Provide more helpful error message in getopt

If provide with an ambiguous long option we now show all the possibilities.

1 files changed, 62 insertions, 0 deletions

diff --git a/posix/tst-getopt_long1.c b/posix/tst-getopt_long1.c
new file mode 100644
index 0000000000..e0ecd12190
--- /dev/null
+++ b/posix/tst-getopt_long1.c
@@ -0,0 +1,62 @@
+static void do_prepare (void);
+#define PREPARE(argc, argv) do_prepare ()
+static int do_test (void);
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
+
+
+static char *fname;
+
+
+static void
+do_prepare (void)
+{
+  if (create_temp_file ("tst-getopt_long1", &fname) < 0)
+    {
+      printf ("cannot create temp file: %m\n");
+      exit (1);
+    }
+}
+
+
+static const struct option opts[] =
+  {
+    { "one", no_argument, NULL, '1' },
+    { "two", no_argument, NULL, '2' },
+    { "one-one", no_argument, NULL, '3' },
+    { "four", no_argument, NULL, '4' },
+    { "onto", no_argument, NULL, '5' },
+    { NULL, 0, NULL, 0 }
+  };
+
+
+static int
+do_test (void)
+{
+  if (freopen (fname, "w+", stderr) == NULL)
+    {
+      printf ("freopen failed: %m\n");
+      return 1;
+    }
+
+  char *argv[] = { "program", "--on" };
+  int argc = 2;
+
+  int c = getopt_long (argc, argv, "12345", opts, NULL);
+  printf ("return value: %c\n", c);
+
+  rewind (stderr);
+  char *line = NULL;
+  size_t len = 0;
+  if (getline (&line, &len, stderr) < 0)
+    {
+      printf ("cannot read stderr redirect: %m\n");
+      return 1;
+    }
+  printf ("message = \"%s\"\n", line);
+
+  static const char expected[] = "\
+program: option '--on' is ambiguous; possibilities: '--one' '--onto' '--one-one'\n";
+
+  return c != '?' || strcmp (line, expected) != 0;
+}