714 lines
17 KiB
C
714 lines
17 KiB
C
/*
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* JSON Parser
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*
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* Copyright IBM, Corp. 2009
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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*
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* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
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* See the COPYING.LIB file in the top-level directory.
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*
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*/
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#include <stdarg.h>
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#include "qemu-common.h"
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#include "qapi/qmp/qstring.h"
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#include "qapi/qmp/qint.h"
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#include "qapi/qmp/qdict.h"
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#include "qapi/qmp/qlist.h"
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#include "qapi/qmp/qfloat.h"
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#include "qapi/qmp/qbool.h"
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#include "qapi/qmp/json-parser.h"
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#include "qapi/qmp/json-lexer.h"
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#include "qapi/qmp/qerror.h"
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typedef struct JSONParserContext
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{
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Error *err;
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struct {
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QObject **buf;
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size_t pos;
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size_t count;
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} tokens;
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} JSONParserContext;
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#define BUG_ON(cond) assert(!(cond))
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/**
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* TODO
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*
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* 0) make errors meaningful again
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* 1) add geometry information to tokens
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* 3) should we return a parsed size?
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* 4) deal with premature EOI
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*/
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static QObject *parse_value(JSONParserContext *ctxt, va_list *ap);
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/**
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* Token manipulators
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*
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* tokens are dictionaries that contain a type, a string value, and geometry information
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* about a token identified by the lexer. These are routines that make working with
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* these objects a bit easier.
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*/
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static const char *token_get_value(QObject *obj)
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{
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return qdict_get_str(qobject_to_qdict(obj), "token");
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}
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static JSONTokenType token_get_type(QObject *obj)
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{
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return qdict_get_int(qobject_to_qdict(obj), "type");
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}
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static int token_is_operator(QObject *obj, char op)
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{
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const char *val;
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if (token_get_type(obj) != JSON_OPERATOR) {
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return 0;
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}
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val = token_get_value(obj);
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return (val[0] == op) && (val[1] == 0);
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}
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static int token_is_keyword(QObject *obj, const char *value)
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{
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if (token_get_type(obj) != JSON_KEYWORD) {
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return 0;
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}
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return strcmp(token_get_value(obj), value) == 0;
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}
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static int token_is_escape(QObject *obj, const char *value)
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{
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if (token_get_type(obj) != JSON_ESCAPE) {
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return 0;
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}
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return (strcmp(token_get_value(obj), value) == 0);
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}
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/**
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* Error handler
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*/
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static void GCC_FMT_ATTR(3, 4) parse_error(JSONParserContext *ctxt,
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QObject *token, const char *msg, ...)
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{
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va_list ap;
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char message[1024];
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va_start(ap, msg);
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vsnprintf(message, sizeof(message), msg, ap);
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va_end(ap);
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if (ctxt->err) {
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error_free(ctxt->err);
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ctxt->err = NULL;
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}
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error_setg(&ctxt->err, "JSON parse error, %s", message);
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}
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/**
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* String helpers
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*
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* These helpers are used to unescape strings.
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*/
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static void wchar_to_utf8(uint16_t wchar, char *buffer, size_t buffer_length)
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{
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if (wchar <= 0x007F) {
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BUG_ON(buffer_length < 2);
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buffer[0] = wchar & 0x7F;
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buffer[1] = 0;
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} else if (wchar <= 0x07FF) {
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BUG_ON(buffer_length < 3);
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buffer[0] = 0xC0 | ((wchar >> 6) & 0x1F);
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buffer[1] = 0x80 | (wchar & 0x3F);
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buffer[2] = 0;
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} else {
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BUG_ON(buffer_length < 4);
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buffer[0] = 0xE0 | ((wchar >> 12) & 0x0F);
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buffer[1] = 0x80 | ((wchar >> 6) & 0x3F);
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buffer[2] = 0x80 | (wchar & 0x3F);
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buffer[3] = 0;
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}
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}
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static int hex2decimal(char ch)
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{
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if (ch >= '0' && ch <= '9') {
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return (ch - '0');
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} else if (ch >= 'a' && ch <= 'f') {
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return 10 + (ch - 'a');
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} else if (ch >= 'A' && ch <= 'F') {
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return 10 + (ch - 'A');
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}
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return -1;
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}
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/**
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* parse_string(): Parse a json string and return a QObject
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*
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* string
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* ""
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* " chars "
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* chars
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* char
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* char chars
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* char
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* any-Unicode-character-
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* except-"-or-\-or-
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* control-character
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* \"
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* \\
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* \/
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* \b
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* \f
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* \n
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* \r
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* \t
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* \u four-hex-digits
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*/
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static QString *qstring_from_escaped_str(JSONParserContext *ctxt, QObject *token)
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{
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const char *ptr = token_get_value(token);
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QString *str;
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int double_quote = 1;
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if (*ptr == '"') {
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double_quote = 1;
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} else {
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double_quote = 0;
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}
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ptr++;
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str = qstring_new();
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while (*ptr &&
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((double_quote && *ptr != '"') || (!double_quote && *ptr != '\''))) {
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if (*ptr == '\\') {
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ptr++;
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switch (*ptr) {
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case '"':
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qstring_append(str, "\"");
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ptr++;
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break;
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case '\'':
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qstring_append(str, "'");
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ptr++;
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break;
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case '\\':
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qstring_append(str, "\\");
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ptr++;
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break;
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case '/':
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qstring_append(str, "/");
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ptr++;
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break;
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case 'b':
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qstring_append(str, "\b");
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ptr++;
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break;
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case 'f':
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qstring_append(str, "\f");
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ptr++;
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break;
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case 'n':
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qstring_append(str, "\n");
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ptr++;
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break;
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case 'r':
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qstring_append(str, "\r");
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ptr++;
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break;
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case 't':
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qstring_append(str, "\t");
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ptr++;
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break;
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case 'u': {
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uint16_t unicode_char = 0;
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char utf8_char[4];
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int i = 0;
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ptr++;
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for (i = 0; i < 4; i++) {
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if (qemu_isxdigit(*ptr)) {
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unicode_char |= hex2decimal(*ptr) << ((3 - i) * 4);
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} else {
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parse_error(ctxt, token,
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"invalid hex escape sequence in string");
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goto out;
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}
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ptr++;
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}
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wchar_to_utf8(unicode_char, utf8_char, sizeof(utf8_char));
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qstring_append(str, utf8_char);
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} break;
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default:
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parse_error(ctxt, token, "invalid escape sequence in string");
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goto out;
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}
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} else {
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char dummy[2];
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dummy[0] = *ptr++;
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dummy[1] = 0;
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qstring_append(str, dummy);
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}
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}
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return str;
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out:
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QDECREF(str);
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return NULL;
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}
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static QObject *parser_context_pop_token(JSONParserContext *ctxt)
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{
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QObject *token;
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g_assert(ctxt->tokens.pos < ctxt->tokens.count);
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token = ctxt->tokens.buf[ctxt->tokens.pos];
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ctxt->tokens.pos++;
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return token;
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}
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/* Note: parser_context_{peek|pop}_token do not increment the
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* token object's refcount. In both cases the references will continue
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* to be tracked and cleaned up in parser_context_free(), so do not
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* attempt to free the token object.
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*/
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static QObject *parser_context_peek_token(JSONParserContext *ctxt)
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{
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QObject *token;
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g_assert(ctxt->tokens.pos < ctxt->tokens.count);
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token = ctxt->tokens.buf[ctxt->tokens.pos];
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return token;
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}
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static JSONParserContext parser_context_save(JSONParserContext *ctxt)
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{
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JSONParserContext saved_ctxt = {0};
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saved_ctxt.tokens.pos = ctxt->tokens.pos;
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saved_ctxt.tokens.count = ctxt->tokens.count;
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saved_ctxt.tokens.buf = ctxt->tokens.buf;
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return saved_ctxt;
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}
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static void parser_context_restore(JSONParserContext *ctxt,
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JSONParserContext saved_ctxt)
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{
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ctxt->tokens.pos = saved_ctxt.tokens.pos;
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ctxt->tokens.count = saved_ctxt.tokens.count;
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ctxt->tokens.buf = saved_ctxt.tokens.buf;
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}
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static void tokens_append_from_iter(QObject *obj, void *opaque)
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{
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JSONParserContext *ctxt = opaque;
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g_assert(ctxt->tokens.pos < ctxt->tokens.count);
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ctxt->tokens.buf[ctxt->tokens.pos++] = obj;
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qobject_incref(obj);
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}
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static JSONParserContext *parser_context_new(QList *tokens)
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{
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JSONParserContext *ctxt;
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size_t count;
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if (!tokens) {
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return NULL;
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}
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count = qlist_size(tokens);
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if (count == 0) {
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return NULL;
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}
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ctxt = g_malloc0(sizeof(JSONParserContext));
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ctxt->tokens.pos = 0;
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ctxt->tokens.count = count;
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ctxt->tokens.buf = g_malloc(count * sizeof(QObject *));
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qlist_iter(tokens, tokens_append_from_iter, ctxt);
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ctxt->tokens.pos = 0;
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return ctxt;
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}
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/* to support error propagation, ctxt->err must be freed separately */
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static void parser_context_free(JSONParserContext *ctxt)
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{
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int i;
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if (ctxt) {
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for (i = 0; i < ctxt->tokens.count; i++) {
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qobject_decref(ctxt->tokens.buf[i]);
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}
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g_free(ctxt->tokens.buf);
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g_free(ctxt);
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}
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}
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/**
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* Parsing rules
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*/
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static int parse_pair(JSONParserContext *ctxt, QDict *dict, va_list *ap)
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{
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QObject *key = NULL, *token = NULL, *value, *peek;
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JSONParserContext saved_ctxt = parser_context_save(ctxt);
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peek = parser_context_peek_token(ctxt);
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if (peek == NULL) {
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parse_error(ctxt, NULL, "premature EOI");
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goto out;
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}
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key = parse_value(ctxt, ap);
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if (!key || qobject_type(key) != QTYPE_QSTRING) {
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parse_error(ctxt, peek, "key is not a string in object");
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goto out;
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}
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token = parser_context_pop_token(ctxt);
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if (token == NULL) {
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parse_error(ctxt, NULL, "premature EOI");
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goto out;
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}
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if (!token_is_operator(token, ':')) {
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parse_error(ctxt, token, "missing : in object pair");
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goto out;
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}
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value = parse_value(ctxt, ap);
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if (value == NULL) {
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parse_error(ctxt, token, "Missing value in dict");
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goto out;
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}
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qdict_put_obj(dict, qstring_get_str(qobject_to_qstring(key)), value);
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qobject_decref(key);
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return 0;
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out:
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parser_context_restore(ctxt, saved_ctxt);
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qobject_decref(key);
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return -1;
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}
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static QObject *parse_object(JSONParserContext *ctxt, va_list *ap)
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{
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QDict *dict = NULL;
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QObject *token, *peek;
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JSONParserContext saved_ctxt = parser_context_save(ctxt);
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token = parser_context_pop_token(ctxt);
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if (token == NULL) {
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goto out;
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}
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if (!token_is_operator(token, '{')) {
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goto out;
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}
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dict = qdict_new();
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peek = parser_context_peek_token(ctxt);
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if (peek == NULL) {
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parse_error(ctxt, NULL, "premature EOI");
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goto out;
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}
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if (!token_is_operator(peek, '}')) {
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if (parse_pair(ctxt, dict, ap) == -1) {
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goto out;
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}
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token = parser_context_pop_token(ctxt);
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if (token == NULL) {
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parse_error(ctxt, NULL, "premature EOI");
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goto out;
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}
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while (!token_is_operator(token, '}')) {
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if (!token_is_operator(token, ',')) {
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parse_error(ctxt, token, "expected separator in dict");
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goto out;
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}
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if (parse_pair(ctxt, dict, ap) == -1) {
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goto out;
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}
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token = parser_context_pop_token(ctxt);
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if (token == NULL) {
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parse_error(ctxt, NULL, "premature EOI");
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goto out;
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}
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}
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} else {
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(void)parser_context_pop_token(ctxt);
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}
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return QOBJECT(dict);
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out:
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parser_context_restore(ctxt, saved_ctxt);
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QDECREF(dict);
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return NULL;
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}
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static QObject *parse_array(JSONParserContext *ctxt, va_list *ap)
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{
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QList *list = NULL;
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QObject *token, *peek;
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JSONParserContext saved_ctxt = parser_context_save(ctxt);
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token = parser_context_pop_token(ctxt);
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if (token == NULL) {
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goto out;
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}
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if (!token_is_operator(token, '[')) {
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goto out;
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}
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list = qlist_new();
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peek = parser_context_peek_token(ctxt);
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if (peek == NULL) {
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parse_error(ctxt, NULL, "premature EOI");
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goto out;
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}
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if (!token_is_operator(peek, ']')) {
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QObject *obj;
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obj = parse_value(ctxt, ap);
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if (obj == NULL) {
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parse_error(ctxt, token, "expecting value");
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goto out;
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}
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qlist_append_obj(list, obj);
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token = parser_context_pop_token(ctxt);
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if (token == NULL) {
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parse_error(ctxt, NULL, "premature EOI");
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goto out;
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}
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while (!token_is_operator(token, ']')) {
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if (!token_is_operator(token, ',')) {
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parse_error(ctxt, token, "expected separator in list");
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goto out;
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}
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obj = parse_value(ctxt, ap);
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if (obj == NULL) {
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parse_error(ctxt, token, "expecting value");
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goto out;
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}
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qlist_append_obj(list, obj);
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token = parser_context_pop_token(ctxt);
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if (token == NULL) {
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parse_error(ctxt, NULL, "premature EOI");
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goto out;
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}
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}
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} else {
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(void)parser_context_pop_token(ctxt);
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}
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return QOBJECT(list);
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out:
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parser_context_restore(ctxt, saved_ctxt);
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QDECREF(list);
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return NULL;
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}
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static QObject *parse_keyword(JSONParserContext *ctxt)
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{
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QObject *token, *ret;
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JSONParserContext saved_ctxt = parser_context_save(ctxt);
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token = parser_context_pop_token(ctxt);
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if (token == NULL) {
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goto out;
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}
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if (token_get_type(token) != JSON_KEYWORD) {
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goto out;
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}
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if (token_is_keyword(token, "true")) {
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ret = QOBJECT(qbool_from_int(true));
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} else if (token_is_keyword(token, "false")) {
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ret = QOBJECT(qbool_from_int(false));
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} else {
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parse_error(ctxt, token, "invalid keyword `%s'", token_get_value(token));
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goto out;
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}
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return ret;
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out:
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parser_context_restore(ctxt, saved_ctxt);
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return NULL;
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}
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static QObject *parse_escape(JSONParserContext *ctxt, va_list *ap)
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{
|
|
QObject *token = NULL, *obj;
|
|
JSONParserContext saved_ctxt = parser_context_save(ctxt);
|
|
|
|
if (ap == NULL) {
|
|
goto out;
|
|
}
|
|
|
|
token = parser_context_pop_token(ctxt);
|
|
if (token == NULL) {
|
|
goto out;
|
|
}
|
|
|
|
if (token_is_escape(token, "%p")) {
|
|
obj = va_arg(*ap, QObject *);
|
|
} else if (token_is_escape(token, "%i")) {
|
|
obj = QOBJECT(qbool_from_int(va_arg(*ap, int)));
|
|
} else if (token_is_escape(token, "%d")) {
|
|
obj = QOBJECT(qint_from_int(va_arg(*ap, int)));
|
|
} else if (token_is_escape(token, "%ld")) {
|
|
obj = QOBJECT(qint_from_int(va_arg(*ap, long)));
|
|
} else if (token_is_escape(token, "%lld") ||
|
|
token_is_escape(token, "%I64d")) {
|
|
obj = QOBJECT(qint_from_int(va_arg(*ap, long long)));
|
|
} else if (token_is_escape(token, "%s")) {
|
|
obj = QOBJECT(qstring_from_str(va_arg(*ap, const char *)));
|
|
} else if (token_is_escape(token, "%f")) {
|
|
obj = QOBJECT(qfloat_from_double(va_arg(*ap, double)));
|
|
} else {
|
|
goto out;
|
|
}
|
|
|
|
return obj;
|
|
|
|
out:
|
|
parser_context_restore(ctxt, saved_ctxt);
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static QObject *parse_literal(JSONParserContext *ctxt)
|
|
{
|
|
QObject *token, *obj;
|
|
JSONParserContext saved_ctxt = parser_context_save(ctxt);
|
|
|
|
token = parser_context_pop_token(ctxt);
|
|
if (token == NULL) {
|
|
goto out;
|
|
}
|
|
|
|
switch (token_get_type(token)) {
|
|
case JSON_STRING:
|
|
obj = QOBJECT(qstring_from_escaped_str(ctxt, token));
|
|
break;
|
|
case JSON_INTEGER: {
|
|
/* A possibility exists that this is a whole-valued float where the
|
|
* fractional part was left out due to being 0 (.0). It's not a big
|
|
* deal to treat these as ints in the parser, so long as users of the
|
|
* resulting QObject know to expect a QInt in place of a QFloat in
|
|
* cases like these.
|
|
*
|
|
* However, in some cases these values will overflow/underflow a
|
|
* QInt/int64 container, thus we should assume these are to be handled
|
|
* as QFloats/doubles rather than silently changing their values.
|
|
*
|
|
* strtoll() indicates these instances by setting errno to ERANGE
|
|
*/
|
|
int64_t value;
|
|
|
|
errno = 0; /* strtoll doesn't set errno on success */
|
|
value = strtoll(token_get_value(token), NULL, 10);
|
|
if (errno != ERANGE) {
|
|
obj = QOBJECT(qint_from_int(value));
|
|
break;
|
|
}
|
|
/* fall through to JSON_FLOAT */
|
|
}
|
|
case JSON_FLOAT:
|
|
/* FIXME dependent on locale */
|
|
obj = QOBJECT(qfloat_from_double(strtod(token_get_value(token), NULL)));
|
|
break;
|
|
default:
|
|
goto out;
|
|
}
|
|
|
|
return obj;
|
|
|
|
out:
|
|
parser_context_restore(ctxt, saved_ctxt);
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static QObject *parse_value(JSONParserContext *ctxt, va_list *ap)
|
|
{
|
|
QObject *obj;
|
|
|
|
obj = parse_object(ctxt, ap);
|
|
if (obj == NULL) {
|
|
obj = parse_array(ctxt, ap);
|
|
}
|
|
if (obj == NULL) {
|
|
obj = parse_escape(ctxt, ap);
|
|
}
|
|
if (obj == NULL) {
|
|
obj = parse_keyword(ctxt);
|
|
}
|
|
if (obj == NULL) {
|
|
obj = parse_literal(ctxt);
|
|
}
|
|
|
|
return obj;
|
|
}
|
|
|
|
QObject *json_parser_parse(QList *tokens, va_list *ap)
|
|
{
|
|
return json_parser_parse_err(tokens, ap, NULL);
|
|
}
|
|
|
|
QObject *json_parser_parse_err(QList *tokens, va_list *ap, Error **errp)
|
|
{
|
|
JSONParserContext *ctxt = parser_context_new(tokens);
|
|
QObject *result;
|
|
|
|
if (!ctxt) {
|
|
return NULL;
|
|
}
|
|
|
|
result = parse_value(ctxt, ap);
|
|
|
|
error_propagate(errp, ctxt->err);
|
|
|
|
parser_context_free(ctxt);
|
|
|
|
return result;
|
|
}
|