RFC 8259 (December 2017) obsoletes RFC 7159 (March 2014). Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20180823164025.12553-59-armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
585 lines
16 KiB
C
585 lines
16 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 "qemu/osdep.h"
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#include "qemu/cutils.h"
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#include "qemu/unicode.h"
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#include "qapi/error.h"
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#include "qemu-common.h"
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#include "qapi/qmp/qbool.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/qnull.h"
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#include "qapi/qmp/qnum.h"
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#include "qapi/qmp/qstring.h"
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#include "json-parser-int.h"
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struct JSONToken {
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JSONTokenType type;
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int x;
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int y;
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char str[];
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};
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typedef struct JSONParserContext
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{
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Error *err;
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JSONToken *current;
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GQueue *buf;
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va_list *ap;
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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);
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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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JSONToken *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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if (ctxt->err) {
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return;
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}
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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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error_setg(&ctxt->err, "JSON parse error, %s", message);
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}
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static int cvt4hex(const char *s)
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{
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int cp, i;
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cp = 0;
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for (i = 0; i < 4; i++) {
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if (!qemu_isxdigit(s[i])) {
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return -1;
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}
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cp <<= 4;
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if (s[i] >= '0' && s[i] <= '9') {
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cp |= s[i] - '0';
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} else if (s[i] >= 'a' && s[i] <= 'f') {
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cp |= 10 + s[i] - 'a';
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} else if (s[i] >= 'A' && s[i] <= 'F') {
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cp |= 10 + s[i] - 'A';
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} else {
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return -1;
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}
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}
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return cp;
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}
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/**
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* parse_string(): Parse a JSON string
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*
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* From RFC 8259 "The JavaScript Object Notation (JSON) Data
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* Interchange Format":
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*
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* char = unescaped /
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* escape (
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* %x22 / ; " quotation mark U+0022
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* %x5C / ; \ reverse solidus U+005C
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* %x2F / ; / solidus U+002F
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* %x62 / ; b backspace U+0008
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* %x66 / ; f form feed U+000C
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* %x6E / ; n line feed U+000A
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* %x72 / ; r carriage return U+000D
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* %x74 / ; t tab U+0009
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* %x75 4HEXDIG ) ; uXXXX U+XXXX
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* escape = %x5C ; \
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* quotation-mark = %x22 ; "
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* unescaped = %x20-21 / %x23-5B / %x5D-10FFFF
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*
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* Extensions over RFC 8259:
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* - Extra escape sequence in strings:
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* 0x27 (apostrophe) is recognized after escape, too
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* - Single-quoted strings:
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* Like double-quoted strings, except they're delimited by %x27
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* (apostrophe) instead of %x22 (quotation mark), and can't contain
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* unescaped apostrophe, but can contain unescaped quotation mark.
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*
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* Note:
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* - Encoding is modified UTF-8.
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* - Invalid Unicode characters are rejected.
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* - Control characters \x00..\x1F are rejected by the lexer.
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*/
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static QString *parse_string(JSONParserContext *ctxt, JSONToken *token)
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{
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const char *ptr = token->str;
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QString *str;
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char quote;
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const char *beg;
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int cp, trailing;
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char *end;
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ssize_t len;
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char utf8_buf[5];
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assert(*ptr == '"' || *ptr == '\'');
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quote = *ptr++;
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str = qstring_new();
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while (*ptr != quote) {
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assert(*ptr);
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switch (*ptr) {
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case '\\':
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beg = ptr++;
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switch (*ptr++) {
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case '"':
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qstring_append_chr(str, '"');
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break;
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case '\'':
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qstring_append_chr(str, '\'');
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break;
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case '\\':
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qstring_append_chr(str, '\\');
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break;
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case '/':
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qstring_append_chr(str, '/');
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break;
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case 'b':
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qstring_append_chr(str, '\b');
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break;
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case 'f':
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qstring_append_chr(str, '\f');
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break;
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case 'n':
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qstring_append_chr(str, '\n');
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break;
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case 'r':
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qstring_append_chr(str, '\r');
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break;
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case 't':
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qstring_append_chr(str, '\t');
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break;
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case 'u':
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cp = cvt4hex(ptr);
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ptr += 4;
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/* handle surrogate pairs */
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if (cp >= 0xD800 && cp <= 0xDBFF
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&& ptr[0] == '\\' && ptr[1] == 'u') {
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/* leading surrogate followed by \u */
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cp = 0x10000 + ((cp & 0x3FF) << 10);
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trailing = cvt4hex(ptr + 2);
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if (trailing >= 0xDC00 && trailing <= 0xDFFF) {
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/* followed by trailing surrogate */
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cp |= trailing & 0x3FF;
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ptr += 6;
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} else {
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cp = -1; /* invalid */
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}
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}
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if (mod_utf8_encode(utf8_buf, sizeof(utf8_buf), cp) < 0) {
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parse_error(ctxt, token,
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"%.*s is not a valid Unicode character",
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(int)(ptr - beg), beg);
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goto out;
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}
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qstring_append(str, utf8_buf);
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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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break;
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case '%':
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if (ctxt->ap && ptr[1] != '%') {
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parse_error(ctxt, token, "can't interpolate into string");
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goto out;
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}
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ptr++;
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/* fall through */
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default:
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cp = mod_utf8_codepoint(ptr, 6, &end);
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if (cp < 0) {
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parse_error(ctxt, token, "invalid UTF-8 sequence in string");
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goto out;
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}
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ptr = end;
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len = mod_utf8_encode(utf8_buf, sizeof(utf8_buf), cp);
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assert(len >= 0);
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qstring_append(str, utf8_buf);
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}
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}
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return str;
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out:
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qobject_unref(str);
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return NULL;
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}
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/* Note: the token object returned by parser_context_peek_token or
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* parser_context_pop_token is deleted as soon as parser_context_pop_token
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* is called again.
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*/
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static JSONToken *parser_context_pop_token(JSONParserContext *ctxt)
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{
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g_free(ctxt->current);
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ctxt->current = g_queue_pop_head(ctxt->buf);
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return ctxt->current;
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}
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static JSONToken *parser_context_peek_token(JSONParserContext *ctxt)
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{
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return g_queue_peek_head(ctxt->buf);
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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)
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{
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QObject *value;
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QString *key = NULL;
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JSONToken *peek, *token;
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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 = qobject_to(QString, parse_value(ctxt));
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if (!key) {
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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->type != JSON_COLON) {
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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);
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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(key), value);
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qobject_unref(key);
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return 0;
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out:
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qobject_unref(key);
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return -1;
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}
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static QObject *parse_object(JSONParserContext *ctxt)
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{
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QDict *dict = NULL;
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JSONToken *token, *peek;
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token = parser_context_pop_token(ctxt);
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assert(token && token->type == JSON_LCURLY);
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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 (peek->type != JSON_RCURLY) {
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if (parse_pair(ctxt, dict) == -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->type != JSON_RCURLY) {
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if (token->type != JSON_COMMA) {
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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) == -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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qobject_unref(dict);
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return NULL;
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}
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static QObject *parse_array(JSONParserContext *ctxt)
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{
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QList *list = NULL;
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JSONToken *token, *peek;
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token = parser_context_pop_token(ctxt);
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assert(token && token->type == JSON_LSQUARE);
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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 (peek->type != JSON_RSQUARE) {
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QObject *obj;
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obj = parse_value(ctxt);
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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->type != JSON_RSQUARE) {
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if (token->type != JSON_COMMA) {
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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);
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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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qobject_unref(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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JSONToken *token;
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token = parser_context_pop_token(ctxt);
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assert(token && token->type == JSON_KEYWORD);
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if (!strcmp(token->str, "true")) {
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return QOBJECT(qbool_from_bool(true));
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} else if (!strcmp(token->str, "false")) {
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return QOBJECT(qbool_from_bool(false));
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} else if (!strcmp(token->str, "null")) {
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return QOBJECT(qnull());
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}
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parse_error(ctxt, token, "invalid keyword '%s'", token->str);
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return NULL;
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}
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static QObject *parse_interpolation(JSONParserContext *ctxt)
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{
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JSONToken *token;
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token = parser_context_pop_token(ctxt);
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assert(token && token->type == JSON_INTERP);
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if (!strcmp(token->str, "%p")) {
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return va_arg(*ctxt->ap, QObject *);
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} else if (!strcmp(token->str, "%i")) {
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return QOBJECT(qbool_from_bool(va_arg(*ctxt->ap, int)));
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} else if (!strcmp(token->str, "%d")) {
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return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, int)));
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} else if (!strcmp(token->str, "%ld")) {
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return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, long)));
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} else if (!strcmp(token->str, "%lld")) {
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return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, long long)));
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} else if (!strcmp(token->str, "%" PRId64)) {
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return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, int64_t)));
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} else if (!strcmp(token->str, "%u")) {
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return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, unsigned int)));
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} else if (!strcmp(token->str, "%lu")) {
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return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, unsigned long)));
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} else if (!strcmp(token->str, "%llu")) {
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return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, unsigned long long)));
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} else if (!strcmp(token->str, "%" PRIu64)) {
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return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, uint64_t)));
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} else if (!strcmp(token->str, "%s")) {
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return QOBJECT(qstring_from_str(va_arg(*ctxt->ap, const char *)));
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} else if (!strcmp(token->str, "%f")) {
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return QOBJECT(qnum_from_double(va_arg(*ctxt->ap, double)));
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}
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parse_error(ctxt, token, "invalid interpolation '%s'", token->str);
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return NULL;
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}
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static QObject *parse_literal(JSONParserContext *ctxt)
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{
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JSONToken *token;
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token = parser_context_pop_token(ctxt);
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assert(token);
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switch (token->type) {
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case JSON_STRING:
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return QOBJECT(parse_string(ctxt, token));
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case JSON_INTEGER: {
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/*
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* Represent JSON_INTEGER as QNUM_I64 if possible, else as
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* QNUM_U64, else as QNUM_DOUBLE. Note that qemu_strtoi64()
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* and qemu_strtou64() fail with ERANGE when it's not
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* possible.
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*
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* qnum_get_int() will then work for any signed 64-bit
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* JSON_INTEGER, qnum_get_uint() for any unsigned 64-bit
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* integer, and qnum_get_double() both for any JSON_INTEGER
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* and any JSON_FLOAT (with precision loss for integers beyond
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* 53 bits)
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*/
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int ret;
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int64_t value;
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uint64_t uvalue;
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ret = qemu_strtoi64(token->str, NULL, 10, &value);
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if (!ret) {
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return QOBJECT(qnum_from_int(value));
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}
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assert(ret == -ERANGE);
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if (token->str[0] != '-') {
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ret = qemu_strtou64(token->str, NULL, 10, &uvalue);
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if (!ret) {
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return QOBJECT(qnum_from_uint(uvalue));
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}
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assert(ret == -ERANGE);
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}
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/* fall through to JSON_FLOAT */
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}
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case JSON_FLOAT:
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/* FIXME dependent on locale; a pervasive issue in QEMU */
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/* FIXME our lexer matches RFC 8259 in forbidding Inf or NaN,
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* but those might be useful extensions beyond JSON */
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return QOBJECT(qnum_from_double(strtod(token->str, NULL)));
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default:
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abort();
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}
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}
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static QObject *parse_value(JSONParserContext *ctxt)
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{
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JSONToken *token;
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token = parser_context_peek_token(ctxt);
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if (token == NULL) {
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parse_error(ctxt, NULL, "premature EOI");
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return NULL;
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}
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switch (token->type) {
|
|
case JSON_LCURLY:
|
|
return parse_object(ctxt);
|
|
case JSON_LSQUARE:
|
|
return parse_array(ctxt);
|
|
case JSON_INTERP:
|
|
return parse_interpolation(ctxt);
|
|
case JSON_INTEGER:
|
|
case JSON_FLOAT:
|
|
case JSON_STRING:
|
|
return parse_literal(ctxt);
|
|
case JSON_KEYWORD:
|
|
return parse_keyword(ctxt);
|
|
default:
|
|
parse_error(ctxt, token, "expecting value");
|
|
return NULL;
|
|
}
|
|
}
|
|
|
|
JSONToken *json_token(JSONTokenType type, int x, int y, GString *tokstr)
|
|
{
|
|
JSONToken *token = g_malloc(sizeof(JSONToken) + tokstr->len + 1);
|
|
|
|
token->type = type;
|
|
memcpy(token->str, tokstr->str, tokstr->len);
|
|
token->str[tokstr->len] = 0;
|
|
token->x = x;
|
|
token->y = y;
|
|
return token;
|
|
}
|
|
|
|
QObject *json_parser_parse(GQueue *tokens, va_list *ap, Error **errp)
|
|
{
|
|
JSONParserContext ctxt = { .buf = tokens, .ap = ap };
|
|
QObject *result;
|
|
|
|
result = parse_value(&ctxt);
|
|
assert(ctxt.err || g_queue_is_empty(ctxt.buf));
|
|
|
|
error_propagate(errp, ctxt.err);
|
|
|
|
while (!g_queue_is_empty(ctxt.buf)) {
|
|
parser_context_pop_token(&ctxt);
|
|
}
|
|
g_free(ctxt.current);
|
|
|
|
return result;
|
|
}
|