core: Add %D specifier for $XDG_DATA_HOME

We already have specifiers that resolve to $XDG_STATE_HOME, and
$XDG_CONFIG_HOME. $XDG_DATA_HOME is in a similar vein.

It allows units belonging to the user service manager to correctly look
into ~/.local/share. I imagine this would be most useful inside of
condition checks (i.e. only run a service on session startup if some
data is not found in ~/.local/share) or in the inotify monitoring of a
.path unit

diff --git a/man/systemd.unit.xml b/man/systemd.unit.xml
index c447cd063887e68643cf8be53ea19c853739f858..f7a6af70597048ad1a8abdc0c9b51b707141d0b0 100644 (file)
--- a/man/systemd.unit.xml
+++ b/man/systemd.unit.xml
@@ -2302,6 +2302,11 @@
             <entry>Credentials directory</entry>
             <entry>This is the value of the <literal>$CREDENTIALS_DIRECTORY</literal> environment variable if available. See section "Credentials" in <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more information.</entry>
           </row>
+          <row>
+            <entry><literal>%D</literal></entry>
+            <entry>Shared data directory</entry>
+            <entry>This is either <filename>/usr/share/</filename> (for the system manager) or the path <literal>$XDG_DATA_HOME</literal> resolves to (for user managers).</entry>
+          </row>
           <row>
             <entry><literal>%E</literal></entry>
             <entry>Configuration directory root</entry>

diff --git a/src/core/unit-printf.c b/src/core/unit-printf.c
index 9f95984eb630419f1a31cde6e45a100103097fed..be4cb139e9b8e6f6bf1500e9bb625a99b460c9bb 100644 (file)
--- a/src/core/unit-printf.c
+++ b/src/core/unit-printf.c
@@ -4,6 +4,7 @@
 #include "cgroup-util.h"
 #include "format-util.h"
 #include "macro.h"
+#include "sd-path.h"
 #include "specifier.h"
 #include "string-util.h"
 #include "strv.h"
@@ -164,6 +165,14 @@ static int specifier_credentials_dir(char specifier, const void *data, const cha
         return 0;
 }
 
+static int specifier_shared_data_dir(char specifier, const void *data, const char *root, const void *userdata, char **ret) {
+        const Unit *u = ASSERT_PTR(userdata);
+
+        assert(ret);
+
+        return sd_path_lookup(MANAGER_IS_SYSTEM(u->manager) ? SD_PATH_SYSTEM_SHARED : SD_PATH_USER_SHARED, NULL, ret);
+}
+
 int unit_name_printf(const Unit *u, const char* format, char **ret) {
         /*
          * This will use the passed string as format string and replace the following specifiers (which should all be
@@ -208,6 +217,7 @@ int unit_full_printf_full(const Unit *u, const char *format, size_t max_length,
          *
          * %C: the cache directory root (e.g. /var/cache or $XDG_CACHE_HOME)
          * %d: the credentials directory ($CREDENTIALS_DIRECTORY)
+         * %D: the shared data root (e.g. /usr/share or $XDG_DATA_HOME)
          * %E: the configuration directory root (e.g. /etc or $XDG_CONFIG_HOME)
          * %L: the log directory root (e.g. /var/log or $XDG_STATE_HOME/log)
          * %S: the state directory root (e.g. /var/lib or $XDG_STATE_HOME)
@@ -245,6 +255,7 @@ int unit_full_printf_full(const Unit *u, const char *format, size_t max_length,
 
                 { 'C', specifier_special_directory,        UINT_TO_PTR(EXEC_DIRECTORY_CACHE) },
                 { 'd', specifier_credentials_dir,          NULL },
+                { 'D', specifier_shared_data_dir,          NULL },
                 { 'E', specifier_special_directory,        UINT_TO_PTR(EXEC_DIRECTORY_CONFIGURATION) },
                 { 'L', specifier_special_directory,        UINT_TO_PTR(EXEC_DIRECTORY_LOGS) },
                 { 'S', specifier_special_directory,        UINT_TO_PTR(EXEC_DIRECTORY_STATE) },