1 files changed, 62 insertions, 0 deletions
diff --git a/src/fundamental/bootspec-fundamental.c b/src/fundamental/bootspec-fundamental.c
new file mode 100644
index 0000000..b2841e3
--- /dev/null
+++ b/src/fundamental/bootspec-fundamental.c
@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "bootspec-fundamental.h"
+
+bool bootspec_pick_name_version_sort_key(
+                const sd_char *os_pretty_name,
+                const sd_char *os_image_id,
+                const sd_char *os_name,
+                const sd_char *os_id,
+                const sd_char *os_image_version,
+                const sd_char *os_version,
+                const sd_char *os_version_id,
+                const sd_char *os_build_id,
+                const sd_char **ret_name,
+                const sd_char **ret_version,
+                const sd_char **ret_sort_key) {
+
+        const sd_char *good_name, *good_version, *good_sort_key;
+
+        /* Find the best human readable title, version string and sort key for a boot entry (using the
+         * os-release(5) fields). Precise is preferred over vague, and human readable over machine
+         * readable. Thus:
+         *
+         * 1. First priority gets the PRETTY_NAME field, which is the primary string intended for display,
+         *    and should already contain both a nice description and a version indication (if that concept
+         *    applies).
+         *
+         * 2. Otherwise we go for IMAGE_ID and IMAGE_VERSION (thus we show details about the image,
+         *    i.e. specific combination of packages and configuration), if that concept applies.
+         *
+         * 3. Otherwise we go for NAME and VERSION (i.e. human readable OS name and version)
+         *
+         * 4. Otherwise we go for ID and VERSION_ID (i.e. machine readable OS name and version)
+         *
+         * 5. Finally, for the version we'll use BUILD_ID (i.e. a machine readable version that identifies
+         *    the original OS build used during installation)
+         *
+         * Note that the display logic will show only the name by default, except if that isn't unique in
+         * which case the version is shown too.
+         *
+         * Note that name/version determined here are used only for display purposes. Boot entry preference
+         * sorting (i.e. algorithmic ordering of boot entries) is done based on the order of the sort key (if
+         * defined) or entry "id" string (i.e. entry file name) otherwise. */
+
+        good_name = os_pretty_name ?: (os_image_id ?: (os_name ?: os_id));
+        good_version = os_image_version ?: (os_version ?: (os_version_id ?: os_build_id));
+        good_sort_key = os_image_id ?: os_id;
+
+        if (!good_name)
+                return false;
+
+        if (ret_name)
+                *ret_name = good_name;
+
+        if (ret_version)
+                *ret_version = good_version;
+
+        if (ret_sort_key)
+                *ret_sort_key = good_sort_key;
+
+        return true;
+}