/* * Copyright 2010, Lloyd Hilaiel. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are * met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. Neither the name of Lloyd Hilaiel nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ #include "yajl_lex.h" #include "yajl_buf.h" #include #include #include #include const char *yajl_tok_name(yajl_tok tok) { switch (tok) { case yajl_tok_bool: return "bool"; case yajl_tok_colon: return "colon"; case yajl_tok_comma: return "comma"; case yajl_tok_eof: return "eof"; case yajl_tok_error: return "error"; case yajl_tok_left_brace: return "open_array"; case yajl_tok_left_bracket: return "open_object"; case yajl_tok_null: return "null"; case yajl_tok_integer: return "integer"; case yajl_tok_double: return "double"; case yajl_tok_right_brace: return "close_array"; case yajl_tok_right_bracket: return "close_object"; case yajl_tok_string: return "string"; case yajl_tok_string_with_escapes: return "string_with_escapes"; } return "unknown"; } /* Impact of the stream parsing feature on the lexer: * * YAJL support stream parsing. That is, the ability to parse the first * bits of a chunk of JSON before the last bits are available (still on * the network or disk). This makes the lexer more complex. The * responsibility of the lexer is to handle transparently the case where * a chunk boundary falls in the middle of a token. This is * accomplished is via a buffer and a character reading abstraction. * * Overview of implementation * * When we lex to end of input string before end of token is hit, we * copy all of the input text composing the token into our lexBuf. * * Every time we read a character, we do so through the readChar function. * readChar's responsibility is to handle pulling all chars from the buffer * before pulling chars from input text */ struct yajl_lexer_t { /* the overal line and char offset into the data */ unsigned int lineOff; unsigned int charOff; /* error */ yajl_lex_error error; /* a input buffer to handle the case where a token is spread over * multiple chunks */ yajl_buf buf; /* in the case where we have data in the lexBuf, bufOff holds * the current offset into the lexBuf. */ unsigned int bufOff; /* are we using the lex buf? */ unsigned int bufInUse; /* shall we allow comments? */ unsigned int allowComments; /* shall we validate utf8 inside strings? */ unsigned int validateUTF8; yajl_alloc_funcs * alloc; }; #define readChar(lxr, txt, off) \ (((lxr)->bufInUse && yajl_buf_len((lxr)->buf) && lxr->bufOff < yajl_buf_len((lxr)->buf)) ? \ (*((const unsigned char *) yajl_buf_data((lxr)->buf) + ((lxr)->bufOff)++)) : \ ((txt)[(*(off))++])) #define unreadChar(lxr, off) ((*(off) > 0) ? (*(off))-- : ((lxr)->bufOff--)) yajl_lexer yajl_lex_alloc(yajl_alloc_funcs * alloc, unsigned int allowComments, unsigned int validateUTF8) { yajl_lexer lxr = (yajl_lexer) YA_MALLOC(alloc, sizeof(struct yajl_lexer_t)); memset((void *) lxr, 0, sizeof(struct yajl_lexer_t)); lxr->buf = yajl_buf_alloc(alloc); lxr->allowComments = allowComments; lxr->validateUTF8 = validateUTF8; lxr->alloc = alloc; return lxr; } yajl_lexer yajl_lex_realloc(yajl_lexer orig) { orig->lineOff = 0; orig->charOff = 0; orig->error = yajl_lex_e_ok; yajl_buf_clear(orig->buf); orig->bufOff = 0; orig->bufInUse = 0; return orig; } void yajl_lex_free(yajl_lexer lxr) { yajl_buf_free(lxr->buf); YA_FREE(lxr->alloc, lxr); return; } /* a lookup table which lets us quickly determine three things: * VEC - valid escaped conrol char * IJC - invalid json char * VHC - valid hex char * note. the solidus '/' may be escaped or not. * note. the */ #define VEC 1 #define IJC 2 #define VHC 4 static const char charLookupTable[256] = { /*00*/ IJC , IJC , IJC , IJC , IJC , IJC , IJC , IJC , /*08*/ IJC , IJC , IJC , IJC , IJC , IJC , IJC , IJC , /*10*/ IJC , IJC , IJC , IJC , IJC , IJC , IJC , IJC , /*18*/ IJC , IJC , IJC , IJC , IJC , IJC , IJC , IJC , /*20*/ 0 , 0 , VEC|IJC, 0 , 0 , 0 , 0 , 0 , /*28*/ 0 , 0 , 0 , 0 , 0 , 0 , 0 , VEC , /*30*/ VHC , VHC , VHC , VHC , VHC , VHC , VHC , VHC , /*38*/ VHC , VHC , 0 , 0 , 0 , 0 , 0 , 0 , /*40*/ 0 , VHC , VHC , VHC , VHC , VHC , VHC , 0 , /*48*/ 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , /*50*/ 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , /*58*/ 0 , 0 , 0 , 0 , VEC|IJC, 0 , 0 , 0 , /*60*/ 0 , VHC , VEC|VHC, VHC , VHC , VHC , VEC|VHC, 0 , /*68*/ 0 , 0 , 0 , 0 , 0 , 0 , VEC , 0 , /*70*/ 0 , 0 , VEC , 0 , VEC , 0 , 0 , 0 , /*78*/ 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , /* include these so we don't have to always check the range of the char */ 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 , 0 }; /** process a variable length utf8 encoded codepoint. * * returns: * yajl_tok_string - if valid utf8 char was parsed and offset was * advanced * yajl_tok_eof - if end of input was hit before validation could * complete * yajl_tok_error - if invalid utf8 was encountered * * NOTE: on error the offset will point to the first char of the * invalid utf8 */ #define UTF8_CHECK_EOF if (*offset >= jsonTextLen) { return yajl_tok_eof; } static yajl_tok yajl_lex_utf8_char(yajl_lexer lexer, const unsigned char * jsonText, unsigned int jsonTextLen, unsigned int * offset, unsigned char curChar) { if (curChar <= 0x7f) { /* single byte */ return yajl_tok_string; } else if ((curChar >> 5) == 0x6) { /* two byte */ UTF8_CHECK_EOF; curChar = readChar(lexer, jsonText, offset); if ((curChar >> 6) == 0x2) return yajl_tok_string; } else if ((curChar >> 4) == 0x0e) { /* three byte */ UTF8_CHECK_EOF; curChar = readChar(lexer, jsonText, offset); if ((curChar >> 6) == 0x2) { UTF8_CHECK_EOF; curChar = readChar(lexer, jsonText, offset); if ((curChar >> 6) == 0x2) return yajl_tok_string; } } else if ((curChar >> 3) == 0x1e) { /* four byte */ UTF8_CHECK_EOF; curChar = readChar(lexer, jsonText, offset); if ((curChar >> 6) == 0x2) { UTF8_CHECK_EOF; curChar = readChar(lexer, jsonText, offset); if ((curChar >> 6) == 0x2) { UTF8_CHECK_EOF; curChar = readChar(lexer, jsonText, offset); if ((curChar >> 6) == 0x2) return yajl_tok_string; } } } return yajl_tok_error; } /* lex a string. input is the lexer, pointer to beginning of * json text, and start of string (offset). * a token is returned which has the following meanings: * yajl_tok_string: lex of string was successful. offset points to * terminating '"'. * yajl_tok_eof: end of text was encountered before we could complete * the lex. * yajl_tok_error: embedded in the string were unallowable chars. offset * points to the offending char */ #define STR_CHECK_EOF \ if (*offset >= jsonTextLen) { \ tok = yajl_tok_eof; \ goto finish_string_lex; \ } static yajl_tok yajl_lex_string(yajl_lexer lexer, const unsigned char * jsonText, unsigned int jsonTextLen, unsigned int * offset) { yajl_tok tok = yajl_tok_error; int hasEscapes = 0; for (;;) { unsigned char curChar; STR_CHECK_EOF; curChar = readChar(lexer, jsonText, offset); /* quote terminates */ if (curChar == '"') { tok = yajl_tok_string; break; } /* backslash escapes a set of control chars, */ else if (curChar == '\\') { hasEscapes = 1; STR_CHECK_EOF; /* special case \u */ curChar = readChar(lexer, jsonText, offset); if (curChar == 'u') { unsigned int i = 0; for (i=0;i<4;i++) { STR_CHECK_EOF; curChar = readChar(lexer, jsonText, offset); if (!(charLookupTable[curChar] & VHC)) { /* back up to offending char */ unreadChar(lexer, offset); lexer->error = yajl_lex_string_invalid_hex_char; goto finish_string_lex; } } } else if (!(charLookupTable[curChar] & VEC)) { /* back up to offending char */ unreadChar(lexer, offset); lexer->error = yajl_lex_string_invalid_escaped_char; goto finish_string_lex; } } /* when not validating UTF8 it's a simple table lookup to determine * if the present character is invalid */ else if(charLookupTable[curChar] & IJC) { /* back up to offending char */ unreadChar(lexer, offset); lexer->error = yajl_lex_string_invalid_json_char; goto finish_string_lex; } /* when in validate UTF8 mode we need to do some extra work */ else if (lexer->validateUTF8) { yajl_tok t = yajl_lex_utf8_char(lexer, jsonText, jsonTextLen, offset, curChar); if (t == yajl_tok_eof) { tok = yajl_tok_eof; goto finish_string_lex; } else if (t == yajl_tok_error) { lexer->error = yajl_lex_string_invalid_utf8; goto finish_string_lex; } } /* accept it, and move on */ } finish_string_lex: /* tell our buddy, the parser, wether he needs to process this string * again */ if (hasEscapes && tok == yajl_tok_string) { tok = yajl_tok_string_with_escapes; } return tok; } #define RETURN_IF_EOF if (*offset >= jsonTextLen) return yajl_tok_eof; static yajl_tok yajl_lex_number(yajl_lexer lexer, const unsigned char * jsonText, unsigned int jsonTextLen, unsigned int * offset) { /** XXX: numbers are the only entities in json that we must lex * _beyond_ in order to know that they are complete. There * is an ambiguous case for integers at EOF. */ unsigned char c; yajl_tok tok = yajl_tok_integer; RETURN_IF_EOF; c = readChar(lexer, jsonText, offset); /* optional leading minus */ if (c == '-') { RETURN_IF_EOF; c = readChar(lexer, jsonText, offset); } /* a single zero, or a series of integers */ if (c == '0') { RETURN_IF_EOF; c = readChar(lexer, jsonText, offset); } else if (c >= '1' && c <= '9') { do { RETURN_IF_EOF; c = readChar(lexer, jsonText, offset); } while (c >= '0' && c <= '9'); } else { unreadChar(lexer, offset); lexer->error = yajl_lex_missing_integer_after_minus; return yajl_tok_error; } /* optional fraction (indicates this is floating point) */ if (c == '.') { int numRd = 0; RETURN_IF_EOF; c = readChar(lexer, jsonText, offset); while (c >= '0' && c <= '9') { numRd++; RETURN_IF_EOF; c = readChar(lexer, jsonText, offset); } if (!numRd) { unreadChar(lexer, offset); lexer->error = yajl_lex_missing_integer_after_decimal; return yajl_tok_error; } tok = yajl_tok_double; } /* optional exponent (indicates this is floating point) */ if (c == 'e' || c == 'E') { RETURN_IF_EOF; c = readChar(lexer, jsonText, offset); /* optional sign */ if (c == '+' || c == '-') { RETURN_IF_EOF; c = readChar(lexer, jsonText, offset); } if (c >= '0' && c <= '9') { do { RETURN_IF_EOF; c = readChar(lexer, jsonText, offset); } while (c >= '0' && c <= '9'); } else { unreadChar(lexer, offset); lexer->error = yajl_lex_missing_integer_after_exponent; return yajl_tok_error; } tok = yajl_tok_double; } /* we always go "one too far" */ unreadChar(lexer, offset); return tok; } static yajl_tok yajl_lex_comment(yajl_lexer lexer, const unsigned char * jsonText, unsigned int jsonTextLen, unsigned int * offset) { unsigned char c; yajl_tok tok = yajl_tok_comment; RETURN_IF_EOF; c = readChar(lexer, jsonText, offset); /* either slash or star expected */ if (c == '/') { /* now we throw away until end of line */ do { RETURN_IF_EOF; c = readChar(lexer, jsonText, offset); } while (c != '\n'); } else if (c == '*') { /* now we throw away until end of comment */ for (;;) { RETURN_IF_EOF; c = readChar(lexer, jsonText, offset); if (c == '*') { RETURN_IF_EOF; c = readChar(lexer, jsonText, offset); if (c == '/') { break; } else { unreadChar(lexer, offset); } } } } else { lexer->error = yajl_lex_invalid_char; tok = yajl_tok_error; } return tok; } yajl_tok yajl_lex_lex(yajl_lexer lexer, const unsigned char * jsonText, unsigned int jsonTextLen, unsigned int * offset, const unsigned char ** outBuf, unsigned int * outLen) { yajl_tok tok = yajl_tok_error; unsigned char c; unsigned int startOffset = *offset; *outBuf = NULL; *outLen = 0; for (;;) { assert(*offset <= jsonTextLen); if (*offset >= jsonTextLen) { tok = yajl_tok_eof; goto lexed; } c = readChar(lexer, jsonText, offset); switch (c) { case '{': tok = yajl_tok_left_bracket; goto lexed; case '}': tok = yajl_tok_right_bracket; goto lexed; case '[': tok = yajl_tok_left_brace; goto lexed; case ']': tok = yajl_tok_right_brace; goto lexed; case ',': tok = yajl_tok_comma; goto lexed; case ':': tok = yajl_tok_colon; goto lexed; case '\t': case '\n': case '\v': case '\f': case '\r': case ' ': startOffset++; break; case 't': { const char * want = "rue"; do { if (*offset >= jsonTextLen) { tok = yajl_tok_eof; goto lexed; } c = readChar(lexer, jsonText, offset); if (c != *want) { unreadChar(lexer, offset); lexer->error = yajl_lex_invalid_string; tok = yajl_tok_error; goto lexed; } } while (*(++want)); tok = yajl_tok_bool; goto lexed; } case 'f': { const char * want = "alse"; do { if (*offset >= jsonTextLen) { tok = yajl_tok_eof; goto lexed; } c = readChar(lexer, jsonText, offset); if (c != *want) { unreadChar(lexer, offset); lexer->error = yajl_lex_invalid_string; tok = yajl_tok_error; goto lexed; } } while (*(++want)); tok = yajl_tok_bool; goto lexed; } case 'n': { const char * want = "ull"; do { if (*offset >= jsonTextLen) { tok = yajl_tok_eof; goto lexed; } c = readChar(lexer, jsonText, offset); if (c != *want) { unreadChar(lexer, offset); lexer->error = yajl_lex_invalid_string; tok = yajl_tok_error; goto lexed; } } while (*(++want)); tok = yajl_tok_null; goto lexed; } case '"': { tok = yajl_lex_string(lexer, (const unsigned char *) jsonText, jsonTextLen, offset); goto lexed; } case '-': case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': { /* integer parsing wants to start from the beginning */ unreadChar(lexer, offset); tok = yajl_lex_number(lexer, (const unsigned char *) jsonText, jsonTextLen, offset); goto lexed; } case '/': /* hey, look, a probable comment! If comments are disabled * it's an error. */ if (!lexer->allowComments) { unreadChar(lexer, offset); lexer->error = yajl_lex_unallowed_comment; tok = yajl_tok_error; goto lexed; } /* if comments are enabled, then we should try to lex * the thing. possible outcomes are * - successful lex (tok_comment, which means continue), * - malformed comment opening (slash not followed by * '*' or '/') (tok_error) * - eof hit. (tok_eof) */ tok = yajl_lex_comment(lexer, (const unsigned char *) jsonText, jsonTextLen, offset); if (tok == yajl_tok_comment) { /* "error" is silly, but that's the initial * state of tok. guilty until proven innocent. */ tok = yajl_tok_error; yajl_buf_clear(lexer->buf); lexer->bufInUse = 0; startOffset = *offset; break; } /* hit error or eof, bail */ goto lexed; default: lexer->error = yajl_lex_invalid_char; tok = yajl_tok_error; goto lexed; } } lexed: /* need to append to buffer if the buffer is in use or * if it's an EOF token */ if (tok == yajl_tok_eof || lexer->bufInUse) { if (!lexer->bufInUse) yajl_buf_clear(lexer->buf); lexer->bufInUse = 1; yajl_buf_append(lexer->buf, jsonText + startOffset, *offset - startOffset); lexer->bufOff = 0; if (tok != yajl_tok_eof) { *outBuf = yajl_buf_data(lexer->buf); *outLen = yajl_buf_len(lexer->buf); lexer->bufInUse = 0; } } else if (tok != yajl_tok_error) { *outBuf = jsonText + startOffset; *outLen = *offset - startOffset; } /* special case for strings. skip the quotes. */ if (tok == yajl_tok_string || tok == yajl_tok_string_with_escapes) { assert(*outLen >= 2); (*outBuf)++; *outLen -= 2; } #ifdef YAJL_LEXER_DEBUG if (tok == yajl_tok_error) { printf("lexical error: %s\n", yajl_lex_error_to_string(yajl_lex_get_error(lexer))); } else if (tok == yajl_tok_eof) { printf("EOF hit\n"); } else { printf("lexed %s: '", tokToStr(tok)); fwrite(*outBuf, 1, *outLen, stdout); printf("'\n"); } #endif return tok; } const char * yajl_lex_error_to_string(yajl_lex_error error) { switch (error) { case yajl_lex_e_ok: return "ok, no error"; case yajl_lex_string_invalid_utf8: return "invalid bytes in UTF8 string."; case yajl_lex_string_invalid_escaped_char: return "inside a string, '\\' occurs before a character " "which it may not."; case yajl_lex_string_invalid_json_char: return "invalid character inside string."; case yajl_lex_string_invalid_hex_char: return "invalid (non-hex) character occurs after '\\u' inside " "string."; case yajl_lex_invalid_char: return "invalid char in json text."; case yajl_lex_invalid_string: return "invalid string in json text."; case yajl_lex_missing_integer_after_exponent: return "malformed number, a digit is required after the exponent."; case yajl_lex_missing_integer_after_decimal: return "malformed number, a digit is required after the " "decimal point."; case yajl_lex_missing_integer_after_minus: return "malformed number, a digit is required after the " "minus sign."; case yajl_lex_unallowed_comment: return "probable comment found in input text, comments are " "not enabled."; } return "unknown error code"; } /** allows access to more specific information about the lexical * error when yajl_lex_lex returns yajl_tok_error. */ yajl_lex_error yajl_lex_get_error(yajl_lexer lexer) { if (lexer == NULL) return (yajl_lex_error) -1; return lexer->error; } unsigned int yajl_lex_current_line(yajl_lexer lexer) { return lexer->lineOff; } unsigned int yajl_lex_current_char(yajl_lexer lexer) { return lexer->charOff; } yajl_tok yajl_lex_peek(yajl_lexer lexer, const unsigned char * jsonText, unsigned int jsonTextLen, unsigned int offset) { const unsigned char * outBuf; unsigned int outLen; unsigned int bufLen = yajl_buf_len(lexer->buf); unsigned int bufOff = lexer->bufOff; unsigned int bufInUse = lexer->bufInUse; yajl_tok tok; tok = yajl_lex_lex(lexer, jsonText, jsonTextLen, &offset, &outBuf, &outLen); if (tok == yajl_tok_eof) { return tok; } lexer->bufOff = bufOff; lexer->bufInUse = bufInUse; yajl_buf_truncate(lexer->buf, bufLen); return tok; }