id128: allow combining --app with show

This effectively exposes sd_id128_get_app_specific() on the commandline.

Fixes https://github.com/systemd/systemd/issues/27514.

diff --git a/man/systemd-id128.xml b/man/systemd-id128.xml
index c4521ea945f10b73feb3affe36f8c1172e5edd7b..bf71a7c3a81a611824b385af28e0ce02ee272242 100644 (file)
--- a/man/systemd-id128.xml
+++ b/man/systemd-id128.xml
@@ -70,12 +70,6 @@
     <para>With <command>boot-id</command>, the identifier of the current boot will be
     printed.</para>
 
-    <para>Both <command>machine-id</command> and <command>boot-id</command> may be combined
-    with the <option>--app-specific=<replaceable>app-id</replaceable></option> switch to
-    generate application-specific IDs. See
-    <citerefentry><refentrytitle>sd_id128_get_machine</refentrytitle><manvolnum>3</manvolnum></citerefentry>
-    for the discussion when this is useful.</para>
-
     <para>With <command>invocation-id</command>, the identifier of the current service invocation
     will be printed. This is available in systemd services. See
     <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
@@ -87,6 +81,12 @@
     then printed with their name, or arbitrary IDs, which are then printed with a placeholder name. Combine
     with <option>--uuid</option> to list the IDs in UUID style, i.e. the way GPT partition type UUIDs are
     usually shown.</para>
+
+    <para><command>machine-id</command>, <command>boot-id</command>, and <command>show</command> may be
+    combined with the <option>--app-specific=<replaceable>app-id</replaceable></option> switch to generate
+    application-specific IDs. See
+    <citerefentry><refentrytitle>sd_id128_get_machine</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+    for the discussion when this is useful.</para>
   </refsect1>
 
   <refsect1>
@@ -116,10 +116,14 @@
         <term><option>-a <replaceable>app-id</replaceable></option></term>
         <term><option>--app-specific=<replaceable>app-id</replaceable></option></term>
 
-        <listitem><para>With this option, an identifier that is the result of hashing the
-        application identifier <replaceable>app-id</replaceable> and the machine identifier will be
-        printed. The <replaceable>app-id</replaceable> argument must be a valid sd-id128 string
-        identifying the application.</para>
+        <listitem><para>With this option, identifiers will be printed that are the result of hashing the
+        application identifier <replaceable>app-id</replaceable> and another ID. The
+        <replaceable>app-id</replaceable> argument must be a valid sd-id128 string identifying the
+        application. When used with <command>machine-id</command>, the other ID will be the machine ID as
+        described in
+        <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>, when
+        used with <command>boot-id</command>, the other ID will be the boot ID, and when used with
+        <command>show</command>, the other ID or IDs should be specified via the positional arguments.</para>
 
         <xi:include href="version-info.xml" xpointer="v240"/>
         </listitem>
@@ -165,6 +169,29 @@ NAME      ID
 user-home 773f91ef66d449b5bd83d683bf40ad16
       </programlisting>
     </example>
+
+    <example>
+      <title>Generate an application-specific UUID</title>
+
+      <programlisting>
+$ systemd-id128 machine-id -u
+3a9d668b-4db7-4939-8a4a-5e78a03bffb7
+
+$ systemd-id128 new -u
+1fb8f24b-02df-458d-9659-cc8ace68e28a
+
+$ systemd-id128 --app=1fb8f24b-02df-458d-9659-cc8ace68e28a
+47b82cb1-5339-43da-b2a6-1c350aef1bd1
+
+$ systemd-id128 -Pu show 3a9d668b-4db7-4939-8a4a-5e78a03bffb7 --app=1fb8f24b-02df-458d-9659-cc8ace68e28a
+47b82cb1-5339-43da-b2a6-1c350aef1bd1
+      </programlisting>
+
+      <para>On a given machine with the ID 3a9d668b-4db7-4939-8a4a-5e78a03bffb7, for the application
+      1fb8f24b-02df-458d-9659-cc8ace68e28a, we generate an application-specific machine ID. If we want to
+      later recreate the same calculation on a different machine, we need to specify both IDs explicitly.
+      </para>
+    </example>
   </refsect1>
 
   <refsect1>

diff --git a/src/id128/id128.c b/src/id128/id128.c
index 0ec2df059a5e38144a560fc00a9d401104998716..29cd2e2dc0e10dac80c4db7d16849a9dbf046423 100644 (file)
--- a/src/id128/id128.c
+++ b/src/id128/id128.c
@@ -68,8 +68,16 @@ static int verb_invocation_id(int argc, char **argv, void *userdata) {
 }
 
 static int show_one(Table **table, const char *name, sd_id128_t uuid, bool first) {
+        sd_id128_t u;
         int r;
 
+        assert(table);
+
+        if (sd_id128_is_null(arg_app))
+                u = uuid;
+        else
+                assert_se(sd_id128_get_app_specific(uuid, arg_app, &u) == 0);
+
         if (arg_mode == ID128_PRINT_PRETTY) {
                 _cleanup_free_ char *id = NULL;
 
@@ -79,7 +87,7 @@ static int show_one(Table **table, const char *name, sd_id128_t uuid, bool first
 
                 ascii_strupper(id);
 
-                r = id128_pretty_print_sample(id, uuid);
+                r = id128_pretty_print_sample(id, u);
                 if (r < 0)
                         return r;
                 if (!first)
@@ -87,7 +95,7 @@ static int show_one(Table **table, const char *name, sd_id128_t uuid, bool first
                 return 0;
 
         } else if (arg_value)
-                return id128_pretty_print(uuid, arg_mode);
+                return id128_pretty_print(u, arg_mode);
 
         else {
                 if (!*table) {
@@ -100,7 +108,7 @@ static int show_one(Table **table, const char *name, sd_id128_t uuid, bool first
                 return table_add_many(*table,
                                       TABLE_STRING, name,
                                       arg_mode == ID128_PRINT_ID128 ? TABLE_ID128 : TABLE_UUID,
-                                      uuid);
+                                      u);
         }
 }
 

diff --git a/src/test/test-id128.c b/src/test/test-id128.c
index ca204d3718828471725c0e01b0310e3fb27cbd4a..10c061b917a45d0f8ba00078a3a057ca70a7e9cf 100644 (file)
--- a/src/test/test-id128.c
+++ b/src/test/test-id128.c
@@ -180,6 +180,7 @@ TEST(id128) {
         assert_se(lseek(fd, 0, SEEK_SET) == 0);
         assert_se(id128_read_fd(fd, ID128_FORMAT_ANY, NULL) == -EUCLEAN);
 
+        /* build/systemd-id128 -a f03daaeb1c334b43a732172944bf772e show 51df0b4bc3b04c9780e299b98ca373b8 */
         assert_se(sd_id128_get_app_specific(SD_ID128_MAKE(51,df,0b,4b,c3,b0,4c,97,80,e2,99,b9,8c,a3,73,b8),
                                             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_equal(id, SD_ID128_MAKE(1d,ee,59,54,e7,5c,4d,6f,b9,6c,c6,c0,4c,a1,8a,86)));

diff --git a/test/units/testsuite-74.id128.sh b/test/units/testsuite-74.id128.sh
index 4e2e1257dc9ec6782bb0d66938bcd57465d8ca04..c1b80d660e85e33df7b5d9ea2077b230f7162bf2 100755 (executable)
--- a/test/units/testsuite-74.id128.sh
+++ b/test/units/testsuite-74.id128.sh
@@ -13,6 +13,14 @@ systemd-id128 show --pretty | tail
 systemd-id128 show --value | tail
 systemd-id128 show 4f68bce3e8cd4db196e7fbcaf984b709 # root-x86-64
 systemd-id128 show --pretty 4f68bce3e8cd4db196e7fbcaf984b709
+systemd-id128 show root-x86-64
+systemd-id128 show --pretty root-x86-64
+[[ "$(systemd-id128 show 4f68bce3e8cd4db196e7fbcaf984b709)" = "$(systemd-id128 show root-x86-64)" ]]
+[[ "$(systemd-id128 show 4f68bce3-e8cd-4db1-96e7-fbcaf984b709)" = "$(systemd-id128 show root-x86-64)" ]]
+
+systemd-id128 show root-x86-64 --app-specific=4f68bce3e8cd4db196e7fbcaf984b709
+systemd-id128 show --pretty root-x86-64 --app-specific=4f68bce3e8cd4db196e7fbcaf984b709
+[[ "$(systemd-id128 show root-x86-64 --app-specific=4f68bce3e8cd4db196e7fbcaf984b709 -P)" = "8ee5535e7cb14c249e1d28b8dfbb939c" ]]
 
 [[ "$(systemd-id128 new | wc -c)" -eq 33 ]]
 systemd-id128 new -p