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qemu/qobject/json-parser.c

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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 "qemu/osdep.h"
#include "qemu/ctype.h"
#include "qemu/cutils.h"
#include "qemu/unicode.h"
#include "qapi/error.h"
#include "qapi/qmp/qbool.h"
#include "qapi/qmp/qdict.h"
#include "qapi/qmp/qlist.h"
#include "qapi/qmp/qnull.h"
#include "qapi/qmp/qnum.h"
#include "qapi/qmp/qstring.h"
#include "json-parser-int.h"
struct JSONToken {
JSONTokenType type;
int x;
int y;
char str[];
};
typedef struct JSONParserContext {
Error *err;
JSONToken *current;
GQueue *buf;
va_list *ap;
} 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);
/**
* Error handler
*/
static void GCC_FMT_ATTR(3, 4) parse_error(JSONParserContext *ctxt,
JSONToken *token, const char *msg, ...)
{
va_list ap;
char message[1024];
if (ctxt->err) {
return;
}
va_start(ap, msg);
vsnprintf(message, sizeof(message), msg, ap);
va_end(ap);
error_setg(&ctxt->err, "JSON parse error, %s", message);
}
static int cvt4hex(const char *s)
{
int cp, i;
cp = 0;
for (i = 0; i < 4; i++) {
if (!qemu_isxdigit(s[i])) {
return -1;
}
cp <<= 4;
if (s[i] >= '0' && s[i] <= '9') {
cp |= s[i] - '0';
} else if (s[i] >= 'a' && s[i] <= 'f') {
cp |= 10 + s[i] - 'a';
} else if (s[i] >= 'A' && s[i] <= 'F') {
cp |= 10 + s[i] - 'A';
} else {
return -1;
}
}
return cp;
}
/**
* parse_string(): Parse a JSON string
*
* From RFC 8259 "The JavaScript Object Notation (JSON) Data
* Interchange Format":
*
* char = unescaped /
* escape (
* %x22 / ; " quotation mark U+0022
* %x5C / ; \ reverse solidus U+005C
* %x2F / ; / solidus U+002F
* %x62 / ; b backspace U+0008
* %x66 / ; f form feed U+000C
* %x6E / ; n line feed U+000A
* %x72 / ; r carriage return U+000D
* %x74 / ; t tab U+0009
* %x75 4HEXDIG ) ; uXXXX U+XXXX
* escape = %x5C ; \
* quotation-mark = %x22 ; "
* unescaped = %x20-21 / %x23-5B / %x5D-10FFFF
*
* Extensions over RFC 8259:
* - Extra escape sequence in strings:
* 0x27 (apostrophe) is recognized after escape, too
* - Single-quoted strings:
* Like double-quoted strings, except they're delimited by %x27
* (apostrophe) instead of %x22 (quotation mark), and can't contain
* unescaped apostrophe, but can contain unescaped quotation mark.
*
* Note:
* - Encoding is modified UTF-8.
* - Invalid Unicode characters are rejected.
* - Control characters \x00..\x1F are rejected by the lexer.
*/
static QString *parse_string(JSONParserContext *ctxt, JSONToken *token)
{
const char *ptr = token->str;
GString *str;
char quote;
const char *beg;
int cp, trailing;
char *end;
ssize_t len;
char utf8_buf[5];
assert(*ptr == '"' || *ptr == '\'');
quote = *ptr++;
str = g_string_new(NULL);
while (*ptr != quote) {
assert(*ptr);
switch (*ptr) {
case '\\':
beg = ptr++;
switch (*ptr++) {
case '"':
g_string_append_c(str, '"');
break;
case '\'':
g_string_append_c(str, '\'');
break;
case '\\':
g_string_append_c(str, '\\');
break;
case '/':
g_string_append_c(str, '/');
break;
case 'b':
g_string_append_c(str, '\b');
break;
case 'f':
g_string_append_c(str, '\f');
break;
case 'n':
g_string_append_c(str, '\n');
break;
case 'r':
g_string_append_c(str, '\r');
break;
case 't':
g_string_append_c(str, '\t');
break;
case 'u':
cp = cvt4hex(ptr);
ptr += 4;
/* handle surrogate pairs */
if (cp >= 0xD800 && cp <= 0xDBFF
&& ptr[0] == '\\' && ptr[1] == 'u') {
/* leading surrogate followed by \u */
cp = 0x10000 + ((cp & 0x3FF) << 10);
trailing = cvt4hex(ptr + 2);
if (trailing >= 0xDC00 && trailing <= 0xDFFF) {
/* followed by trailing surrogate */
cp |= trailing & 0x3FF;
ptr += 6;
} else {
cp = -1; /* invalid */
}
}
if (mod_utf8_encode(utf8_buf, sizeof(utf8_buf), cp) < 0) {
parse_error(ctxt, token,
"%.*s is not a valid Unicode character",
(int)(ptr - beg), beg);
goto out;
}
g_string_append(str, utf8_buf);
break;
default:
parse_error(ctxt, token, "invalid escape sequence in string");
goto out;
}
break;
case '%':
if (ctxt->ap) {
if (ptr[1] != '%') {
parse_error(ctxt, token, "can't interpolate into string");
goto out;
}
ptr++;
}
/* fall through */
default:
cp = mod_utf8_codepoint(ptr, 6, &end);
if (cp < 0) {
parse_error(ctxt, token, "invalid UTF-8 sequence in string");
goto out;
}
ptr = end;
len = mod_utf8_encode(utf8_buf, sizeof(utf8_buf), cp);
assert(len >= 0);
g_string_append(str, utf8_buf);
}
}
return qstring_from_gstring(str);
out:
g_string_free(str, true);
return NULL;
}
/* Note: the token object returned by parser_context_peek_token or
* parser_context_pop_token is deleted as soon as parser_context_pop_token
* is called again.
*/
static JSONToken *parser_context_pop_token(JSONParserContext *ctxt)
{
g_free(ctxt->current);
ctxt->current = g_queue_pop_head(ctxt->buf);
return ctxt->current;
}
static JSONToken *parser_context_peek_token(JSONParserContext *ctxt)
{
return g_queue_peek_head(ctxt->buf);
}
/**
* Parsing rules
*/
static int parse_pair(JSONParserContext *ctxt, QDict *dict)
{
QObject *key_obj = NULL;
QString *key;
QObject *value;
JSONToken *peek, *token;
peek = parser_context_peek_token(ctxt);
if (peek == NULL) {
parse_error(ctxt, NULL, "premature EOI");
goto out;
}
key_obj = parse_value(ctxt);
key = qobject_to(QString, key_obj);
if (!key) {
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->type != JSON_COLON) {
parse_error(ctxt, token, "missing : in object pair");
goto out;
}
value = parse_value(ctxt);
if (value == NULL) {
parse_error(ctxt, token, "Missing value in dict");
goto out;
}
if (qdict_haskey(dict, qstring_get_str(key))) {
parse_error(ctxt, token, "duplicate key");
goto out;
}
qdict_put_obj(dict, qstring_get_str(key), value);
qobject_unref(key_obj);
return 0;
out:
qobject_unref(key_obj);
return -1;
}
static QObject *parse_object(JSONParserContext *ctxt)
{
QDict *dict = NULL;
JSONToken *token, *peek;
token = parser_context_pop_token(ctxt);
assert(token && token->type == JSON_LCURLY);
dict = qdict_new();
peek = parser_context_peek_token(ctxt);
if (peek == NULL) {
parse_error(ctxt, NULL, "premature EOI");
goto out;
}
if (peek->type != JSON_RCURLY) {
if (parse_pair(ctxt, dict) == -1) {
goto out;
}
token = parser_context_pop_token(ctxt);
if (token == NULL) {
parse_error(ctxt, NULL, "premature EOI");
goto out;
}
while (token->type != JSON_RCURLY) {
if (token->type != JSON_COMMA) {
parse_error(ctxt, token, "expected separator in dict");
goto out;
}
if (parse_pair(ctxt, dict) == -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:
qobject_unref(dict);
return NULL;
}
static QObject *parse_array(JSONParserContext *ctxt)
{
QList *list = NULL;
JSONToken *token, *peek;
token = parser_context_pop_token(ctxt);
assert(token && token->type == JSON_LSQUARE);
list = qlist_new();
peek = parser_context_peek_token(ctxt);
if (peek == NULL) {
parse_error(ctxt, NULL, "premature EOI");
goto out;
}
if (peek->type != JSON_RSQUARE) {
QObject *obj;
obj = parse_value(ctxt);
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->type != JSON_RSQUARE) {
if (token->type != JSON_COMMA) {
parse_error(ctxt, token, "expected separator in list");
goto out;
}
obj = parse_value(ctxt);
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:
qobject_unref(list);
return NULL;
}
static QObject *parse_keyword(JSONParserContext *ctxt)
{
JSONToken *token;
token = parser_context_pop_token(ctxt);
assert(token && token->type == JSON_KEYWORD);
if (!strcmp(token->str, "true")) {
return QOBJECT(qbool_from_bool(true));
} else if (!strcmp(token->str, "false")) {
return QOBJECT(qbool_from_bool(false));
} else if (!strcmp(token->str, "null")) {
return QOBJECT(qnull());
}
parse_error(ctxt, token, "invalid keyword '%s'", token->str);
return NULL;
}
static QObject *parse_interpolation(JSONParserContext *ctxt)
{
JSONToken *token;
token = parser_context_pop_token(ctxt);
assert(token && token->type == JSON_INTERP);
if (!strcmp(token->str, "%p")) {
return va_arg(*ctxt->ap, QObject *);
} else if (!strcmp(token->str, "%i")) {
return QOBJECT(qbool_from_bool(va_arg(*ctxt->ap, int)));
} else if (!strcmp(token->str, "%d")) {
return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, int)));
} else if (!strcmp(token->str, "%ld")) {
return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, long)));
} else if (!strcmp(token->str, "%lld")) {
return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, long long)));
} else if (!strcmp(token->str, "%" PRId64)) {
return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, int64_t)));
} else if (!strcmp(token->str, "%u")) {
return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, unsigned int)));
} else if (!strcmp(token->str, "%lu")) {
return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, unsigned long)));
} else if (!strcmp(token->str, "%llu")) {
return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, unsigned long long)));
} else if (!strcmp(token->str, "%" PRIu64)) {
return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, uint64_t)));
} else if (!strcmp(token->str, "%s")) {
return QOBJECT(qstring_from_str(va_arg(*ctxt->ap, const char *)));
} else if (!strcmp(token->str, "%f")) {
return QOBJECT(qnum_from_double(va_arg(*ctxt->ap, double)));
}
parse_error(ctxt, token, "invalid interpolation '%s'", token->str);
return NULL;
}
static QObject *parse_literal(JSONParserContext *ctxt)
{
JSONToken *token;
token = parser_context_pop_token(ctxt);
assert(token);
switch (token->type) {
case JSON_STRING:
return QOBJECT(parse_string(ctxt, token));
case JSON_INTEGER: {
/*
* Represent JSON_INTEGER as QNUM_I64 if possible, else as
* QNUM_U64, else as QNUM_DOUBLE. Note that qemu_strtoi64()
* and qemu_strtou64() fail with ERANGE when it's not
* possible.
*
* qnum_get_int() will then work for any signed 64-bit
* JSON_INTEGER, qnum_get_uint() for any unsigned 64-bit
* integer, and qnum_get_double() both for any JSON_INTEGER
* and any JSON_FLOAT (with precision loss for integers beyond
* 53 bits)
*/
int ret;
int64_t value;
uint64_t uvalue;
ret = qemu_strtoi64(token->str, NULL, 10, &value);
if (!ret) {
return QOBJECT(qnum_from_int(value));
}
assert(ret == -ERANGE);
if (token->str[0] != '-') {
ret = qemu_strtou64(token->str, NULL, 10, &uvalue);
if (!ret) {
return QOBJECT(qnum_from_uint(uvalue));
}
assert(ret == -ERANGE);
}
}
/* fall through to JSON_FLOAT */
case JSON_FLOAT:
/* FIXME dependent on locale; a pervasive issue in QEMU */
/* FIXME our lexer matches RFC 8259 in forbidding Inf or NaN,
* but those might be useful extensions beyond JSON */
return QOBJECT(qnum_from_double(strtod(token->str, NULL)));
default:
abort();
}
}
static QObject *parse_value(JSONParserContext *ctxt)
{
JSONToken *token;
token = parser_context_peek_token(ctxt);
if (token == NULL) {
parse_error(ctxt, NULL, "premature EOI");
return NULL;
}
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;
}
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