core: add support for expanding state/cache/log directory root in unit files

This augments %t which already resolves to the runtime directory root, and
should be useful for units that want to pass any of these paths in
command line arguments.

Example:

ExecStart=/usr/bin/mydaemon --datadir=%S/mydaemon

Why not expose a specifier resolving directly to the configured
state/runtime/cache/log dir? Three reasons:

1. Specifiers should be independent of configuration of the unit itself,
   and StateDirectory= and friends are unit configuration.  See
   03fc9c723c and related work.

2. We permit multiple StateDirectory= values per unit, and it hence
   wouldn't be clear which one is passed.

3. We already have %t for the runtime directory root, and we should
   continue with the same scheme.
This commit is contained in:
Lennart Poettering 2017-10-11 14:02:36 +02:00
parent 530c1c3028
commit 14068e17f3
2 changed files with 28 additions and 5 deletions

View File

@ -1272,10 +1272,25 @@
</row>
<row>
<entry><literal>%t</literal></entry>
<entry>Runtime directory</entry>
<entry>Runtime directory root</entry>
<entry>This is either <filename>/run</filename> (for the system manager) or the path <literal>$XDG_RUNTIME_DIR</literal> resolves to (for user managers).</entry>
</row>
<row>
<entry><literal>%S</literal></entry>
<entry>State directory root </entry>
<entry>This is either <filename>/var/lib</filename> (for the system manager) or the path <literal>$XDG_CONFIG_HOME</literal> resolves to (for user managers).</entry>
</row>
<row>
<entry><literal>%C</literal></entry>
<entry>Cache directory root </entry>
<entry>This is either <filename>/var/cache</filename> (for the system manager) or the path <literal>$XDG_CACHE_HOME</literal> resolves to (for user managers).</entry>
</row>
<row>
<entry><literal>%L</literal></entry>
<entry>Logs directory root </entry>
<entry>This is either <filename>/var/log</filename> (for the system manager) or the path <literal>$XDG_CONFIG_HOME</literal> resolves to with <filename>/log</filename> appended (for user managers).</entry>
</row>
<row>
<entry><literal>%u</literal></entry>
<entry>User name</entry>
<entry>This is the name of the user running the service manager instance. In case of the system manager this resolves to <literal>root</literal>.</entry>

View File

@ -143,13 +143,13 @@ static int specifier_cgroup_slice(char specifier, void *data, void *userdata, ch
return 0;
}
static int specifier_runtime(char specifier, void *data, void *userdata, char **ret) {
static int specifier_special_directory(char specifier, void *data, void *userdata, char **ret) {
Unit *u = userdata;
char *n = NULL;
assert(u);
n = strdup(u->manager->prefix[EXEC_DIRECTORY_RUNTIME]);
n = strdup(u->manager->prefix[PTR_TO_UINT(data)]);
if (!n)
return -ENOMEM;
@ -244,10 +244,15 @@ int unit_full_printf(Unit *u, const char *format, char **ret) {
* (which are likely not suitable for unescaped inclusion in unit names):
*
* %f: the unescaped instance if set, otherwise the id unescaped as path
*
* %c: cgroup path of unit (deprecated)
* %r: where units in this slice are placed in the cgroup tree (deprecated)
* %R: the root of this systemd's instance tree (deprecated)
* %t: the runtime directory to place sockets in (e.g. "/run" or $XDG_RUNTIME_DIR)
*
* %t: the runtime directory root (e.g. /run or $XDG_RUNTIME_DIR)
* %S: the state directory root (e.g. /var/lib or $XDG_CONFIG_HOME)
* %C: the cache directory root (e.g. /var/cache or $XDG_CACHE_HOME)
* %L: the log directory root (e.g. /var/log or $XDG_CONFIG_HOME/log)
*
* %h: the homedir of the running user
* %s: the shell of the running user
@ -271,7 +276,10 @@ int unit_full_printf(Unit *u, const char *format, char **ret) {
{ 'c', specifier_cgroup, NULL },
{ 'r', specifier_cgroup_slice, NULL },
{ 'R', specifier_cgroup_root, NULL },
{ 't', specifier_runtime, NULL },
{ 't', specifier_special_directory, UINT_TO_PTR(EXEC_DIRECTORY_RUNTIME) },
{ 'S', specifier_special_directory, UINT_TO_PTR(EXEC_DIRECTORY_STATE) },
{ 'C', specifier_special_directory, UINT_TO_PTR(EXEC_DIRECTORY_CACHE) },
{ 'L', specifier_special_directory, UINT_TO_PTR(EXEC_DIRECTORY_LOGS) },
{ 'U', specifier_user_id, NULL },
{ 'u', specifier_user_name, NULL },