Update

src/examples/ls.c

+#include <syscall.h>
+#include <stdio.h>
+#include <string.h>
+
+static bool
+list_dir (const char *dir, bool verbose)
+{
+  int dir_fd = open (dir);
+  if (dir_fd == -1)
+    {
+      printf ("%s: not found\n", dir);
+      return false;
+    }
+
+  if (isdir (dir_fd))
+    {
+      char name[READDIR_MAX_LEN];
+
+      printf ("%s", dir);
+      if (verbose)
+        printf (" (inumber %d)", inumber (dir_fd));
+      printf (":\n");
+
+      while (readdir (dir_fd, name))
+        {
+          printf ("%s", name);
+          if (verbose)
+            {
+              char full_name[128];
+              int entry_fd;
+
+              snprintf (full_name, sizeof full_name, "%s/%s", dir, name);
+              entry_fd = open (full_name);
+
+              printf (": ");
+              if (entry_fd != -1)
+                {
+                  if (isdir (entry_fd))
+                    printf ("directory");
+                  else
+                    printf ("%d-byte file", filesize (entry_fd));
+                  printf (", inumber %d", inumber (entry_fd));
+                }
+              else
+                printf ("open failed");
+              close (entry_fd);
+            }
+          printf ("\n");
+        }
+    }
+  else
+    printf ("%s: not a directory\n", dir);
+  close (dir_fd);
+  return true;
+}
+
+int
+main (int argc, char *argv[])
+{
+  bool success = true;
+  bool verbose = false;
+
+  if (argc > 1 && !strcmp (argv[1], "-l"))
+    {
+      verbose = true;
+      argv++;
+      argc--;
+    }
+
+  if (argc <= 1)
+    success = list_dir (".", verbose);
+  else
+    {
+      int i;
+      for (i = 1; i < argc; i++)
+        if (!list_dir (argv[i], verbose))
+          success = false;
+    }
+  return success ? EXIT_SUCCESS : EXIT_FAILURE;
+}