From: Sven Eden <yamakuzure@gmx.net>
Date: Tue, 9 Jan 2018 08:13:45 +0000 (+0100)
Subject: Prep 235: Although systemd slices are unsupported, make cg_path_get_slice() available... 
X-Git-Tag: v235.1~8
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=commitdiff_plain;h=540f9616974c11cc76eb0c9cc0d81c80f356f54c;p=elogind.git

Prep 235: Although systemd slices are unsupported, make cg_path_get_slice() available, but in 'elogind jargon'
---

diff --git a/src/basic/cgroup-util.c b/src/basic/cgroup-util.c
index c4aec37ff..7e7d4c8f1 100644
--- a/src/basic/cgroup-util.c
+++ b/src/basic/cgroup-util.c
@@ -1812,9 +1812,12 @@ int cg_pid_get_session(pid_t pid, char **session) {
 }
 
 int cg_path_get_owner_uid(const char *path, uid_t *uid) {
-#if 0 /// elogind does not support systemd slices
+#if 0 /// elogind needs one more value
         _cleanup_free_ char *slice = NULL;
         char *start, *end;
+#else
+        _cleanup_free_ char *slice = NULL, *p = NULL, *s = NULL;
+#endif // 0
         int r;
 
         assert(path);
@@ -1823,6 +1826,7 @@ int cg_path_get_owner_uid(const char *path, uid_t *uid) {
         if (r < 0)
                 return r;
 
+#if 0 /// elogind does not support systemd slices
         start = startswith(slice, "user-");
         if (!start)
                 return -ENXIO;
@@ -1831,27 +1835,11 @@ int cg_path_get_owner_uid(const char *path, uid_t *uid) {
                 return -ENXIO;
 
         *end = 0;
+
         if (parse_uid(start, uid) < 0)
                 return -ENXIO;
-
-        return 0;
 #else
-        _cleanup_free_ char *p = NULL, *s = NULL;
-        char *start;
-        int r;
-
-        assert(path);
-
-        /* Basically this is a simple session->uid mapping here.
-           The path argument will be something like "/<session id>"
-           and that is something we can map.
-        */
-
-        start = startswith(path, "/");
-        if (start)
-                p = strappend("/run/systemd/sessions/", start);
-        else
-                p = strappend("/run/systemd/sessions/", path);
+        p = strappend("/run/systemd/sessions/", slice);
 
         r = parse_env_file(p, NEWLINE, "UID", &s, NULL);
         if (r == -ENOENT)
@@ -1861,8 +1849,11 @@ int cg_path_get_owner_uid(const char *path, uid_t *uid) {
         if (isempty(s))
                 return -EIO;
 
-        return parse_uid(s, uid);
+        if (parse_uid(s, uid) < 0)
+                return -ENXIO;
 #endif // 0
+
+        return 0;
 }
 
 int cg_pid_get_owner_uid(pid_t pid, uid_t *uid) {
@@ -1876,13 +1867,13 @@ int cg_pid_get_owner_uid(pid_t pid, uid_t *uid) {
         return cg_path_get_owner_uid(cgroup, uid);
 }
 
-#if 0 /// UNNEEDED by elogind
 int cg_path_get_slice(const char *p, char **slice) {
         const char *e = NULL;
 
         assert(p);
         assert(slice);
 
+#if 0 /// elogind does not support systemd slices
         /* Finds the right-most slice unit from the beginning, but
          * stops before we come to the first non-slice unit. */
 
@@ -1911,8 +1902,26 @@ int cg_path_get_slice(const char *p, char **slice) {
                 e = p;
                 p += n;
         }
+#else
+        /* In elogind, what is reported here, is the location of
+         * the session. This is derived from /proc/<self|PID>/cgroup.
+         * In there we look at the controller, which will look something
+         * like "1:name=openrc:/3".
+         * The last part gets extracted (and is now p), which is "/3" in
+         * this case. The three is the session id, and that can be mapped.
+         */
+        e = startswith(p, "/");
+
+        if (e)
+                *slice = strdup(e);
+        else
+                *slice = strdup(p);
+
+        return 0;
+#endif // 0
 }
 
+#if 0 /// UNNEEDED by elogind
 int cg_pid_get_slice(pid_t pid, char **slice) {
         _cleanup_free_ char *cgroup = NULL;
         int r;
diff --git a/src/basic/cgroup-util.h b/src/basic/cgroup-util.h
index e8423dd0d..7b95370d3 100644
--- a/src/basic/cgroup-util.h
+++ b/src/basic/cgroup-util.h
@@ -211,7 +211,9 @@ int cg_path_get_owner_uid(const char *path, uid_t *uid);
 int cg_path_get_unit(const char *path, char **unit);
 int cg_path_get_user_unit(const char *path, char **unit);
 int cg_path_get_machine_name(const char *path, char **machine);
+#endif // 0
 int cg_path_get_slice(const char *path, char **slice);
+#if 0 /// UNNEEDED by elogind
 int cg_path_get_user_slice(const char *path, char **slice);
 #endif // 0
 
diff --git a/src/libelogind/sd-bus/bus-creds.c b/src/libelogind/sd-bus/bus-creds.c
index 57e7b0c57..28bbdf0da 100644
--- a/src/libelogind/sd-bus/bus-creds.c
+++ b/src/libelogind/sd-bus/bus-creds.c
@@ -543,15 +543,12 @@ _public_ int sd_bus_creds_get_owner_uid(sd_bus_creds *c, uid_t *uid) {
         assert(c->cgroup);
 
         r = cg_shift_path(c->cgroup, c->cgroup_root, &shifted);
+        log_debug_elogind("Shifted to %s from %s/%s for c->uid %u (result %d)",
+                          shifted, c->cgroup_root, c->cgroup, c->uid, r);
         if (r < 0)
                 return r;
 
-#if 0 /// elogind does not support systemd slices
         return cg_path_get_owner_uid(shifted, uid);
-#else
-        *uid = c->uid;
-        return 0;
-#endif // 0
 }
 
 _public_ int sd_bus_creds_get_cmdline(sd_bus_creds *c, char ***cmdline) {