nghttpx: Add --include option to read additional configuration from given file

src/shrpx.cc

@@ -1502,6 +1502,11 @@ Misc:
   --conf=<PATH>
               Load configuration from <PATH>.
               Default: )" << get_config()->conf_path.get() << R"(
+  --include=<PATH>
+              Load additional configurations from <PATH>.  File <PATH>
+              is  read  when  configuration  parser  encountered  this
+              option.  This option can be used multiple times, or even
+              recursively.
   -v, --version
               Print version and exit.
   -h, --help  Print this help and exit.
@@ -1648,6 +1653,7 @@ int main(int argc, char **argv) {
         {SHRPX_OPT_HEADER_FIELD_BUFFER, required_argument, &flag, 80},
         {SHRPX_OPT_MAX_HEADER_FIELDS, required_argument, &flag, 81},
         {SHRPX_OPT_ADD_REQUEST_HEADER, required_argument, &flag, 82},
+        {SHRPX_OPT_INCLUDE, required_argument, &flag, 83},
         {nullptr, 0, nullptr, 0}};
 
     int option_index = 0;
@@ -2010,6 +2016,10 @@ int main(int argc, char **argv) {
         // --add-request-header
         cmdcfgs.emplace_back(SHRPX_OPT_ADD_REQUEST_HEADER, optarg);
         break;
+      case 83:
+        // --include
+        cmdcfgs.emplace_back(SHRPX_OPT_INCLUDE, optarg);
+        break;
       default:
         break;
       }

src/shrpx_config.cc

@@ -1219,6 +1219,10 @@ int parse_config(const char *opt, const char *optarg) {
     return parse_uint(&mod_config()->max_header_fields, opt, optarg);
   }
 
+  if (util::strieq(opt, SHRPX_OPT_INCLUDE)) {
+    return load_config(optarg);
+  }
+
   if (util::strieq(opt, "conf")) {
     LOG(WARN) << "conf: ignored";
 
@@ -1248,7 +1252,8 @@ int load_config(const char *filename) {
     for (i = 0; i < size && line[i] != '='; ++i)
       ;
     if (i == size) {
-      LOG(ERROR) << "Bad configuration format at line " << linenum;
+      LOG(ERROR) << "Bad configuration format in " << filename << " at line "
+                 << linenum;
       return -1;
     }
     line[i] = '\0';

src/shrpx_config.h

@@ -165,6 +165,7 @@ constexpr char SHRPX_OPT_OCSP_UPDATE_INTERVAL[] = "ocsp-update-interval";
 constexpr char SHRPX_OPT_NO_OCSP[] = "no-ocsp";
 constexpr char SHRPX_OPT_HEADER_FIELD_BUFFER[] = "header-field-buffer";
 constexpr char SHRPX_OPT_MAX_HEADER_FIELDS[] = "max-header-fields";
+constexpr char SHRPX_OPT_INCLUDE[] = "include";
 
 union sockaddr_union {
   sockaddr_storage storage;