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.

1 files changed, 48 insertions, 0 deletions

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 *);