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Diffstat (limited to 'src/common/jsonapi.c')
| -rw-r--r-- | src/common/jsonapi.c | 1134 |
1 files changed, 1134 insertions, 0 deletions
diff --git a/src/common/jsonapi.c b/src/common/jsonapi.c new file mode 100644 index 0000000..d376ab1 --- /dev/null +++ b/src/common/jsonapi.c @@ -0,0 +1,1134 @@ +/*------------------------------------------------------------------------- + * + * jsonapi.c + * JSON parser and lexer interfaces + * + * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * IDENTIFICATION + * src/common/jsonapi.c + * + *------------------------------------------------------------------------- + */ +#ifndef FRONTEND +#include "postgres.h" +#else +#include "postgres_fe.h" +#endif + +#include "common/jsonapi.h" +#include "mb/pg_wchar.h" + +#ifdef FRONTEND +#include "common/logging.h" +#else +#include "miscadmin.h" +#endif + +#ifdef FRONTEND +#define check_stack_depth() +#define json_log_and_abort(...) \ + do { pg_log_fatal(__VA_ARGS__); exit(1); } while(0) +#else +#define json_log_and_abort(...) elog(ERROR, __VA_ARGS__) +#endif + +/* + * The context of the parser is maintained by the recursive descent + * mechanism, but is passed explicitly to the error reporting routine + * for better diagnostics. + */ +typedef enum /* contexts of JSON parser */ +{ + JSON_PARSE_VALUE, /* expecting a value */ + JSON_PARSE_STRING, /* expecting a string (for a field name) */ + JSON_PARSE_ARRAY_START, /* saw '[', expecting value or ']' */ + JSON_PARSE_ARRAY_NEXT, /* saw array element, expecting ',' or ']' */ + JSON_PARSE_OBJECT_START, /* saw '{', expecting label or '}' */ + JSON_PARSE_OBJECT_LABEL, /* saw object label, expecting ':' */ + JSON_PARSE_OBJECT_NEXT, /* saw object value, expecting ',' or '}' */ + JSON_PARSE_OBJECT_COMMA, /* saw object ',', expecting next label */ + JSON_PARSE_END /* saw the end of a document, expect nothing */ +} JsonParseContext; + +static inline JsonParseErrorType json_lex_string(JsonLexContext *lex); +static inline JsonParseErrorType json_lex_number(JsonLexContext *lex, char *s, + bool *num_err, int *total_len); +static inline JsonParseErrorType parse_scalar(JsonLexContext *lex, JsonSemAction *sem); +static JsonParseErrorType parse_object_field(JsonLexContext *lex, JsonSemAction *sem); +static JsonParseErrorType parse_object(JsonLexContext *lex, JsonSemAction *sem); +static JsonParseErrorType parse_array_element(JsonLexContext *lex, JsonSemAction *sem); +static JsonParseErrorType parse_array(JsonLexContext *lex, JsonSemAction *sem); +static JsonParseErrorType report_parse_error(JsonParseContext ctx, JsonLexContext *lex); +static char *extract_token(JsonLexContext *lex); + +/* the null action object used for pure validation */ +JsonSemAction nullSemAction = +{ + NULL, NULL, NULL, NULL, NULL, + NULL, NULL, NULL, NULL, NULL +}; + +/* Recursive Descent parser support routines */ + +/* + * lex_peek + * + * what is the current look_ahead token? +*/ +static inline JsonTokenType +lex_peek(JsonLexContext *lex) +{ + return lex->token_type; +} + +/* + * lex_expect + * + * move the lexer to the next token if the current look_ahead token matches + * the parameter token. Otherwise, report an error. + */ +static inline JsonParseErrorType +lex_expect(JsonParseContext ctx, JsonLexContext *lex, JsonTokenType token) +{ + if (lex_peek(lex) == token) + return json_lex(lex); + else + return report_parse_error(ctx, lex); +} + +/* chars to consider as part of an alphanumeric token */ +#define JSON_ALPHANUMERIC_CHAR(c) \ + (((c) >= 'a' && (c) <= 'z') || \ + ((c) >= 'A' && (c) <= 'Z') || \ + ((c) >= '0' && (c) <= '9') || \ + (c) == '_' || \ + IS_HIGHBIT_SET(c)) + +/* + * Utility function to check if a string is a valid JSON number. + * + * str is of length len, and need not be null-terminated. + */ +bool +IsValidJsonNumber(const char *str, int len) +{ + bool numeric_error; + int total_len; + JsonLexContext dummy_lex; + + if (len <= 0) + return false; + + /* + * json_lex_number expects a leading '-' to have been eaten already. + * + * having to cast away the constness of str is ugly, but there's not much + * easy alternative. + */ + if (*str == '-') + { + dummy_lex.input = unconstify(char *, str) + 1; + dummy_lex.input_length = len - 1; + } + else + { + dummy_lex.input = unconstify(char *, str); + dummy_lex.input_length = len; + } + + json_lex_number(&dummy_lex, dummy_lex.input, &numeric_error, &total_len); + + return (!numeric_error) && (total_len == dummy_lex.input_length); +} + +/* + * makeJsonLexContextCstringLen + * + * lex constructor, with or without StringInfo object for de-escaped lexemes. + * + * Without is better as it makes the processing faster, so only make one + * if really required. + */ +JsonLexContext * +makeJsonLexContextCstringLen(char *json, int len, int encoding, bool need_escapes) +{ + JsonLexContext *lex = palloc0(sizeof(JsonLexContext)); + + lex->input = lex->token_terminator = lex->line_start = json; + lex->line_number = 1; + lex->input_length = len; + lex->input_encoding = encoding; + if (need_escapes) + lex->strval = makeStringInfo(); + return lex; +} + +/* + * pg_parse_json + * + * Publicly visible entry point for the JSON parser. + * + * lex is a lexing context, set up for the json to be processed by calling + * makeJsonLexContext(). sem is a structure of function pointers to semantic + * action routines to be called at appropriate spots during parsing, and a + * pointer to a state object to be passed to those routines. + */ +JsonParseErrorType +pg_parse_json(JsonLexContext *lex, JsonSemAction *sem) +{ + JsonTokenType tok; + JsonParseErrorType result; + + /* get the initial token */ + result = json_lex(lex); + if (result != JSON_SUCCESS) + return result; + + tok = lex_peek(lex); + + /* parse by recursive descent */ + switch (tok) + { + case JSON_TOKEN_OBJECT_START: + result = parse_object(lex, sem); + break; + case JSON_TOKEN_ARRAY_START: + result = parse_array(lex, sem); + break; + default: + result = parse_scalar(lex, sem); /* json can be a bare scalar */ + } + + if (result == JSON_SUCCESS) + result = lex_expect(JSON_PARSE_END, lex, JSON_TOKEN_END); + + return result; +} + +/* + * json_count_array_elements + * + * Returns number of array elements in lex context at start of array token + * until end of array token at same nesting level. + * + * Designed to be called from array_start routines. + */ +JsonParseErrorType +json_count_array_elements(JsonLexContext *lex, int *elements) +{ + JsonLexContext copylex; + int count; + JsonParseErrorType result; + + /* + * It's safe to do this with a shallow copy because the lexical routines + * don't scribble on the input. They do scribble on the other pointers + * etc, so doing this with a copy makes that safe. + */ + memcpy(©lex, lex, sizeof(JsonLexContext)); + copylex.strval = NULL; /* not interested in values here */ + copylex.lex_level++; + + count = 0; + result = lex_expect(JSON_PARSE_ARRAY_START, ©lex, + JSON_TOKEN_ARRAY_START); + if (result != JSON_SUCCESS) + return result; + if (lex_peek(©lex) != JSON_TOKEN_ARRAY_END) + { + while (1) + { + count++; + result = parse_array_element(©lex, &nullSemAction); + if (result != JSON_SUCCESS) + return result; + if (copylex.token_type != JSON_TOKEN_COMMA) + break; + result = json_lex(©lex); + if (result != JSON_SUCCESS) + return result; + } + } + result = lex_expect(JSON_PARSE_ARRAY_NEXT, ©lex, + JSON_TOKEN_ARRAY_END); + if (result != JSON_SUCCESS) + return result; + + *elements = count; + return JSON_SUCCESS; +} + +/* + * Recursive Descent parse routines. There is one for each structural + * element in a json document: + * - scalar (string, number, true, false, null) + * - array ( [ ] ) + * - array element + * - object ( { } ) + * - object field + */ +static inline JsonParseErrorType +parse_scalar(JsonLexContext *lex, JsonSemAction *sem) +{ + char *val = NULL; + json_scalar_action sfunc = sem->scalar; + JsonTokenType tok = lex_peek(lex); + JsonParseErrorType result; + + /* a scalar must be a string, a number, true, false, or null */ + if (tok != JSON_TOKEN_STRING && tok != JSON_TOKEN_NUMBER && + tok != JSON_TOKEN_TRUE && tok != JSON_TOKEN_FALSE && + tok != JSON_TOKEN_NULL) + return report_parse_error(JSON_PARSE_VALUE, lex); + + /* if no semantic function, just consume the token */ + if (sfunc == NULL) + return json_lex(lex); + + /* extract the de-escaped string value, or the raw lexeme */ + if (lex_peek(lex) == JSON_TOKEN_STRING) + { + if (lex->strval != NULL) + val = pstrdup(lex->strval->data); + } + else + { + int len = (lex->token_terminator - lex->token_start); + + val = palloc(len + 1); + memcpy(val, lex->token_start, len); + val[len] = '\0'; + } + + /* consume the token */ + result = json_lex(lex); + if (result != JSON_SUCCESS) + return result; + + /* invoke the callback */ + (*sfunc) (sem->semstate, val, tok); + + return JSON_SUCCESS; +} + +static JsonParseErrorType +parse_object_field(JsonLexContext *lex, JsonSemAction *sem) +{ + /* + * An object field is "fieldname" : value where value can be a scalar, + * object or array. Note: in user-facing docs and error messages, we + * generally call a field name a "key". + */ + + char *fname = NULL; /* keep compiler quiet */ + json_ofield_action ostart = sem->object_field_start; + json_ofield_action oend = sem->object_field_end; + bool isnull; + JsonTokenType tok; + JsonParseErrorType result; + + if (lex_peek(lex) != JSON_TOKEN_STRING) + return report_parse_error(JSON_PARSE_STRING, lex); + if ((ostart != NULL || oend != NULL) && lex->strval != NULL) + fname = pstrdup(lex->strval->data); + result = json_lex(lex); + if (result != JSON_SUCCESS) + return result; + + result = lex_expect(JSON_PARSE_OBJECT_LABEL, lex, JSON_TOKEN_COLON); + if (result != JSON_SUCCESS) + return result; + + tok = lex_peek(lex); + isnull = tok == JSON_TOKEN_NULL; + + if (ostart != NULL) + (*ostart) (sem->semstate, fname, isnull); + + switch (tok) + { + case JSON_TOKEN_OBJECT_START: + result = parse_object(lex, sem); + break; + case JSON_TOKEN_ARRAY_START: + result = parse_array(lex, sem); + break; + default: + result = parse_scalar(lex, sem); + } + if (result != JSON_SUCCESS) + return result; + + if (oend != NULL) + (*oend) (sem->semstate, fname, isnull); + return JSON_SUCCESS; +} + +static JsonParseErrorType +parse_object(JsonLexContext *lex, JsonSemAction *sem) +{ + /* + * an object is a possibly empty sequence of object fields, separated by + * commas and surrounded by curly braces. + */ + json_struct_action ostart = sem->object_start; + json_struct_action oend = sem->object_end; + JsonTokenType tok; + JsonParseErrorType result; + + check_stack_depth(); + + if (ostart != NULL) + (*ostart) (sem->semstate); + + /* + * Data inside an object is at a higher nesting level than the object + * itself. Note that we increment this after we call the semantic routine + * for the object start and restore it before we call the routine for the + * object end. + */ + lex->lex_level++; + + Assert(lex_peek(lex) == JSON_TOKEN_OBJECT_START); + result = json_lex(lex); + if (result != JSON_SUCCESS) + return result; + + tok = lex_peek(lex); + switch (tok) + { + case JSON_TOKEN_STRING: + result = parse_object_field(lex, sem); + while (result == JSON_SUCCESS && lex_peek(lex) == JSON_TOKEN_COMMA) + { + result = json_lex(lex); + if (result != JSON_SUCCESS) + break; + result = parse_object_field(lex, sem); + } + break; + case JSON_TOKEN_OBJECT_END: + break; + default: + /* case of an invalid initial token inside the object */ + result = report_parse_error(JSON_PARSE_OBJECT_START, lex); + } + if (result != JSON_SUCCESS) + return result; + + result = lex_expect(JSON_PARSE_OBJECT_NEXT, lex, JSON_TOKEN_OBJECT_END); + if (result != JSON_SUCCESS) + return result; + + lex->lex_level--; + + if (oend != NULL) + (*oend) (sem->semstate); + + return JSON_SUCCESS; +} + +static JsonParseErrorType +parse_array_element(JsonLexContext *lex, JsonSemAction *sem) +{ + json_aelem_action astart = sem->array_element_start; + json_aelem_action aend = sem->array_element_end; + JsonTokenType tok = lex_peek(lex); + JsonParseErrorType result; + + bool isnull; + + isnull = tok == JSON_TOKEN_NULL; + + if (astart != NULL) + (*astart) (sem->semstate, isnull); + + /* an array element is any object, array or scalar */ + switch (tok) + { + case JSON_TOKEN_OBJECT_START: + result = parse_object(lex, sem); + break; + case JSON_TOKEN_ARRAY_START: + result = parse_array(lex, sem); + break; + default: + result = parse_scalar(lex, sem); + } + + if (result != JSON_SUCCESS) + return result; + + if (aend != NULL) + (*aend) (sem->semstate, isnull); + + return JSON_SUCCESS; +} + +static JsonParseErrorType +parse_array(JsonLexContext *lex, JsonSemAction *sem) +{ + /* + * an array is a possibly empty sequence of array elements, separated by + * commas and surrounded by square brackets. + */ + json_struct_action astart = sem->array_start; + json_struct_action aend = sem->array_end; + JsonParseErrorType result; + + check_stack_depth(); + + if (astart != NULL) + (*astart) (sem->semstate); + + /* + * Data inside an array is at a higher nesting level than the array + * itself. Note that we increment this after we call the semantic routine + * for the array start and restore it before we call the routine for the + * array end. + */ + lex->lex_level++; + + result = lex_expect(JSON_PARSE_ARRAY_START, lex, JSON_TOKEN_ARRAY_START); + if (result == JSON_SUCCESS && lex_peek(lex) != JSON_TOKEN_ARRAY_END) + { + result = parse_array_element(lex, sem); + + while (result == JSON_SUCCESS && lex_peek(lex) == JSON_TOKEN_COMMA) + { + result = json_lex(lex); + if (result != JSON_SUCCESS) + break; + result = parse_array_element(lex, sem); + } + } + if (result != JSON_SUCCESS) + return result; + + result = lex_expect(JSON_PARSE_ARRAY_NEXT, lex, JSON_TOKEN_ARRAY_END); + if (result != JSON_SUCCESS) + return result; + + lex->lex_level--; + + if (aend != NULL) + (*aend) (sem->semstate); + + return JSON_SUCCESS; +} + +/* + * Lex one token from the input stream. + */ +JsonParseErrorType +json_lex(JsonLexContext *lex) +{ + char *s; + int len; + JsonParseErrorType result; + + /* Skip leading whitespace. */ + s = lex->token_terminator; + len = s - lex->input; + while (len < lex->input_length && + (*s == ' ' || *s == '\t' || *s == '\n' || *s == '\r')) + { + if (*s++ == '\n') + { + ++lex->line_number; + lex->line_start = s; + } + len++; + } + lex->token_start = s; + + /* Determine token type. */ + if (len >= lex->input_length) + { + lex->token_start = NULL; + lex->prev_token_terminator = lex->token_terminator; + lex->token_terminator = s; + lex->token_type = JSON_TOKEN_END; + } + else + { + switch (*s) + { + /* Single-character token, some kind of punctuation mark. */ + case '{': + lex->prev_token_terminator = lex->token_terminator; + lex->token_terminator = s + 1; + lex->token_type = JSON_TOKEN_OBJECT_START; + break; + case '}': + lex->prev_token_terminator = lex->token_terminator; + lex->token_terminator = s + 1; + lex->token_type = JSON_TOKEN_OBJECT_END; + break; + case '[': + lex->prev_token_terminator = lex->token_terminator; + lex->token_terminator = s + 1; + lex->token_type = JSON_TOKEN_ARRAY_START; + break; + case ']': + lex->prev_token_terminator = lex->token_terminator; + lex->token_terminator = s + 1; + lex->token_type = JSON_TOKEN_ARRAY_END; + break; + case ',': + lex->prev_token_terminator = lex->token_terminator; + lex->token_terminator = s + 1; + lex->token_type = JSON_TOKEN_COMMA; + break; + case ':': + lex->prev_token_terminator = lex->token_terminator; + lex->token_terminator = s + 1; + lex->token_type = JSON_TOKEN_COLON; + break; + case '"': + /* string */ + result = json_lex_string(lex); + if (result != JSON_SUCCESS) + return result; + lex->token_type = JSON_TOKEN_STRING; + break; + case '-': + /* Negative number. */ + result = json_lex_number(lex, s + 1, NULL, NULL); + if (result != JSON_SUCCESS) + return result; + lex->token_type = JSON_TOKEN_NUMBER; + break; + case '0': + case '1': + case '2': + case '3': + case '4': + case '5': + case '6': + case '7': + case '8': + case '9': + /* Positive number. */ + result = json_lex_number(lex, s, NULL, NULL); + if (result != JSON_SUCCESS) + return result; + lex->token_type = JSON_TOKEN_NUMBER; + break; + default: + { + char *p; + + /* + * We're not dealing with a string, number, legal + * punctuation mark, or end of string. The only legal + * tokens we might find here are true, false, and null, + * but for error reporting purposes we scan until we see a + * non-alphanumeric character. That way, we can report + * the whole word as an unexpected token, rather than just + * some unintuitive prefix thereof. + */ + for (p = s; p - s < lex->input_length - len && JSON_ALPHANUMERIC_CHAR(*p); p++) + /* skip */ ; + + /* + * We got some sort of unexpected punctuation or an + * otherwise unexpected character, so just complain about + * that one character. + */ + if (p == s) + { + lex->prev_token_terminator = lex->token_terminator; + lex->token_terminator = s + 1; + return JSON_INVALID_TOKEN; + } + + /* + * We've got a real alphanumeric token here. If it + * happens to be true, false, or null, all is well. If + * not, error out. + */ + lex->prev_token_terminator = lex->token_terminator; + lex->token_terminator = p; + if (p - s == 4) + { + if (memcmp(s, "true", 4) == 0) + lex->token_type = JSON_TOKEN_TRUE; + else if (memcmp(s, "null", 4) == 0) + lex->token_type = JSON_TOKEN_NULL; + else + return JSON_INVALID_TOKEN; + } + else if (p - s == 5 && memcmp(s, "false", 5) == 0) + lex->token_type = JSON_TOKEN_FALSE; + else + return JSON_INVALID_TOKEN; + + } + } /* end of switch */ + } + + return JSON_SUCCESS; +} + +/* + * The next token in the input stream is known to be a string; lex it. + */ +static inline JsonParseErrorType +json_lex_string(JsonLexContext *lex) +{ + char *s; + int len; + int hi_surrogate = -1; + + if (lex->strval != NULL) + resetStringInfo(lex->strval); + + Assert(lex->input_length > 0); + s = lex->token_start; + len = lex->token_start - lex->input; + for (;;) + { + s++; + len++; + /* Premature end of the string. */ + if (len >= lex->input_length) + { + lex->token_terminator = s; + return JSON_INVALID_TOKEN; + } + else if (*s == '"') + break; + else if ((unsigned char) *s < 32) + { + /* Per RFC4627, these characters MUST be escaped. */ + /* Since *s isn't printable, exclude it from the context string */ + lex->token_terminator = s; + return JSON_ESCAPING_REQUIRED; + } + else if (*s == '\\') + { + /* OK, we have an escape character. */ + s++; + len++; + if (len >= lex->input_length) + { + lex->token_terminator = s; + return JSON_INVALID_TOKEN; + } + else if (*s == 'u') + { + int i; + int ch = 0; + + for (i = 1; i <= 4; i++) + { + s++; + len++; + if (len >= lex->input_length) + { + lex->token_terminator = s; + return JSON_INVALID_TOKEN; + } + else if (*s >= '0' && *s <= '9') + ch = (ch * 16) + (*s - '0'); + else if (*s >= 'a' && *s <= 'f') + ch = (ch * 16) + (*s - 'a') + 10; + else if (*s >= 'A' && *s <= 'F') + ch = (ch * 16) + (*s - 'A') + 10; + else + { + lex->token_terminator = s + pg_encoding_mblen_bounded(lex->input_encoding, s); + return JSON_UNICODE_ESCAPE_FORMAT; + } + } + if (lex->strval != NULL) + { + /* + * Combine surrogate pairs. + */ + if (is_utf16_surrogate_first(ch)) + { + if (hi_surrogate != -1) + return JSON_UNICODE_HIGH_SURROGATE; + hi_surrogate = ch; + continue; + } + else if (is_utf16_surrogate_second(ch)) + { + if (hi_surrogate == -1) + return JSON_UNICODE_LOW_SURROGATE; + ch = surrogate_pair_to_codepoint(hi_surrogate, ch); + hi_surrogate = -1; + } + + if (hi_surrogate != -1) + return JSON_UNICODE_LOW_SURROGATE; + + /* + * Reject invalid cases. We can't have a value above + * 0xFFFF here (since we only accepted 4 hex digits + * above), so no need to test for out-of-range chars. + */ + if (ch == 0) + { + /* We can't allow this, since our TEXT type doesn't */ + return JSON_UNICODE_CODE_POINT_ZERO; + } + + /* + * Add the represented character to lex->strval. In the + * backend, we can let pg_unicode_to_server() handle any + * required character set conversion; in frontend, we can + * only deal with trivial conversions. + * + * Note: pg_unicode_to_server() will throw an error for a + * conversion failure, rather than returning a failure + * indication. That seems OK. + */ +#ifndef FRONTEND + { + char cbuf[MAX_UNICODE_EQUIVALENT_STRING + 1]; + + pg_unicode_to_server(ch, (unsigned char *) cbuf); + appendStringInfoString(lex->strval, cbuf); + } +#else + if (lex->input_encoding == PG_UTF8) + { + /* OK, we can map the code point to UTF8 easily */ + char utf8str[5]; + int utf8len; + + unicode_to_utf8(ch, (unsigned char *) utf8str); + utf8len = pg_utf_mblen((unsigned char *) utf8str); + appendBinaryStringInfo(lex->strval, utf8str, utf8len); + } + else if (ch <= 0x007f) + { + /* The ASCII range is the same in all encodings */ + appendStringInfoChar(lex->strval, (char) ch); + } + else + return JSON_UNICODE_HIGH_ESCAPE; +#endif /* FRONTEND */ + } + } + else if (lex->strval != NULL) + { + if (hi_surrogate != -1) + return JSON_UNICODE_LOW_SURROGATE; + + switch (*s) + { + case '"': + case '\\': + case '/': + appendStringInfoChar(lex->strval, *s); + break; + case 'b': + appendStringInfoChar(lex->strval, '\b'); + break; + case 'f': + appendStringInfoChar(lex->strval, '\f'); + break; + case 'n': + appendStringInfoChar(lex->strval, '\n'); + break; + case 'r': + appendStringInfoChar(lex->strval, '\r'); + break; + case 't': + appendStringInfoChar(lex->strval, '\t'); + break; + default: + /* Not a valid string escape, so signal error. */ + lex->token_start = s; + lex->token_terminator = s + pg_encoding_mblen_bounded(lex->input_encoding, s); + return JSON_ESCAPING_INVALID; + } + } + else if (strchr("\"\\/bfnrt", *s) == NULL) + { + /* + * Simpler processing if we're not bothered about de-escaping + * + * It's very tempting to remove the strchr() call here and + * replace it with a switch statement, but testing so far has + * shown it's not a performance win. + */ + lex->token_start = s; + lex->token_terminator = s + pg_encoding_mblen_bounded(lex->input_encoding, s); + return JSON_ESCAPING_INVALID; + } + + } + else if (lex->strval != NULL) + { + if (hi_surrogate != -1) + return JSON_UNICODE_LOW_SURROGATE; + + appendStringInfoChar(lex->strval, *s); + } + + } + + if (hi_surrogate != -1) + return JSON_UNICODE_LOW_SURROGATE; + + /* Hooray, we found the end of the string! */ + lex->prev_token_terminator = lex->token_terminator; + lex->token_terminator = s + 1; + return JSON_SUCCESS; +} + +/* + * The next token in the input stream is known to be a number; lex it. + * + * In JSON, a number consists of four parts: + * + * (1) An optional minus sign ('-'). + * + * (2) Either a single '0', or a string of one or more digits that does not + * begin with a '0'. + * + * (3) An optional decimal part, consisting of a period ('.') followed by + * one or more digits. (Note: While this part can be omitted + * completely, it's not OK to have only the decimal point without + * any digits afterwards.) + * + * (4) An optional exponent part, consisting of 'e' or 'E', optionally + * followed by '+' or '-', followed by one or more digits. (Note: + * As with the decimal part, if 'e' or 'E' is present, it must be + * followed by at least one digit.) + * + * The 's' argument to this function points to the ostensible beginning + * of part 2 - i.e. the character after any optional minus sign, or the + * first character of the string if there is none. + * + * If num_err is not NULL, we return an error flag to *num_err rather than + * raising an error for a badly-formed number. Also, if total_len is not NULL + * the distance from lex->input to the token end+1 is returned to *total_len. + */ +static inline JsonParseErrorType +json_lex_number(JsonLexContext *lex, char *s, + bool *num_err, int *total_len) +{ + bool error = false; + int len = s - lex->input; + + /* Part (1): leading sign indicator. */ + /* Caller already did this for us; so do nothing. */ + + /* Part (2): parse main digit string. */ + if (len < lex->input_length && *s == '0') + { + s++; + len++; + } + else if (len < lex->input_length && *s >= '1' && *s <= '9') + { + do + { + s++; + len++; + } while (len < lex->input_length && *s >= '0' && *s <= '9'); + } + else + error = true; + + /* Part (3): parse optional decimal portion. */ + if (len < lex->input_length && *s == '.') + { + s++; + len++; + if (len == lex->input_length || *s < '0' || *s > '9') + error = true; + else + { + do + { + s++; + len++; + } while (len < lex->input_length && *s >= '0' && *s <= '9'); + } + } + + /* Part (4): parse optional exponent. */ + if (len < lex->input_length && (*s == 'e' || *s == 'E')) + { + s++; + len++; + if (len < lex->input_length && (*s == '+' || *s == '-')) + { + s++; + len++; + } + if (len == lex->input_length || *s < '0' || *s > '9') + error = true; + else + { + do + { + s++; + len++; + } while (len < lex->input_length && *s >= '0' && *s <= '9'); + } + } + + /* + * Check for trailing garbage. As in json_lex(), any alphanumeric stuff + * here should be considered part of the token for error-reporting + * purposes. + */ + for (; len < lex->input_length && JSON_ALPHANUMERIC_CHAR(*s); s++, len++) + error = true; + + if (total_len != NULL) + *total_len = len; + + if (num_err != NULL) + { + /* let the caller handle any error */ + *num_err = error; + } + else + { + /* return token endpoint */ + lex->prev_token_terminator = lex->token_terminator; + lex->token_terminator = s; + /* handle error if any */ + if (error) + return JSON_INVALID_TOKEN; + } + + return JSON_SUCCESS; +} + +/* + * Report a parse error. + * + * lex->token_start and lex->token_terminator must identify the current token. + */ +static JsonParseErrorType +report_parse_error(JsonParseContext ctx, JsonLexContext *lex) +{ + /* Handle case where the input ended prematurely. */ + if (lex->token_start == NULL || lex->token_type == JSON_TOKEN_END) + return JSON_EXPECTED_MORE; + + /* Otherwise choose the error type based on the parsing context. */ + switch (ctx) + { + case JSON_PARSE_END: + return JSON_EXPECTED_END; + case JSON_PARSE_VALUE: + return JSON_EXPECTED_JSON; + case JSON_PARSE_STRING: + return JSON_EXPECTED_STRING; + case JSON_PARSE_ARRAY_START: + return JSON_EXPECTED_ARRAY_FIRST; + case JSON_PARSE_ARRAY_NEXT: + return JSON_EXPECTED_ARRAY_NEXT; + case JSON_PARSE_OBJECT_START: + return JSON_EXPECTED_OBJECT_FIRST; + case JSON_PARSE_OBJECT_LABEL: + return JSON_EXPECTED_COLON; + case JSON_PARSE_OBJECT_NEXT: + return JSON_EXPECTED_OBJECT_NEXT; + case JSON_PARSE_OBJECT_COMMA: + return JSON_EXPECTED_STRING; + } + + /* + * We don't use a default: case, so that the compiler will warn about + * unhandled enum values. But this needs to be here anyway to cover the + * possibility of an incorrect input. + */ + json_log_and_abort("unexpected json parse state: %d", (int) ctx); + return JSON_SUCCESS; /* silence stupider compilers */ +} + +/* + * Construct a detail message for a JSON error. + */ +char * +json_errdetail(JsonParseErrorType error, JsonLexContext *lex) +{ + switch (error) + { + case JSON_SUCCESS: + /* fall through to the error code after switch */ + break; + case JSON_ESCAPING_INVALID: + return psprintf(_("Escape sequence \"\\%s\" is invalid."), + extract_token(lex)); + case JSON_ESCAPING_REQUIRED: + return psprintf(_("Character with value 0x%02x must be escaped."), + (unsigned char) *(lex->token_terminator)); + case JSON_EXPECTED_END: + return psprintf(_("Expected end of input, but found \"%s\"."), + extract_token(lex)); + case JSON_EXPECTED_ARRAY_FIRST: + return psprintf(_("Expected array element or \"]\", but found \"%s\"."), + extract_token(lex)); + case JSON_EXPECTED_ARRAY_NEXT: + return psprintf(_("Expected \",\" or \"]\", but found \"%s\"."), + extract_token(lex)); + case JSON_EXPECTED_COLON: + return psprintf(_("Expected \":\", but found \"%s\"."), + extract_token(lex)); + case JSON_EXPECTED_JSON: + return psprintf(_("Expected JSON value, but found \"%s\"."), + extract_token(lex)); + case JSON_EXPECTED_MORE: + return _("The input string ended unexpectedly."); + case JSON_EXPECTED_OBJECT_FIRST: + return psprintf(_("Expected string or \"}\", but found \"%s\"."), + extract_token(lex)); + case JSON_EXPECTED_OBJECT_NEXT: + return psprintf(_("Expected \",\" or \"}\", but found \"%s\"."), + extract_token(lex)); + case JSON_EXPECTED_STRING: + return psprintf(_("Expected string, but found \"%s\"."), + extract_token(lex)); + case JSON_INVALID_TOKEN: + return psprintf(_("Token \"%s\" is invalid."), + extract_token(lex)); + case JSON_UNICODE_CODE_POINT_ZERO: + return _("\\u0000 cannot be converted to text."); + case JSON_UNICODE_ESCAPE_FORMAT: + return _("\"\\u\" must be followed by four hexadecimal digits."); + case JSON_UNICODE_HIGH_ESCAPE: + /* note: this case is only reachable in frontend not backend */ + return _("Unicode escape values cannot be used for code point values above 007F when the encoding is not UTF8."); + case JSON_UNICODE_HIGH_SURROGATE: + return _("Unicode high surrogate must not follow a high surrogate."); + case JSON_UNICODE_LOW_SURROGATE: + return _("Unicode low surrogate must follow a high surrogate."); + } + + /* + * We don't use a default: case, so that the compiler will warn about + * unhandled enum values. But this needs to be here anyway to cover the + * possibility of an incorrect input. + */ + json_log_and_abort("unexpected json parse error type: %d", (int) error); + return NULL; /* silence stupider compilers */ +} + +/* + * Extract the current token from a lexing context, for error reporting. + */ +static char * +extract_token(JsonLexContext *lex) +{ + int toklen = lex->token_terminator - lex->token_start; + char *token = palloc(toklen + 1); + + memcpy(token, lex->token_start, toklen); + token[toklen] = '\0'; + return token; +} |