Port --enable-checking=all to Fedora 14 x86.

* alloc.c (XMALLOC_OVERRUN_CHECK_OVERHEAD, XMALLOC_OVERRUN_CHECK_SIZE):
Move to lisp.h.
(xmalloc_put_size, xmalloc_get_size, overrun_check_malloc)
(overrun_check_realloc, overrun_check_free):
Use XMALLOC_OVERRUN_SIZE_SIZE, not sizeof (size_t).
That way, xmalloc returns a properly-aligned pointer even if
XMALLOC_OVERRUN_CHECK is defined.  The old debugging code happened
to align OK on typical 64-bit hosts, but not on Fedora 14 x86.
* charset.c (syms_of_charset): Take XMALLOC_OVERRUN_CHECK_OVERHEAD
into account when calculating the initial malloc maximum.
* lisp.h (XMALLOC_OVERRUN_CHECK_OVERHEAD, XMALLOC_OVERRUN_CHECK_SIZE):
Move here from alloc.c, so that charset.c can use it too.
Properly align; the old code wasn't right for common 32-bit hosts
when configured with --enable-checking=all.
(XMALLOC_BASE_ALIGNMENT, COMMON_MULTIPLE, XMALLOC_HEADER_ALIGNMENT)
(XMALLOC_OVERRUN_SIZE_SIZE): New macros.

4 files changed, 84 insertions, 33 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index dcbeffac1b4..d6e5390c84f 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,23 @@
+2011-09-30  Paul Eggert  <eggert@cs.ucla.edu>
+
+	Port --enable-checking=all to Fedora 14 x86.
+	* alloc.c (XMALLOC_OVERRUN_CHECK_OVERHEAD, XMALLOC_OVERRUN_CHECK_SIZE):
+	Move to lisp.h.
+	(xmalloc_put_size, xmalloc_get_size, overrun_check_malloc)
+	(overrun_check_realloc, overrun_check_free):
+	Use XMALLOC_OVERRUN_SIZE_SIZE, not sizeof (size_t).
+	That way, xmalloc returns a properly-aligned pointer even if
+	XMALLOC_OVERRUN_CHECK is defined.  The old debugging code happened
+	to align OK on typical 64-bit hosts, but not on Fedora 14 x86.
+	* charset.c (syms_of_charset): Take XMALLOC_OVERRUN_CHECK_OVERHEAD
+	into account when calculating the initial malloc maximum.
+	* lisp.h (XMALLOC_OVERRUN_CHECK_OVERHEAD, XMALLOC_OVERRUN_CHECK_SIZE):
+	Move here from alloc.c, so that charset.c can use it too.
+	Properly align; the old code wasn't right for common 32-bit hosts
+	when configured with --enable-checking=all.
+	(XMALLOC_BASE_ALIGNMENT, COMMON_MULTIPLE, XMALLOC_HEADER_ALIGNMENT)
+	(XMALLOC_OVERRUN_SIZE_SIZE): New macros.
+
 2011-09-29  Eli Zaretskii  <eliz@gnu.org>
 
 	* sysdep.c (snprintf) [EOVERFLOW]: If EOVERFLOW is not defined,
diff --git a/src/alloc.c b/src/alloc.c
index ad1741e308f..4c5094b8f48 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -482,27 +482,10 @@ buffer_memory_full (EMACS_INT nbytes)
   xsignal (Qnil, Vmemory_signal_data);
 }
 
-
-#ifndef XMALLOC_OVERRUN_CHECK
-#define XMALLOC_OVERRUN_CHECK_OVERHEAD 0
-#else
+#ifdef XMALLOC_OVERRUN_CHECK
 
 /* Check for overrun in malloc'ed buffers by wrapping a header and trailer
-   around each block.
-
-   The header consists of 16 fixed bytes followed by sizeof (size_t) bytes
-   containing the original block size in little-endian order,
-   while the trailer consists of 16 fixed bytes.
-
-   The header is used to detect whether this block has been allocated
-   through these functions -- as it seems that some low-level libc
-   functions may bypass the malloc hooks.
-*/
-
-
-#define XMALLOC_OVERRUN_CHECK_SIZE 16
-#define XMALLOC_OVERRUN_CHECK_OVERHEAD \
-  (2 * XMALLOC_OVERRUN_CHECK_SIZE + sizeof (size_t))
+   around each block.  */
 
 static char const xmalloc_overrun_check_header[XMALLOC_OVERRUN_CHECK_SIZE] =
   { '\x9a', '\x9b', '\xae', '\xaf',
@@ -522,9 +505,9 @@ static void
 xmalloc_put_size (unsigned char *ptr, size_t size)
 {
   int i;
-  for (i = 0; i < sizeof (size_t); i++)
+  for (i = 0; i < XMALLOC_OVERRUN_SIZE_SIZE; i++)
     {
-      *--ptr = size & (1 << CHAR_BIT) - 1;
+      *--ptr = size & ((1 << CHAR_BIT) - 1);
       size >>= CHAR_BIT;
     }
 }
@@ -534,8 +517,8 @@ xmalloc_get_size (unsigned char *ptr)
 {
   size_t size = 0;
   int i;
-  ptr -= sizeof (size_t);
-  for (i = 0; i < sizeof (size_t); i++)
+  ptr -= XMALLOC_OVERRUN_SIZE_SIZE;
+  for (i = 0; i < XMALLOC_OVERRUN_SIZE_SIZE; i++)
     {
       size <<= CHAR_BIT;
       size += *ptr++;
@@ -579,7 +562,7 @@ overrun_check_malloc (size_t size)
   if (val && check_depth == 1)
     {
       memcpy (val, xmalloc_overrun_check_header, XMALLOC_OVERRUN_CHECK_SIZE);
-      val += XMALLOC_OVERRUN_CHECK_SIZE + sizeof (size_t);
+      val += XMALLOC_OVERRUN_CHECK_SIZE + XMALLOC_OVERRUN_SIZE_SIZE;
       xmalloc_put_size (val, size);
       memcpy (val + size, xmalloc_overrun_check_trailer,
 	      XMALLOC_OVERRUN_CHECK_SIZE);
@@ -603,7 +586,7 @@ overrun_check_realloc (POINTER_TYPE *block, size_t size)
   if (val
       && check_depth == 1
       && memcmp (xmalloc_overrun_check_header,
-		 val - XMALLOC_OVERRUN_CHECK_SIZE - sizeof (size_t),
+		 val - XMALLOC_OVERRUN_CHECK_SIZE - XMALLOC_OVERRUN_SIZE_SIZE,
 		 XMALLOC_OVERRUN_CHECK_SIZE) == 0)
     {
       size_t osize = xmalloc_get_size (val);
@@ -611,8 +594,8 @@ overrun_check_realloc (POINTER_TYPE *block, size_t size)
 		  XMALLOC_OVERRUN_CHECK_SIZE))
 	abort ();
       memset (val + osize, 0, XMALLOC_OVERRUN_CHECK_SIZE);
-      val -= XMALLOC_OVERRUN_CHECK_SIZE + sizeof (size_t);
-      memset (val, 0, XMALLOC_OVERRUN_CHECK_SIZE + sizeof (size_t));
+      val -= XMALLOC_OVERRUN_CHECK_SIZE + XMALLOC_OVERRUN_SIZE_SIZE;
+      memset (val, 0, XMALLOC_OVERRUN_CHECK_SIZE + XMALLOC_OVERRUN_SIZE_SIZE);
     }
 
   val = (unsigned char *) realloc ((POINTER_TYPE *)val, size + overhead);
@@ -620,7 +603,7 @@ overrun_check_realloc (POINTER_TYPE *block, size_t size)
   if (val && check_depth == 1)
     {
       memcpy (val, xmalloc_overrun_check_header, XMALLOC_OVERRUN_CHECK_SIZE);
-      val += XMALLOC_OVERRUN_CHECK_SIZE + sizeof (size_t);
+      val += XMALLOC_OVERRUN_CHECK_SIZE + XMALLOC_OVERRUN_SIZE_SIZE;
       xmalloc_put_size (val, size);
       memcpy (val + size, xmalloc_overrun_check_trailer,
 	      XMALLOC_OVERRUN_CHECK_SIZE);
@@ -640,7 +623,7 @@ overrun_check_free (POINTER_TYPE *block)
   if (val
       && check_depth == 1
       && memcmp (xmalloc_overrun_check_header,
-		 val - XMALLOC_OVERRUN_CHECK_SIZE - sizeof (size_t),
+		 val - XMALLOC_OVERRUN_CHECK_SIZE - XMALLOC_OVERRUN_SIZE_SIZE,
 		 XMALLOC_OVERRUN_CHECK_SIZE) == 0)
     {
       size_t osize = xmalloc_get_size (val);
@@ -648,12 +631,12 @@ overrun_check_free (POINTER_TYPE *block)
 		  XMALLOC_OVERRUN_CHECK_SIZE))
 	abort ();
 #ifdef XMALLOC_CLEAR_FREE_MEMORY
-      val -= XMALLOC_OVERRUN_CHECK_SIZE + sizeof (size_t);
+      val -= XMALLOC_OVERRUN_CHECK_SIZE + XMALLOC_OVERRUN_SIZE_SIZE;
       memset (val, 0xff, osize + XMALLOC_OVERRUN_CHECK_OVERHEAD);
 #else
       memset (val + osize, 0, XMALLOC_OVERRUN_CHECK_SIZE);
-      val -= XMALLOC_OVERRUN_CHECK_SIZE + sizeof (size_t);
-      memset (val, 0, XMALLOC_OVERRUN_CHECK_SIZE + sizeof (size_t));
+      val -= XMALLOC_OVERRUN_CHECK_SIZE + XMALLOC_OVERRUN_SIZE_SIZE;
+      memset (val, 0, XMALLOC_OVERRUN_CHECK_SIZE + XMALLOC_OVERRUN_SIZE_SIZE);
 #endif
     }
 
diff --git a/src/charset.c b/src/charset.c
index 6967b9df611..1209ac6b68d 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -2337,7 +2337,7 @@ syms_of_charset (void)
      mmap for larger allocations, and these don't work well across dumped
      systems.  */
   enum {
-    initial_malloc_max = (1 << 16) - 1,
+    initial_malloc_max = (1 << 16) - 1 - XMALLOC_OVERRUN_CHECK_OVERHEAD,
     charset_table_size_init = initial_malloc_max / sizeof (struct charset)
   };
 
diff --git a/src/lisp.h b/src/lisp.h
index e9a525a32b5..7aba299f162 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -3568,6 +3568,54 @@ extern int initialized;
 
 extern int immediate_quit;	    /* Nonzero means ^G can quit instantly */
 
+/* Overhead for overrun check in malloc'ed buffers.  The check
+   operates by wrapping a header and trailer around each block.
+
+   The header consists of XMALLOC_OVERRUN_CHECK_SIZE fixed bytes
+   followed by XMALLOC_OVERRUN_SIZE_SIZE bytes containing the original
+   block size in little-endian order.  The trailer consists of
+   XMALLOC_OVERRUN_CHECK_SIZE fixed bytes.
+
+   The header is used to detect whether this block has been allocated
+   through these functions, as some low-level libc functions may
+   bypass the malloc hooks.  */
+
+#ifndef XMALLOC_OVERRUN_CHECK
+# define XMALLOC_OVERRUN_CHECK_OVERHEAD 0
+#else
+
+# define XMALLOC_OVERRUN_CHECK_SIZE 16
+# define XMALLOC_OVERRUN_CHECK_OVERHEAD \
+   (2 * XMALLOC_OVERRUN_CHECK_SIZE + XMALLOC_OVERRUN_SIZE_SIZE)
+
+/* Define XMALLOC_OVERRUN_SIZE_SIZE so that (1) it's large enough to
+   hold a size_t value and (2) the header size is a multiple of the
+   alignment that Emacs needs for C types and for USE_LSB_TAG.  */
+# define XMALLOC_BASE_ALIGNMENT				\
+   offsetof (						\
+     struct {						\
+       union { long double d; intmax_t i; void *p; } u;	\
+       char c;						\
+     },							\
+     c)
+# ifdef USE_LSB_TAG
+/* A common multiple of the positive integers A and B.  Ideally this
+   would be the least common multiple, but there's no way to do that
+   as a constant expression in C, so do the best that we can easily do.  */
+#  define COMMON_MULTIPLE(a, b) \
+     ((a) % (b) == 0 ? (a) : (b) % (a) == 0 ? (b) : (a) * (b))
+#  define XMALLOC_HEADER_ALIGNMENT \
+     COMMON_MULTIPLE (1 << GCTYPEBITS, XMALLOC_BASE_ALIGNMENT)
+# else
+#  define XMALLOC_HEADER_ALIGNMENT XMALLOC_BASE_ALIGNMENT
+# endif
+# define XMALLOC_OVERRUN_SIZE_SIZE				\
+   (((XMALLOC_OVERRUN_CHECK_SIZE + sizeof (size_t)		\
+      + XMALLOC_HEADER_ALIGNMENT - 1)				\
+     / XMALLOC_HEADER_ALIGNMENT * XMALLOC_HEADER_ALIGNMENT)	\
+    - XMALLOC_OVERRUN_CHECK_SIZE)
+#endif
+
 extern POINTER_TYPE *xmalloc (size_t);
 extern POINTER_TYPE *xrealloc (POINTER_TYPE *, size_t);
 extern void xfree (POINTER_TYPE *);