flux-job: add shorthand paths to eventlog, wait-event

Problem: The eventlog and wait-event subcommands of flux-job(1) take
a `-p, --path=PATH` option to specify alternate eventlogs on which
to operate, but these options require the full KVS path in the job
namespace which can be annoyingly lengthy, e.g. guest.exec.eventlog.
Since these eventlogs are standard and may be commonly used with the
command, it is not user-friendly to require full paths in this case.

Support short names for well-known standard eventlog paths such as
'exec' for 'guest.exec.eventlog', 'output' for 'guest.output' and
'input' for 'guest.input'.

Author: grondo

src/cmd/job/eventlog.c

@@ -41,8 +41,8 @@ struct optparse_option eventlog_opts[] =  {
                "(default if omitted), 'never', or 'auto' (default)."
     },
     { .name = "path", .key = 'p', .has_arg = 1, .arginfo = "PATH",
-      .usage = "Specify alternate eventlog path suffix "
-               "(e.g. \"guest.exec.eventlog\")",
+      .usage = "Specify alternate eventlog name or path suffix "
+               "(e.g. \"exec\", \"output\", or \"guest.exec.eventlog\")",
     },
     OPTPARSE_TABLE_END
 };
@@ -78,8 +78,8 @@ struct optparse_option wait_event_opts[] =  {
                "(default if omitted), 'never', or 'auto' (default)."
     },
     { .name = "path", .key = 'p', .has_arg = 1, .arginfo = "PATH",
-      .usage = "Specify alternate eventlog path suffix "
-               "(e.g. \"guest.exec.eventlog\")",
+      .usage = "Specify alternate eventlog name or path suffix "
+               "(e.g. \"exec\", \"output\", or \"guest.exec.eventlog\")",
     },
     { .name = "waitcreate", .key = 'W', .has_arg = 0,
       .usage = "If path does not exist, wait for its creation",
@@ -96,6 +96,31 @@ struct eventlog_ctx {
     struct eventlog_formatter *evf;
 };
 
+struct path_shortname {
+    const char *name;
+    const char *path;
+};
+
+/*  Set of shorthand names for common job eventlog paths:
+ */
+struct path_shortname eventlog_paths[] = {
+    { "exec",   "guest.exec.eventlog" },
+    { "output", "guest.output"        },
+    { "input",  "guest.input"         },
+    { NULL,     NULL                  },
+};
+
+const char *path_lookup (const char *name)
+{
+    const struct path_shortname *path = eventlog_paths;
+    while (path->name) {
+        if (streq (name, path->name))
+            return path->path;
+        path++;
+    }
+    return name;
+}
+
 static void formatter_parse_options (optparse_t *p,
                                      struct eventlog_formatter *evf)
 {
@@ -169,7 +194,7 @@ int cmd_eventlog (optparse_t *p, int argc, char **argv)
 
     ctx.jobid = argv[optindex++];
     ctx.id = parse_jobid (ctx.jobid);
-    ctx.path = optparse_get_str (p, "path", "eventlog");
+    ctx.path = path_lookup (optparse_get_str (p, "path", "eventlog"));
     ctx.p = p;
 
     if (!(ctx.evf = eventlog_formatter_create ()))
@@ -341,7 +366,7 @@ int cmd_wait_event (optparse_t *p, int argc, char **argv)
     ctx.id = parse_jobid (ctx.jobid);
     ctx.p = p;
     ctx.wait_event = argv[optindex++];
-    ctx.path = optparse_get_str (p, "path", "eventlog");
+    ctx.path = path_lookup (optparse_get_str (p, "path", "eventlog"));
     timeout = optparse_get_duration (p, "timeout", -1.0);
     if (optparse_hasopt (p, "waitcreate"))
         flags |= FLUX_JOB_EVENT_WATCH_WAITCREATE;