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fix(mcp): an integer argument outside int range takes the default #2256

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fix(mcp): an integer argument outside int range takes the default #2256

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15 changes: 13 additions & 2 deletions src/mcp/mcp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1583,8 +1583,19 @@ int cbm_mcp_get_int_arg(const char *args_json, const char *key, int default_val)
yyjson_val *root = yyjson_doc_get_root(doc);
yyjson_val *val = yyjson_obj_get(root, key);
int result = default_val;
if (val && yyjson_is_int(val)) {
result = yyjson_get_int(val);
/* yyjson_get_int truncates 64-bit integers to int (2^32 + 1 became 1);
* read the full width and treat anything outside int range like a
* non-integer, i.e. fall back to the caller's default. */
if (val && yyjson_is_sint(val)) {
int64_t parsed = yyjson_get_sint(val);
if (parsed >= INT_MIN && parsed <= INT_MAX) {
result = (int)parsed;
}
} else if (val && yyjson_is_uint(val)) {
uint64_t parsed = yyjson_get_uint(val);
if (parsed <= (uint64_t)INT_MAX) {
result = (int)parsed;
}
}
yyjson_doc_free(doc);
return result;
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17 changes: 17 additions & 0 deletions tests/test_mcp.c
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Expand Up @@ -1771,6 +1771,23 @@ TEST(mcp_get_int_arg) {
ASSERT_EQ(val, 5);
val = cbm_mcp_get_int_arg(args, "missing", 42);
ASSERT_EQ(val, 42);
/* Out-of-int-range integers return the default instead of truncating:
* 2^32 + 1 used to read back as 1 through yyjson_get_int's int cast. */
val = cbm_mcp_get_int_arg("{\"limit\":4294967297}", "limit", 17);
ASSERT_EQ(val, 17);
val = cbm_mcp_get_int_arg("{\"limit\":-4294967297}", "limit", 19);
ASSERT_EQ(val, 19);
val = cbm_mcp_get_int_arg("{\"limit\":2147483648}", "limit", 23);
ASSERT_EQ(val, 23);
val = cbm_mcp_get_int_arg("{\"limit\":-9223372036854775808}", "limit", 29);
ASSERT_EQ(val, 29);
/* Boundary values and a negative in-range value still pass through. */
val = cbm_mcp_get_int_arg("{\"limit\":2147483647}", "limit", 0);
ASSERT_EQ(val, 2147483647);
val = cbm_mcp_get_int_arg("{\"limit\":-2147483648}", "limit", 0);
ASSERT_EQ(val, -2147483648);
val = cbm_mcp_get_int_arg("{\"limit\":-7}", "limit", 0);
ASSERT_EQ(val, -7);
PASS();
}

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