udev hwdb: Support shipping pre-compiled database in system images

In some cases it is preferable to ship system images with a pre-generated
binary hwdb database, to avoid having to build it at runtime, avoid shipping
the source hwdb files, or avoid storing large binary files in /etc.

So if hwdb.bin does not exist in /etc/udev/, fall back to looking for it in
UDEVLIBEXECDIR. This keeps the possibility to add files to /etc/udev/hwdb.d/
and re-generating the database which trumps the one in /usr/lib.

Add a new --usr flag to "udevadm hwdb --update" which puts the database
into UDEVLIBEXECDIR.

Adjust systemd-udev-hwdb-update.service to not generate the file in /etc if we
already have it in /usr.

1 files changed, 12 insertions, 1 deletions

diff --git a/src/udev/udevadm-hwdb.c b/src/udev/udevadm-hwdb.c
index 64273fbe8d..3ca755e2ed 100644
--- a/src/udev/udevadm-hwdb.c
+++ b/src/udev/udevadm-hwdb.c
@@ -536,14 +536,20 @@ static int import_file(struct udev *udev, struct trie *trie, const char *filenam
 static void help(void) {
         printf("Usage: udevadm hwdb OPTIONS\n"
                "  -u,--update          update the hardware database\n"
+               "  --usr                generate in " UDEVLIBEXECDIR " instead of /etc/udev\n"
                "  -t,--test=MODALIAS   query database and print result\n"
                "  -r,--root=PATH       alternative root path in the filesystem\n"
                "  -h,--help\n\n");
 }
 
 static int adm_hwdb(struct udev *udev, int argc, char *argv[]) {
+        enum {
+                ARG_USR = 0x100,
+        };
+
         static const struct option options[] = {
                 { "update", no_argument,       NULL, 'u' },
+                { "usr",    no_argument,       NULL, ARG_USR },
                 { "test",   required_argument, NULL, 't' },
                 { "root",   required_argument, NULL, 'r' },
                 { "help",   no_argument,       NULL, 'h' },
@@ -551,6 +557,7 @@ static int adm_hwdb(struct udev *udev, int argc, char *argv[]) {
         };
         const char *test = NULL;
         const char *root = "";
+        const char *hwdb_bin_dir = "/etc/udev";
         bool update = false;
         struct trie *trie = NULL;
         int err, c;
@@ -561,6 +568,9 @@ static int adm_hwdb(struct udev *udev, int argc, char *argv[]) {
                 case 'u':
                         update = true;
                         break;
+                case ARG_USR:
+                        hwdb_bin_dir = UDEVLIBEXECDIR;
+                        break;
                 case 't':
                         test = optarg;
                         break;
@@ -634,7 +644,8 @@ static int adm_hwdb(struct udev *udev, int argc, char *argv[]) {
                 log_debug("strings dedup'ed: %8zu bytes (%8zu)",
                           trie->strings->dedup_len, trie->strings->dedup_count);
 
-                if (asprintf(&hwdb_bin, "%s/etc/udev/hwdb.bin", root) < 0) {
+                hwdb_bin = strjoin(root, "/", hwdb_bin_dir, "/hwdb.bin", NULL);
+                if (!hwdb_bin) {
                         rc = EXIT_FAILURE;
                         goto out;
                 }