core: introduce specifiers for /tmp and /var/tmp

This corresponds nicely with the specifiers we already pass for
/var/lib, /var/cache, /run and so on.

This is particular useful to update the test-path service files to
operate without guessable files, thus allowing multiple parallel
test-path invocations to pass without issues (the idea is to set $TMPDIR
early on in the test to some private directory, and then only use the
new %T or %V specifier to refer to it).

src/core/unit-printf.c

@@ -232,6 +232,8 @@ int unit_full_printf(Unit *u, const char *format, char **ret) {
          * %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)
+         * %T: the temporary directory (e.g. /tmp, or $TMPDIR, $TEMP, $TMP)
+         * %V: the temporary directory for large, persistent stuff (e.g. /var/tmp, or $TMPDIR, $TEMP, $TMP)
          *
          * %h: the homedir of the running user
          * %s: the shell of the running user
@@ -257,10 +259,13 @@ 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_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) },
+                { 'T', specifier_tmp_dir,                  NULL },
+                { 'V', specifier_var_tmp_dir,              NULL },
 
                 { 'U', specifier_user_id,                  NULL },
                 { 'u', specifier_user_name,                NULL },

src/shared/specifier.c

@@ -15,6 +15,7 @@
 #include "sd-id128.h"
 
 #include "alloc-util.h"
+#include "fs-util.h"
 #include "hostname-util.h"
 #include "macro.h"
 #include "specifier.h"
@@ -222,6 +223,40 @@ int specifier_user_shell(char specifier, void *data, void *userdata, char **ret)
         return get_shell(ret);
 }
 
+int specifier_tmp_dir(char specifier, void *data, void *userdata, char **ret) {
+        const char *p;
+        char *copy;
+        int r;
+
+        r = tmp_dir(&p);
+        if (r < 0)
+                return r;
+
+        copy = strdup(p);
+        if (!copy)
+                return -ENOMEM;
+
+        *ret = copy;
+        return 0;
+}
+
+int specifier_var_tmp_dir(char specifier, void *data, void *userdata, char **ret) {
+        const char *p;
+        char *copy;
+        int r;
+
+        r = var_tmp_dir(&p);
+        if (r < 0)
+                return r;
+
+        copy = strdup(p);
+        if (!copy)
+                return -ENOMEM;
+
+        *ret = copy;
+        return 0;
+}
+
 int specifier_escape_strv(char **l, char ***ret) {
         char **z, **p, **q;
 

src/shared/specifier.h

@@ -31,6 +31,9 @@ int specifier_user_id(char specifier, void *data, void *userdata, char **ret);
 int specifier_user_home(char specifier, void *data, void *userdata, char **ret);
 int specifier_user_shell(char specifier, void *data, void *userdata, char **ret);
 
+int specifier_tmp_dir(char specifier, void *data, void *userdata, char **ret);
+int specifier_var_tmp_dir(char specifier, void *data, void *userdata, char **ret);
+
 static inline char* specifier_escape(const char *string) {
         return strreplace(string, "%", "%%");
 }

src/sysusers/sysusers.c

@@ -1359,10 +1359,12 @@ static bool item_equal(Item *a, Item *b) {
 static int parse_line(const char *fname, unsigned line, const char *buffer) {
 
         static const Specifier specifier_table[] = {
-                { 'm', specifier_machine_id, NULL },
-                { 'b', specifier_boot_id, NULL },
-                { 'H', specifier_host_name, NULL },
+                { 'm', specifier_machine_id,     NULL },
+                { 'b', specifier_boot_id,        NULL },
+                { 'H', specifier_host_name,      NULL },
                 { 'v', specifier_kernel_release, NULL },
+                { 'T', specifier_tmp_dir,        NULL },
+                { 'V', specifier_var_tmp_dir,    NULL },
                 {}
         };
 

src/tmpfiles/tmpfiles.c

@@ -179,10 +179,13 @@ static const Specifier specifier_table[] = {
         { 'U', specifier_user_id,         NULL },
         { 'u', specifier_user_name,       NULL },
         { 'h', specifier_user_home,       NULL },
+
         { 't', specifier_directory,       UINT_TO_PTR(DIRECTORY_RUNTIME) },
         { 'S', specifier_directory,       UINT_TO_PTR(DIRECTORY_STATE) },
         { 'C', specifier_directory,       UINT_TO_PTR(DIRECTORY_CACHE) },
         { 'L', specifier_directory,       UINT_TO_PTR(DIRECTORY_LOGS) },
+        { 'T', specifier_tmp_dir,         NULL },
+        { 'V', specifier_var_tmp_dir,     NULL },
         {}
 };