systemctl: tweak the "systemctl list-units" output a bit

Make the underlining between the header and the body and between the units of
different types span the whole width of the table.

Let's never make the table wider than necessary (which is relevant due the
above).

When space is limited and we can't show the full ID or description string
prefer showing the full ID over the full description. The ID is after all
something people might want to copy/paste, while the description is mostly just
helpful decoration.

1 files changed, 19 insertions, 14 deletions

diff --git a/src/systemctl/systemctl.c b/src/systemctl/systemctl.c
index 558186bd8a..fb5a539bc6 100644
--- a/src/systemctl/systemctl.c
+++ b/src/systemctl/systemctl.c
@@ -410,23 +410,24 @@ static bool output_show_unit(const UnitInfo *u, char **patterns) {
 }
 
 static int output_units_list(const UnitInfo *unit_infos, unsigned c) {
-        unsigned circle_len = 0, id_len, max_id_len, load_len, active_len, sub_len, job_len;
+        unsigned circle_len = 0, id_len, max_id_len, load_len, active_len, sub_len, job_len, desc_len, max_desc_len;
         const UnitInfo *u;
         unsigned n_shown = 0;
-        int job_count = 0, desc_len;
+        int job_count = 0;
 
         max_id_len = strlen("UNIT");
         load_len = strlen("LOAD");
         active_len = strlen("ACTIVE");
         sub_len = strlen("SUB");
         job_len = strlen("JOB");
-        desc_len = 0;
+        max_desc_len = strlen("DESCRIPTION");
 
         for (u = unit_infos; u < unit_infos + c; u++) {
                 max_id_len = MAX(max_id_len, strlen(u->id) + (u->machine ? strlen(u->machine)+1 : 0));
                 load_len = MAX(load_len, strlen(u->load_state));
                 active_len = MAX(active_len, strlen(u->active_state));
                 sub_len = MAX(sub_len, strlen(u->sub_state));
+                max_desc_len = MAX(max_desc_len, strlen(u->description));
 
                 if (u->job_id != 0) {
                         job_len = MAX(job_len, strlen(u->job_type));
@@ -442,7 +443,7 @@ static int output_units_list(const UnitInfo *unit_infos, unsigned c) {
         if (!arg_full && original_stdout_is_tty) {
                 unsigned basic_len;
 
-                id_len = MIN(max_id_len, 25u);
+                id_len = MIN(max_id_len, 25u); /* as much as it needs, but at most 25 for now */
                 basic_len = circle_len + 5 + id_len + 5 + active_len + sub_len;
 
                 if (job_count)
@@ -455,19 +456,21 @@ static int output_units_list(const UnitInfo *unit_infos, unsigned c) {
                         /* Either UNIT already got 25, or is fully satisfied.
                          * Grant up to 25 to DESC now. */
                         incr = MIN(extra_len, 25u);
-                        desc_len += incr;
+                        desc_len = incr;
                         extra_len -= incr;
 
-                        /* split the remaining space between UNIT and DESC,
-                         * but do not give UNIT more than it needs. */
+                        /* Of the remainder give as much as the ID needs to the ID, and give the rest to the
+                         * description but not more than it needs. */
                         if (extra_len > 0) {
-                                incr = MIN(extra_len / 2, max_id_len - id_len);
+                                incr = MIN(max_id_len - id_len, extra_len);
                                 id_len += incr;
-                                desc_len += extra_len - incr;
+                                desc_len += MIN(extra_len - incr, max_desc_len - desc_len);
                         }
                 }
-        } else
+        } else {
                 id_len = max_id_len;
+                desc_len = max_desc_len;
+        }
 
         for (u = unit_infos; u < unit_infos + c; u++) {
                 _cleanup_free_ char *e = NULL, *j = NULL;
@@ -493,8 +496,9 @@ static int output_units_list(const UnitInfo *unit_infos, unsigned c) {
                         if (job_count)
                                 printf("%-*s ", job_len, "JOB");
 
-                        printf("%.*s%s\n",
-                               !arg_full && arg_no_pager ? desc_len : -1,
+                        printf("%-*.*s%s\n",
+                               desc_len,
+                               !arg_full && arg_no_pager ? (int) desc_len : -1,
                                "DESCRIPTION",
                                ansi_normal());
                 }
@@ -550,8 +554,9 @@ static int output_units_list(const UnitInfo *unit_infos, unsigned c) {
                        sub_len, u->sub_state, off_active,
                        job_count ? job_len + 1 : 0, u->job_id ? u->job_type : "");
 
-                printf("%.*s%s\n",
-                       desc_len > 0 ? desc_len : -1,
+                printf("%-*.*s%s\n",
+                       desc_len,
+                       !arg_full && arg_no_pager ? (int) desc_len : -1,
                        u->description,
                        off_underline);
         }