/* * 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/cutils.h" #include "qemu/unicode.h" #include "qapi/error.h" #include "qemu-common.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; QString *str; char quote; const char *beg; int cp, trailing; char *end; ssize_t len; char utf8_buf[5]; assert(*ptr == '"' || *ptr == '\''); quote = *ptr++; str = qstring_new(); while (*ptr != quote) { assert(*ptr); switch (*ptr) { case '\\': beg = ptr++; switch (*ptr++) { case '"': qstring_append_chr(str, '"'); break; case '\'': qstring_append_chr(str, '\''); break; case '\\': qstring_append_chr(str, '\\'); break; case '/': qstring_append_chr(str, '/'); break; case 'b': qstring_append_chr(str, '\b'); break; case 'f': qstring_append_chr(str, '\f'); break; case 'n': qstring_append_chr(str, '\n'); break; case 'r': qstring_append_chr(str, '\r'); break; case 't': qstring_append_chr(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; } qstring_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); qstring_append(str, utf8_buf); } } return str; out: qobject_unref(str); 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 *value; QString *key = NULL; JSONToken *peek, *token; peek = parser_context_peek_token(ctxt); if (peek == NULL) { parse_error(ctxt, NULL, "premature EOI"); goto out; } key = qobject_to(QString, parse_value(ctxt)); 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); return 0; out: qobject_unref(key); 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; }