Daemon: Make user/group switching available separately

diff --git a/ucw/daemon.c b/ucw/daemon.c
index 268bda461bcae397b2ee07a091253c694dcf48fc..486d08445c856089f88233fbd9c3c834f6eed3d1 100644 (file)
--- a/ucw/daemon.c
+++ b/ucw/daemon.c
@@ -1,7 +1,7 @@
 /*
  *     UCW Library -- Daemonization
  *
- *     (c) 2012 Martin Mares <mj@ucw.cz>
+ *     (c) 2012--2014 Martin Mares <mj@ucw.cz>
  *
  *     This software may be freely distributed and used according to the terms
  *     of the GNU Lesser General Public License.
@@ -22,7 +22,7 @@
 #include <sys/stat.h>
 #include <sys/file.h>
 
-static void
+void
 daemon_resolve_ugid(struct daemon_params *dp)
 {
   // Resolve user name
@@ -79,6 +79,16 @@ daemon_resolve_ugid(struct daemon_params *dp)
     }
 }
 
+void daemon_switch_ugid(struct daemon_params *dp)
+{
+  if (dp->want_setgid && setresgid(dp->run_as_gid, dp->run_as_gid, dp->run_as_gid) < 0)
+    die("Cannot set GID to %d: %m", (int) dp->run_as_gid);
+  if (dp->want_setgid > 1 && initgroups(dp->run_as_user, dp->run_as_gid) < 0)
+    die("Cannot initialize groups: %m");
+  if (dp->want_setuid && setresuid(dp->run_as_uid, dp->run_as_uid, dp->run_as_uid) < 0)
+    die("Cannot set UID to %d: %m", (int) dp->run_as_uid);
+}
+
 void
 daemon_init(struct daemon_params *dp)
 {
@@ -127,12 +137,7 @@ daemon_run(struct daemon_params *dp, void (*body)(struct daemon_params *dp))
     }
 
   // Switch GID and UID
-  if (dp->want_setgid && setresgid(dp->run_as_gid, dp->run_as_gid, dp->run_as_gid) < 0)
-    die("Cannot set GID to %d: %m", (int) dp->run_as_gid);
-  if (dp->want_setgid > 1 && initgroups(dp->run_as_user, dp->run_as_gid) < 0)
-    die("Cannot initialize groups: %m");
-  if (dp->want_setuid && setresuid(dp->run_as_uid, dp->run_as_uid, dp->run_as_uid) < 0)
-    die("Cannot set UID to %d: %m", (int) dp->run_as_uid);
+  daemon_switch_ugid(dp);
 
   // Create a new session and close stdio
   setsid();

diff --git a/ucw/daemon.h b/ucw/daemon.h
index d7b1a22a61060f9eb48f6b43d2d0b89dd501af0b..51fe0cbdf6485438397818771b31d18dfc00c09a 100644 (file)
--- a/ucw/daemon.h
+++ b/ucw/daemon.h
@@ -1,7 +1,7 @@
 /*
  *     UCW Library -- Daemonization
  *
- *     (c) 2012 Martin Mares <mj@ucw.cz>
+ *     (c) 2012--2014 Martin Mares <mj@ucw.cz>
  *
  *     This software may be freely distributed and used according to the terms
  *     of the GNU Lesser General Public License.
@@ -63,6 +63,21 @@ void daemon_run(struct daemon_params *dp, void (*body)(struct daemon_params *dp)
  **/
 void daemon_exit(struct daemon_params *dp);
 
+/**
+ * Parse `run_as_user` and `run_as_group` and remember the results in internal fields.
+ * This is called automatically by daemon_init(), but also provided as a separate
+ * function in case you want to use daemon_switch_ugid(). Upon parse error, it calls die().
+ **/
+void daemon_resolve_ugid(struct daemon_params *dp);
+
+/**
+ * Switch user and group as specified by the `run_as_user` and `run_as_group`.
+ * This is performed automatically by daemon_run(), but sometimes you might want to
+ * switch the user and group separately. In this case, you have to call daemon_resolve_ugid()
+ * beforehand.
+ **/
+void daemon_switch_ugid(struct daemon_params *dp);
+
 #define DAEMON_ERR_LEN 256
 
 /** Parameters passed to @daemon_control() **/