1 files changed, 95 insertions, 0 deletions
diff --git a/src/udev/udevadm-util.c b/src/udev/udevadm-util.c
new file mode 100644
index 0000000..39d0c7e
--- /dev/null
+++ b/src/udev/udevadm-util.c
@@ -0,0 +1,95 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <errno.h>
+
+#include "alloc-util.h"
+#include "bus-error.h"
+#include "bus-util.h"
+#include "device-private.h"
+#include "path-util.h"
+#include "udevadm-util.h"
+#include "unit-name.h"
+
+static int find_device_from_path(const char *path, sd_device **ret) {
+        if (path_startswith(path, "/sys/"))
+                return sd_device_new_from_syspath(ret, path);
+
+        if (path_startswith(path, "/dev/")) {
+                struct stat st;
+
+                if (stat(path, &st) < 0)
+                        return -errno;
+
+                return device_new_from_stat_rdev(ret, &st);
+        }
+
+        return -EINVAL;
+}
+
+static int find_device_from_unit(const char *unit_name, sd_device **ret) {
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+        _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
+        _cleanup_free_ char *unit_path = NULL, *syspath = NULL;
+        int r;
+
+        if (!unit_name_is_valid(unit_name, UNIT_NAME_PLAIN))
+                return -EINVAL;
+
+        if (unit_name_to_type(unit_name) != UNIT_DEVICE)
+                return -EINVAL;
+
+        r = bus_connect_system_systemd(&bus);
+        if (r < 0) {
+                _cleanup_free_ char *path = NULL;
+
+                log_debug_errno(r, "Failed to open connection to systemd, using unit name as syspath: %m");
+
+                r = unit_name_to_path(unit_name, &path);
+                if (r < 0)
+                        return log_debug_errno(r, "Failed to convert \"%s\" to a device path: %m", unit_name);
+
+                return find_device_from_path(path, ret);
+        }
+
+        unit_path = unit_dbus_path_from_name(unit_name);
+        if (!unit_path)
+                return -ENOMEM;
+
+        r = sd_bus_get_property_string(
+                        bus,
+                        "org.freedesktop.systemd1",
+                        unit_path,
+                        "org.freedesktop.systemd1.Device",
+                        "SysFSPath",
+                        &error,
+                        &syspath);
+        if (r < 0)
+                return log_debug_errno(r, "Failed to get SysFSPath= dbus property for %s: %s",
+                                       unit_name, bus_error_message(&error, r));
+
+        return sd_device_new_from_syspath(ret, syspath);
+}
+
+int find_device(const char *id, const char *prefix, sd_device **ret) {
+        _cleanup_free_ char *path = NULL;
+        int r;
+
+        assert(id);
+        assert(ret);
+
+        if (prefix) {
+                if (!path_startswith(id, prefix)) {
+                        id = path = path_join(prefix, id);
+                        if (!path)
+                                return -ENOMEM;
+                }
+        } else {
+                /* In cases where the argument is generic (no prefix specified),
+                 * check if the argument looks like a device unit name. */
+                r = find_device_from_unit(id, ret);
+                if (r >= 0)
+                        return r;
+        }
+
+        return find_device_from_path(id, ret);
+}