Implement _dl_catch_error, _dl_signal_error in libc.so [BZ #16628]

This change moves the main implementation of _dl_catch_error,
_dl_signal_error to libc.so, where TLS variables can be used
directly.  This removes a writable function pointer from the
rtld_global variable.

For use during initial relocation, minimal implementations of these
functions are provided in ld.so.  These are eventually interposed
by the libc.so implementations.  This is implemented by compiling
elf/dl-error-skeleton.c twice, via elf/dl-error.c and
elf/dl-error-minimal.c.

As a side effect of this change, the static version of dl-error.c
no longer includes support for the
_dl_signal_cerror/_dl_receive_error mechanism because it is only
used in ld.so.

1 files changed, 105 insertions, 0 deletions

diff --git a/elf/tst-latepthread.c b/elf/tst-latepthread.c
new file mode 100644
index 0000000000..9449ef6c2d
--- /dev/null
+++ b/elf/tst-latepthread.c
@@ -0,0 +1,105 @@
+/* Test that loading libpthread does not break ld.so exceptions (bug 16628).
+   Copyright (C) 2016 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/>.  */
+
+#include <dlfcn.h>
+#include <signal.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+static int
+do_test (void)
+{
+  void *handle = dlopen ("tst-latepthreadmod.so", RTLD_LOCAL | RTLD_LAZY);
+  if (handle == NULL)
+    {
+      printf ("error: dlopen failed: %s\n", dlerror ());
+      return 1;
+    }
+  void *ptr = dlsym (handle, "trigger_dynlink_failure");
+  if (ptr == NULL)
+    {
+      printf ("error: dlsym failed: %s\n", dlerror ());
+      return 1;
+    }
+  int (*func) (void) = ptr;
+
+  /* Run the actual test in a subprocess, to capture the error.  */
+  int fds[2];
+  if (pipe (fds) < 0)
+    {
+      printf ("error: pipe: %m\n");
+      return 1;
+    }
+  pid_t pid = fork ();
+  if (pid < 0)
+    {
+      printf ("error: fork: %m\n");
+      return 1;
+    }
+  else if (pid == 0)
+    {
+      if (dup2 (fds[1], STDERR_FILENO) < 0)
+        _exit (2);
+      /* Trigger an abort.  */
+      func ();
+      _exit (3);
+    }
+  /* NB: This assumes that the abort message is so short that the pipe
+     does not block.  */
+  int status;
+  if (waitpid (pid, &status, 0) < 0)
+    {
+      printf ("error: waitpid: %m\n");
+      return 1;
+    }
+
+  /* Check the printed error message.  */
+  if (close (fds[1]) < 0)
+   {
+     printf ("error: close: %m\n");
+     return 1;
+   }
+  char buf[512];
+  /* Leave room for the NUL terminator.  */
+  ssize_t ret = read (fds[0], buf, sizeof (buf) - 1);
+  if (ret < 0)
+    {
+      printf ("error: read: %m\n");
+      return 1;
+    }
+  if (ret > 0 && buf[ret - 1] == '\n')
+    --ret;
+  buf[ret] = '\0';
+  printf ("info: exit status: %d, message: %s\n", status, buf);
+  if (strstr (buf, "undefined symbol: this_function_is_not_defined") == NULL)
+    {
+      printf ("error: message does not contain expected string\n");
+      return 1;
+    }
+  if (!WIFEXITED (status) || WEXITSTATUS (status) != 127)
+    {
+      printf ("error: unexpected process exit status\n");
+      return 1;
+    }
+  return 0;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"