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Diffstat (limited to 'qemu/qobject/json-lexer.c')
| -rw-r--r-- | qemu/qobject/json-lexer.c | 373 |
1 files changed, 373 insertions, 0 deletions
diff --git a/qemu/qobject/json-lexer.c b/qemu/qobject/json-lexer.c new file mode 100644 index 000000000..b19623e22 --- /dev/null +++ b/qemu/qobject/json-lexer.c @@ -0,0 +1,373 @@ +/* + * 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 "qapi/qmp/qstring.h" +#include "qapi/qmp/qlist.h" +#include "qapi/qmp/qdict.h" +#include "qapi/qmp/qint.h" +#include "qemu-common.h" +#include "qapi/qmp/json-lexer.h" + +#define MAX_TOKEN_SIZE (64ULL << 20) + +/* + * \"([^\\\"]|(\\\"\\'\\\\\\/\\b\\f\\n\\r\\t\\u[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]))*\" + * '([^\\']|(\\\"\\'\\\\\\/\\b\\f\\n\\r\\t\\u[0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F]))*' + * 0|([1-9][0-9]*(.[0-9]+)?([eE]([-+])?[0-9]+)) + * [{}\[\],:] + * [a-z]+ + * + */ + +enum json_lexer_state { + IN_ERROR = 0, + IN_DQ_UCODE3, + IN_DQ_UCODE2, + IN_DQ_UCODE1, + IN_DQ_UCODE0, + IN_DQ_STRING_ESCAPE, + IN_DQ_STRING, + IN_SQ_UCODE3, + IN_SQ_UCODE2, + IN_SQ_UCODE1, + IN_SQ_UCODE0, + IN_SQ_STRING_ESCAPE, + IN_SQ_STRING, + IN_ZERO, + IN_DIGITS, + IN_DIGIT, + IN_EXP_E, + IN_MANTISSA, + IN_MANTISSA_DIGITS, + IN_NONZERO_NUMBER, + IN_NEG_NONZERO_NUMBER, + IN_KEYWORD, + IN_ESCAPE, + IN_ESCAPE_L, + IN_ESCAPE_LL, + IN_ESCAPE_I, + IN_ESCAPE_I6, + IN_ESCAPE_I64, + IN_WHITESPACE, + IN_START, +}; + +#define TERMINAL(state) [0 ... 0x7F] = (state) + +/* Return whether TERMINAL is a terminal state and the transition to it + from OLD_STATE required lookahead. This happens whenever the table + below uses the TERMINAL macro. */ +#define TERMINAL_NEEDED_LOOKAHEAD(old_state, terminal) \ + (json_lexer[(old_state)][0] == (terminal)) + +static const uint8_t json_lexer[][256] = { + /* double quote string */ + [IN_DQ_UCODE3] = { + ['0' ... '9'] = IN_DQ_STRING, + ['a' ... 'f'] = IN_DQ_STRING, + ['A' ... 'F'] = IN_DQ_STRING, + }, + [IN_DQ_UCODE2] = { + ['0' ... '9'] = IN_DQ_UCODE3, + ['a' ... 'f'] = IN_DQ_UCODE3, + ['A' ... 'F'] = IN_DQ_UCODE3, + }, + [IN_DQ_UCODE1] = { + ['0' ... '9'] = IN_DQ_UCODE2, + ['a' ... 'f'] = IN_DQ_UCODE2, + ['A' ... 'F'] = IN_DQ_UCODE2, + }, + [IN_DQ_UCODE0] = { + ['0' ... '9'] = IN_DQ_UCODE1, + ['a' ... 'f'] = IN_DQ_UCODE1, + ['A' ... 'F'] = IN_DQ_UCODE1, + }, + [IN_DQ_STRING_ESCAPE] = { + ['b'] = IN_DQ_STRING, + ['f'] = IN_DQ_STRING, + ['n'] = IN_DQ_STRING, + ['r'] = IN_DQ_STRING, + ['t'] = IN_DQ_STRING, + ['/'] = IN_DQ_STRING, + ['\\'] = IN_DQ_STRING, + ['\''] = IN_DQ_STRING, + ['\"'] = IN_DQ_STRING, + ['u'] = IN_DQ_UCODE0, + }, + [IN_DQ_STRING] = { + [1 ... 0xBF] = IN_DQ_STRING, + [0xC2 ... 0xF4] = IN_DQ_STRING, + ['\\'] = IN_DQ_STRING_ESCAPE, + ['"'] = JSON_STRING, + }, + + /* single quote string */ + [IN_SQ_UCODE3] = { + ['0' ... '9'] = IN_SQ_STRING, + ['a' ... 'f'] = IN_SQ_STRING, + ['A' ... 'F'] = IN_SQ_STRING, + }, + [IN_SQ_UCODE2] = { + ['0' ... '9'] = IN_SQ_UCODE3, + ['a' ... 'f'] = IN_SQ_UCODE3, + ['A' ... 'F'] = IN_SQ_UCODE3, + }, + [IN_SQ_UCODE1] = { + ['0' ... '9'] = IN_SQ_UCODE2, + ['a' ... 'f'] = IN_SQ_UCODE2, + ['A' ... 'F'] = IN_SQ_UCODE2, + }, + [IN_SQ_UCODE0] = { + ['0' ... '9'] = IN_SQ_UCODE1, + ['a' ... 'f'] = IN_SQ_UCODE1, + ['A' ... 'F'] = IN_SQ_UCODE1, + }, + [IN_SQ_STRING_ESCAPE] = { + ['b'] = IN_SQ_STRING, + ['f'] = IN_SQ_STRING, + ['n'] = IN_SQ_STRING, + ['r'] = IN_SQ_STRING, + ['t'] = IN_SQ_STRING, + ['/'] = IN_SQ_STRING, + ['\\'] = IN_SQ_STRING, + ['\''] = IN_SQ_STRING, + ['\"'] = IN_SQ_STRING, + ['u'] = IN_SQ_UCODE0, + }, + [IN_SQ_STRING] = { + [1 ... 0xBF] = IN_SQ_STRING, + [0xC2 ... 0xF4] = IN_SQ_STRING, + ['\\'] = IN_SQ_STRING_ESCAPE, + ['\''] = JSON_STRING, + }, + + /* Zero */ + [IN_ZERO] = { + TERMINAL(JSON_INTEGER), + ['0' ... '9'] = IN_ERROR, + ['.'] = IN_MANTISSA, + }, + + /* Float */ + [IN_DIGITS] = { + TERMINAL(JSON_FLOAT), + ['0' ... '9'] = IN_DIGITS, + }, + + [IN_DIGIT] = { + ['0' ... '9'] = IN_DIGITS, + }, + + [IN_EXP_E] = { + ['-'] = IN_DIGIT, + ['+'] = IN_DIGIT, + ['0' ... '9'] = IN_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_NONZERO_NUMBER] = { + TERMINAL(JSON_INTEGER), + ['0' ... '9'] = IN_NONZERO_NUMBER, + ['e'] = IN_EXP_E, + ['E'] = IN_EXP_E, + ['.'] = IN_MANTISSA, + }, + + [IN_NEG_NONZERO_NUMBER] = { + ['0'] = IN_ZERO, + ['1' ... '9'] = IN_NONZERO_NUMBER, + }, + + /* keywords */ + [IN_KEYWORD] = { + TERMINAL(JSON_KEYWORD), + ['a' ... 'z'] = IN_KEYWORD, + }, + + /* whitespace */ + [IN_WHITESPACE] = { + TERMINAL(JSON_SKIP), + [' '] = IN_WHITESPACE, + ['\t'] = IN_WHITESPACE, + ['\r'] = IN_WHITESPACE, + ['\n'] = IN_WHITESPACE, + }, + + /* escape */ + [IN_ESCAPE_LL] = { + ['d'] = JSON_ESCAPE, + }, + + [IN_ESCAPE_L] = { + ['d'] = JSON_ESCAPE, + ['l'] = IN_ESCAPE_LL, + }, + + [IN_ESCAPE_I64] = { + ['d'] = JSON_ESCAPE, + }, + + [IN_ESCAPE_I6] = { + ['4'] = IN_ESCAPE_I64, + }, + + [IN_ESCAPE_I] = { + ['6'] = IN_ESCAPE_I6, + }, + + [IN_ESCAPE] = { + ['d'] = JSON_ESCAPE, + ['i'] = JSON_ESCAPE, + ['p'] = JSON_ESCAPE, + ['s'] = JSON_ESCAPE, + ['f'] = JSON_ESCAPE, + ['l'] = IN_ESCAPE_L, + ['I'] = IN_ESCAPE_I, + }, + + /* top level rule */ + [IN_START] = { + ['"'] = IN_DQ_STRING, + ['\''] = IN_SQ_STRING, + ['0'] = IN_ZERO, + ['1' ... '9'] = IN_NONZERO_NUMBER, + ['-'] = IN_NEG_NONZERO_NUMBER, + ['{'] = JSON_OPERATOR, + ['}'] = JSON_OPERATOR, + ['['] = JSON_OPERATOR, + [']'] = JSON_OPERATOR, + [','] = JSON_OPERATOR, + [':'] = JSON_OPERATOR, + ['a' ... 'z'] = IN_KEYWORD, + ['%'] = IN_ESCAPE, + [' '] = IN_WHITESPACE, + ['\t'] = IN_WHITESPACE, + ['\r'] = IN_WHITESPACE, + ['\n'] = IN_WHITESPACE, + }, +}; + +void json_lexer_init(JSONLexer *lexer, JSONLexerEmitter func) +{ + lexer->emit = func; + lexer->state = IN_START; + lexer->token = qstring_new(); + lexer->x = lexer->y = 0; +} + +static int json_lexer_feed_char(JSONLexer *lexer, char ch, bool flush) +{ + int char_consumed, new_state; + + lexer->x++; + if (ch == '\n') { + lexer->x = 0; + lexer->y++; + } + + do { + new_state = json_lexer[lexer->state][(uint8_t)ch]; + char_consumed = !TERMINAL_NEEDED_LOOKAHEAD(lexer->state, new_state); + if (char_consumed) { + qstring_append_chr(lexer->token, ch); + } + + switch (new_state) { + case JSON_OPERATOR: + case JSON_ESCAPE: + case JSON_INTEGER: + case JSON_FLOAT: + case JSON_KEYWORD: + case JSON_STRING: + lexer->emit(lexer, lexer->token, new_state, lexer->x, lexer->y); + /* fall through */ + case JSON_SKIP: + QDECREF(lexer->token); + lexer->token = qstring_new(); + new_state = IN_START; + break; + case IN_ERROR: + /* XXX: To avoid having previous bad input leaving the parser in an + * unresponsive state where we consume unpredictable amounts of + * subsequent "good" input, percolate this error state up to the + * tokenizer/parser by forcing a NULL object to be emitted, then + * reset state. + * + * Also note that this handling is required for reliable channel + * negotiation between QMP and the guest agent, since chr(0xFF) + * is placed at the beginning of certain events to ensure proper + * delivery when the channel is in an unknown state. chr(0xFF) is + * never a valid ASCII/UTF-8 sequence, so this should reliably + * induce an error/flush state. + */ + lexer->emit(lexer, lexer->token, JSON_ERROR, lexer->x, lexer->y); + QDECREF(lexer->token); + lexer->token = qstring_new(); + new_state = IN_START; + lexer->state = new_state; + return 0; + default: + break; + } + lexer->state = new_state; + } while (!char_consumed && !flush); + + /* Do not let a single token grow to an arbitrarily large size, + * this is a security consideration. + */ + if (lexer->token->length > MAX_TOKEN_SIZE) { + lexer->emit(lexer, lexer->token, lexer->state, lexer->x, lexer->y); + QDECREF(lexer->token); + lexer->token = qstring_new(); + lexer->state = IN_START; + } + + return 0; +} + +int json_lexer_feed(JSONLexer *lexer, const char *buffer, size_t size) +{ + size_t i; + + for (i = 0; i < size; i++) { + int err; + + err = json_lexer_feed_char(lexer, buffer[i], false); + if (err < 0) { + return err; + } + } + + return 0; +} + +int json_lexer_flush(JSONLexer *lexer) +{ + return lexer->state == IN_START ? 0 : json_lexer_feed_char(lexer, 0, true); +} + +void json_lexer_destroy(JSONLexer *lexer) +{ + QDECREF(lexer->token); +} |