path: root/libmudflap/mf-hooks1.c

/* Mudflap: narrow-pointer bounds-checking by tree rewriting.
   Copyright (C) 2002, 2003, 2004, 2009 Free Software Foundation, Inc.
   Contributed by Frank Ch. Eigler <fche@redhat.com>
   and Graydon Hoare <graydon@redhat.com>

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.

GCC 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 General Public License
for more details.

Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
<http://www.gnu.org/licenses/>.  */

#include "config.h"

#ifndef HAVE_SOCKLEN_T
#define socklen_t int
#endif


/* These attempt to coax various unix flavours to declare all our
   needed tidbits in the system headers.  */
#if !defined(__FreeBSD__)  && !defined(__APPLE__)
#define _POSIX_SOURCE
#endif /* Some BSDs break <sys/socket.h> if this is defined. */
#define _GNU_SOURCE
#define _XOPEN_SOURCE
#define _BSD_TYPES
#define __EXTENSIONS__
#define _ALL_SOURCE
#define _LARGE_FILE_API
#define _XOPEN_SOURCE_EXTENDED 1

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <assert.h>
#include <errno.h>
#include <limits.h>
#include <time.h>

#include "mf-runtime.h"
#include "mf-impl.h"

#ifdef _MUDFLAP
#error "Do not compile this file with -fmudflap!"
#endif


/* Memory allocation related hook functions.  Some of these are
   intercepted via linker wrapping or symbol interposition.  Others
   use plain macros in mf-runtime.h.  */


#if PIC

enum { BS = 4096, NB=10 };
static char __mf_0fn_bufs[NB][BS];
static unsigned __mf_0fn_bufs_used[NB];


/* A special bootstrap variant. */
void *
__mf_0fn_malloc (size_t c)
{
  unsigned i;

  for (i=0; i<NB; i++)
    {
      if (! __mf_0fn_bufs_used[i] && c < BS)
	{
	  __mf_0fn_bufs_used[i] = 1;
	  return & __mf_0fn_bufs[i][0];
	}
    }
  return NULL;
}
#endif


#undef malloc
WRAPPER(void *, malloc, size_t c)
{
  size_t size_with_crumple_zones;
  DECLARE(void *, malloc, size_t c);
  void *result;
  BEGIN_PROTECT (malloc, c);

  size_with_crumple_zones =
    CLAMPADD(c,CLAMPADD(__mf_opts.crumple_zone,
			__mf_opts.crumple_zone));
  BEGIN_MALLOC_PROTECT ();
  result = (char *) CALL_REAL (malloc, size_with_crumple_zones);
  END_MALLOC_PROTECT ();

  if (LIKELY(result))
    {
      result += __mf_opts.crumple_zone;
      __mf_register (result, c, __MF_TYPE_HEAP, "malloc region");
      /* XXX: register __MF_TYPE_NOACCESS for crumple zones.  */
    }

  return result;
}


#ifdef PIC
/* A special bootstrap variant. */
void *
__mf_0fn_calloc (size_t c, size_t n)
{
  return __mf_0fn_malloc (c * n);
}
#endif


#undef calloc
WRAPPER(void *, calloc, size_t c, size_t n)
{
  size_t size_with_crumple_zones;
  DECLARE(void *, calloc, size_t, size_t);
  DECLARE(void *, malloc, size_t);
  DECLARE(void *, memset, void *, int, size_t);
  char *result;
  BEGIN_PROTECT (calloc, c, n);

  size_with_crumple_zones =
    CLAMPADD((c * n), /* XXX: CLAMPMUL */
	     CLAMPADD(__mf_opts.crumple_zone,
		      __mf_opts.crumple_zone));
  BEGIN_MALLOC_PROTECT ();
  result = (char *) CALL_REAL (malloc, size_with_crumple_zones);
  END_MALLOC_PROTECT ();

  if (LIKELY(result))
    memset (result, 0, size_with_crumple_zones);

  if (LIKELY(result))
    {
      result += __mf_opts.crumple_zone;
      __mf_register (result, c*n /* XXX: clamp */, __MF_TYPE_HEAP_I, "calloc region");
      /* XXX: register __MF_TYPE_NOACCESS for crumple zones.  */
    }

  return result;
}


#if PIC
/* A special bootstrap variant. */
void *
__mf_0fn_realloc (void *buf, size_t c)
{
  return NULL;
}
#endif


#undef realloc
WRAPPER(void *, realloc, void *buf, size_t c)
{
  DECLARE(void * , realloc, void *, size_t);
  size_t size_with_crumple_zones;
  char *base = buf;
  unsigned saved_wipe_heap;
  char *result;
  BEGIN_PROTECT (realloc, buf, c);

  if (LIKELY(buf))
    base -= __mf_opts.crumple_zone;

  size_with_crumple_zones =
    CLAMPADD(c, CLAMPADD(__mf_opts.crumple_zone,
			 __mf_opts.crumple_zone));
  BEGIN_MALLOC_PROTECT ();
  result = (char *) CALL_REAL (realloc, base, size_with_crumple_zones);
  END_MALLOC_PROTECT ();

  /* Ensure heap wiping doesn't occur during this peculiar
     unregister/reregister pair.  */
  LOCKTH ();
  __mf_set_state (reentrant);
  saved_wipe_heap = __mf_opts.wipe_heap;
  __mf_opts.wipe_heap = 0;

  if (LIKELY(buf))
    __mfu_unregister (buf, 0, __MF_TYPE_HEAP_I);
  /* NB: underlying region may have been __MF_TYPE_HEAP. */

  if (LIKELY(result))
    {
      result += __mf_opts.crumple_zone;
      __mfu_register (result, c, __MF_TYPE_HEAP_I, "realloc region");
      /* XXX: register __MF_TYPE_NOACCESS for crumple zones.  */
    }

  /* Restore previous setting.  */
  __mf_opts.wipe_heap = saved_wipe_heap;

  __mf_set_state (active);
  UNLOCKTH ();

  return result;
}


#if PIC
/* A special bootstrap variant. */
void
__mf_0fn_free (void *buf)
{
  return;
}
#endif

#undef free
WRAPPER(void, free, void *buf)
{
  /* Use a circular queue to delay some number (__mf_opts.free_queue_length) of free()s.  */
  static void *free_queue [__MF_FREEQ_MAX];
  static unsigned free_ptr = 0;
  static int freeq_initialized = 0;
  DECLARE(void, free, void *);

  BEGIN_PROTECT (free, buf);

  if (UNLIKELY(buf == NULL))
    return;

#if PIC
  /* Check whether the given buffer might have come from a
     __mf_0fn_malloc/calloc call that for whatever reason was not
     redirected back to __mf_0fn_free.  If so, we just ignore the
     call. */
  if (UNLIKELY((uintptr_t) buf >= (uintptr_t) __mf_0fn_bufs &&
               (uintptr_t) buf < ((uintptr_t) __mf_0fn_bufs + sizeof(__mf_0fn_bufs))))
  {
    VERBOSE_TRACE ("skipping free of boot (0fn) alloc buffer %p\n", buf);
    return;
  }
#endif

  LOCKTH ();
  if (UNLIKELY(!freeq_initialized))
    {
      memset (free_queue, 0,
		     __MF_FREEQ_MAX * sizeof (void *));
      freeq_initialized = 1;
    }
  UNLOCKTH ();

  __mf_unregister (buf, 0, __MF_TYPE_HEAP_I);
  /* NB: underlying region may have been __MF_TYPE_HEAP. */

  if (UNLIKELY(__mf_opts.free_queue_length > 0))
    {
      char *freeme = NULL;
      LOCKTH ();
      if (free_queue [free_ptr] != NULL)
	{
	  freeme = free_queue [free_ptr];
	  freeme -= __mf_opts.crumple_zone;
	}
      free_queue [free_ptr] = buf;
      free_ptr = (free_ptr == (__mf_opts.free_queue_length-1) ? 0 : free_ptr + 1);
      UNLOCKTH ();
      if (freeme)
	{
	  if (__mf_opts.trace_mf_calls)
	    {
	      VERBOSE_TRACE ("freeing deferred pointer %p (crumple %u)\n",
			     (void *) freeme,
			     __mf_opts.crumple_zone);
	    }
	  BEGIN_MALLOC_PROTECT ();
	  CALL_REAL (free, freeme);
	  END_MALLOC_PROTECT ();
	}
    }
  else
    {
      /* back pointer up a bit to the beginning of crumple zone */
      char *base = (char *)buf;
      base -= __mf_opts.crumple_zone;
      if (__mf_opts.trace_mf_calls)
	{
	  VERBOSE_TRACE ("freeing pointer %p = %p - %u\n",
			 (void *) base,
			 (void *) buf,
			 __mf_opts.crumple_zone);
	}
      BEGIN_MALLOC_PROTECT ();
      CALL_REAL (free, base);
      END_MALLOC_PROTECT ();
    }
}


/* We can only wrap mmap if the target supports it.  Likewise for munmap.
   We assume we have both if we have mmap.  */
#ifdef HAVE_MMAP

#if PIC
/* A special bootstrap variant. */
void *
__mf_0fn_mmap (void *start, size_t l, int prot, int f, int fd, off_t off)
{
#if defined(__FreeBSD__)
  if (f == 0x1000 && fd == -1 && prot == 0 && off == 0)
    return 0;
#endif /* Ignore red zone allocation request for initial thread's stack. */

  return (void *) -1;
}
#endif


#undef mmap
WRAPPER(void *, mmap,
	void  *start,  size_t length, int prot,
	int flags, int fd, off_t offset)
{
  DECLARE(void *, mmap, void *, size_t, int,
			    int, int, off_t);
  void *result;
  BEGIN_PROTECT (mmap, start, length, prot, flags, fd, offset);

  result = CALL_REAL (mmap, start, length, prot,
			flags, fd, offset);

  /*
  VERBOSE_TRACE ("mmap (%08lx, %08lx, ...) => %08lx\n",
		 (uintptr_t) start, (uintptr_t) length,
		 (uintptr_t) result);
  */

  if (result != (void *)-1)
    {
      /* Register each page as a heap object.  Why not register it all
	 as a single segment?  That's so that a later munmap() call
	 can unmap individual pages.  XXX: would __MF_TYPE_GUESS make
	 this more automatic?  */
      size_t ps = getpagesize ();
      uintptr_t base = (uintptr_t) result;
      uintptr_t offset;

      for (offset=0; offset<length; offset+=ps)
	{
	  /* XXX: We could map PROT_NONE to __MF_TYPE_NOACCESS. */
	  /* XXX: Unaccessed HEAP pages are reported as leaks.  Is this
	     appropriate for unaccessed mmap pages? */
	  __mf_register ((void *) CLAMPADD (base, offset), ps,
			 __MF_TYPE_HEAP_I, "mmap page");
	}
    }

  return result;
}


#if PIC
/* A special bootstrap variant. */
int
__mf_0fn_munmap (void *start, size_t length)
{
  return -1;
}
#endif


#undef munmap
WRAPPER(int , munmap, void *start, size_t length)
{
  DECLARE(int, munmap, void *, size_t);
  int result;
  BEGIN_PROTECT (munmap, start, length);

  result = CALL_REAL (munmap, start, length);

  /*
  VERBOSE_TRACE ("munmap (%08lx, %08lx, ...) => %08lx\n",
		 (uintptr_t) start, (uintptr_t) length,
		 (uintptr_t) result);
  */

  if (result == 0)
    {
      /* Unregister each page as a heap object.  */
      size_t ps = getpagesize ();
      uintptr_t base = (uintptr_t) start & (~ (ps - 1)); /* page align */
      uintptr_t offset;

      for (offset=0; offset<length; offset+=ps)
	__mf_unregister ((void *) CLAMPADD (base, offset), ps, __MF_TYPE_HEAP_I);
    }
  return result;
}
#endif /* HAVE_MMAP */


/* This wrapper is a little different, as it's called indirectly from
   __mf_fini also to clean up pending allocations.  */
void *
__mf_wrap_alloca_indirect (size_t c)
{
  DECLARE (void *, malloc, size_t);
  DECLARE (void, free, void *);

  /* This struct, a linked list, tracks alloca'd objects.  The newest
     object is at the head of the list.  If we detect that we've
     popped a few levels of stack, then the listed objects are freed
     as needed.  NB: The tracking struct is allocated with
     real_malloc; the user data with wrap_malloc.
  */
  struct alloca_tracking { void *ptr; void *stack; struct alloca_tracking* next; };
  static struct alloca_tracking *alloca_history = NULL;

  void *stack = __builtin_frame_address (0);
  void *result;
  struct alloca_tracking *track;

  TRACE ("%s\n", __PRETTY_FUNCTION__);
  VERBOSE_TRACE ("alloca stack level %p\n", (void *) stack);

  /* XXX: thread locking! */

  /* Free any previously alloca'd blocks that belong to deeper-nested functions,
     which must therefore have exited by now.  */

#define DEEPER_THAN < /* XXX: for x86; steal find_stack_direction() from libiberty/alloca.c */

  while (alloca_history &&
	 ((uintptr_t) alloca_history->stack DEEPER_THAN (uintptr_t) stack))
    {
      struct alloca_tracking *next = alloca_history->next;
      __mf_unregister (alloca_history->ptr, 0, __MF_TYPE_HEAP);
      BEGIN_MALLOC_PROTECT ();
      CALL_REAL (free, alloca_history->ptr);
      CALL_REAL (free, alloca_history);
      END_MALLOC_PROTECT ();
      alloca_history = next;
    }

  /* Allocate new block.  */
  result = NULL;
  if (LIKELY (c > 0)) /* alloca(0) causes no allocation.  */
    {
      BEGIN_MALLOC_PROTECT ();
      track = (struct alloca_tracking *) CALL_REAL (malloc,
						    sizeof (struct alloca_tracking));
      END_MALLOC_PROTECT ();
      if (LIKELY (track != NULL))
	{
	  BEGIN_MALLOC_PROTECT ();
	  result = CALL_REAL (malloc, c);
	  END_MALLOC_PROTECT ();
	  if (UNLIKELY (result == NULL))
	    {
	      BEGIN_MALLOC_PROTECT ();
	      CALL_REAL (free, track);
	      END_MALLOC_PROTECT ();
	      /* Too bad.  XXX: What about errno?  */
	    }
	  else
	    {
	      __mf_register (result, c, __MF_TYPE_HEAP, "alloca region");
	      track->ptr = result;
	      track->stack = stack;
	      track->next = alloca_history;
	      alloca_history = track;
	    }
	}
    }

  return result;
}


#undef alloca
WRAPPER(void *, alloca, size_t c)
{
  return __mf_wrap_alloca_indirect (c);
}