If jq filter wasn't an actual file, use $PWD as package root search path

linker.c

@@ -25,6 +25,24 @@ static int load_library(jq_state *jq, jv lib_path, int is_data, int raw,
                         const char *as, block *out_block,
                         struct lib_loading_state *lib_state);
 
+static jv get_package_root_search_start(jq_state *jq, jv lib_origin) {
+  // PROGRAM_ORIGIN is $PWD if PROGRAM_ORIGIN_FILE is not a PROGRAM_FROM_ACTUAL_FILE.
+  // Use PROGRAM_ORIGIN when getting the package root for PROGRAM_ORIGIN_FILE instead
+  // of lib_origin, but only in that specific case.
+  // file (more specifically a file in the same directory as the PROGRAM_ORIGIN file).
+  // TODO: pass the full file path, not just the directory path "lib_origin" to this
+  // function, then use PROGRAM_ORIGIN_FILE for comparison.
+  jv package_root_search_from;
+  if (jv_get_kind(jq_get_attr(jq, jv_string("PROGRAM_FROM_ACTUAL_FILE"))) == JV_KIND_FALSE
+        && strcmp(jv_string_value(jq_get_attr(jq, jv_string("PROGRAM_ORIGIN"))),jv_string_value(lib_origin)) == 0) {
+      // It's a (named/anonymous) FIFO pipe; use PROGRAM_ORIGIN (which is $PWD) instead.
+      package_root_search_from = jv_copy(jq_get_prog_origin(jq));
+    } else {
+       package_root_search_from = jv_copy(lib_origin);
+    }
+    return package_root_search_from;
+}
+
 
 // Given a lib_path to search first, creates a chain of search paths
 // in the following order:
@@ -48,14 +66,17 @@ static jv build_lib_search_chain(jq_state *jq, jv search_path, jv jq_origin, jv
                                jv_string_value(path) + sizeof ("$ORIGIN/") - 1);
     } else if (jv_get_kind(lib_origin) == JV_KIND_STRING &&
                strncmp("$PACKAGEROOT/",jv_string_value(path),sizeof("$PACKAGEROOT/")-1) == 0) {
+      jv package_root_search_from = get_package_root_search_start(jq, lib_origin);
+      jv package_root = jq_find_package_root(package_root_search_from);
+
       // Could also use non-string package_root values as error message output.
-      jv package_root = jq_find_package_root(lib_origin);
       if (jv_get_kind(package_root) == JV_KIND_STRING) {
         expanded_elt = jv_string_fmt("%s/%s",
                                  jv_string_value(package_root),
                                  jv_string_value(path) + sizeof ("$PACKAGEROOT/") - 1);
       }
       jv_free(package_root);
+      jv_free(package_root_search_from);
     } else {
       expanded_elt = expand_path(path);
       if (!jv_is_valid(expanded_elt)) {