ps: possibility to display login session for a process

Library systemd-login offers possibility to display name
of login session for specific pid.
Note that not all processes are part of a login session
(e.g. system service processes, user processes that are shared
between multiple sessions of the same user, or kernel threads).

This patch adds output option "sd_session" which will
show name of session or "-", when process does not belong
to any session.

To maintain compatibility with non-systemd systems,
procps must be configured with --with-systemd option
to enable this option.

diff --git a/ps/output.c b/ps/output.c
index 39b77637f68389d8931fa3d442803cf6fbab7f76..f1cf6bc03226e95d73a59b39c42fbbd822fa94ac 100644 (file)
--- a/ps/output.c
+++ b/ps/output.c
@@ -1191,6 +1191,25 @@ fail:
   outbuf[1] = '\0';
   return 1;
 }
+
+static int pr_sd_session(char *restrict const outbuf, const proc_t *restrict const pp){
+  int r;
+  size_t len;
+  char *session;
+
+  r = sd_pid_get_session(pp->tgid, &session);
+  if(r<0) goto fail;
+  len = snprintf(outbuf, COLWID, "%s", session);
+  free(session);
+  return len;
+
+fail:
+  outbuf[0] = '-';
+  outbuf[1] = '\0';
+  return 1;
+}
+
+
 #endif
 /****************** FLASK & seLinux security stuff **********************/
 // move the bulk of this to libproc sometime
@@ -1519,6 +1538,7 @@ static const format_struct format_array[] = {
 {"scnt",      "SCNT",    pr_nop,      sr_nop,     4,   0,    DEC, AN|RIGHT},  /* man page misspelling of scount? */
 {"scount",    "SC",      pr_nop,      sr_nop,     4,   0,    AIX, AN|RIGHT},  /* scnt==scount, DEC claims both */
 #ifdef WITH_SYSTEMD
+{"sd_session","SESSION", pr_sd_session, sr_nop,  11,   0,    LNX, ET|LEFT},
 {"sd_unit",   "UNIT",    pr_sd_unit,  sr_nop,    31,   0,    LNX, ET|LEFT},
 #endif
 {"sess",      "SESS",    pr_sess,     sr_session, 5,   0,    XXX, PO|PIDMAX|RIGHT},

diff --git a/ps/ps.1 b/ps/ps.1
index 0d66cf95cd482c1fe6774f8cb31027c7482a8cf9..f953e23ad1ee6da34272e351cbcf4fef3186e770 100644 (file)
--- a/ps/ps.1
+++ b/ps/ps.1
@@ -1489,6 +1489,10 @@ SCHED_FIFO, SCHED_RR, SCHED_BATCH, SCHED_ISO, and SCHED_IDLE are respectively
 displayed as 0, 1, 2, 3, 4, and 5.
 T}
 
+sd_session     SESSION T{
+displays login session identifier of a process.
+T}
+
 sd_unit        UNIT    T{
 displays systemd unit which a process belongs to.
 T}