_change_callback - switch to a different callback from now on |
| * |
| * @ctx: pointer to your struct lejp_ctx |
| * @callback: your user callback which will received parsed tokens |
| * |
| * This tells the old callback it was destroyed, in case you want to take any |
| * action because that callback "lost focus", then changes to the new |
| * callback and tells it first that it was constructed, and then started. |
| * |
| * Changing callback is a cheap and powerful trick to split out handlers |
| * according to information earlier in the parse. For example you may have |
| * a JSON pair "schema" whose value defines what can be expected for the rest |
| * of the JSON. Rather than having one huge callback for all cases, you can |
| * have an initial one looking for "schema" which then calls |
| * lejp_change_callback() to a handler specific for the schema. |
| * |
| * Notice that afterwards, you need to construct the context again anyway to |
| * parse another JSON object, and the callback is reset then to the main, |
| * schema-interpreting one. The construction action is very lightweight. |
| */ |
| |
| void |
| lejp_change_callback(struct lejp_ctx *ctx, |
| char (*callback)(struct lejp_ctx *ctx, char reason)) |
| { |
| ctx->callback(ctx, LEJPCB_DESTRUCTED); |
| ctx->callback = callback; |
| ctx->callback(ctx, LEJPCB_CONSTRUCTED); |
| ctx->callback(ctx, LEJPCB_START); |
| } |
| |
| static void |
| lejp_check_path_match(struct lejp_ctx *ctx) |
| { |
| const char *p, *q; |
| int n; |
| |
| /* we only need to check if a match is not active */ |
| for (n = 0; !ctx->path_match && n < ctx->count_paths; n++) { |
| ctx->wildcount = 0; |
| p = ctx->path; |
| q = ctx->paths[n]; |
| while (*p && *q) { |
| if (*q != '*') { |
| if (*p != *q) |
| break; |
| p++; |
| q++; |
| continue; |
| } |
| ctx->wild[ctx->wildcount++] = p - ctx->path; |
| q++; |
| while (*p && *p != '.') |
| p++; |
| } |
| if (*p || *q) |
| continue; |
| |
| ctx->path_match = n + 1; |
| ctx->path_match_len = ctx->ppos; |
| return; |
| } |
| |
| if (!ctx->path_match) |
| ctx->wildcount = 0; |
| } |
| |
| int |
| lejp_get_wildcard(struct lejp_ctx *ctx, int wildcard, char *dest, int len) |
| { |
| int n; |
| |
| if (wildcard >= ctx->wildcount || !len) |
| return 0; |
| |
| n = ctx->wild[wildcard]; |
| |
| while (--len && n < ctx->ppos && ctx->path[n] != '.') |
| *dest++ = ctx->path[n++]; |
| |
| *dest = '\0'; |
| n++; |
| |
| return n - ctx->wild[wildcard]; |
| } |
| |
| /** |
| * lejp_parse - interpret some more incoming data incrementally |
| * |
| * @ctx: previously constructed parsing context |
| * @json: char buffer with the new data to interpret |
| * @len: amount of data in the buffer |
| * |
| * Because lejp is a stream parser, it incrementally parses as new data |
| * becomes available, maintaining all state in the context struct. So an |
| * incomplete JSON is a normal situation, getting you a LEJP_CONTINUE |
| * return, signalling there's no error but to call again with more data when |
| * it comes to complete the parsing. Successful parsing completes with a |
| * 0 or positive integer indicating how much of the last input buffer was |
| * unused. |
| */ |
| |
| int |
| lejp_parse(struct lejp_ctx *ctx, const unsigned char *json, int len) |
| { |
| unsigned char c, n, s, ret = LEJP_REJECT_UNKNOWN; |
| static const char esc_char[] = "\"\\/bfnrt"; |
| static const char esc_tran[] = "\"\\/\b\f\n\r\t"; |
| static const char tokens[] = "rue alse ull "; |
| |
| if (!ctx->sp && !ctx->ppos) |
| ctx->callback(ctx, LEJPCB_START); |
| |
| while (len--) { |
| c = *json++; |
| |
| s = ctx->st[ctx->sp].s; |
| |
| /* skip whitespace unless we should care */ |
| if (c == ' ' || c == '\t' || c == '\n' || c == '\r' || c == '#') { |
| if (c == '\n') { |
| ctx->line++; |
| ctx->st[ctx->sp].s &= ~LEJP_FLAG_WS_COMMENTLINE; |
| } |
| if (!(s & LEJP_FLAG_WS_KEEP)) { |
| if (c == '#') |
| ctx->st[ctx->sp].s |= |
| LEJP_FLAG_WS_COMMENTLINE; |
| continue; |
| } |
| } |
| |
| if (ctx->st[ctx->sp].s & LEJP_FLAG_WS_COMMENTLINE) |
| continue; |
| |
| switch (s) { |
| case LEJP_IDLE: |
| if (c != '{') { |
| ret = LEJP_REJECT_IDLE_NO_BRACE; |
| goto reject; |
| } |
| ctx->callback(ctx, LEJPCB_OBJECT_START); |
| ctx->st[ctx->sp].s = LEJP_MEMBERS; |
| break; |
| case LEJP_MEMBERS: |
| if (c == '}') { |
| ctx->st[ctx->sp].s = LEJP_IDLE; |
| ret = LEJP_REJECT_MEMBERS_NO_CLOSE; |
| goto reject; |
| } |
| ctx->st[ctx->sp].s = LEJP_M_P; |
| goto redo_character; |
| case LEJP_M_P: |
| if (c != '\"') { |
| ret = LEJP_REJECT_MP_NO_OPEN_QUOTE; |
| goto reject; |
| } |
| /* push */ |
| ctx->st[ctx->sp].s = LEJP_MP_DELIM; |
| c = LEJP_MP_STRING; |
| goto add_stack_level; |
| |
| case LEJP_MP_STRING: |
| if (c == '\"') { |
| if (!ctx->sp) { |
| ret = LEJP_REJECT_MP_STRING_UNDERRUN; |
| goto reject; |
| } |
| if (ctx->st[ctx->sp - 1].s != LEJP_MP_DELIM) { |
| ctx->buf[ctx->npos] = '\0'; |
| if (ctx->callback(ctx, |
| LEJPCB_VAL_STR_END) < 0) { |
| ret = LEJP_REJECT_CALLBACK; |
| goto reject; |
| } |
| } |
| /* pop */ |
| ctx->sp--; |
| break; |
| } |
| if (c == '\\') { |
| ctx->st[ctx->sp].s = LEJP_MP_STRING_ESC; |
| break; |
| } |
| if (c < ' ') {/* "control characters" not allowed */ |
| ret = LEJP_REJECT_MP_ILLEGAL_CTRL; |
| goto reject; |
| } |
| goto emit_string_char; |
| |
| case LEJP_MP_STRING_ESC: |
| if (c == 'u') { |
| ctx->st[ctx->sp].s = LEJP_MP_STRING_ESC_U1; |
| ctx->uni = 0; |
| break; |
| } |
| for (n = 0; n < sizeof(esc_char); n++) { |
| if (c != esc_char[n]) |
| continue; |
| /* found it */ |
| c = esc_tran[n]; |
| ctx->st[ctx->sp].s = LEJP_MP_STRING; |
| goto emit_string_char; |
| } |
| ret = LEJP_REJECT_MP_STRING_ESC_ILLEGAL_ESC; |
| /* illegal escape char */ |
| goto reject; |
| |
| case LEJP_MP_STRING_ESC_U1: |
| case LEJP_MP_STRING_ESC_U2: |
| case LEJP_MP_STRING_ESC_U3: |
| case LEJP_MP_STRING_ESC_U4: |
| ctx->uni <<= 4; |
| if (c >= '0' && c <= '9') |
| ctx->uni |= c - '0'; |
| else |
| if (c >= 'a' && c <= 'f') |
| ctx->uni = c - 'a' + 10; |
| else |
| if (c >= 'A' && c <= 'F') |
| ctx->uni = c - 'A' + 10; |
| else { |
| ret = LEJP_REJECT_ILLEGAL_HEX; |
| goto reject; |
| } |
| ctx->st[ctx->sp].s++; |
| switch (s) { |
| case LEJP_MP_STRING_ESC_U2: |
| if (ctx->uni < 0x08) |
| break; |
| /* |
| * 0x08-0xff (0x0800 - 0xffff) |
| * emit 3-byte UTF-8 |
| */ |
| c = 0xe0 | ((ctx->uni >> 4) & 0xf); |
| goto emit_string_char; |
| |
| case LEJP_MP_STRING_ESC_U3: |
| if (ctx->uni >= 0x080) { |
| /* |
| * 0x080 - 0xfff (0x0800 - 0xffff) |
| * middle 3-byte seq |
| * send ....XXXXXX.. |
| */ |
| c = 0x80 | ((ctx->uni >> 2) & 0x3f); |
| goto emit_string_char; |
| } |
| if (ctx->uni < 0x008) |
| break; |
| /* |
| * 0x008 - 0x7f (0x0080 - 0x07ff) |
| * start 2-byte seq |
| */ |
| c = 0xc0 | (ctx->uni >> 2); |
| goto emit_string_char; |
| |
| case LEJP_MP_STRING_ESC_U4: |
| if (ctx->uni >= 0x0080) |
| /* end of 2 or 3-byte seq */ |
| c = 0x80 | (ctx->uni & 0x3f); |
| else |
| /* literal */ |
| c = (unsigned char)ctx->uni; |
| |
| ctx->st[ctx->sp].s = LEJP_MP_STRING; |
| goto emit_string_char; |
| default: |
| break; |
| } |
| break; |
| |
| case LEJP_MP_DELIM: |
| if (c != ':') { |
| ret = LEJP_REJECT_MP_DELIM_MISSING_COLON; |
| goto reject; |
| } |
| ctx->st[ctx->sp].s = LEJP_MP_VALUE; |
| ctx->path[ctx->ppos] = '\0'; |
| |
| lejp_check_path_match(ctx); |
| ctx->callback(ctx, LEJPCB_PAIR_NAME); |
| break; |
| |
| case LEJP_MP_VALUE: |
| if (c >= '0' && c <= '9') { |
| ctx->npos = 0; |
| ctx->dcount = 0; |
| ctx->f = 0; |
| ctx->st[ctx->sp].s = LEJP_MP_VALUE_NUM_INT; |
| goto redo_character; |
| } |
| switch (c) { |
| case'\"': |
| /* push */ |
| ctx->st[ctx->sp].s = LEJP_MP_COMMA_OR_END; |
| c = LEJP_MP_STRING; |
| ctx->npos = 0; |
| ctx->buf[0] = '\0'; |
| ctx->callback(ctx, LEJPCB_VAL_STR_START); |
| goto add_stack_level; |
| |
| case '{': |
| /* push */ |
| ctx->st[ctx->sp].s = LEJP_MP_COMMA_OR_END; |
| c = LEJP_MEMBERS; |
| lejp_check_path_match(ctx); |
| ctx->callback(ctx, LEJPCB_OBJECT_START); |
| ctx->path_match = 0; |
| goto add_stack_level; |
| |
| case '[': |
| /* push */ |
| ctx->st[ctx->sp].s = LEJP_MP_ARRAY_END; |
| c = LEJP_MP_VALUE; |
| ctx->path[ctx->ppos++] = '['; |
| ctx->path[ctx->ppos++] = ']'; |
| ctx->path[ctx->ppos] = '\0'; |
| ctx->callback(ctx, LEJPCB_ARRAY_START); |
| ctx->i[ctx->ipos++] = 0; |
| if (ctx->ipos > ARRAY_SIZE(ctx->i)) { |
| ret = LEJP_REJECT_MP_DELIM_ISTACK; |
| goto reject; |
| } |
| goto add_stack_level; |
| |
| case 't': /* true */ |
| ctx->uni = 0; |
| ctx->st[ctx->sp].s = LEJP_MP_VALUE_TOK; |
| break; |
| |
| case 'f': |
| ctx->uni = 4; |
| ctx->st[ctx->sp].s = LEJP_MP_VALUE_TOK; |
| break; |
| |
| case 'n': |
| ctx->uni = 4 + 5; |
| ctx->st[ctx->sp].s = LEJP_MP_VALUE_TOK; |
| break; |
| default: |
| ret = LEJP_REJECT_MP_DELIM_BAD_VALUE_START; |
| goto reject; |
| } |
| break; |
| |
| case LEJP_MP_VALUE_NUM_INT: |
| if (!ctx->npos && c == '-') { |
| ctx->f |= LEJP_SEEN_MINUS; |
| goto append_npos; |
| } |
| |
| if (ctx->dcount < 10 && c >= '0' && c <= '9') { |
| if (ctx->f & LEJP_SEEN_POINT) |
| ctx->f |= LEJP_SEEN_POST_POINT; |
| ctx->dcount++; |
| goto append_npos; |
| } |
| if (c == '.') { |
| if (ctx->dcount || (ctx->f & LEJP_SEEN_POINT)) { |
| ret = LEJP_REJECT_MP_VAL_NUM_FORMAT; |
| goto reject; |
| } |
| ctx->f |= LEJP_SEEN_POINT; |
| goto append_npos; |
| } |
| /* |
| * before exponent, if we had . we must have had at |
| * least one more digit |
| */ |
| if ((ctx->f & |
| (LEJP_SEEN_POINT | LEJP_SEEN_POST_POINT)) == |
| LEJP_SEEN_POINT) { |
| ret = LEJP_REJECT_MP_VAL_NUM_INT_NO_FRAC; |
| goto reject; |
| } |
| if (c == 'e' || c == 'E') { |
| if (ctx->f & LEJP_SEEN_EXP) { |
| ret = LEJP_REJECT_MP_VAL_NUM_FORMAT; |
| goto reject; |
| } |
| ctx->f |= LEJP_SEEN_EXP; |
| ctx->st[ctx->sp].s = LEJP_MP_VALUE_NUM_EXP; |
| goto append_npos; |
| } |
| /* if none of the above, did we even have a number? */ |
| if (!ctx->dcount) { |
| ret = LEJP_REJECT_MP_VAL_NUM_FORMAT; |
| goto reject; |
| } |
| |
| ctx->buf[ctx->npos] = '\0'; |
| if (ctx->f & LEJP_SEEN_POINT) |
| ctx->callback(ctx, LEJPCB_VAL_NUM_FLOAT); |
| else |
| ctx->callback(ctx, LEJPCB_VAL_NUM_INT); |
| |
| /* then this is the post-number character, loop */ |
| ctx->st[ctx->sp].s = LEJP_MP_COMMA_OR_END; |
| goto redo_character; |
| |
| case LEJP_MP_VALUE_NUM_EXP: |
| ctx->st[ctx->sp].s = LEJP_MP_VALUE_NUM_INT; |
| if (c >= '0' && c <= '9') |
| goto redo_character; |
| if (c == '+' || c == '-') |
| goto append_npos; |
| ret = LEJP_REJECT_MP_VAL_NUM_EXP_BAD_EXP; |
| goto reject; |
| |
| case LEJP_MP_VALUE_TOK: /* true, false, null */ |
| if (c != tokens[ctx->uni]) { |
| ret = LEJP_REJECT_MP_VAL_TOK_UNKNOWN; |
| goto reject; |
| } |
| ctx->uni++; |
| if (tokens[ctx->uni] != ' ') |
| break; |
| switch (ctx->uni) { |
| case 3: |
| ctx->buf[0] = '1'; |
| ctx->buf[1] = '\0'; |
| ctx->callback(ctx, LEJPCB_VAL_TRUE); |
| break; |
| case 8: |
| ctx->buf[0] = '0'; |
| ctx->buf[1] = '\0'; |
| ctx->callback(ctx, LEJPCB_VAL_FALSE); |
| break; |
| case 12: |
| ctx->buf[0] = '\0'; |
| ctx->callback(ctx, LEJPCB_VAL_NULL); |
| break; |
| } |
| ctx->st[ctx->sp].s = LEJP_MP_COMMA_OR_END; |
| break; |
| |
| case LEJP_MP_COMMA_OR_END: |
| ctx->path[ctx->ppos] = '\0'; |
| if (c == ',') { |
| /* increment this stack level's index */ |
| ctx->st[ctx->sp].s = LEJP_M_P; |
| if (!ctx->sp) { |
| ctx->ppos = 0; |
| /* |
| * since we came back to root level, |
| * no path can still match |
| */ |
| ctx->path_match = 0; |
| break; |
| } |
| ctx->ppos = ctx->st[ctx->sp - 1].p; |
| ctx->path[ctx->ppos] = '\0'; |
| if (ctx->path_match && |
| ctx->ppos <= ctx->path_match_len) |
| /* |
| * we shrank the path to be |
| * smaller than the matching point |
| */ |
| ctx->path_match = 0; |
| |
| if (ctx->st[ctx->sp - 1].s != LEJP_MP_ARRAY_END) |
| break; |
| /* top level is definitely an array... */ |
| if (ctx->ipos) |
| ctx->i[ctx->ipos - 1]++; |
| ctx->st[ctx->sp].s = LEJP_MP_VALUE; |
| break; |
| } |
| if (c == ']') { |
| if (!ctx->sp) { |
| ret = LEJP_REJECT_MP_C_OR_E_UNDERF; |
| goto reject; |
| } |
| /* pop */ |
| ctx->sp--; |
| if (ctx->st[ctx->sp].s != LEJP_MP_ARRAY_END) { |
| ret = LEJP_REJECT_MP_C_OR_E_NOTARRAY; |
| goto reject; |
| } |
| /* drop the path [n] bit */ |
| ctx->ppos = ctx->st[ctx->sp - 1].p; |
| ctx->ipos = ctx->st[ctx->sp - 1].i; |
| ctx->path[ctx->ppos] = '\0'; |
| if (ctx->path_match && |
| ctx->ppos <= ctx->path_match_len) |
| /* |
| * we shrank the path to be |
| * smaller than the matching point |
| */ |
| ctx->path_match = 0; |
| |
| /* do LEJP_MP_ARRAY_END processing */ |
| goto redo_character; |
| } |
| if (c == '}') { |
| if (ctx->sp == 0) { |
| lejp_check_path_match(ctx); |
| ctx->callback(ctx, LEJPCB_OBJECT_END); |
| ctx->callback(ctx, LEJPCB_COMPLETE); |
| /* done, return unused amount */ |
| return len; |
| } |
| /* pop */ |
| ctx->sp--; |
| ctx->ppos = ctx->st[ctx->sp - 1].p; |
| ctx->ipos = ctx->st[ctx->sp - 1].i; |
| ctx->path[ctx->ppos] = '\0'; |
| if (ctx->path_match && |
| ctx->ppos <= ctx->path_match_len) |
| /* |
| * we shrank the path to be |
| * smaller than the matching point |
| */ |
| ctx->path_match = 0; |
| lejp_check_path_match(ctx); |
| ctx->callback(ctx, LEJPCB_OBJECT_END); |
| break; |
| } |
| |
| ret = LEJP_REJECT_MP_C_OR_E_NEITHER; |
| goto reject; |
| |
| case LEJP_MP_ARRAY_END: |
| ctx->path[ctx->ppos] = '\0'; |
| if (c == ',') { |
| /* increment this stack level's index */ |
| if (ctx->ipos) |
| ctx->i[ctx->ipos - 1]++; |
| ctx->st[ctx->sp].s = LEJP_MP_VALUE; |
| if (ctx->sp) |
| ctx->ppos = ctx->st[ctx->sp - 1].p; |
| ctx->path[ctx->ppos] = '\0'; |
| break; |
| } |
| if (c != ']') { |
| ret = LEJP_REJECT_MP_ARRAY_END_MISSING; |
| goto reject; |
| } |
| |
| ctx->st[ctx->sp].s = LEJP_MP_COMMA_OR_END; |
| ctx->callback(ctx, LEJPCB_ARRAY_END); |
| break; |
| } |
| |
| continue; |
| |
| emit_string_char: |
| if (!ctx->sp || ctx->st[ctx->sp - 1].s != LEJP_MP_DELIM) { |
| /* assemble the string value into chunks */ |
| ctx->buf[ctx->npos++] = c; |
| if (ctx->npos == sizeof(ctx->buf) - 1) { |
| ctx->callback(ctx, LEJPCB_VAL_STR_CHUNK); |
| ctx->npos = 0; |
| } |
| continue; |
| } |
| /* name part of name:value pair */ |
| ctx->path[ctx->ppos++] = c; |
| continue; |
| |
| add_stack_level: |
| /* push on to the object stack */ |
| if (ctx->ppos && ctx->st[ctx->sp].s != LEJP_MP_COMMA_OR_END && |
| ctx->st[ctx->sp].s != LEJP_MP_ARRAY_END) |
| ctx->path[ctx->ppos++] = '.'; |
| |
| ctx->st[ctx->sp].p = ctx->ppos; |
| ctx->st[ctx->sp].i = ctx->ipos; |
| if (++ctx->sp == ARRAY_SIZE(ctx->st)) { |
| ret = LEJP_REJECT_STACK_OVERFLOW; |
| goto reject; |
| } |
| ctx->path[ctx->ppos] = '\0'; |
| ctx->st[ctx->sp].s = c; |
| ctx->st[ctx->sp].b = 0; |
| continue; |
| |
| append_npos: |
| if (ctx->npos >= sizeof(ctx->buf)) { |
| ret = LEJP_REJECT_NUM_TOO_LONG; |
| goto reject; |
| } |
| ctx->buf[ctx->npos++] = c; |
| continue; |
| |
| redo_character: |
| json--; |
| len++; |
| } |
| |
| return LEJP_CONTINUE; |
| |
| reject: |
| ctx->callback(ctx, LEJPCB_FAILED); |
| return ret; |
| } |