1 files changed, 270 insertions, 0 deletions
diff --git a/malloc/tst-interpose-aux.c b/malloc/tst-interpose-aux.c
new file mode 100644
index 0000000000..77866b2e5d
--- /dev/null
+++ b/malloc/tst-interpose-aux.c
@@ -0,0 +1,270 @@
+/* Minimal malloc implementation for 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 "tst-interpose-aux.h"
+
+#include <errno.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/uio.h>
+#include <unistd.h>
+
+#if INTERPOSE_THREADS
+#include <pthread.h>
+#endif
+
+/* Print the error message and terminate the process with status 1.  */
+__attribute__ ((noreturn))
+__attribute__ ((format (printf, 1, 2)))
+static void *
+fail (const char *format, ...)
+{
+  /* This assumes that vsnprintf will not call malloc.  It does not do
+     so for the format strings we use.  */
+  char message[4096];
+  va_list ap;
+  va_start (ap, format);
+  vsnprintf (message, sizeof (message), format, ap);
+  va_end (ap);
+
+  enum { count = 3 };
+  struct iovec iov[count];
+
+  iov[0].iov_base = (char *) "error: ";
+  iov[1].iov_base = (char *) message;
+  iov[2].iov_base = (char *) "\n";
+
+  for (int i = 0; i < count; ++i)
+    iov[i].iov_len = strlen (iov[i].iov_base);
+
+  int unused __attribute__ ((unused));
+  unused = writev (STDOUT_FILENO, iov, count);
+  _exit (1);
+}
+
+#if INTERPOSE_THREADS
+static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+#endif
+
+static void
+lock (void)
+{
+#if INTERPOSE_THREADS
+  int ret = pthread_mutex_lock (&mutex);
+  if (ret != 0)
+    {
+      errno = ret;
+      fail ("pthread_mutex_lock: %m");
+    }
+#endif
+}
+
+static void
+unlock (void)
+{
+#if INTERPOSE_THREADS
+  int ret = pthread_mutex_unlock (&mutex);
+  if (ret != 0)
+    {
+      errno = ret;
+      fail ("pthread_mutex_unlock: %m");
+    }
+#endif
+}
+
+struct __attribute__ ((aligned (__alignof__ (max_align_t)))) allocation_header
+{
+  size_t allocation_index;
+  size_t allocation_size;
+};
+
+/* Array of known allocations, to track invalid frees.  */
+enum { max_allocations = 65536 };
+static struct allocation_header *allocations[max_allocations];
+static size_t allocation_index;
+static size_t deallocation_count;
+
+/* Sanity check for successful malloc interposition.  */
+__attribute__ ((destructor))
+static void
+check_for_allocations (void)
+{
+  if (allocation_index == 0)
+    {
+      /* Make sure that malloc is called at least once from libc.  */
+      void *volatile ptr = strdup ("ptr");
+      free (ptr);
+      /* Compiler barrier.  The strdup function calls malloc, which
+         updates allocation_index, but strdup is marked __THROW, so
+         the compiler could optimize away the reload.  */
+      __asm__ volatile ("" ::: "memory");
+      /* If the allocation count is still zero, it means we did not
+         interpose malloc successfully.  */
+      if (allocation_index == 0)
+        fail ("malloc does not seem to have been interposed");
+    }
+}
+
+static struct allocation_header *get_header (const char *op, void *ptr)
+{
+  struct allocation_header *header = ((struct allocation_header *) ptr) - 1;
+  if (header->allocation_index >= allocation_index)
+    fail ("%s: %p: invalid allocation index: %zu (not less than %zu)",
+          op, ptr, header->allocation_index, allocation_index);
+  if (allocations[header->allocation_index] != header)
+    fail ("%s: %p: allocation pointer does not point to header, but %p",
+          op, ptr, allocations[header->allocation_index]);
+  return header;
+}
+
+/* Internal helper functions.  Those must be called while the lock is
+   acquired.  */
+
+static void *
+malloc_internal (size_t size)
+{
+  if (allocation_index == max_allocations)
+    {
+      errno = ENOMEM;
+      return NULL;
+    }
+  size_t allocation_size = size + sizeof (struct allocation_header);
+  if (allocation_size < size)
+    {
+      errno = ENOMEM;
+      return NULL;
+    }
+
+  size_t index = allocation_index++;
+  void *result = mmap (NULL, allocation_size, PROT_READ | PROT_WRITE,
+                       MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  if (result == MAP_FAILED)
+    return NULL;
+  allocations[index] = result;
+  *allocations[index] = (struct allocation_header)
+    {
+      .allocation_index = index,
+      .allocation_size = allocation_size
+    };
+  return allocations[index] + 1;
+}
+
+static void
+free_internal (const char *op, struct allocation_header *header)
+{
+  size_t index = header->allocation_index;
+  int result = mprotect (header, header->allocation_size, PROT_NONE);
+  if (result != 0)
+    fail ("%s: mprotect (%p, %zu): %m", op, header, header->allocation_size);
+  /* Catch double-free issues.  */
+  allocations[index] = NULL;
+  ++deallocation_count;
+}
+
+static void *
+realloc_internal (void *ptr, size_t new_size)
+{
+  struct allocation_header *header = get_header ("realloc", ptr);
+  size_t old_size = header->allocation_size - sizeof (struct allocation_header);
+  if (old_size >= new_size)
+    return ptr;
+
+  void *newptr = malloc_internal (new_size);
+  if (newptr == NULL)
+    return NULL;
+  memcpy (newptr, ptr, old_size);
+  free_internal ("realloc", header);
+  return newptr;
+}
+
+/* Public interfaces.  These functions must perform locking.  */
+
+size_t
+malloc_allocation_count (void)
+{
+  lock ();
+  size_t count = allocation_index;
+  unlock ();
+  return count;
+}
+
+size_t
+malloc_deallocation_count (void)
+{
+  lock ();
+  size_t count = deallocation_count;
+  unlock ();
+  return count;
+}
+void *
+malloc (size_t size)
+{
+  lock ();
+  void *result = malloc_internal (size);
+  unlock ();
+  return result;
+}
+
+void
+free (void *ptr)
+{
+  if (ptr == NULL)
+    return;
+  lock ();
+  struct allocation_header *header = get_header ("free", ptr);
+  free_internal ("free", header);
+  unlock ();
+}
+
+void *
+calloc (size_t a, size_t b)
+{
+  if (b > 0 && a > SIZE_MAX / b)
+    {
+      errno = ENOMEM;
+      return NULL;
+    }
+  lock ();
+  /* malloc_internal uses mmap, so the memory is zeroed.  */
+  void *result = malloc_internal (a * b);
+  unlock ();
+  return result;
+}
+
+void *
+realloc (void *ptr, size_t n)
+{
+  if (n ==0)
+    {
+      free (ptr);
+      return NULL;
+    }
+  else if (ptr == NULL)
+    return malloc (n);
+  else
+    {
+      lock ();
+      void *result = realloc_internal (ptr, n);
+      unlock ();
+      return result;
+    }
+}