Add JSON_EMBED encoding flag

The JSON_EMBED encoding flag causes the opening and closing characters
of the top-level array ('[', ']') or object ('{', '}') to be omitted
during encoding. This feature makes it possible to concatenate multiple
arrays or objects in the stream output. It also makes it possible to
perform outputs of partial composes.

One such example of a partial compose is when outputting a JWE object.
The output is a JSON object. But it has one top-level attribute
("ciphertext") that can grow out of proportion with the rest of the
metadata. With the JSON_EMBED flag, the other metadata can be composed
ahead of time and dumped during the beginning of output, where the
"ciphertext" and "tag" attributes can be streamed out in chunks. Thus,
the header material can be composed with Jansson and the ciphertext
itself can be composed manually.

1 files changed, 34 insertions, 0 deletions

diff --git a/test/suites/api/test_dump.c b/test/suites/api/test_dump.c
index 8d59d40..17c495a 100644
--- a/test/suites/api/test_dump.c
+++ b/test/suites/api/test_dump.c
@@ -278,6 +278,39 @@ static void dumpfd()
 #endif
 }
 
+static void embed()
+{
+    static const char *plains[] = {
+        "{\"bar\":[],\"foo\":{}}",
+        "[[],{}]",
+        "{}",
+        "[]",
+        NULL
+    };
+
+    size_t i;
+
+    for(i = 0; plains[i]; i++) {
+        const char *plain = plains[i];
+        json_t *parse = NULL;
+        char *embed = NULL;
+        size_t psize = 0;
+        size_t esize = 0;
+
+        psize = strlen(plain) - 2;
+        embed = calloc(1, psize);
+        parse = json_loads(plain, 0, NULL);
+        esize = json_dumpb(parse, embed, psize,
+                           JSON_COMPACT | JSON_SORT_KEYS | JSON_EMBED);
+        json_decref(parse);
+        if(esize != psize)
+            fail("json_dumpb(JSON_EMBED) returned an invalid size");
+        if(strncmp(plain + 1, embed, esize) != 0)
+            fail("json_dumps(JSON_EMBED) returned an invalid value");
+        free(embed);
+    }
+}
+
 static void run_tests()
 {
     encode_null();
@@ -289,4 +322,5 @@ static void run_tests()
     dump_file();
     dumpb();
     dumpfd();
+    embed();
 }