Fix bugs in pushd / popd / dirs.

The stack was printed in the reverse order.  Until the last commit, the
spec tests didn't expose this.

Printing os.getcwd() in 'dirs' isn't correct.  The correct semantics are
that the dir_stack is initialized to the current directory, and it is
reset upon the 'cd' builtin.

popd fails if the stack is of length 1.

Tests all pass now.

core/builtin.py

@@ -443,7 +443,7 @@ def Shift(argv, mem):
  return mem.Shift(n)


def Cd(argv, mem):
def Cd(argv, mem, dir_stack):
  # TODO: Parse flags, error checking, etc.
  try:
    dest_dir = argv[0]
@@ -479,7 +479,13 @@ def Cd(argv, mem):
    # TODO: Add line number, etc.
    util.error("cd %r: %s", dest_dir, os.strerror(e.errno))
    return 1

  # Set $PWD.
  state.SetGlobalString(mem, 'PWD', dest_dir)

  # Truncate the directory stack.
  dir_stack[:] = [dest_dir]

  return 0


@@ -488,19 +494,18 @@ def Cd(argv, mem):
SINGLE_LINE = 3

def _PrintDirStack(dir_stack, mode):
  dirs = [os.getcwd()]
  dirs.extend(dir_stack)
  to_print = list(reversed(dir_stack))

  if mode == WITH_PREFIX:
    for i, entry in enumerate(dirs):
    for i, entry in enumerate(to_print):
      print('%2d  %s' % (i, entry))

  elif mode == WITHOUT_PREFIX:
    for entry in dirs:
    for entry in to_print:
      print(entry)

  elif mode == SINGLE_LINE:
    print(' '.join(dirs))
    print(' '.join(to_print))

  sys.stdout.flush()

@@ -515,25 +520,23 @@ def Pushd(argv, dir_stack):
    return 1

  dest_dir = argv[0]
  current_dir = os.getcwd()
  try:
    os.chdir(dest_dir)
  except OSError as e:
    util.error("pushd: %r: %s", dest_dir, os.strerror(e.errno))
    return 1

  dir_stack.append(current_dir)
  dir_stack.append(dest_dir)
  _PrintDirStack(dir_stack, SINGLE_LINE)
  return 0


def Popd(argv, dir_stack):
  try:
    dest_dir = dir_stack.pop()
  except IndexError:
  if len(dir_stack) <= 1:
    util.error('popd: directory stack is empty')
    return 1

  dest_dir = dir_stack.pop()
  try:
    os.chdir(dest_dir)
  except OSError as e:
@@ -554,9 +557,10 @@ def Dirs(argv, dir_stack):
  arg, i = DIRS_SPEC.Parse(argv)
  if arg.l:
    util.warn('*** dirs -l not implemented ***')
  # Following `bash` behavior for order of operations
  # Following bash behavior
  if arg.c:
    del dir_stack[:]
    # This initialization is also in the executor.
    dir_stack[:] = [os.getcwd()]
  elif arg.v:
    _PrintDirStack(dir_stack, WITH_PREFIX)
  elif arg.p:

core/cmd_exec.py

@@ -124,7 +124,7 @@ def __init__(self, mem, status_lines, funcs, completion, comp_lookup,

    self.traps = {}
    self.fd_state = process.FdState()
    self.dir_stack = []
    self.dir_stack = [os.getcwd()]

    # TODO: Pass these in from main()
    self.aliases = {}  # alias name -> string
@@ -242,7 +242,7 @@ def _RunBuiltin(self, builtin_id, argv):
      status = builtin.Shift(argv, self.mem)

    elif builtin_id == EBuiltin.CD:
      status = builtin.Cd(argv, self.mem)
      status = builtin.Cd(argv, self.mem, self.dir_stack)

    elif builtin_id == EBuiltin.SET:
      status = builtin.Set(argv, self.exec_opts, self.mem)