virtio-scsi: suppress virtqueue kick during processing
[qemu.git] / qobject / json-streamer.c
1 /*
2 * JSON streaming support
3 *
4 * Copyright IBM, Corp. 2009
5 *
6 * Authors:
7 * Anthony Liguori <aliguori@us.ibm.com>
8 *
9 * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
10 * See the COPYING.LIB file in the top-level directory.
11 *
12 */
13
14 #include "qemu/osdep.h"
15 #include "qemu-common.h"
16 #include "qapi/qmp/json-lexer.h"
17 #include "qapi/qmp/json-streamer.h"
18
19 #define MAX_TOKEN_SIZE (64ULL << 20)
20 #define MAX_TOKEN_COUNT (2ULL << 20)
21 #define MAX_NESTING (1ULL << 10)
22
23 static void json_message_free_token(void *token, void *opaque)
24 {
25 g_free(token);
26 }
27
28 static void json_message_free_tokens(JSONMessageParser *parser)
29 {
30 if (parser->tokens) {
31 g_queue_foreach(parser->tokens, json_message_free_token, NULL);
32 g_queue_free(parser->tokens);
33 parser->tokens = NULL;
34 }
35 }
36
37 static void json_message_process_token(JSONLexer *lexer, GString *input,
38 JSONTokenType type, int x, int y)
39 {
40 JSONMessageParser *parser = container_of(lexer, JSONMessageParser, lexer);
41 JSONToken *token;
42 GQueue *tokens;
43
44 switch (type) {
45 case JSON_LCURLY:
46 parser->brace_count++;
47 break;
48 case JSON_RCURLY:
49 parser->brace_count--;
50 break;
51 case JSON_LSQUARE:
52 parser->bracket_count++;
53 break;
54 case JSON_RSQUARE:
55 parser->bracket_count--;
56 break;
57 default:
58 break;
59 }
60
61 token = g_malloc(sizeof(JSONToken) + input->len + 1);
62 token->type = type;
63 memcpy(token->str, input->str, input->len);
64 token->str[input->len] = 0;
65 token->x = x;
66 token->y = y;
67
68 parser->token_size += input->len;
69
70 g_queue_push_tail(parser->tokens, token);
71
72 if (type == JSON_ERROR) {
73 goto out_emit_bad;
74 } else if (parser->brace_count < 0 ||
75 parser->bracket_count < 0 ||
76 (parser->brace_count == 0 &&
77 parser->bracket_count == 0)) {
78 goto out_emit;
79 } else if (parser->token_size > MAX_TOKEN_SIZE ||
80 g_queue_get_length(parser->tokens) > MAX_TOKEN_COUNT ||
81 parser->bracket_count + parser->brace_count > MAX_NESTING) {
82 /* Security consideration, we limit total memory allocated per object
83 * and the maximum recursion depth that a message can force.
84 */
85 goto out_emit_bad;
86 }
87
88 return;
89
90 out_emit_bad:
91 /*
92 * Clear out token list and tell the parser to emit an error
93 * indication by passing it a NULL list
94 */
95 json_message_free_tokens(parser);
96 out_emit:
97 /* send current list of tokens to parser and reset tokenizer */
98 parser->brace_count = 0;
99 parser->bracket_count = 0;
100 /* parser->emit takes ownership of parser->tokens. Remove our own
101 * reference to parser->tokens before handing it out to parser->emit.
102 */
103 tokens = parser->tokens;
104 parser->tokens = g_queue_new();
105 parser->emit(parser, tokens);
106 parser->token_size = 0;
107 }
108
109 void json_message_parser_init(JSONMessageParser *parser,
110 void (*func)(JSONMessageParser *, GQueue *))
111 {
112 parser->emit = func;
113 parser->brace_count = 0;
114 parser->bracket_count = 0;
115 parser->tokens = g_queue_new();
116 parser->token_size = 0;
117
118 json_lexer_init(&parser->lexer, json_message_process_token);
119 }
120
121 int json_message_parser_feed(JSONMessageParser *parser,
122 const char *buffer, size_t size)
123 {
124 return json_lexer_feed(&parser->lexer, buffer, size);
125 }
126
127 int json_message_parser_flush(JSONMessageParser *parser)
128 {
129 return json_lexer_flush(&parser->lexer);
130 }
131
132 void json_message_parser_destroy(JSONMessageParser *parser)
133 {
134 json_lexer_destroy(&parser->lexer);
135 json_message_free_tokens(parser);
136 }