elf: Cleanup and improve tst-execstack

Reviewed-by: Florian Weimer <fweimer@redhat.com>

elf/tst-execstack.c

@@ -1,24 +1,32 @@
 /* Test program for making nonexecutable stacks executable
-   on load of a DSO that requires executable stacks.  */
+   on load of a DSO that requires executable stacks.
 
-#include <dlfcn.h>
-#include <stdbool.h>
-#include <stdio.h>
-#include <string.h>
-#include <unistd.h>
+   Copyright (C) 2003-2024 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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <array_length.h>
 #include <error.h>
 #include <stackinfo.h>
-
-static void
-print_maps (void)
-{
-#if 0
-  char *cmd = NULL;
-  asprintf (&cmd, "cat /proc/%d/maps", getpid ());
-  system (cmd);
-  free (cmd);
-#endif
-}
+#include <stdbool.h>
+#include <string.h>
+#include <support/xdlfcn.h>
+#include <support/xthread.h>
+#include <support/check.h>
+#include <support/xstdio.h>
 
 static void deeper (void (*f) (void));
 
@@ -38,8 +46,8 @@ static void *
 waiter_thread (void *arg)
 {
   void **f = arg;
-  pthread_barrier_wait (&startup_barrier);
-  pthread_barrier_wait (&go_barrier);
+  xpthread_barrier_wait (&startup_barrier);
+  xpthread_barrier_wait (&go_barrier);
 
   (*((void (*) (void)) *f)) ();
 
@@ -88,47 +96,26 @@ do_test (void)
 #if USE_PTHREADS
   /* Create some threads while stacks are nonexecutable.  */
   #define N 5
-  pthread_t thr[N];
 
-  pthread_barrier_init (&startup_barrier, NULL, N + 1);
-  pthread_barrier_init (&go_barrier, NULL, N + 1);
+  xpthread_barrier_init (&startup_barrier, NULL, N + 1);
+  xpthread_barrier_init (&go_barrier, NULL, N + 1);
 
   for (int i = 0; i < N; ++i)
-    {
-      int rc = pthread_create (&thr[i], NULL, &waiter_thread, &f);
-      if (rc)
-	error (1, rc, "pthread_create");
-    }
+    xpthread_create (NULL, &waiter_thread, &f);
 
   /* Make sure they are all there using their stacks.  */
-  pthread_barrier_wait (&startup_barrier);
+  xpthread_barrier_wait (&startup_barrier);
   puts ("threads waiting");
 #endif
 
-  print_maps ();
-
 #if USE_PTHREADS
   void *old_stack_addr, *new_stack_addr;
   size_t stack_size;
   pthread_t me = pthread_self ();
   pthread_attr_t attr;
-  int ret = 0;
-
-  ret = pthread_getattr_np (me, &attr);
-  if (ret)
-    {
-      printf ("before execstack: pthread_getattr_np returned error: %s\n",
-	      strerror (ret));
-      return 1;
-    }
-
-  ret = pthread_attr_getstack (&attr, &old_stack_addr, &stack_size);
-  if (ret)
-    {
-      printf ("before execstack: pthread_attr_getstack returned error: %s\n",
-	      strerror (ret));
-      return 1;
-    }
+  TEST_VERIFY_EXIT (pthread_getattr_np (me, &attr) == 0);
+  TEST_VERIFY_EXIT (pthread_attr_getstack (&attr, &old_stack_addr,
+					    &stack_size) == 0);
 # if _STACK_GROWS_DOWN
     old_stack_addr += stack_size;
 # else
@@ -149,36 +136,17 @@ do_test (void)
       return allow_execstack;
     }
 
-  f = dlsym (h, "tryme");
-  if (f == NULL)
-    {
-      printf ("symbol not found: %s\n", dlerror ());
-      return 1;
-    }
+  f = xdlsym (h, "tryme");
 
   /* Test if that really made our stack executable.
      The `tryme' function should crash if not.  */
 
   (*((void (*) (void)) f)) ();
 
-  print_maps ();
-
 #if USE_PTHREADS
-  ret = pthread_getattr_np (me, &attr);
-  if (ret)
-    {
-      printf ("after execstack: pthread_getattr_np returned error: %s\n",
-	      strerror (ret));
-      return 1;
-    }
-
-  ret = pthread_attr_getstack (&attr, &new_stack_addr, &stack_size);
-  if (ret)
-    {
-      printf ("after execstack: pthread_attr_getstack returned error: %s\n",
-	      strerror (ret));
-      return 1;
-    }
+  TEST_VERIFY_EXIT (pthread_getattr_np (me, &attr) == 0);
+  TEST_VERIFY_EXIT (pthread_attr_getstack (&attr, &new_stack_addr,
+					    &stack_size) == 0);
 
 # if _STACK_GROWS_DOWN
     new_stack_addr += stack_size;
@@ -194,33 +162,21 @@ do_test (void)
      stacksize and stackaddr respectively.  If the size changes due to the
      above, then both stacksize and stackaddr can change, but the stack bottom
      should remain the same, which is computed as stackaddr + stacksize.  */
-  if (old_stack_addr != new_stack_addr)
-    {
-      printf ("Stack end changed, old: %p, new: %p\n",
-	      old_stack_addr, new_stack_addr);
-      return 1;
-    }
+  TEST_VERIFY_EXIT (old_stack_addr == new_stack_addr);
   printf ("Stack address remains the same: %p\n", old_stack_addr);
 #endif
 
   /* Test that growing the stack region gets new executable pages too.  */
   deeper ((void (*) (void)) f);
 
-  print_maps ();
-
 #if USE_PTHREADS
   /* Test that a fresh thread now gets an executable stack.  */
-  {
-    pthread_t th;
-    int rc = pthread_create (&th, NULL, &tryme_thread, f);
-    if (rc)
-      error (1, rc, "pthread_create");
-  }
+  xpthread_create (NULL, &tryme_thread, f);
 
   puts ("threads go");
   /* The existing threads' stacks should have been changed.
      Let them run to test it.  */
-  pthread_barrier_wait (&go_barrier);
+  xpthread_barrier_wait (&go_barrier);
 
   pthread_exit ((void *) (long int) (! allow_execstack));
 #endif