/* Test cancellation of getpwuid_r.

   Copyright (C) 2016-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

/* Test if cancellation of getpwuid_r incorrectly leaves internal

   function state locked resulting in hang of subsequent calls to

   getpwuid_r.  The main thread creates a second thread which will do

   the calls to getpwuid_r.  A semaphore is used by the second thread to

   signal to the main thread that it is as close as it can be to the

   call site of getpwuid_r.  The goal of the semaphore is to avoid any

   cancellable function calls between the sem_post and the call to

   getpwuid_r.  The main thread then attempts to cancel the second

   thread.  Without the fixes the cancellation happens at any number of

   calls to cancellable functions in getpuid_r, but with the fix the

   cancellation either does not happen or happens only at expected

   points where the internal state is consistent.  We use an explicit

   pthread_testcancel call to terminate the loop in a timely fashion

   if the implementation does not have a cancellation point.  */

#include <stdio.h>

#include <stdlib.h>

#include <pthread.h>

#include <pwd.h>

#include <nss.h>

#include <sys/types.h>

#include <unistd.h>

#include <semaphore.h>

#include <errno.h>

#include <support/support.h>

sem_t started;

char *wbuf;

long wbufsz;

void

worker_free (void *arg)

{

  free (arg);

}

static void *

worker (void *arg)

{

  int ret;

  unsigned int iter = 0;

  struct passwd pwbuf, *pw;

  uid_t uid;

  uid = geteuid ();

  /* Use a reasonable sized buffer.  Note that _SC_GETPW_R_SIZE_MAX is

     just a hint and not any kind of maximum value.  */

  wbufsz = sysconf (_SC_GETPW_R_SIZE_MAX);

  if (wbufsz == -1)

    wbufsz = 1024;

  wbuf = xmalloc (wbufsz);

  pthread_cleanup_push (worker_free, wbuf);

  sem_post (&started);

  while (1)

    {

      iter++;

      ret = getpwuid_r (uid, &pwbuf, wbuf, wbufsz, &pw;;

      /* The call to getpwuid_r may not cancel so we need to test

	 for cancellation after some number of iterations of the

	 function.  Choose an arbitrary 100,000 iterations of running

	 getpwuid_r in a tight cancellation loop before testing for

	 cancellation.  */

      if (iter > 100000)

	pthread_testcancel ();

      if (ret == ERANGE)

	{

	  /* Increase the buffer size.  */

	  free (wbuf);

	  wbufsz = wbufsz * 2;

	  wbuf = xmalloc (wbufsz);

	}

    }

  pthread_cleanup_pop (1);

  return NULL;

}

static int

do_test (void)

{

  int ret;

  char *buf;

  long bufsz;

  void *retval;

  struct passwd pwbuf, *pw;

  pthread_t thread;

  /* Configure the test to only use files. We control the files plugin

     as part of glibc so we assert that it should be deferred

     cancellation safe.  */

  __nss_configure_lookup ("passwd", "files");

  /* Use a reasonable sized buffer.  Note that  _SC_GETPW_R_SIZE_MAX is

     just a hint and not any kind of maximum value.  */

  bufsz = sysconf (_SC_GETPW_R_SIZE_MAX);

  if (bufsz == -1)

    bufsz = 1024;

  buf = xmalloc (bufsz);

  sem_init (&started, 0, 0);

  pthread_create (&thread, NULL, worker, NULL);

  do

  {

    ret = sem_wait (&started);

    if (ret == -1 && errno != EINTR)

      {

        printf ("FAIL: Failed to wait for second thread to start.\n");

	exit (EXIT_FAILURE);

      }

  }

  while (ret != 0);

  printf ("INFO: Cancelling thread\n");

  if ((ret = pthread_cancel (thread)) != 0)

    {

      printf ("FAIL: Failed to cancel thread. Returned %d\n", ret);

      exit (EXIT_FAILURE);

    }

  printf ("INFO: Joining...\n");

  pthread_join (thread, &retval);

  if (retval != PTHREAD_CANCELED)

    {

      printf ("FAIL: Thread was not cancelled.\n");

      exit (EXIT_FAILURE);

    }

  printf ("INFO: Joined, trying getpwuid_r call\n");

  /* Before the fix in 312be3f9f5eab1643d7dcc7728c76d413d4f2640 for this

     issue the cancellation point could happen in any number of internal

     calls, and therefore locks would be left held and the following

     call to getpwuid_r would block and the test would time out.  */

  do

    {

      ret = getpwuid_r (geteuid (), &pwbuf, buf, bufsz, &pw;;

      if (ret == ERANGE)

	{

	  /* Increase the buffer size.  */

	  free (buf);

	  bufsz = bufsz * 2;

	  buf = xmalloc (bufsz);

	}

    }

  while (ret == ERANGE);

  free (buf);

  /* Before the fix we would never get here.  */

  printf ("PASS: Canceled getpwuid_r successfully"

	  " and called it again without blocking.\n");

  return 0;

}

#define TIMEOUT 900

#include <support/test-driver.c>