Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 134 insertions, 0 deletions

diff --git a/qobject/json-streamer.c b/qobject/json-streamer.c
new file mode 100644
index 000000000..b93d97b99
--- /dev/null
+++ b/qobject/json-streamer.c
@@ -0,0 +1,134 @@
+/*
+ * JSON streaming support
+ *
+ * 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 "qapi/error.h"
+#include "json-parser-int.h"
+
+#define MAX_TOKEN_SIZE (64ULL << 20)
+#define MAX_TOKEN_COUNT (2ULL << 20)
+#define MAX_NESTING (1 << 10)
+
+static void json_message_free_tokens(JSONMessageParser *parser)
+{
+    JSONToken *token;
+
+    while ((token = g_queue_pop_head(&parser->tokens))) {
+        g_free(token);
+    }
+}
+
+void json_message_process_token(JSONLexer *lexer, GString *input,
+                                JSONTokenType type, int x, int y)
+{
+    JSONMessageParser *parser = container_of(lexer, JSONMessageParser, lexer);
+    QObject *json = NULL;
+    Error *err = NULL;
+    JSONToken *token;
+
+    switch (type) {
+    case JSON_LCURLY:
+        parser->brace_count++;
+        break;
+    case JSON_RCURLY:
+        parser->brace_count--;
+        break;
+    case JSON_LSQUARE:
+        parser->bracket_count++;
+        break;
+    case JSON_RSQUARE:
+        parser->bracket_count--;
+        break;
+    case JSON_ERROR:
+        error_setg(&err, "JSON parse error, stray '%s'", input->str);
+        goto out_emit;
+    case JSON_END_OF_INPUT:
+        if (g_queue_is_empty(&parser->tokens)) {
+            return;
+        }
+        json = json_parser_parse(&parser->tokens, parser->ap, &err);
+        goto out_emit;
+    default:
+        break;
+    }
+
+    /*
+     * Security consideration, we limit total memory allocated per object
+     * and the maximum recursion depth that a message can force.
+     */
+    if (parser->token_size + input->len + 1 > MAX_TOKEN_SIZE) {
+        error_setg(&err, "JSON token size limit exceeded");
+        goto out_emit;
+    }
+    if (g_queue_get_length(&parser->tokens) + 1 > MAX_TOKEN_COUNT) {
+        error_setg(&err, "JSON token count limit exceeded");
+        goto out_emit;
+    }
+    if (parser->bracket_count + parser->brace_count > MAX_NESTING) {
+        error_setg(&err, "JSON nesting depth limit exceeded");
+        goto out_emit;
+    }
+
+    token = json_token(type, x, y, input);
+    parser->token_size += input->len;
+
+    g_queue_push_tail(&parser->tokens, token);
+
+    if ((parser->brace_count > 0 || parser->bracket_count > 0)
+        && parser->brace_count >= 0 && parser->bracket_count >= 0) {
+        return;
+    }
+
+    json = json_parser_parse(&parser->tokens, parser->ap, &err);
+
+out_emit:
+    parser->brace_count = 0;
+    parser->bracket_count = 0;
+    json_message_free_tokens(parser);
+    parser->token_size = 0;
+    parser->emit(parser->opaque, json, err);
+}
+
+void json_message_parser_init(JSONMessageParser *parser,
+                              void (*emit)(void *opaque, QObject *json,
+                                           Error *err),
+                              void *opaque, va_list *ap)
+{
+    parser->emit = emit;
+    parser->opaque = opaque;
+    parser->ap = ap;
+    parser->brace_count = 0;
+    parser->bracket_count = 0;
+    g_queue_init(&parser->tokens);
+    parser->token_size = 0;
+
+    json_lexer_init(&parser->lexer, !!ap);
+}
+
+void json_message_parser_feed(JSONMessageParser *parser,
+                             const char *buffer, size_t size)
+{
+    json_lexer_feed(&parser->lexer, buffer, size);
+}
+
+void json_message_parser_flush(JSONMessageParser *parser)
+{
+    json_lexer_flush(&parser->lexer);
+    assert(g_queue_is_empty(&parser->tokens));
+}
+
+void json_message_parser_destroy(JSONMessageParser *parser)
+{
+    json_lexer_destroy(&parser->lexer);
+    json_message_free_tokens(parser);
+}