malloc: Simplify static malloc interposition [BZ #20432]

Existing interposed mallocs do not define the glibc-internal
fork callbacks (and they should not), so statically interposed
mallocs lead to link failures because the strong reference from
fork pulls in glibc's malloc, resulting in multiple definitions
of malloc-related symbols.

1 files changed, 204 insertions, 0 deletions

diff --git a/malloc/tst-interpose-skeleton.c b/malloc/tst-interpose-skeleton.c
new file mode 100644
index 0000000..d1ebc9a
--- /dev/null
+++ b/malloc/tst-interpose-skeleton.c
@@ -0,0 +1,204 @@
+/* Test driver for malloc interposition tests.
+   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; see the file COPYING.LIB.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#if INTERPOSE_THREADS
+#include <pthread.h>
+#endif
+
+static int do_test (void);
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
+
+/* Fills BUFFER with a test string.  */
+static void
+line_string (int number, char *buffer, size_t length)
+{
+  for (size_t i = 0; i < length - 2; ++i)
+    buffer[i] = 'A' + ((number + i) % 26);
+  buffer[length - 2] = '\n';
+  buffer[length - 1] = '\0';
+}
+
+/* Perform the tests.  */
+static void *
+run_tests (void *closure)
+{
+  char *temp_file_path;
+  int fd = create_temp_file ("tst-malloc-interpose", &temp_file_path);
+  if (fd < 0)
+    _exit (1);
+
+  /* Line lengths excluding the line terminator.  */
+  static const int line_lengths[] = { 0, 45, 80, 2, 8201, 0, 17, -1 };
+
+  /* Fill the test file with data.  */
+  {
+    FILE *fp = fdopen (fd, "w");
+    for (int lineno = 0; line_lengths[lineno] >= 0; ++lineno)
+      {
+        char buffer[line_lengths[lineno] + 2];
+        line_string (lineno, buffer, sizeof (buffer));
+        fprintf (fp, "%s", buffer);
+      }
+
+    if (ferror (fp))
+      {
+        printf ("error: fprintf: %m\n");
+        _exit (1);
+      }
+    if (fclose (fp) != 0)
+      {
+        printf ("error: fclose: %m\n");
+        _exit (1);
+      }
+  }
+
+  /* Read the test file.  This tests libc-internal allocation with
+     realloc.  */
+  {
+    FILE *fp = fopen (temp_file_path, "r");
+
+    char *actual = NULL;
+    size_t actual_size = 0;
+    for (int lineno = 0; ; ++lineno)
+      {
+        errno = 0;
+        ssize_t result = getline (&actual, &actual_size, fp);
+        if (result == 0)
+          {
+            printf ("error: invalid return value 0 from getline\n");
+            _exit (1);
+          }
+        if (result < 0 && errno != 0)
+          {
+            printf ("error: getline: %m\n");
+            _exit (1);
+          }
+        if (result < 0 && line_lengths[lineno] >= 0)
+          {
+            printf ("error: unexpected end of file after line %d\n", lineno);
+            _exit (1);
+          }
+        if (result > 0 && line_lengths[lineno] < 0)
+          {
+            printf ("error: no end of file after line %d\n", lineno);
+            _exit (1);
+          }
+        if (result == -1 && line_lengths[lineno] == -1)
+          /* End of file reached as expected.  */
+          break;
+
+        if (result != line_lengths[lineno] + 1)
+          {
+            printf ("error: line length mismatch: expected %d, got %zd\n",
+                    line_lengths[lineno], result);
+            _exit (1);
+          }
+
+        char expected[line_lengths[lineno] + 2];
+        line_string (lineno, expected, sizeof (expected));
+        if (strcmp (actual, expected) != 0)
+          {
+            printf ("error: line mismatch\n");
+            printf ("error:   expected: [[%s]]\n", expected);
+            printf ("error:   actual:   [[%s]]\n", actual);
+            _exit (1);
+          }
+      }
+
+    if (fclose (fp) != 0)
+      {
+        printf ("error: fclose (after reading): %m\n");
+        _exit (1);
+      }
+  }
+
+  free (temp_file_path);
+
+  /* Make sure that fork is working.  */
+  pid_t pid = fork ();
+  if (pid == -1)
+    {
+      printf ("error: fork: %m\n");
+      _exit (1);
+    }
+  enum { exit_code = 55 };
+  if (pid == 0)
+    _exit (exit_code);
+  int status;
+  int ret = waitpid (pid, &status, 0);
+  if (ret < 0)
+    {
+      printf ("error: waitpid: %m\n");
+      _exit (1);
+    }
+  if (!WIFEXITED (status) || WEXITSTATUS (status) != exit_code)
+    {
+      printf ("error: unexpected exit status from child process: %d\n",
+              status);
+      _exit (1);
+    }
+
+  return NULL;
+}
+
+/* This is used to detect if malloc has not been successfully
+   interposed.  The interposed malloc does not use brk/sbrk.  */
+static void *initial_brk;
+__attribute__ ((constructor))
+static void
+set_initial_brk (void)
+{
+  initial_brk = sbrk (0);
+}
+
+/* Terminate the process if the break value has been changed.  */
+__attribute__ ((destructor))
+static void
+check_brk (void)
+{
+  void *current = sbrk (0);
+  if (current != initial_brk)
+    {
+      printf ("error: brk changed from %p to %p; no interposition?\n",
+              initial_brk, current);
+      _exit (1);
+    }
+}
+
+static int
+do_test (void)
+{
+  check_brk ();
+
+#if INTERPOSE_THREADS
+  pthread_t thr = xpthread_create (NULL, run_tests, NULL);
+  xpthread_join (thr);
+#else
+  run_tests (NULL);
+#endif
+
+  check_brk ();
+
+  return 0;
+}