ss: netlink_show_one() clean-up, minor output fix

Patches 1/3 and 2/3 streamline process context prints in netlink_show_one(). Patch 3/3 fixes a display issue happening when Netid or State columns are not displayed.

In general, the output layout of 'ss', also in the cases handled here, still has a number of issues. I will address further issues more structurally in a later patchset.

Stefano Brivio (3):
ss: Remove useless width specifier in process context print
ss: Streamline process context printing in netlink_show_one()
ss: Fix width calculations when Netid or State columns are missing

v2: Coding style fixes in 3/3

 misc/ss.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

2.9.4

Both local address and service, and remote address and service fields are already printed out in netlink_show_one() before we start printing process context, by calling sock_addr_print() twice.

At this point, sock_addr_print() has already forced the remote service field to be 'serv_width' wide -- that is, 'serv_width' width has already been consumed, before we print process context.

Hence, it makes no sense to force the display width of process context to be 'serv_width' wide again: previous prints have filled up the line already. Remove the width specifier and prefix with a space instead, to keep this consistent with fields which are displayed after the first output line.

---
 misc/ss.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

index dfb438f9162c..fa026eb0934b 100644
@@ -3594,10 +3594,10 @@ static int netlink_show_one(struct filter *f,
 			getpidcon(pid, &pid_context);
 
 		if (pid_context != NULL) {
-			printf("proc_ctx=%-*s ", serv_width, pid_context);
+			printf(" proc_ctx=%s", pid_context);
 			free(pid_context);
 		} else {
-			printf("proc_ctx=%-*s ", serv_width, "unavailable");
+			printf(" proc_ctx=unavailable");
 		}
 	}
 

2.9.4

There's no need to check 'pid_context' before calling free().

---
 misc/ss.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

index fa026eb0934b..fb80d84122fc 100644
@@ -3593,12 +3593,8 @@ static int netlink_show_one(struct filter *f,
 		else if (pid > 0)
 			getpidcon(pid, &pid_context);
 
-		if (pid_context != NULL) {
-			printf(" proc_ctx=%s", pid_context);
-			free(pid_context);
-		} else {
-			printf(" proc_ctx=unavailable");
-		}
+		printf(" proc_ctx=%s", pid_context ? : "unavailable");
+		free(pid_context);
 	}
 
 	if (show_details) {

2.9.4

If Netid or State columns are missing, we must not subtract one for each of these two columns from the remaining screen width, while distributing available space to columns. This one character corresponding to one delimiting space has to be subtracted only if the columns are actually printed.

Further, in the existing implementation, if the screen width is an odd number, one additional character is added to the width of one of the two columns.

But if both are not printed, this filling character needs to be added somewhere else, in order to have the right spacing allowing us to fill lines completely.

Address and port fields are printed in pairs (local and remote), so we can't distribute the space to any of them, because it would be doubled. Instead, print this additional space to the right of the Send-Q column, to keep code changes to a minimum.

This is particularly visible with 'ss -f netlink -Z'. Before this patch, with an 80 column terminal, we have:

$ ss -f netlink -Z|head -n3
Recv-Q Send-Q Local Address:Port                 Peer Address:Port
0      0            rtnl:evolution-calen/2049           *                     pr
oc_ctx=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
0      0            rtnl:clock-applet/1944              *                     pr
oc_ctx=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023

and with an 81 column terminal:

$ ss -f netlink -Z|head -n3
Recv-Q Send-Q Local Address:Port                 Peer Address:Port
0      0            rtnl:evolution-calen/2049           *                     pro
c_ctx=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
0      0            rtnl:clock-applet/1944              *                     pro
c_ctx=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023

After this patch, in both cases, the output is:

$ ss -f netlink -Z|head -n3
Recv-Q Send-Q Local Address:Port                 Peer Address:Port
0      0             rtnl:evolution-calen/2049            *
 proc_ctx=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
0      0             rtnl:clock-applet/1944               *
 proc_ctx=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023

---
v2: Add whitespace around '=' in odd_width_pad assignments, replace
conditional terms in addrp_width adjustment by explicit if clauses

 misc/ss.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

index fb80d84122fc..56a9ad415ce1 100644
@@ -107,6 +107,7 @@ int netid_width;
 int state_width;
 int addr_width;
 int serv_width;
+char *odd_width_pad = "";
 
 static const char *TCP_PROTO = "tcp";
 static const char *SCTP_PROTO = "sctp";

@@ -838,7 +839,7 @@ static void sock_state_print(struct sockstat *s)
 			printf("%-*s ", state_width, sstate_name[s->state]);
 	}
 
-	printf("%-6d %-6d ", s->rq, s->wq);
+	printf("%-6d %-6d %s", s->rq, s->wq, odd_width_pad);
 }
 
 static void sock_details_print(struct sockstat *s)

@@ -4364,8 +4365,10 @@ int main(int argc, char *argv[])
 	}
 
 	addrp_width = screen_width;
-	addrp_width -= netid_width+1;
-	addrp_width -= state_width+1;
+	if (netid_width)
+		addrp_width -= netid_width + 1;
+	if (state_width)
+		addrp_width -= state_width + 1;
 	addrp_width -= 14;
 
 	if (addrp_width&1) {

@@ -4373,6 +4376,8 @@ int main(int argc, char *argv[])
 			netid_width++;
 		else if (state_width)
 			state_width++;
+		else
+			odd_width_pad = " ";
 	}
 
 	addrp_width /= 2;

@@ -4390,7 +4395,7 @@ int main(int argc, char *argv[])
 			printf("%-*s ", netid_width, "Netid");
 		if (state_width)
 			printf("%-*s ", state_width, "State");
-		printf("%-6s %-6s ", "Recv-Q", "Send-Q");
+		printf("%-6s %-6s %s", "Recv-Q", "Send-Q", odd_width_pad);
 	}
 
 	/* Make enough space for the local/remote port field */

2.9.4