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sd-json: when parsing optionally insist top-level variant is object or array

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Typically, the top-level JSON object has to be an object, in any json
document we parse, hence let's add a simple way to enforce that.

Make use of this in various places.

(Note, various other JSON parsers insist on this logic right from the
beginning, but I actually thinking making this insisting optional like
this patch does it is the cleaner approach)
This commit is contained in:
Lennart Poettering
2026-03-20 15:34:56 +01:00
committed by Daan De Meyer
parent bc6380ae07
commit 2c74a91cb8
28 changed files with 405 additions and 53 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/libsystemd/sd-json/sd-json.c
+42 -3
View File
@@ -3039,7 +3039,6 @@ static int json_parse_internal(
int r;
assert_return(input, -EINVAL);
assert_return(ret, -EINVAL);
p = *input;
@@ -3111,12 +3110,16 @@ static int json_parse_internal(
break;
case JSON_TOKEN_OBJECT_OPEN:
if (!IN_SET(current->expect, EXPECT_TOPLEVEL, EXPECT_OBJECT_VALUE, EXPECT_ARRAY_FIRST_ELEMENT, EXPECT_ARRAY_NEXT_ELEMENT)) {
r = -EINVAL;
goto finish;
}
if (n_stack == 1 && FLAGS_SET(flags, SD_JSON_PARSE_MUST_BE_ARRAY) && !FLAGS_SET(flags, SD_JSON_PARSE_MUST_BE_OBJECT)) {
r = -EINVAL;
goto finish;
}
if (!GREEDY_REALLOC(stack, n_stack+1)) {
r = -ENOMEM;
goto finish;
@@ -3168,6 +3171,11 @@ static int json_parse_internal(
goto finish;
}
if (n_stack == 1 && !FLAGS_SET(flags, SD_JSON_PARSE_MUST_BE_ARRAY) && FLAGS_SET(flags, SD_JSON_PARSE_MUST_BE_OBJECT)) {
r = -EINVAL;
goto finish;
}
if (!GREEDY_REALLOC(stack, n_stack+1)) {
r = -ENOMEM;
goto finish;
@@ -3217,6 +3225,11 @@ static int json_parse_internal(
goto finish;
}
if (n_stack == 1 && (flags & (SD_JSON_PARSE_MUST_BE_ARRAY|SD_JSON_PARSE_MUST_BE_OBJECT)) != 0) {
r = -EINVAL;
goto finish;
}
r = sd_json_variant_new_string(&add, string);
if (r < 0)
goto finish;
@@ -3240,6 +3253,11 @@ static int json_parse_internal(
goto finish;
}
if (n_stack == 1 && (flags & (SD_JSON_PARSE_MUST_BE_ARRAY|SD_JSON_PARSE_MUST_BE_OBJECT)) != 0) {
r = -EINVAL;
goto finish;
}
r = sd_json_variant_new_real(&add, value.real);
if (r < 0)
goto finish;
@@ -3261,6 +3279,11 @@ static int json_parse_internal(
goto finish;
}
if (n_stack == 1 && (flags & (SD_JSON_PARSE_MUST_BE_ARRAY|SD_JSON_PARSE_MUST_BE_OBJECT)) != 0) {
r = -EINVAL;
goto finish;
}
r = sd_json_variant_new_integer(&add, value.integer);
if (r < 0)
goto finish;
@@ -3282,6 +3305,11 @@ static int json_parse_internal(
goto finish;
}
if (n_stack == 1 && (flags & (SD_JSON_PARSE_MUST_BE_ARRAY|SD_JSON_PARSE_MUST_BE_OBJECT)) != 0) {
r = -EINVAL;
goto finish;
}
r = sd_json_variant_new_unsigned(&add, value.unsig);
if (r < 0)
goto finish;
@@ -3303,6 +3331,11 @@ static int json_parse_internal(
goto finish;
}
if (n_stack == 1 && (flags & (SD_JSON_PARSE_MUST_BE_ARRAY|SD_JSON_PARSE_MUST_BE_OBJECT)) != 0) {
r = -EINVAL;
goto finish;
}
r = sd_json_variant_new_boolean(&add, value.boolean);
if (r < 0)
goto finish;
@@ -3324,6 +3357,11 @@ static int json_parse_internal(
goto finish;
}
if (n_stack == 1 && (flags & (SD_JSON_PARSE_MUST_BE_ARRAY|SD_JSON_PARSE_MUST_BE_OBJECT)) != 0) {
r = -EINVAL;
goto finish;
}
r = sd_json_variant_new_null(&add);
if (r < 0)
goto finish;
@@ -3365,7 +3403,8 @@ done:
assert(n_stack == 1);
assert(stack[0].n_elements == 1);
*ret = sd_json_variant_ref(stack[0].elements[0]);
if (ret)
*ret = sd_json_variant_ref(stack[0].elements[0]);
*input = p;
r = 0;
src/libsystemd/sd-varlink/sd-varlink.c
+2 -2
View File
@@ -1009,14 +1009,14 @@ static int varlink_parse_message(sd_varlink *v) {
sz = e - begin + 1;
r = sd_json_parse(begin, 0, &v->current, NULL, NULL);
r = sd_json_parse(begin, SD_JSON_PARSE_MUST_BE_OBJECT, &v->current, /* reterr_line= */ NULL, /* reterr_column= */ NULL);
if (v->input_sensitive)
explicit_bzero_safe(begin, sz);
if (r < 0) {
/* If we encounter a parse failure flush all data. We cannot possibly recover from this,
* hence drop all buffered data now. */
v->input_buffer_index = v->input_buffer_size = v->input_buffer_unscanned = 0;
return varlink_log_errno(v, r, "Failed to parse JSON: %m");
return varlink_log_errno(v, r, "Failed to parse JSON object: %m");
}
if (v->input_sensitive) {