Merge pull request #25646 from yuwata/sd-id128-enomedium

sd-id128: make sd_id128_get_machine() return -ENOMEDIUM when not initialized

16 files changed, 157 insertions, 121 deletions

diff --git a/man/sd_id128_get_machine.xml b/man/sd_id128_get_machine.xml
index a778f8a2b0..dbc6d4885d 100644
--- a/man/sd_id128_get_machine.xml
+++ b/man/sd_id128_get_machine.xml
@@ -129,19 +129,33 @@
         <varlistentry>
           <term><constant>-ENOENT</constant></term>
 
-          <listitem><para>Returned by <function>sd_id128_get_machine()</function>,
-          <function>sd_id128_get_machine_app_specific()</function>, and
-          <function>sd_id128_get_boot_app_specific()</function> when <filename>/etc/machine-id</filename> is
-          missing.</para></listitem>
+          <listitem><para>Returned by <function>sd_id128_get_machine()</function> and
+          <function>sd_id128_get_machine_app_specific()</function> when <filename>/etc/machine-id</filename>
+          is missing.</para></listitem>
         </varlistentry>
 
         <varlistentry>
           <term><constant>-ENOMEDIUM</constant></term>
 
-          <listitem><para>Returned by <function>sd_id128_get_machine()</function>,
-          <function>sd_id128_get_machine_app_specific()</function>, and
-          <function>sd_id128_get_boot_app_specific()</function> when <filename>/etc/machine-id</filename> is
-          empty or all zeros.</para></listitem>
+          <listitem><para>Returned by <function>sd_id128_get_machine()</function> and
+          <function>sd_id128_get_machine_app_specific()</function> when <filename>/etc/machine-id</filename>
+          is empty or all zeros.</para></listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>-ENOPKG</constant></term>
+
+          <listitem><para>Returned by <function>sd_id128_get_machine()</function> and
+          <function>sd_id128_get_machine_app_specific()</function> when the content of
+          <filename>/etc/machine-id</filename> is <literal>uninitialized</literal>.</para></listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>-ENOSYS</constant></term>
+
+          <listitem><para>Returned by <function>sd_id128_get_boot()</function> and
+          <function>sd_id128_get_boot_app_specific()</function> when <filename>/proc/</filename> is not
+          mounted.</para></listitem>
         </varlistentry>
 
         <varlistentry>
diff --git a/src/boot/bootctl.c b/src/boot/bootctl.c
index 0df456827c..44a5a371b9 100644
--- a/src/boot/bootctl.c
+++ b/src/boot/bootctl.c
@@ -179,7 +179,7 @@ static int load_etc_machine_id(void) {
         int r;
 
         r = sd_id128_get_machine(&arg_machine_id);
-        if (IN_SET(r, -ENOENT, -ENOMEDIUM)) /* Not set or empty */
+        if (IN_SET(r, -ENOENT, -ENOMEDIUM, -ENOPKG)) /* Not set or empty */
                 return 0;
         if (r < 0)
                 return log_error_errno(r, "Failed to get machine-id: %m");
diff --git a/src/fundamental/string-util-fundamental.h b/src/fundamental/string-util-fundamental.h
index ecf32e519f..d823147881 100644
--- a/src/fundamental/string-util-fundamental.h
+++ b/src/fundamental/string-util-fundamental.h
@@ -110,6 +110,10 @@ static inline bool ascii_isdigit(sd_char a) {
         return a >= '0' && a <= '9';
 }
 
+static inline bool ascii_ishex(sd_char a) {
+        return ascii_isdigit(a) || (a >= 'a' && a <= 'f') || (a >= 'A' && a <= 'F');
+}
+
 static inline bool ascii_isalpha(sd_char a) {
         /* A pure ASCII, locale independent version of isalpha() */
         return (a >= 'a' && a <= 'z') || (a >= 'A' && a <= 'Z');
diff --git a/src/libsystemd/sd-id128/id128-util.c b/src/libsystemd/sd-id128/id128-util.c
index 4f52c14f64..3395ba2e58 100644
--- a/src/libsystemd/sd-id128/id128-util.c
+++ b/src/libsystemd/sd-id128/id128-util.c
@@ -13,59 +13,48 @@
 #include "sync-util.h"
 
 bool id128_is_valid(const char *s) {
-        size_t i, l;
+        size_t l;
 
         assert(s);
 
         l = strlen(s);
-        if (l == 32) {
 
+        if (l == SD_ID128_STRING_MAX - 1)
                 /* Plain formatted 128bit hex string */
+                return in_charset(s, HEXDIGITS);
 
-                for (i = 0; i < l; i++) {
-                        char c = s[i];
-
-                        if (!ascii_isdigit(c) &&
-                            !(c >= 'a' && c <= 'f') &&
-                            !(c >= 'A' && c <= 'F'))
-                                return false;
-                }
-
-        } else if (l == 36) {
-
+        if (l == SD_ID128_UUID_STRING_MAX - 1) {
                 /* Formatted UUID */
-
-                for (i = 0; i < l; i++) {
+                for (size_t i = 0; i < l; i++) {
                         char c = s[i];
 
                         if (IN_SET(i, 8, 13, 18, 23)) {
                                 if (c != '-')
                                         return false;
-                        } else {
-                                if (!ascii_isdigit(c) &&
-                                    !(c >= 'a' && c <= 'f') &&
-                                    !(c >= 'A' && c <= 'F'))
-                                        return false;
-                        }
+                        } else if (!ascii_ishex(c))
+                                return false;
                 }
+                return true;
+        }
 
-        } else
-                return false;
-
-        return true;
+        return false;
 }
 
-int id128_read_fd(int fd, Id128Format f, sd_id128_t *ret) {
-        char buffer[36 + 2];
+int id128_read_fd(int fd, Id128FormatFlag f, sd_id128_t *ret) {
+        char buffer[SD_ID128_UUID_STRING_MAX + 1]; /* +1 is for trailing newline */
         ssize_t l;
 
         assert(fd >= 0);
-        assert(f < _ID128_FORMAT_MAX);
 
         /* Reads an 128bit ID from a file, which may either be in plain format (32 hex digits), or in UUID format, both
          * optionally followed by a newline and nothing else. ID files should really be newline terminated, but if they
          * aren't that's OK too, following the rule of "Be conservative in what you send, be liberal in what you
-         * accept". */
+         * accept".
+         *
+         * This returns the following:
+         *     -ENOMEDIUM: an empty string,
+         *     -ENOPKG:    "uninitialized" or "uninitialized\n",
+         *     -EINVAL:    other invalid strings. */
 
         l = loop_read(fd, buffer, sizeof(buffer), false); /* we expect a short read of either 32/33 or 36/37 chars */
         if (l < 0)
@@ -75,33 +64,32 @@ int id128_read_fd(int fd, Id128Format f, sd_id128_t *ret) {
 
         switch (l) {
 
-        case 13:
-        case 14:
-                /* Treat an "uninitialized" id file like an empty one */
-                return f == ID128_PLAIN_OR_UNINIT && strneq(buffer, "uninitialized\n", l) ? -ENOMEDIUM : -EINVAL;
+        case STRLEN("uninitialized"):
+        case STRLEN("uninitialized\n"):
+                return strneq(buffer, "uninitialized\n", l) ? -ENOPKG : -EINVAL;
 
-        case 33: /* plain UUID with trailing newline */
-                if (buffer[32] != '\n')
+        case SD_ID128_STRING_MAX: /* plain UUID with trailing newline */
+                if (buffer[SD_ID128_STRING_MAX-1] != '\n')
                         return -EINVAL;
 
                 _fallthrough_;
-        case 32: /* plain UUID without trailing newline */
-                if (f == ID128_UUID)
+        case SD_ID128_STRING_MAX-1: /* plain UUID without trailing newline */
+                if (!FLAGS_SET(f, ID128_FORMAT_PLAIN))
                         return -EINVAL;
 
-                buffer[32] = 0;
+                buffer[SD_ID128_STRING_MAX-1] = 0;
                 break;
 
-        case 37: /* RFC UUID with trailing newline */
-                if (buffer[36] != '\n')
+        case SD_ID128_UUID_STRING_MAX: /* RFC UUID with trailing newline */
+                if (buffer[SD_ID128_UUID_STRING_MAX-1] != '\n')
                         return -EINVAL;
 
                 _fallthrough_;
-        case 36: /* RFC UUID without trailing newline */
-                if (IN_SET(f, ID128_PLAIN, ID128_PLAIN_OR_UNINIT))
+        case SD_ID128_UUID_STRING_MAX-1: /* RFC UUID without trailing newline */
+                if (!FLAGS_SET(f, ID128_FORMAT_UUID))
                         return -EINVAL;
 
-                buffer[36] = 0;
+                buffer[SD_ID128_UUID_STRING_MAX-1] = 0;
                 break;
 
         default:
@@ -111,7 +99,7 @@ int id128_read_fd(int fd, Id128Format f, sd_id128_t *ret) {
         return sd_id128_from_string(buffer, ret);
 }
 
-int id128_read(const char *p, Id128Format f, sd_id128_t *ret) {
+int id128_read(const char *p, Id128FormatFlag f, sd_id128_t *ret) {
         _cleanup_close_ int fd = -1;
 
         fd = open(p, O_RDONLY|O_CLOEXEC|O_NOCTTY);
@@ -121,29 +109,28 @@ int id128_read(const char *p, Id128Format f, sd_id128_t *ret) {
         return id128_read_fd(fd, f, ret);
 }
 
-int id128_write_fd(int fd, Id128Format f, sd_id128_t id, bool do_sync) {
-        char buffer[36 + 2];
+int id128_write_fd(int fd, Id128FormatFlag f, sd_id128_t id) {
+        char buffer[SD_ID128_UUID_STRING_MAX + 1]; /* +1 is for trailing newline */
         size_t sz;
         int r;
 
         assert(fd >= 0);
-        assert(f < _ID128_FORMAT_MAX);
+        assert(IN_SET((f & ID128_FORMAT_ANY), ID128_FORMAT_PLAIN, ID128_FORMAT_UUID));
 
-        if (f != ID128_UUID) {
+        if (FLAGS_SET(f, ID128_FORMAT_PLAIN)) {
                 assert_se(sd_id128_to_string(id, buffer));
-                buffer[SD_ID128_STRING_MAX - 1] = '\n';
                 sz = SD_ID128_STRING_MAX;
         } else {
                 assert_se(sd_id128_to_uuid_string(id, buffer));
-                buffer[SD_ID128_UUID_STRING_MAX - 1] = '\n';
                 sz = SD_ID128_UUID_STRING_MAX;
         }
 
+        buffer[sz - 1] = '\n';
         r = loop_write(fd, buffer, sz, false);
         if (r < 0)
                 return r;
 
-        if (do_sync) {
+        if (FLAGS_SET(f, ID128_SYNC_ON_WRITE)) {
                 r = fsync_full(fd);
                 if (r < 0)
                         return r;
@@ -152,14 +139,14 @@ int id128_write_fd(int fd, Id128Format f, sd_id128_t id, bool do_sync) {
         return 0;
 }
 
-int id128_write(const char *p, Id128Format f, sd_id128_t id, bool do_sync) {
+int id128_write(const char *p, Id128FormatFlag f, sd_id128_t id) {
         _cleanup_close_ int fd = -1;
 
         fd = open(p, O_WRONLY|O_CREAT|O_CLOEXEC|O_NOCTTY|O_TRUNC, 0444);
         if (fd < 0)
                 return -errno;
 
-        return id128_write_fd(fd, f, id, do_sync);
+        return id128_write_fd(fd, f, id);
 }
 
 void id128_hash_func(const sd_id128_t *p, struct siphash *state) {
@@ -194,9 +181,9 @@ int id128_get_product(sd_id128_t *ret) {
         /* Reads the systems product UUID from DMI or devicetree (where it is located on POWER). This is
          * particularly relevant in VM environments, where VM managers typically place a VM uuid there. */
 
-        r = id128_read("/sys/class/dmi/id/product_uuid", ID128_UUID, &uuid);
+        r = id128_read("/sys/class/dmi/id/product_uuid", ID128_FORMAT_UUID, &uuid);
         if (r == -ENOENT)
-                r = id128_read("/proc/device-tree/vm,uuid", ID128_UUID, &uuid);
+                r = id128_read("/proc/device-tree/vm,uuid", ID128_FORMAT_UUID, &uuid);
         if (r < 0)
                 return r;
 
diff --git a/src/libsystemd/sd-id128/id128-util.h b/src/libsystemd/sd-id128/id128-util.h
index 17b180c10c..4b91a16bd1 100644
--- a/src/libsystemd/sd-id128/id128-util.h
+++ b/src/libsystemd/sd-id128/id128-util.h
@@ -10,22 +10,19 @@
 
 bool id128_is_valid(const char *s) _pure_;
 
-typedef enum Id128Format {
-        ID128_ANY,
-        ID128_PLAIN,  /* formatted as 32 hex chars as-is */
-        ID128_PLAIN_OR_UNINIT,  /* formatted as 32 hex chars as-is; allow special "uninitialized"
-                                 * value when reading from file (id128_read() and id128_read_fd()).
-                                 *
-                                 * This format should be used when reading a machine-id file. */
-        ID128_UUID,   /* formatted as 36 character uuid string */
-        _ID128_FORMAT_MAX,
-} Id128Format;
-
-int id128_read_fd(int fd, Id128Format f, sd_id128_t *ret);
-int id128_read(const char *p, Id128Format f, sd_id128_t *ret);
-
-int id128_write_fd(int fd, Id128Format f, sd_id128_t id, bool do_sync);
-int id128_write(const char *p, Id128Format f, sd_id128_t id, bool do_sync);
+typedef enum Id128FormatFlag {
+        ID128_FORMAT_PLAIN = 1 << 0,  /* formatted as 32 hex chars as-is */
+        ID128_FORMAT_UUID  = 1 << 1,  /* formatted as 36 character uuid string */
+        ID128_FORMAT_ANY   = ID128_FORMAT_PLAIN | ID128_FORMAT_UUID,
+
+        ID128_SYNC_ON_WRITE = 1 << 2, /* Sync the file after write. Used only when writing an ID. */
+} Id128FormatFlag;
+
+int id128_read_fd(int fd, Id128FormatFlag f, sd_id128_t *ret);
+int id128_read(const char *p, Id128FormatFlag f, sd_id128_t *ret);
+
+int id128_write_fd(int fd, Id128FormatFlag f, sd_id128_t id);
+int id128_write(const char *p, Id128FormatFlag f, sd_id128_t id);
 
 void id128_hash_func(const sd_id128_t *p, struct siphash *state);
 int id128_compare_func(const sd_id128_t *a, const sd_id128_t *b) _pure_;
diff --git a/src/libsystemd/sd-id128/sd-id128.c b/src/libsystemd/sd-id128/sd-id128.c
index c8f051196d..8f9801ae37 100644
--- a/src/libsystemd/sd-id128/sd-id128.c
+++ b/src/libsystemd/sd-id128/sd-id128.c
@@ -15,17 +15,21 @@
 #include "macro.h"
 #include "missing_syscall.h"
 #include "random-util.h"
+#include "stat-util.h"
 #include "user-util.h"
 
 _public_ char *sd_id128_to_string(sd_id128_t id, char s[_SD_ARRAY_STATIC SD_ID128_STRING_MAX]) {
+        size_t k = 0;
+
         assert_return(s, NULL);
 
-        for (size_t n = 0; n < 16; n++) {
-                s[n*2] = hexchar(id.bytes[n] >> 4);
-                s[n*2+1] = hexchar(id.bytes[n] & 0xF);
+        for (size_t n = 0; n < sizeof(sd_id128_t); n++) {
+                s[k++] = hexchar(id.bytes[n] >> 4);
+                s[k++] = hexchar(id.bytes[n] & 0xF);
         }
 
-        s[SD_ID128_STRING_MAX-1] = 0;
+        assert(k == SD_ID128_STRING_MAX - 1);
+        s[k] = 0;
 
         return s;
 }
@@ -37,7 +41,7 @@ _public_ char *sd_id128_to_uuid_string(sd_id128_t id, char s[_SD_ARRAY_STATIC SD
 
         /* Similar to sd_id128_to_string() but formats the result as UUID instead of plain hex chars */
 
-        for (size_t n = 0; n < 16; n++) {
+        for (size_t n = 0; n < sizeof(sd_id128_t); n++) {
 
                 if (IN_SET(n, 4, 6, 8, 10))
                         s[k++] = '-';
@@ -52,14 +56,14 @@ _public_ char *sd_id128_to_uuid_string(sd_id128_t id, char s[_SD_ARRAY_STATIC SD
         return s;
 }
 
-_public_ int sd_id128_from_string(const char s[], sd_id128_t *ret) {
-        unsigned n, i;
+_public_ int sd_id128_from_string(const char *s, sd_id128_t *ret) {
+        size_t n, i;
         sd_id128_t t;
         bool is_guid = false;
 
         assert_return(s, -EINVAL);
 
-        for (n = 0, i = 0; n < 16;) {
+        for (n = 0, i = 0; n < sizeof(sd_id128_t);) {
                 int a, b;
 
                 if (s[i] == '-') {
@@ -89,7 +93,7 @@ _public_ int sd_id128_from_string(const char s[], sd_id128_t *ret) {
                 t.bytes[n++] = (a << 4) | b;
         }
 
-        if (i != (is_guid ? 36 : 32))
+        if (i != (is_guid ? SD_ID128_UUID_STRING_MAX : SD_ID128_STRING_MAX) - 1)
                 return -EINVAL;
 
         if (s[i] != 0)
@@ -123,7 +127,7 @@ _public_ int sd_id128_get_machine(sd_id128_t *ret) {
         assert_return(ret, -EINVAL);
 
         if (sd_id128_is_null(saved_machine_id)) {
-                r = id128_read("/etc/machine-id", ID128_PLAIN, &saved_machine_id);
+                r = id128_read("/etc/machine-id", ID128_FORMAT_PLAIN, &saved_machine_id);
                 if (r < 0)
                         return r;
 
@@ -142,9 +146,14 @@ _public_ int sd_id128_get_boot(sd_id128_t *ret) {
         assert_return(ret, -EINVAL);
 
         if (sd_id128_is_null(saved_boot_id)) {
-                r = id128_read("/proc/sys/kernel/random/boot_id", ID128_UUID, &saved_boot_id);
+                r = id128_read("/proc/sys/kernel/random/boot_id", ID128_FORMAT_UUID, &saved_boot_id);
+                if (r == -ENOENT && proc_mounted() == 0)
+                        return -ENOSYS;
                 if (r < 0)
                         return r;
+
+                if (sd_id128_is_null(saved_boot_id))
+                        return -ENOMEDIUM;
         }
 
         *ret = saved_boot_id;
diff --git a/src/libsystemd/sd-journal/journal-file.c b/src/libsystemd/sd-journal/journal-file.c
index 507958dabd..ab518fea80 100644
--- a/src/libsystemd/sd-journal/journal-file.c
+++ b/src/libsystemd/sd-journal/journal-file.c
@@ -384,7 +384,7 @@ static int journal_file_refresh_header(JournalFile *f) {
         assert(f->header);
 
         r = sd_id128_get_machine(&f->header->machine_id);
-        if (IN_SET(r, -ENOENT, -ENOMEDIUM))
+        if (IN_SET(r, -ENOENT, -ENOMEDIUM, -ENOPKG))
                 /* We don't have a machine-id, let's continue without */
                 zero(f->header->machine_id);
         else if (r < 0)
diff --git a/src/machine-id-setup/machine-id-setup-main.c b/src/machine-id-setup/machine-id-setup-main.c
index 6aef48650d..9101f4e11a 100644
--- a/src/machine-id-setup/machine-id-setup-main.c
+++ b/src/machine-id-setup/machine-id-setup-main.c
@@ -164,7 +164,7 @@ static int run(int argc, char *argv[]) {
                         return r;
 
                 etc_machine_id = prefix_roota(arg_root, "/etc/machine-id");
-                r = id128_read(etc_machine_id, ID128_PLAIN, &id);
+                r = id128_read(etc_machine_id, ID128_FORMAT_PLAIN, &id);
                 if (r < 0)
                         return log_error_errno(r, "Failed to read machine ID back: %m");
         } else {
diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index 1282c8b98b..96611058fe 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -2196,7 +2196,7 @@ static int setup_boot_id(void) {
         if (r < 0)
                 return log_error_errno(r, "Failed to generate random boot id: %m");
 
-        r = id128_write(path, ID128_UUID, rnd, false);
+        r = id128_write(path, ID128_FORMAT_UUID, rnd);
         if (r < 0)
                 return log_error_errno(r, "Failed to write boot id: %m");
 
@@ -2830,9 +2830,9 @@ static int setup_machine_id(const char *directory) {
 
         etc_machine_id = prefix_roota(directory, "/etc/machine-id");
 
-        r = id128_read(etc_machine_id, ID128_PLAIN_OR_UNINIT, &id);
+        r = id128_read(etc_machine_id, ID128_FORMAT_PLAIN, &id);
         if (r < 0) {
-                if (!IN_SET(r, -ENOENT, -ENOMEDIUM)) /* If the file is missing or empty, we don't mind */
+                if (!IN_SET(r, -ENOENT, -ENOMEDIUM, -ENOPKG)) /* If the file is missing, empty, or uninitialized, we don't mind */
                         return log_error_errno(r, "Failed to read machine ID from container image: %m");
 
                 if (sd_id128_is_null(arg_uuid)) {
diff --git a/src/partition/repart.c b/src/partition/repart.c
index a627d84305..1e647e2ec9 100644
--- a/src/partition/repart.c
+++ b/src/partition/repart.c
@@ -4741,8 +4741,8 @@ static int context_read_seed(Context *context, const char *root) {
                 else if (fd < 0)
                         return log_error_errno(fd, "Failed to determine machine ID of image: %m");
                 else {
-                        r = id128_read_fd(fd, ID128_PLAIN_OR_UNINIT, &context->seed);
-                        if (r == -ENOMEDIUM)
+                        r = id128_read_fd(fd, ID128_FORMAT_PLAIN, &context->seed);
+                        if (IN_SET(r, -ENOMEDIUM, -ENOPKG))
                                 log_info("No machine ID set, using randomized partition UUIDs.");
                         else if (r < 0)
                                 return log_error_errno(r, "Failed to parse machine ID of image: %m");
diff --git a/src/shared/discover-image.c b/src/shared/discover-image.c
index 8bc165ef4c..eb4d23f0e8 100644
--- a/src/shared/discover-image.c
+++ b/src/shared/discover-image.c
@@ -1158,7 +1158,7 @@ int image_read_metadata(Image *i) {
                         if (fd < 0)
                                 log_debug_errno(errno, "Failed to open %s: %m", path);
                         else {
-                                r = id128_read_fd(fd, ID128_PLAIN, &machine_id);
+                                r = id128_read_fd(fd, ID128_FORMAT_PLAIN, &machine_id);
                                 if (r < 0)
                                         log_debug_errno(r, "Image %s contains invalid machine ID.", i->name);
                         }
diff --git a/src/shared/machine-id-setup.c b/src/shared/machine-id-setup.c
index c694a185ba..2e33a23cb9 100644
--- a/src/shared/machine-id-setup.c
+++ b/src/shared/machine-id-setup.c
@@ -37,7 +37,7 @@ static int generate_machine_id(const char *root, sd_id128_t *ret) {
         dbus_machine_id = prefix_roota(root, "/var/lib/dbus/machine-id");
         fd = open(dbus_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
         if (fd >= 0) {
-                if (id128_read_fd(fd, ID128_PLAIN, ret) >= 0) {
+                if (id128_read_fd(fd, ID128_FORMAT_PLAIN, ret) >= 0) {
                         log_info("Initializing machine ID from D-Bus machine ID.");
                         return 0;
                 }
@@ -122,7 +122,7 @@ int machine_id_setup(const char *root, bool force_transient, sd_id128_t machine_
         if (sd_id128_is_null(machine_id)) {
 
                 /* Try to read any existing machine ID */
-                if (id128_read_fd(fd, ID128_PLAIN, ret) >= 0)
+                if (id128_read_fd(fd, ID128_FORMAT_PLAIN, ret) >= 0)
                         return 0;
 
                 /* Hmm, so, the id currently stored is not useful, then let's generate one */
@@ -151,7 +151,7 @@ int machine_id_setup(const char *root, bool force_transient, sd_id128_t machine_
                         if (r < 0)
                                 return log_error_errno(r, "Failed to sync %s: %m", etc_machine_id);
                 } else {
-                        r = id128_write_fd(fd, ID128_PLAIN, machine_id, true);
+                        r = id128_write_fd(fd, ID128_FORMAT_PLAIN | ID128_SYNC_ON_WRITE, machine_id);
                         if (r < 0)
                                 return log_error_errno(r, "Failed to write %s: %m", etc_machine_id);
                         else
@@ -167,7 +167,7 @@ int machine_id_setup(const char *root, bool force_transient, sd_id128_t machine_
         run_machine_id = prefix_roota(root, "/run/machine-id");
 
         RUN_WITH_UMASK(0022)
-                r = id128_write(run_machine_id, ID128_PLAIN, machine_id, false);
+                r = id128_write(run_machine_id, ID128_FORMAT_PLAIN, machine_id);
         if (r < 0) {
                 (void) unlink(run_machine_id);
                 return log_error_errno(r, "Cannot write %s: %m", run_machine_id);
@@ -239,7 +239,7 @@ int machine_id_commit(const char *root) {
                                        "%s is not on a temporary file system.",
                                        etc_machine_id);
 
-        r = id128_read_fd(fd, ID128_PLAIN, &id);
+        r = id128_read_fd(fd, ID128_FORMAT_PLAIN, &id);
         if (r < 0)
                 return log_error_errno(r, "We didn't find a valid machine ID in %s: %m", etc_machine_id);
 
@@ -260,7 +260,7 @@ int machine_id_commit(const char *root) {
                 return r;
 
         /* Update a persistent version of etc_machine_id */
-        r = id128_write(etc_machine_id, ID128_PLAIN, id, true);
+        r = id128_write(etc_machine_id, ID128_FORMAT_PLAIN | ID128_SYNC_ON_WRITE, id);
         if (r < 0)
                 return log_error_errno(r, "Cannot write %s. This is mandatory to get a persistent machine ID: %m", etc_machine_id);
 
diff --git a/src/shared/specifier.c b/src/shared/specifier.c
index d54ab9f5a9..cd651768bd 100644
--- a/src/shared/specifier.c
+++ b/src/shared/specifier.c
@@ -195,7 +195,7 @@ int specifier_machine_id(char specifier, const void *data, const char *root, con
                         /* Translate error for missing os-release file to EUNATCH. */
                         return fd == -ENOENT ? -EUNATCH : fd;
 
-                r = id128_read_fd(fd, ID128_PLAIN, &id);
+                r = id128_read_fd(fd, ID128_FORMAT_PLAIN, &id);
         } else
                 r = sd_id128_get_machine(&id);
         if (r < 0)
diff --git a/src/test/test-condition.c b/src/test/test-condition.c
index 5144eb4687..901d80eb3d 100644
--- a/src/test/test-condition.c
+++ b/src/test/test-condition.c
@@ -250,7 +250,7 @@ TEST(condition_test_host) {
         int r;
 
         r = sd_id128_get_machine(&id);
-        if (IN_SET(r, -ENOENT, -ENOMEDIUM))
+        if (IN_SET(r, -ENOENT, -ENOMEDIUM, -ENOPKG))
                 return (void) log_tests_skipped("/etc/machine-id missing");
         assert_se(r >= 0);
 
diff --git a/src/test/test-fs-util.c b/src/test/test-fs-util.c
index 8c4b632ed0..16c6774a65 100644
--- a/src/test/test-fs-util.c
+++ b/src/test/test-fs-util.c
@@ -325,7 +325,7 @@ TEST(chase_symlinks) {
                 assert_se(fd >= 0);
                 safe_close(pfd);
 
-                assert_se(id128_read_fd(fd, ID128_PLAIN, &a) >= 0);
+                assert_se(id128_read_fd(fd, ID128_FORMAT_PLAIN, &a) >= 0);
                 assert_se(sd_id128_get_machine(&b) >= 0);
                 assert_se(sd_id128_equal(a, b));
         }
diff --git a/src/test/test-id128.c b/src/test/test-id128.c
index 4b71c5c00b..6de0cec426 100644
--- a/src/test/test-id128.c
+++ b/src/test/test-id128.c
@@ -86,17 +86,17 @@ TEST(id128) {
 
         /* First, write as UUID */
         assert_se(sd_id128_randomize(&id) >= 0);
-        assert_se(id128_write_fd(fd, ID128_UUID, id, false) >= 0);
+        assert_se(id128_write_fd(fd, ID128_FORMAT_UUID, id) >= 0);
 
         assert_se(lseek(fd, 0, SEEK_SET) == 0);
-        assert_se(id128_read_fd(fd, ID128_PLAIN, &id2) == -EINVAL);
+        assert_se(id128_read_fd(fd, ID128_FORMAT_PLAIN, &id2) == -EINVAL);
 
         assert_se(lseek(fd, 0, SEEK_SET) == 0);
-        assert_se(id128_read_fd(fd, ID128_UUID, &id2) >= 0);
+        assert_se(id128_read_fd(fd, ID128_FORMAT_UUID, &id2) >= 0);
         assert_se(sd_id128_equal(id, id2));
 
         assert_se(lseek(fd, 0, SEEK_SET) == 0);
-        assert_se(id128_read_fd(fd, ID128_ANY, &id2) >= 0);
+        assert_se(id128_read_fd(fd, ID128_FORMAT_ANY, &id2) >= 0);
         assert_se(sd_id128_equal(id, id2));
 
         /* Second, write as plain */
@@ -104,17 +104,17 @@ TEST(id128) {
         assert_se(ftruncate(fd, 0) >= 0);
 
         assert_se(sd_id128_randomize(&id) >= 0);
-        assert_se(id128_write_fd(fd, ID128_PLAIN, id, false) >= 0);
+        assert_se(id128_write_fd(fd, ID128_FORMAT_PLAIN, id) >= 0);
 
         assert_se(lseek(fd, 0, SEEK_SET) == 0);
-        assert_se(id128_read_fd(fd, ID128_UUID, &id2) == -EINVAL);
+        assert_se(id128_read_fd(fd, ID128_FORMAT_UUID, &id2) == -EINVAL);
 
         assert_se(lseek(fd, 0, SEEK_SET) == 0);
-        assert_se(id128_read_fd(fd, ID128_PLAIN, &id2) >= 0);
+        assert_se(id128_read_fd(fd, ID128_FORMAT_PLAIN, &id2) >= 0);
         assert_se(sd_id128_equal(id, id2));
 
         assert_se(lseek(fd, 0, SEEK_SET) == 0);
-        assert_se(id128_read_fd(fd, ID128_ANY, &id2) >= 0);
+        assert_se(id128_read_fd(fd, ID128_FORMAT_ANY, &id2) >= 0);
         assert_se(sd_id128_equal(id, id2));
 
         /* Third, write plain without trailing newline */
@@ -125,13 +125,13 @@ TEST(id128) {
         assert_se(write(fd, sd_id128_to_string(id, t), 32) == 32);
 
         assert_se(lseek(fd, 0, SEEK_SET) == 0);
-        assert_se(id128_read_fd(fd, ID128_UUID, &id2) == -EINVAL);
+        assert_se(id128_read_fd(fd, ID128_FORMAT_UUID, &id2) == -EINVAL);
 
         assert_se(lseek(fd, 0, SEEK_SET) == 0);
-        assert_se(id128_read_fd(fd, ID128_PLAIN, &id2) >= 0);
+        assert_se(id128_read_fd(fd, ID128_FORMAT_PLAIN, &id2) >= 0);
         assert_se(sd_id128_equal(id, id2));
 
-        /* Third, write UUID without trailing newline */
+        /* Fourth, write UUID without trailing newline */
         assert_se(lseek(fd, 0, SEEK_SET) == 0);
         assert_se(ftruncate(fd, 0) >= 0);
 
@@ -139,12 +139,37 @@ TEST(id128) {
         assert_se(write(fd, sd_id128_to_uuid_string(id, q), 36) == 36);
 
         assert_se(lseek(fd, 0, SEEK_SET) == 0);
-        assert_se(id128_read_fd(fd, ID128_PLAIN, &id2) == -EINVAL);
+        assert_se(id128_read_fd(fd, ID128_FORMAT_PLAIN, &id2) == -EINVAL);
 
         assert_se(lseek(fd, 0, SEEK_SET) == 0);
-        assert_se(id128_read_fd(fd, ID128_UUID, &id2) >= 0);
+        assert_se(id128_read_fd(fd, ID128_FORMAT_UUID, &id2) >= 0);
         assert_se(sd_id128_equal(id, id2));
 
+        /* Fifth, tests for "uninitialized" */
+        assert_se(lseek(fd, 0, SEEK_SET) == 0);
+        assert_se(ftruncate(fd, 0) >= 0);
+        assert_se(write(fd, "uninitialized", STRLEN("uninitialized")) == STRLEN("uninitialized"));
+        assert_se(lseek(fd, 0, SEEK_SET) == 0);
+        assert_se(id128_read_fd(fd, ID128_FORMAT_ANY, NULL) == -ENOPKG);
+
+        assert_se(lseek(fd, 0, SEEK_SET) == 0);
+        assert_se(ftruncate(fd, 0) >= 0);
+        assert_se(write(fd, "uninitialized\n", STRLEN("uninitialized\n")) == STRLEN("uninitialized\n"));
+        assert_se(lseek(fd, 0, SEEK_SET) == 0);
+        assert_se(id128_read_fd(fd, ID128_FORMAT_ANY, NULL) == -ENOPKG);
+
+        assert_se(lseek(fd, 0, SEEK_SET) == 0);
+        assert_se(ftruncate(fd, 0) >= 0);
+        assert_se(write(fd, "uninitialized\nfoo", STRLEN("uninitialized\nfoo")) == STRLEN("uninitialized\nfoo"));
+        assert_se(lseek(fd, 0, SEEK_SET) == 0);
+        assert_se(id128_read_fd(fd, ID128_FORMAT_ANY, NULL) == -EINVAL);
+
+        assert_se(lseek(fd, 0, SEEK_SET) == 0);
+        assert_se(ftruncate(fd, 0) >= 0);
+        assert_se(write(fd, "uninit", STRLEN("uninit")) == STRLEN("uninit"));
+        assert_se(lseek(fd, 0, SEEK_SET) == 0);
+        assert_se(id128_read_fd(fd, ID128_FORMAT_ANY, NULL) == -EINVAL);
+
         if (sd_booted() > 0 && access("/etc/machine-id", F_OK) >= 0) {
                 assert_se(sd_id128_get_machine_app_specific(SD_ID128_MAKE(f0,3d,aa,eb,1c,33,4b,43,a7,32,17,29,44,bf,77,2e), &id) >= 0);
                 assert_se(sd_id128_get_machine_app_specific(SD_ID128_MAKE(f0,3d,aa,eb,1c,33,4b,43,a7,32,17,29,44,bf,77,2e), &id2) >= 0);