4b1c0cd7c7
Since the JSON grammer doesn't accept U+0000 anywhere, this merely
exchanges one kind of parse error for another. It's purely for
consistency with qobject_to_json(), which accepts \xC0\x80 (see commit
e2ec3f9768).
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180823164025.12553-26-armbru@redhat.com>
592 lines
15 KiB
C
592 lines
15 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 "qapi/qmp/json-parser.h"
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#include "qapi/qmp/json-lexer.h"
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#include "qapi/qmp/json-streamer.h"
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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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} 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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* 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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/**
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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,
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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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int cp;
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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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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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break;
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case '\'':
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qstring_append(str, "'");
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break;
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case '\\':
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qstring_append(str, "\\");
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break;
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case '/':
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qstring_append(str, "/");
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break;
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case 'b':
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qstring_append(str, "\b");
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break;
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case 'f':
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qstring_append(str, "\f");
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break;
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case 'n':
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qstring_append(str, "\n");
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break;
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case 'r':
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qstring_append(str, "\r");
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break;
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case 't':
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qstring_append(str, "\t");
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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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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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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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assert(!g_queue_is_empty(ctxt->buf));
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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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assert(!g_queue_is_empty(ctxt->buf));
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return g_queue_peek_head(ctxt->buf);
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}
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static JSONParserContext *parser_context_new(GQueue *tokens)
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{
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JSONParserContext *ctxt;
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if (!tokens) {
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return NULL;
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}
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ctxt = g_malloc0(sizeof(JSONParserContext));
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ctxt->buf = tokens;
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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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if (ctxt) {
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while (!g_queue_is_empty(ctxt->buf)) {
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parser_context_pop_token(ctxt);
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}
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g_free(ctxt->current);
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g_queue_free(ctxt->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 *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, ap));
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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, 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(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, va_list *ap)
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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, 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->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, 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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qobject_unref(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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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, 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->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, 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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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_escape(JSONParserContext *ctxt, va_list *ap)
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{
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JSONToken *token;
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if (ap == NULL) {
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return NULL;
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}
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token = parser_context_pop_token(ctxt);
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assert(token && token->type == JSON_ESCAPE);
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if (!strcmp(token->str, "%p")) {
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return va_arg(*ap, QObject *);
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} else if (!strcmp(token->str, "%i")) {
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return QOBJECT(qbool_from_bool(va_arg(*ap, int)));
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} else if (!strcmp(token->str, "%d")) {
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return QOBJECT(qnum_from_int(va_arg(*ap, int)));
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} else if (!strcmp(token->str, "%ld")) {
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return QOBJECT(qnum_from_int(va_arg(*ap, long)));
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} else if (!strcmp(token->str, "%lld") ||
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!strcmp(token->str, "%I64d")) {
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return QOBJECT(qnum_from_int(va_arg(*ap, long long)));
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} else if (!strcmp(token->str, "%u")) {
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return QOBJECT(qnum_from_uint(va_arg(*ap, unsigned int)));
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} else if (!strcmp(token->str, "%lu")) {
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return QOBJECT(qnum_from_uint(va_arg(*ap, unsigned long)));
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} else if (!strcmp(token->str, "%llu") ||
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!strcmp(token->str, "%I64u")) {
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return QOBJECT(qnum_from_uint(va_arg(*ap, unsigned long long)));
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} else if (!strcmp(token->str, "%s")) {
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return QOBJECT(qstring_from_str(va_arg(*ap, const char *)));
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} else if (!strcmp(token->str, "%f")) {
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return QOBJECT(qnum_from_double(va_arg(*ap, double)));
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}
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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(qstring_from_escaped_str(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 7159 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, va_list *ap)
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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) {
|
|
parse_error(ctxt, NULL, "premature EOI");
|
|
return NULL;
|
|
}
|
|
|
|
switch (token->type) {
|
|
case JSON_LCURLY:
|
|
return parse_object(ctxt, ap);
|
|
case JSON_LSQUARE:
|
|
return parse_array(ctxt, ap);
|
|
case JSON_ESCAPE:
|
|
return parse_escape(ctxt, ap);
|
|
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;
|
|
}
|
|
}
|
|
|
|
QObject *json_parser_parse(GQueue *tokens, va_list *ap)
|
|
{
|
|
return json_parser_parse_err(tokens, ap, NULL);
|
|
}
|
|
|
|
QObject *json_parser_parse_err(GQueue *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;
|
|
}
|