flux-top: fix formatting with ASCII jobids

Problem: When jobids are being encoded with ascii 'f', jobs in
the flux-top(1) joblist pane are not aligned with the header row.
This occurs because mvwprintw(3) doesn't seem to handle multibyte
UTF-8 characters properly. (This appears to be why the JOBID column
is formatted with %12s while the jobs are formatted with %13.13s
currently).

Detect whether ascii 'f' is being used in jobids by testing the result
of strlen(3) for jobid 0 encoded as f58. If the result is 2 then
ascii jobids are being used, so use 13 for the JOBID column width,
otherwise the multibyte 'ƒ' is most likely being used so use 12 for
the JOBID width.

Author: grondo

src/cmd/top/joblist_pane.c

@@ -27,6 +27,7 @@ static const struct dimension win_dim = { 0, 6, 80, 60 };
 
 struct joblist_pane {
     struct top *top;
+    int jobid_width;
     WINDOW *win;
     json_t *jobs_all;
     json_t *jobs;
@@ -85,15 +86,17 @@ void joblist_pane_draw (struct joblist_pane *joblist)
         mvwprintw (joblist->win,
                    0,
                    0,
-                   "%12s %8s %8s %2s %6s %6s %7s %-*s",
+                   "%*s %8s %8s %2s %6s %6s %7s %-*s",
+                   joblist->jobid_width,
                    "JOBID", "QUEUE", "USER", "ST",
                    "NTASKS", "NNODES", "RUNTIME",
                    name_width, "NAME");
     else
         mvwprintw (joblist->win,
                    0,
                    0,
-                   "%12s %8s %2s %6s %6s %7s %-*s",
+                   "%*s %8s %2s %6s %6s %7s %-*s",
+                   joblist->jobid_width,
                    "JOBID","USER", "ST", "NTASKS", "NNODES", "RUNTIME",
                    name_width, "NAME");
 
@@ -413,6 +416,24 @@ void joblist_pane_set_current (struct joblist_pane *joblist, bool next)
     }
 }
 
+/*
+ *  Workaround for mvwprintw(3) issues with multibyte jobid 'ƒ' character.
+ *
+ *  Empirically, the JOBID column must be formatted as %12s when the 'ƒ'
+ *  character appears in f58 encoded jobids, but %13s when ascii 'f' is used.
+ *  Guess at the current jobid encoding by determining if the f58 encoding
+ *  of jobid 0 has a length of 2 (ascii) or 3 (utf-8).
+ *
+ */
+static int estimate_jobid_width (void)
+{
+    const char *id = idf58 (0);
+    if (strlen (id) == 2)
+        return 13;
+    else
+        return 12;
+}
+
 struct joblist_pane *joblist_pane_create (struct top *top)
 {
     struct joblist_pane *joblist;
@@ -422,6 +443,7 @@ struct joblist_pane *joblist_pane_create (struct top *top)
     if (!(joblist->ucache = ucache_create ()))
         fatal (errno, "could not create ucache");
     joblist->top = top;
+    joblist->jobid_width = estimate_jobid_width ();
     joblist->current = FLUX_JOBID_ANY;
     joblist->show_queue = queues_configured (top->queues);
     if (!(joblist->win = newwin (win_dim.y_length,