Function load_config_file

src/discover/userconfig.c:256–313

* Read a JSON file and parse extra_extensions from it. * Silently ignores missing files. Logs warnings for corrupt JSON. * Returns 0 on success (or absent file), -1 on alloc failure. */

 * Returns 0 on success (or absent file), -1 on alloc failure.
 */
static int load_config_file(const char *path, cbm_userext_t **entries, int *count,
                            char source_sha256[CBM_SHA256_HEX_LEN + 1]) {
    userconfig_source_digest("missing-or-unreadable", NULL, 0, source_sha256);
    FILE *f = cbm_fopen(path, "rb");
    if (!f) {
        return 0; /* file absent — silently ignore */
    }

    if (fseek(f, 0, SEEK_END) != 0) {
        (void)fclose(f);
        userconfig_source_digest("seek-error", NULL, 0, source_sha256);
        return 0;
    }
    long len = ftell(f);
    if (fseek(f, 0, SEEK_SET) != 0) {
        (void)fclose(f);
        userconfig_source_digest("seek-error", NULL, 0, source_sha256);
        return 0;
    }

    if (len <= 0 || len > MAX_CONFIG_SIZE) {
        (void)fclose(f);
        if (len > MAX_CONFIG_SIZE) {
            cbm_log_warn("userconfig.file_too_large", "path", path);
            userconfig_source_digest("oversized", NULL, 0, source_sha256);
        } else {
            userconfig_source_digest("empty", NULL, 0, source_sha256);
        }
        return 0;
    }

    char *buf = malloc((size_t)len + SKIP_ONE);
    if (!buf) {
        (void)fclose(f);
        return CBM_NOT_FOUND;
    }

    size_t nread = fread(buf, SKIP_ONE, (size_t)len, f);
    (void)fclose(f);
    if (nread > (size_t)len) {
        nread = (size_t)len;
    }
    buf[nread] = '\0';
    userconfig_source_digest("present", buf, nread, source_sha256);

    yyjson_doc *doc = yyjson_read(buf, nread, 0);
    free(buf);

    if (!doc) {
        cbm_log_warn("userconfig.corrupt_json", "path", path);
        return 0; /* corrupt JSON — silently ignore (fail-open) */
    }

    yyjson_val *root = yyjson_doc_get_root(doc);
    int rc = parse_extra_extensions(root, entries, count, path);
    yyjson_doc_free(doc);
    return rc;
}