cmd/flux-kvs: add ls subcommand

Add new subcommand:
   flux kvs ls [-R] [-d] [-w COLS] [-1] [key]

This is supposed to be similar to ls(1) as discussed
in flux-framework#1158.

src/cmd/flux-kvs.c

@@ -25,6 +25,7 @@
 #if HAVE_CONFIG_H
 #include "config.h"
 #endif
+#include <sys/ioctl.h>
 #include <flux/core.h>
 #include <flux/optparse.h>
 #include <unistd.h>
@@ -48,6 +49,7 @@ int cmd_dropcache (optparse_t *p, int argc, char **argv);
 int cmd_copy (optparse_t *p, int argc, char **argv);
 int cmd_move (optparse_t *p, int argc, char **argv);
 int cmd_dir (optparse_t *p, int argc, char **argv);
+int cmd_ls (optparse_t *p, int argc, char **argv);
 
 static void dump_kvs_dir (kvsdir_t *dir, bool Ropt, bool dopt);
 
@@ -61,6 +63,25 @@ static struct optparse_option dir_opts[] =  {
     OPTPARSE_TABLE_END
 };
 
+static struct optparse_option ls_opts[] =  {
+    { .name = "recursive", .key = 'R', .has_arg = 0,
+      .usage = "List directory recursively",
+    },
+    { .name = "directory", .key = 'd', .has_arg = 0,
+      .usage = "List directory instead of contents",
+    },
+    { .name = "width", .key = 'w', .has_arg = 1,
+      .usage = "Set output width to COLS.  0 width means no limit",
+    },
+    { .name = "1", .key = '1', .has_arg = 0,
+      .usage = "Force one entry per line",
+    },
+    { .name = "classify", .key = 'F', .has_arg = 0,
+      .usage = "Append indicator (one of .@) to entries",
+    },
+    OPTPARSE_TABLE_END
+};
+
 static struct optparse_option watch_opts[] =  {
     { .name = "recursive", .key = 'R', .has_arg = 0,
       .usage = "Recursively display keys under subdirectories",
@@ -116,6 +137,13 @@ static struct optparse_subcommand subcommands[] = {
       0,
       dir_opts
     },
+    { "ls",
+      "[-R] [-d] [-w COLS] [-1] [-W] [key]",
+      "List directory",
+      cmd_ls,
+      0,
+      ls_opts
+    },
     { "unlink",
       "key [key...]",
       "Remove key",
@@ -816,6 +844,140 @@ int cmd_dir (optparse_t *p, int argc, char **argv)
     return (0);
 }
 
+static int get_dir_maxname (kvsdir_t *dir)
+{
+    kvsitr_t *itr;
+    const char *name;
+    int max = 0;
+
+    if (!(itr = kvsitr_create (dir)))
+        log_err_exit ("kvsitr_create");
+    while ((name = kvsitr_next (itr)))
+        if (max < strlen (name))
+            max = strlen (name);
+    kvsitr_destroy (itr);
+    return max;
+}
+
+static int get_win_cols (void)
+{
+    struct winsize w;
+
+    if (ioctl (STDIN_FILENO, TIOCGWINSZ, &w) < 0)
+        log_err_exit ("ioctl TIOCGSIZE");
+    return w.ws_col;
+}
+
+static const char *get_decorator (kvsdir_t *dir, const char *name)
+{
+    if (kvsdir_isdir (dir, name))
+        return ".";
+    else if (kvsdir_issymlink (dir, name))
+        return "@";
+    else
+        return "";
+}
+
+static void list_kvs_dir_single (kvsdir_t *dir, int wincols, optparse_t *p)
+{
+    kvsitr_t *itr;
+    const char *name;
+    int tabstop = get_dir_maxname (dir) + 4;
+    int col = 0;
+    char *namebuf;
+
+    if (!(namebuf = malloc (tabstop + 2)))
+        log_err_exit ("malloc");
+    if (!(itr = kvsitr_create (dir)))
+        log_err_exit ("kvsitr_create");
+    while ((name = kvsitr_next (itr))) {
+        if (wincols != 0 && col + tabstop > wincols && col > 0) {
+            printf ("\n");
+            col = 0;
+        }
+        strcpy (namebuf, name);
+        if (optparse_hasopt (p, "classify"))
+            strcat (namebuf, get_decorator (dir, name));
+        printf ("%-*s", tabstop, namebuf);
+        col += tabstop;
+    }
+    printf ("\n");
+    kvsitr_destroy (itr);
+    free (namebuf);
+}
+
+static void list_kvs_dir (flux_t *h, const char *key, optparse_t *p,
+                          int wincols, int level)
+{
+    flux_future_t *f;
+    kvsdir_t *dir;
+    kvsitr_t *itr;
+    const char *name, *json_str;
+
+    if (!(f = flux_kvs_lookup (h, FLUX_KVS_READDIR, key))
+                || flux_kvs_lookup_get (f, &json_str) < 0) {
+        log_err ("%s", key);
+        goto done;
+    }
+    if (optparse_hasopt (p, "directory")) {
+        printf ("%s\n", key);
+        goto done;
+    }
+
+    /* List the directory
+     */
+    if (optparse_hasopt (p, "recursive"))
+        printf ("%s%s:\n", level > 0 ? "\n" : "", key);
+    if (!(dir = kvsdir_create (h, NULL, key, json_str)))
+        log_err_exit ("kvsdir_create");
+    list_kvs_dir_single (dir, wincols, p);
+
+    /* List subdirectories
+     */
+    if (optparse_hasopt (p, "recursive")) {
+        if (!(itr = kvsitr_create (dir)))
+            log_err_exit ("kvsitr_create");
+        while ((name = kvsitr_next (itr))) {
+            if (kvsdir_isdir (dir, name)) {
+                char *nkey;
+                if (!(nkey = kvsdir_key_at (dir, name))) {
+                    log_err ("%s: kvsdir_key_at failed", name);
+                    continue;
+                }
+                list_kvs_dir (h, nkey, p, wincols, level + 1);
+                free (nkey);
+            }
+        }
+        kvsdir_destroy (dir);
+    }
+done:
+    flux_future_destroy (f);
+}
+
+int cmd_ls (optparse_t *p, int argc, char **argv)
+{
+    flux_t *h = (flux_t *)optparse_get_data (p, "flux_handle");
+    int optindex = optparse_option_index (p);
+    const char *key = ".";
+    int wincols;
+
+    /* 'wincols' is the number of columns available in the current window,
+     * with 0 meaning "unlimited".  1 effectively forces single column output.
+     */
+    wincols = optparse_get_int (p, "width", get_win_cols ());
+    if (wincols < 0 || optparse_hasopt (p, "1"))
+        wincols = 1;
+
+    if (optindex < argc)
+        key = argv[optindex++];
+    if (optindex < argc)
+        log_msg_exit ("dir: specify zero or one directory");
+
+    list_kvs_dir (h, key, p, wincols, 0);
+
+    return (0);
+}
+
 int cmd_copy (optparse_t *p, int argc, char **argv)
 {
     flux_t *h = (flux_t *)optparse_get_data (p, "flux_handle");