mirror of
https://gitlab.com/qemu-project/qemu.git
synced 2024-12-08 06:00:35 +03:00
1e960b4602
The lexer ignores whitespace like this: on whitespace on non-ws spontaneously IN_START --> IN_WHITESPACE --> JSON_SKIP --> IN_START ^ | \__/ on whitespace This accumulates a whitespace token in state IN_WHITESPACE, only to throw it away on the transition via JSON_SKIP to the start state. Wasteful. Go from IN_START to IN_START on whitespace directly, dropping the whitespace character. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20180831075841.13363-7-armbru@redhat.com>
366 lines
10 KiB
C
366 lines
10 KiB
C
/*
|
|
* JSON lexer
|
|
*
|
|
* Copyright IBM, Corp. 2009
|
|
*
|
|
* Authors:
|
|
* Anthony Liguori <aliguori@us.ibm.com>
|
|
*
|
|
* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
|
|
* See the COPYING.LIB file in the top-level directory.
|
|
*
|
|
*/
|
|
|
|
#include "qemu/osdep.h"
|
|
#include "json-parser-int.h"
|
|
|
|
#define MAX_TOKEN_SIZE (64ULL << 20)
|
|
|
|
/*
|
|
* From RFC 8259 "The JavaScript Object Notation (JSON) Data
|
|
* Interchange Format", with [comments in brackets]:
|
|
*
|
|
* The set of tokens includes six structural characters, strings,
|
|
* numbers, and three literal names.
|
|
*
|
|
* These are the six structural characters:
|
|
*
|
|
* begin-array = ws %x5B ws ; [ left square bracket
|
|
* begin-object = ws %x7B ws ; { left curly bracket
|
|
* end-array = ws %x5D ws ; ] right square bracket
|
|
* end-object = ws %x7D ws ; } right curly bracket
|
|
* name-separator = ws %x3A ws ; : colon
|
|
* value-separator = ws %x2C ws ; , comma
|
|
*
|
|
* Insignificant whitespace is allowed before or after any of the six
|
|
* structural characters.
|
|
* [This lexer accepts it before or after any token, which is actually
|
|
* the same, as the grammar always has structural characters between
|
|
* other tokens.]
|
|
*
|
|
* ws = *(
|
|
* %x20 / ; Space
|
|
* %x09 / ; Horizontal tab
|
|
* %x0A / ; Line feed or New line
|
|
* %x0D ) ; Carriage return
|
|
*
|
|
* [...] three literal names:
|
|
* false null true
|
|
* [This lexer accepts [a-z]+, and leaves rejecting unknown literal
|
|
* names to the parser.]
|
|
*
|
|
* [Numbers:]
|
|
*
|
|
* number = [ minus ] int [ frac ] [ exp ]
|
|
* decimal-point = %x2E ; .
|
|
* digit1-9 = %x31-39 ; 1-9
|
|
* e = %x65 / %x45 ; e E
|
|
* exp = e [ minus / plus ] 1*DIGIT
|
|
* frac = decimal-point 1*DIGIT
|
|
* int = zero / ( digit1-9 *DIGIT )
|
|
* minus = %x2D ; -
|
|
* plus = %x2B ; +
|
|
* zero = %x30 ; 0
|
|
*
|
|
* [Strings:]
|
|
* string = quotation-mark *char quotation-mark
|
|
*
|
|
* char = unescaped /
|
|
* escape (
|
|
* %x22 / ; " quotation mark U+0022
|
|
* %x5C / ; \ reverse solidus U+005C
|
|
* %x2F / ; / solidus U+002F
|
|
* %x62 / ; b backspace U+0008
|
|
* %x66 / ; f form feed U+000C
|
|
* %x6E / ; n line feed U+000A
|
|
* %x72 / ; r carriage return U+000D
|
|
* %x74 / ; t tab U+0009
|
|
* %x75 4HEXDIG ) ; uXXXX U+XXXX
|
|
* escape = %x5C ; \
|
|
* quotation-mark = %x22 ; "
|
|
* unescaped = %x20-21 / %x23-5B / %x5D-10FFFF
|
|
* [This lexer accepts any non-control character after escape, and
|
|
* leaves rejecting invalid ones to the parser.]
|
|
*
|
|
*
|
|
* Extensions over RFC 8259:
|
|
* - Extra escape sequence in strings:
|
|
* 0x27 (apostrophe) is recognized after escape, too
|
|
* - Single-quoted strings:
|
|
* Like double-quoted strings, except they're delimited by %x27
|
|
* (apostrophe) instead of %x22 (quotation mark), and can't contain
|
|
* unescaped apostrophe, but can contain unescaped quotation mark.
|
|
* - Interpolation, if enabled:
|
|
* The lexer accepts %[A-Za-z0-9]*, and leaves rejecting invalid
|
|
* ones to the parser.
|
|
*
|
|
* Note:
|
|
* - Input must be encoded in modified UTF-8.
|
|
* - Decoding and validating is left to the parser.
|
|
*/
|
|
|
|
enum json_lexer_state {
|
|
IN_RECOVERY = 1,
|
|
IN_DQ_STRING_ESCAPE,
|
|
IN_DQ_STRING,
|
|
IN_SQ_STRING_ESCAPE,
|
|
IN_SQ_STRING,
|
|
IN_ZERO,
|
|
IN_EXP_DIGITS,
|
|
IN_EXP_SIGN,
|
|
IN_EXP_E,
|
|
IN_MANTISSA,
|
|
IN_MANTISSA_DIGITS,
|
|
IN_DIGITS,
|
|
IN_SIGN,
|
|
IN_KEYWORD,
|
|
IN_INTERP,
|
|
IN_START,
|
|
IN_START_INTERP, /* must be IN_START + 1 */
|
|
};
|
|
|
|
QEMU_BUILD_BUG_ON(JSON_ERROR != 0);
|
|
QEMU_BUILD_BUG_ON(IN_RECOVERY != JSON_ERROR + 1);
|
|
QEMU_BUILD_BUG_ON((int)JSON_MIN <= (int)IN_START_INTERP);
|
|
QEMU_BUILD_BUG_ON(JSON_MAX >= 0x80);
|
|
QEMU_BUILD_BUG_ON(IN_START_INTERP != IN_START + 1);
|
|
|
|
#define LOOKAHEAD 0x80
|
|
#define TERMINAL(state) [0 ... 0xFF] = ((state) | LOOKAHEAD)
|
|
|
|
static const uint8_t json_lexer[][256] = {
|
|
/* Relies on default initialization to IN_ERROR! */
|
|
|
|
/* error recovery */
|
|
[IN_RECOVERY] = {
|
|
/*
|
|
* Skip characters until a structural character, an ASCII
|
|
* control character other than '\t', or impossible UTF-8
|
|
* bytes '\xFE', '\xFF'. Structural characters and line
|
|
* endings are promising resynchronization points. Clients
|
|
* may use the others to force the JSON parser into known-good
|
|
* state; see docs/interop/qmp-spec.txt.
|
|
*/
|
|
[0 ... 0x1F] = IN_START | LOOKAHEAD,
|
|
[0x20 ... 0xFD] = IN_RECOVERY,
|
|
[0xFE ... 0xFF] = IN_START | LOOKAHEAD,
|
|
['\t'] = IN_RECOVERY,
|
|
['['] = IN_START | LOOKAHEAD,
|
|
[']'] = IN_START | LOOKAHEAD,
|
|
['{'] = IN_START | LOOKAHEAD,
|
|
['}'] = IN_START | LOOKAHEAD,
|
|
[':'] = IN_START | LOOKAHEAD,
|
|
[','] = IN_START | LOOKAHEAD,
|
|
},
|
|
|
|
/* double quote string */
|
|
[IN_DQ_STRING_ESCAPE] = {
|
|
[0x20 ... 0xFD] = IN_DQ_STRING,
|
|
},
|
|
[IN_DQ_STRING] = {
|
|
[0x20 ... 0xFD] = IN_DQ_STRING,
|
|
['\\'] = IN_DQ_STRING_ESCAPE,
|
|
['"'] = JSON_STRING,
|
|
},
|
|
|
|
/* single quote string */
|
|
[IN_SQ_STRING_ESCAPE] = {
|
|
[0x20 ... 0xFD] = IN_SQ_STRING,
|
|
},
|
|
[IN_SQ_STRING] = {
|
|
[0x20 ... 0xFD] = IN_SQ_STRING,
|
|
['\\'] = IN_SQ_STRING_ESCAPE,
|
|
['\''] = JSON_STRING,
|
|
},
|
|
|
|
/* Zero */
|
|
[IN_ZERO] = {
|
|
TERMINAL(JSON_INTEGER),
|
|
['0' ... '9'] = JSON_ERROR,
|
|
['.'] = IN_MANTISSA,
|
|
},
|
|
|
|
/* Float */
|
|
[IN_EXP_DIGITS] = {
|
|
TERMINAL(JSON_FLOAT),
|
|
['0' ... '9'] = IN_EXP_DIGITS,
|
|
},
|
|
|
|
[IN_EXP_SIGN] = {
|
|
['0' ... '9'] = IN_EXP_DIGITS,
|
|
},
|
|
|
|
[IN_EXP_E] = {
|
|
['-'] = IN_EXP_SIGN,
|
|
['+'] = IN_EXP_SIGN,
|
|
['0' ... '9'] = IN_EXP_DIGITS,
|
|
},
|
|
|
|
[IN_MANTISSA_DIGITS] = {
|
|
TERMINAL(JSON_FLOAT),
|
|
['0' ... '9'] = IN_MANTISSA_DIGITS,
|
|
['e'] = IN_EXP_E,
|
|
['E'] = IN_EXP_E,
|
|
},
|
|
|
|
[IN_MANTISSA] = {
|
|
['0' ... '9'] = IN_MANTISSA_DIGITS,
|
|
},
|
|
|
|
/* Number */
|
|
[IN_DIGITS] = {
|
|
TERMINAL(JSON_INTEGER),
|
|
['0' ... '9'] = IN_DIGITS,
|
|
['e'] = IN_EXP_E,
|
|
['E'] = IN_EXP_E,
|
|
['.'] = IN_MANTISSA,
|
|
},
|
|
|
|
[IN_SIGN] = {
|
|
['0'] = IN_ZERO,
|
|
['1' ... '9'] = IN_DIGITS,
|
|
},
|
|
|
|
/* keywords */
|
|
[IN_KEYWORD] = {
|
|
TERMINAL(JSON_KEYWORD),
|
|
['a' ... 'z'] = IN_KEYWORD,
|
|
},
|
|
|
|
/* interpolation */
|
|
[IN_INTERP] = {
|
|
TERMINAL(JSON_INTERP),
|
|
['A' ... 'Z'] = IN_INTERP,
|
|
['a' ... 'z'] = IN_INTERP,
|
|
['0' ... '9'] = IN_INTERP,
|
|
},
|
|
|
|
/*
|
|
* Two start states:
|
|
* - IN_START recognizes JSON tokens with our string extensions
|
|
* - IN_START_INTERP additionally recognizes interpolation.
|
|
*/
|
|
[IN_START ... IN_START_INTERP] = {
|
|
['"'] = IN_DQ_STRING,
|
|
['\''] = IN_SQ_STRING,
|
|
['0'] = IN_ZERO,
|
|
['1' ... '9'] = IN_DIGITS,
|
|
['-'] = IN_SIGN,
|
|
['{'] = JSON_LCURLY,
|
|
['}'] = JSON_RCURLY,
|
|
['['] = JSON_LSQUARE,
|
|
[']'] = JSON_RSQUARE,
|
|
[','] = JSON_COMMA,
|
|
[':'] = JSON_COLON,
|
|
['a' ... 'z'] = IN_KEYWORD,
|
|
[' '] = IN_START,
|
|
['\t'] = IN_START,
|
|
['\r'] = IN_START,
|
|
['\n'] = IN_START,
|
|
},
|
|
[IN_START_INTERP]['%'] = IN_INTERP,
|
|
};
|
|
|
|
static inline uint8_t next_state(JSONLexer *lexer, char ch, bool flush,
|
|
bool *char_consumed)
|
|
{
|
|
uint8_t next;
|
|
|
|
assert(lexer->state <= ARRAY_SIZE(json_lexer));
|
|
next = json_lexer[lexer->state][(uint8_t)ch];
|
|
*char_consumed = !flush && !(next & LOOKAHEAD);
|
|
return next & ~LOOKAHEAD;
|
|
}
|
|
|
|
void json_lexer_init(JSONLexer *lexer, bool enable_interpolation)
|
|
{
|
|
lexer->start_state = lexer->state = enable_interpolation
|
|
? IN_START_INTERP : IN_START;
|
|
lexer->token = g_string_sized_new(3);
|
|
lexer->x = lexer->y = 0;
|
|
}
|
|
|
|
static void json_lexer_feed_char(JSONLexer *lexer, char ch, bool flush)
|
|
{
|
|
int new_state;
|
|
bool char_consumed = false;
|
|
|
|
lexer->x++;
|
|
if (ch == '\n') {
|
|
lexer->x = 0;
|
|
lexer->y++;
|
|
}
|
|
|
|
while (flush ? lexer->state != lexer->start_state : !char_consumed) {
|
|
new_state = next_state(lexer, ch, flush, &char_consumed);
|
|
if (char_consumed) {
|
|
assert(!flush);
|
|
g_string_append_c(lexer->token, ch);
|
|
}
|
|
|
|
switch (new_state) {
|
|
case JSON_LCURLY:
|
|
case JSON_RCURLY:
|
|
case JSON_LSQUARE:
|
|
case JSON_RSQUARE:
|
|
case JSON_COLON:
|
|
case JSON_COMMA:
|
|
case JSON_INTERP:
|
|
case JSON_INTEGER:
|
|
case JSON_FLOAT:
|
|
case JSON_KEYWORD:
|
|
case JSON_STRING:
|
|
json_message_process_token(lexer, lexer->token, new_state,
|
|
lexer->x, lexer->y);
|
|
/* fall through */
|
|
case IN_START:
|
|
g_string_truncate(lexer->token, 0);
|
|
new_state = lexer->start_state;
|
|
break;
|
|
case JSON_ERROR:
|
|
json_message_process_token(lexer, lexer->token, JSON_ERROR,
|
|
lexer->x, lexer->y);
|
|
new_state = IN_RECOVERY;
|
|
/* fall through */
|
|
case IN_RECOVERY:
|
|
g_string_truncate(lexer->token, 0);
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
lexer->state = new_state;
|
|
}
|
|
|
|
/* Do not let a single token grow to an arbitrarily large size,
|
|
* this is a security consideration.
|
|
*/
|
|
if (lexer->token->len > MAX_TOKEN_SIZE) {
|
|
json_message_process_token(lexer, lexer->token, lexer->state,
|
|
lexer->x, lexer->y);
|
|
g_string_truncate(lexer->token, 0);
|
|
lexer->state = lexer->start_state;
|
|
}
|
|
}
|
|
|
|
void json_lexer_feed(JSONLexer *lexer, const char *buffer, size_t size)
|
|
{
|
|
size_t i;
|
|
|
|
for (i = 0; i < size; i++) {
|
|
json_lexer_feed_char(lexer, buffer[i], false);
|
|
}
|
|
}
|
|
|
|
void json_lexer_flush(JSONLexer *lexer)
|
|
{
|
|
json_lexer_feed_char(lexer, 0, true);
|
|
assert(lexer->state == lexer->start_state);
|
|
json_message_process_token(lexer, lexer->token, JSON_END_OF_INPUT,
|
|
lexer->x, lexer->y);
|
|
}
|
|
|
|
void json_lexer_destroy(JSONLexer *lexer)
|
|
{
|
|
g_string_free(lexer->token, true);
|
|
}
|