blobmsg_json: add new functions blobmsg_format_json_value*

The current blobmsg_format_json* functions will return invalid JSON when
the "list" argument is given as false (blobmsg_format_element() will
output the name of the blob_attr as if the value is printed as part of a
JSON object).

To avoid breaking software relying on this behaviour, introduce new
functions which will never print the blob_attr name and thus always
produce valid JSON.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
Acked-by: Jo-Philipp Wich <jo@mein.io>
Signed-off-by: Felix Fietkau <nbd@nbd.name> [cosmetic style fix]

diff --git a/blobmsg_json.c b/blobmsg_json.c
index 2e318b2fcc96619cf0b5c032fcb460a97c5dfb6c..8a6ed8f8e44342495bb1038e26ed508ea54ea5b3 100644 (file)
--- a/blobmsg_json.c
+++ b/blobmsg_json.c
@@ -214,7 +214,7 @@ static void blobmsg_format_string(struct strbuf *s, const char *str)
 
 static void blobmsg_format_json_list(struct strbuf *s, struct blob_attr *attr, int len, bool array);
 
-static void blobmsg_format_element(struct strbuf *s, struct blob_attr *attr, bool array, bool head)
+static void blobmsg_format_element(struct strbuf *s, struct blob_attr *attr, bool without_name, bool head)
 {
        const char *data_str;
        char buf[32];
@@ -224,7 +224,7 @@ static void blobmsg_format_element(struct strbuf *s, struct blob_attr *attr, boo
        if (!blobmsg_check_attr(attr, false))
                return;
 
-       if (!array && blobmsg_name(attr)[0]) {
+       if (!without_name && blobmsg_name(attr)[0]) {
                blobmsg_format_string(s, blobmsg_name(attr));
                blobmsg_puts(s, ": ", s->indent ? 2 : 1);
        }
@@ -293,27 +293,31 @@ static void blobmsg_format_json_list(struct strbuf *s, struct blob_attr *attr, i
        blobmsg_puts(s, (array ? "]" : "}"), 1);
 }
 
+static void setup_strbuf(struct strbuf *s, struct blob_attr *attr, blobmsg_json_format_t cb, void *priv, int indent)
+{
+       s->len = blob_len(attr);
+       s->buf = malloc(s->len);
+       s->pos = 0;
+       s->custom_format = cb;
+       s->priv = priv;
+       s->indent = false;
+
+       if (indent >= 0) {
+               s->indent = true;
+               s->indent_level = indent;
+       }
+}
+
 char *blobmsg_format_json_with_cb(struct blob_attr *attr, bool list, blobmsg_json_format_t cb, void *priv, int indent)
 {
        struct strbuf s;
        bool array;
        char *ret;
 
-       s.len = blob_len(attr);
-       s.pos = 0;
-       s.custom_format = cb;
-       s.priv = priv;
-       s.indent = false;
-
-       s.buf = malloc(s.len);
+       setup_strbuf(&s, attr, cb, priv, indent);
        if (!s.buf)
                return NULL;
 
-       if (indent >= 0) {
-               s.indent = true;
-               s.indent_level = indent;
-       }
-
        array = blob_is_extended(attr) &&
                blobmsg_type(attr) == BLOBMSG_TYPE_ARRAY;
 
@@ -337,3 +341,30 @@ char *blobmsg_format_json_with_cb(struct blob_attr *attr, bool list, blobmsg_jso
 
        return ret;
 }
+
+char *blobmsg_format_json_value_with_cb(struct blob_attr *attr, blobmsg_json_format_t cb, void *priv, int indent)
+{
+       struct strbuf s;
+       char *ret;
+
+       setup_strbuf(&s, attr, cb, priv, indent);
+       if (!s.buf)
+               return NULL;
+
+       blobmsg_format_element(&s, attr, true, false);
+
+       if (!s.len) {
+               free(s.buf);
+               return NULL;
+       }
+
+       ret = realloc(s.buf, s.pos + 1);
+       if (!ret) {
+               free(s.buf);
+               return NULL;
+       }
+
+       ret[s.pos] = 0;
+
+       return ret;
+}

diff --git a/blobmsg_json.h b/blobmsg_json.h
index cd9ed33e4c49d258ded70598a26c71b61a8d17b1..9dfc02dcd02f02f143adbc7fc4e28137e0a486e6 100644 (file)
--- a/blobmsg_json.h
+++ b/blobmsg_json.h
@@ -42,4 +42,18 @@ static inline char *blobmsg_format_json_indent(struct blob_attr *attr, bool list
        return blobmsg_format_json_with_cb(attr, list, NULL, NULL, indent);
 }
 
+char *blobmsg_format_json_value_with_cb(struct blob_attr *attr,
+                                       blobmsg_json_format_t cb, void *priv,
+                                       int indent);
+
+static inline char *blobmsg_format_json_value(struct blob_attr *attr)
+{
+       return blobmsg_format_json_value_with_cb(attr, NULL, NULL, -1);
+}
+
+static inline char *blobmsg_format_json_value_indent(struct blob_attr *attr, int indent)
+{
+       return blobmsg_format_json_value_with_cb(attr, NULL, NULL, indent);
+}
+
 #endif