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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.
This commit is contained in:
Martin Pitt 2014-10-17 15:01:01 +02:00
parent 2f952a2577
commit 33488f1979
5 changed files with 63 additions and 8 deletions
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4
man/udev.xml
View File

@ -766,7 +766,9 @@
<para>The content of all hwdb files is read by
<citerefentry><refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum></citerefentry>
and compiled to a binary database located at <filename>/etc/udev/hwdb.bin</filename>.
and compiled to a binary database located at <filename>/etc/udev/hwdb.bin</filename>,
or alternatively <filename>/usr/lib/udev/hwdb.bin</filename> if you want ship the compiled
database in an immutable image.
During runtime only the binary database is used.</para>
</refsect1>

9
man/udevadm.xml
View File

@ -493,6 +493,15 @@
notified about it.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--usr</option></term>
<listitem>
<para>Put the compiled database into <filename>/usr/lib/udev/hwdb.bin</filename> instead.
Use this if you want to ship a pre-compiled database in immutable system images, or
don't use <filename>/etc/udev/hwdb.d</filename> and want to avoid large binary files in
<filename>/etc</filename>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-t</option></term>
<term><option>--test=<replaceable>string</replaceable></option></term>

42
src/libudev/libudev-hwdb.c
View File

@ -256,6 +256,11 @@ static int trie_search_f(struct udev_hwdb *hwdb, const char *search) {
return 0;
}
static const char hwdb_bin_paths[] =
"/etc/udev/hwdb.bin\0"
UDEVLIBEXECDIR "/hwdb.bin\0";
/**
* udev_hwdb_new:
* @udev: udev library context
@ -266,6 +271,7 @@ static int trie_search_f(struct udev_hwdb *hwdb, const char *search) {
**/
_public_ struct udev_hwdb *udev_hwdb_new(struct udev *udev) {
struct udev_hwdb *hwdb;
const char *hwdb_bin_path;
const char sig[] = HWDB_SIG;
hwdb = new0(struct udev_hwdb, 1);
@ -275,30 +281,43 @@ _public_ struct udev_hwdb *udev_hwdb_new(struct udev *udev) {
hwdb->refcount = 1;
udev_list_init(udev, &hwdb->properties_list, true);
hwdb->f = fopen("/etc/udev/hwdb.bin", "re");
/* find hwdb.bin in hwdb_bin_paths */
NULSTR_FOREACH(hwdb_bin_path, hwdb_bin_paths) {
hwdb->f = fopen(hwdb_bin_path, "re");
if (hwdb->f)
break;
else if (errno == ENOENT)
continue;
else {
udev_dbg(udev, "error reading %s: %m", hwdb_bin_path);
udev_hwdb_unref(hwdb);
return NULL;
}
}
if (!hwdb->f) {
udev_dbg(udev, "error reading /etc/udev/hwdb.bin: %m");
udev_err(udev, "hwdb.bin does not exist, please run udevadm hwdb --update");
udev_hwdb_unref(hwdb);
return NULL;
}
if (fstat(fileno(hwdb->f), &hwdb->st) < 0 ||
(size_t)hwdb->st.st_size < offsetof(struct trie_header_f, strings_len) + 8) {
udev_dbg(udev, "error reading /etc/udev/hwdb.bin: %m");
udev_dbg(udev, "error reading %s: %m", hwdb_bin_path);
udev_hwdb_unref(hwdb);
return NULL;
}
hwdb->map = mmap(0, hwdb->st.st_size, PROT_READ, MAP_SHARED, fileno(hwdb->f), 0);
if (hwdb->map == MAP_FAILED) {
udev_dbg(udev, "error mapping /etc/udev/hwdb.bin: %m");
udev_dbg(udev, "error mapping %s: %m", hwdb_bin_path);
udev_hwdb_unref(hwdb);
return NULL;
}
if (memcmp(hwdb->map, sig, sizeof(hwdb->head->signature)) != 0 ||
(size_t)hwdb->st.st_size != le64toh(hwdb->head->file_size)) {
udev_dbg(udev, "error recognizing the format of /etc/udev/hwdb.bin");
udev_dbg(udev, "error recognizing the format of %s", hwdb_bin_path);
udev_hwdb_unref(hwdb);
return NULL;
}
@ -352,14 +371,25 @@ _public_ struct udev_hwdb *udev_hwdb_unref(struct udev_hwdb *hwdb) {
}
bool udev_hwdb_validate(struct udev_hwdb *hwdb) {
bool found = false;
const char* p;
struct stat st;
if (!hwdb)
return false;
if (!hwdb->f)
return false;
if (stat("/etc/udev/hwdb.bin", &st) < 0)
/* if hwdb.bin doesn't exist anywhere, we need to update */
NULSTR_FOREACH(p, hwdb_bin_paths) {
if (stat(p, &st) >= 0) {
found = true;
break;
}
}
if (!found)
return true;
if (timespec_load(&hwdb->st.st_mtim) != timespec_load(&st.st_mtim))
return true;
return false;

13
src/udev/udevadm-hwdb.c
View File

@ -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;
}

3
units/systemd-udev-hwdb-update.service.in
View File

@ -13,6 +13,9 @@ Conflicts=shutdown.target
After=systemd-remount-fs.service
Before=sysinit.target shutdown.target systemd-update-done.service
ConditionNeedsUpdate=/etc
ConditionPathExists=|!@udevlibexecdir@/hwdb.bin
ConditionPathExists=|/etc/udev/hwdb.bin
ConditionDirectoryNotEmpty=|/etc/udev/hwdb.d/
[Service]
Type=oneshot