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95385fe9ac
xemu/qobject/json-parser.c
Paolo Bonzini 95385fe9ac qjson: store tokens in a GQueue 
Even though we still have the "streamer" concept, the tokens can now
be deleted as they are read.  While doing so convert from QList to
GQueue, since the next step will make tokens not a QObject and we
will have to do the conversion anyway.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1448300659-23559-4-git-send-email-pbonzini@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
2015-11-26 10:07:07 +01:00

598 lines
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/*
* JSON Parser
*
* Copyright IBM, Corp. 2009
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
* See the COPYING.LIB file in the top-level directory.
*
*/
#include <stdarg.h>
#include "qemu-common.h"
#include "qapi/qmp/qstring.h"
#include "qapi/qmp/qint.h"
#include "qapi/qmp/qdict.h"
#include "qapi/qmp/qlist.h"
#include "qapi/qmp/qfloat.h"
#include "qapi/qmp/qbool.h"
#include "qapi/qmp/json-parser.h"
#include "qapi/qmp/json-lexer.h"
typedef struct JSONParserContext
{
Error *err;
QObject *current;
GQueue *buf;
} JSONParserContext;
#define BUG_ON(cond) assert(!(cond))
/**
* TODO
*
* 0) make errors meaningful again
* 1) add geometry information to tokens
* 3) should we return a parsed size?
* 4) deal with premature EOI
*/
static QObject *parse_value(JSONParserContext *ctxt, va_list *ap);
/**
* Token manipulators
*
* tokens are dictionaries that contain a type, a string value, and geometry information
* about a token identified by the lexer. These are routines that make working with
* these objects a bit easier.
*/
static const char *token_get_value(QObject *obj)
{
return qdict_get_str(qobject_to_qdict(obj), "token");
}
static JSONTokenType token_get_type(QObject *obj)
{
return qdict_get_int(qobject_to_qdict(obj), "type");
}
/**
* Error handler
*/
static void GCC_FMT_ATTR(3, 4) parse_error(JSONParserContext *ctxt,
QObject *token, const char *msg, ...)
{
va_list ap;
char message[1024];
va_start(ap, msg);
vsnprintf(message, sizeof(message), msg, ap);
va_end(ap);
if (ctxt->err) {
error_free(ctxt->err);
ctxt->err = NULL;
}
error_setg(&ctxt->err, "JSON parse error, %s", message);
}
/**
* String helpers
*
* These helpers are used to unescape strings.
*/
static void wchar_to_utf8(uint16_t wchar, char *buffer, size_t buffer_length)
{
if (wchar <= 0x007F) {
BUG_ON(buffer_length < 2);
buffer[0] = wchar & 0x7F;
buffer[1] = 0;
} else if (wchar <= 0x07FF) {
BUG_ON(buffer_length < 3);
buffer[0] = 0xC0 | ((wchar >> 6) & 0x1F);
buffer[1] = 0x80 | (wchar & 0x3F);
buffer[2] = 0;
} else {
BUG_ON(buffer_length < 4);
buffer[0] = 0xE0 | ((wchar >> 12) & 0x0F);
buffer[1] = 0x80 | ((wchar >> 6) & 0x3F);
buffer[2] = 0x80 | (wchar & 0x3F);
buffer[3] = 0;
}
}
static int hex2decimal(char ch)
{
if (ch >= '0' && ch <= '9') {
return (ch - '0');
} else if (ch >= 'a' && ch <= 'f') {
return 10 + (ch - 'a');
} else if (ch >= 'A' && ch <= 'F') {
return 10 + (ch - 'A');
}
return -1;
}
/**
* parse_string(): Parse a json string and return a QObject
*
* string
* ""
* " chars "
* chars
* char
* char chars
* char
* any-Unicode-character-
* except-"-or-\-or-
* control-character
* \"
* \\
* \/
* \b
* \f
* \n
* \r
* \t
* \u four-hex-digits
*/
static QString *qstring_from_escaped_str(JSONParserContext *ctxt, QObject *token)
{
const char *ptr = token_get_value(token);
QString *str;
int double_quote = 1;
if (*ptr == '"') {
double_quote = 1;
} else {
double_quote = 0;
}
ptr++;
str = qstring_new();
while (*ptr &&
((double_quote && *ptr != '"') || (!double_quote && *ptr != '\''))) {
if (*ptr == '\\') {
ptr++;
switch (*ptr) {
case '"':
qstring_append(str, "\"");
ptr++;
break;
case '\'':
qstring_append(str, "'");
ptr++;
break;
case '\\':
qstring_append(str, "\\");
ptr++;
break;
case '/':
qstring_append(str, "/");
ptr++;
break;
case 'b':
qstring_append(str, "\b");
ptr++;
break;
case 'f':
qstring_append(str, "\f");
ptr++;
break;
case 'n':
qstring_append(str, "\n");
ptr++;
break;
case 'r':
qstring_append(str, "\r");
ptr++;
break;
case 't':
qstring_append(str, "\t");
ptr++;
break;
case 'u': {
uint16_t unicode_char = 0;
char utf8_char[4];
int i = 0;
ptr++;
for (i = 0; i < 4; i++) {
if (qemu_isxdigit(*ptr)) {
unicode_char |= hex2decimal(*ptr) << ((3 - i) * 4);
} else {
parse_error(ctxt, token,
"invalid hex escape sequence in string");
goto out;
}
ptr++;
}
wchar_to_utf8(unicode_char, utf8_char, sizeof(utf8_char));
qstring_append(str, utf8_char);
} break;
default:
parse_error(ctxt, token, "invalid escape sequence in string");
goto out;
}
} else {
char dummy[2];
dummy[0] = *ptr++;
dummy[1] = 0;
qstring_append(str, dummy);
}
}
return str;
out:
QDECREF(str);
return NULL;
}
/* Note: unless the token object returned by parser_context_peek_token
* or parser_context_pop_token is explicitly incref'd, it will be
* deleted as soon as parser_context_pop_token is called again.
*/
static QObject *parser_context_pop_token(JSONParserContext *ctxt)
{
qobject_decref(ctxt->current);
assert(!g_queue_is_empty(ctxt->buf));
ctxt->current = g_queue_pop_head(ctxt->buf);
return ctxt->current;
}
static QObject *parser_context_peek_token(JSONParserContext *ctxt)
{
assert(!g_queue_is_empty(ctxt->buf));
return g_queue_peek_head(ctxt->buf);
}
static JSONParserContext *parser_context_new(GQueue *tokens)
{
JSONParserContext *ctxt;
if (!tokens) {
return NULL;
}
ctxt = g_malloc0(sizeof(JSONParserContext));
ctxt->buf = tokens;
return ctxt;
}
/* to support error propagation, ctxt->err must be freed separately */
static void parser_context_free(JSONParserContext *ctxt)
{
if (ctxt) {
while (!g_queue_is_empty(ctxt->buf)) {
parser_context_pop_token(ctxt);
}
qobject_decref(ctxt->current);
g_queue_free(ctxt->buf);
g_free(ctxt);
}
}
/**
* Parsing rules
*/
static int parse_pair(JSONParserContext *ctxt, QDict *dict, va_list *ap)
{
QObject *key = NULL, *token = NULL, *value, *peek;
peek = parser_context_peek_token(ctxt);
if (peek == NULL) {
parse_error(ctxt, NULL, "premature EOI");
goto out;
}
key = parse_value(ctxt, ap);
if (!key || qobject_type(key) != QTYPE_QSTRING) {
parse_error(ctxt, peek, "key is not a string in object");
goto out;
}
token = parser_context_pop_token(ctxt);
if (token == NULL) {
parse_error(ctxt, NULL, "premature EOI");
goto out;
}
if (token_get_type(token) != JSON_COLON) {
parse_error(ctxt, token, "missing : in object pair");
goto out;
}
value = parse_value(ctxt, ap);
if (value == NULL) {
parse_error(ctxt, token, "Missing value in dict");
goto out;
}
qdict_put_obj(dict, qstring_get_str(qobject_to_qstring(key)), value);
qobject_decref(key);
return 0;
out:
qobject_decref(key);
return -1;
}
static QObject *parse_object(JSONParserContext *ctxt, va_list *ap)
{
QDict *dict = NULL;
QObject *token, *peek;
token = parser_context_pop_token(ctxt);
assert(token && token_get_type(token) == JSON_LCURLY);
dict = qdict_new();
peek = parser_context_peek_token(ctxt);
if (peek == NULL) {
parse_error(ctxt, NULL, "premature EOI");
goto out;
}
if (token_get_type(peek) != JSON_RCURLY) {
if (parse_pair(ctxt, dict, ap) == -1) {
goto out;
}
token = parser_context_pop_token(ctxt);
if (token == NULL) {
parse_error(ctxt, NULL, "premature EOI");
goto out;
}
while (token_get_type(token) != JSON_RCURLY) {
if (token_get_type(token) != JSON_COMMA) {
parse_error(ctxt, token, "expected separator in dict");
goto out;
}
if (parse_pair(ctxt, dict, ap) == -1) {
goto out;
}
token = parser_context_pop_token(ctxt);
if (token == NULL) {
parse_error(ctxt, NULL, "premature EOI");
goto out;
}
}
} else {
(void)parser_context_pop_token(ctxt);
}
return QOBJECT(dict);
out:
QDECREF(dict);
return NULL;
}
static QObject *parse_array(JSONParserContext *ctxt, va_list *ap)
{
QList *list = NULL;
QObject *token, *peek;
token = parser_context_pop_token(ctxt);
assert(token && token_get_type(token) == JSON_LSQUARE);
list = qlist_new();
peek = parser_context_peek_token(ctxt);
if (peek == NULL) {
parse_error(ctxt, NULL, "premature EOI");
goto out;
}
if (token_get_type(peek) != JSON_RSQUARE) {
QObject *obj;
obj = parse_value(ctxt, ap);
if (obj == NULL) {
parse_error(ctxt, token, "expecting value");
goto out;
}
qlist_append_obj(list, obj);
token = parser_context_pop_token(ctxt);
if (token == NULL) {
parse_error(ctxt, NULL, "premature EOI");
goto out;
}
while (token_get_type(token) != JSON_RSQUARE) {
if (token_get_type(token) != JSON_COMMA) {
parse_error(ctxt, token, "expected separator in list");
goto out;
}
obj = parse_value(ctxt, ap);
if (obj == NULL) {
parse_error(ctxt, token, "expecting value");
goto out;
}
qlist_append_obj(list, obj);
token = parser_context_pop_token(ctxt);
if (token == NULL) {
parse_error(ctxt, NULL, "premature EOI");
goto out;
}
}
} else {
(void)parser_context_pop_token(ctxt);
}
return QOBJECT(list);
out:
QDECREF(list);
return NULL;
}
static QObject *parse_keyword(JSONParserContext *ctxt)
{
QObject *token;
const char *val;
token = parser_context_pop_token(ctxt);
assert(token && token_get_type(token) == JSON_KEYWORD);
val = token_get_value(token);
if (!strcmp(val, "true")) {
return QOBJECT(qbool_from_bool(true));
} else if (!strcmp(val, "false")) {
return QOBJECT(qbool_from_bool(false));
} else if (!strcmp(val, "null")) {
return qnull();
}
parse_error(ctxt, token, "invalid keyword '%s'", val);
return NULL;
}
static QObject *parse_escape(JSONParserContext *ctxt, va_list *ap)
{
QObject *token;
const char *val;
if (ap == NULL) {
return NULL;
}
token = parser_context_pop_token(ctxt);
assert(token && token_get_type(token) == JSON_ESCAPE);
val = token_get_value(token);
if (!strcmp(val, "%p")) {
return va_arg(*ap, QObject *);
} else if (!strcmp(val, "%i")) {
return QOBJECT(qbool_from_bool(va_arg(*ap, int)));
} else if (!strcmp(val, "%d")) {
return QOBJECT(qint_from_int(va_arg(*ap, int)));
} else if (!strcmp(val, "%ld")) {
return QOBJECT(qint_from_int(va_arg(*ap, long)));
} else if (!strcmp(val, "%lld") ||
!strcmp(val, "%I64d")) {
return QOBJECT(qint_from_int(va_arg(*ap, long long)));
} else if (!strcmp(val, "%s")) {
return QOBJECT(qstring_from_str(va_arg(*ap, const char *)));
} else if (!strcmp(val, "%f")) {
return QOBJECT(qfloat_from_double(va_arg(*ap, double)));
}
return NULL;
}
static QObject *parse_literal(JSONParserContext *ctxt)
{
QObject *token;
token = parser_context_pop_token(ctxt);
assert(token);
switch (token_get_type(token)) {
case JSON_STRING:
return QOBJECT(qstring_from_escaped_str(ctxt, token));
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) {
return QOBJECT(qint_from_int(value));
}
/* fall through to JSON_FLOAT */
}
case JSON_FLOAT:
/* FIXME dependent on locale */
return QOBJECT(qfloat_from_double(strtod(token_get_value(token),
NULL)));
default:
abort();
}
}
static QObject *parse_value(JSONParserContext *ctxt, va_list *ap)
{
QObject *token;
token = parser_context_peek_token(ctxt);
if (token == NULL) {
parse_error(ctxt, NULL, "premature EOI");
return NULL;
}
switch (token_get_type(token)) {
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;
}
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