GNU C Library master sources branch master updated. glibc-2.28.9000-397-g0c1719e

fw@sourceware.org fw@sourceware.org
Sat Dec 15 17:59:00 GMT 2018


This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
the project "GNU C Library master sources".

The branch, master has been updated
       via  0c1719e65b2a5a80331d4f635612799f853b0479 (commit)
      from  033a2c0a20393c7e48000d83c2ca7ac8ea292d9e (commit)

Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.

- Log -----------------------------------------------------------------
http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=0c1719e65b2a5a80331d4f635612799f853b0479

commit 0c1719e65b2a5a80331d4f635612799f853b0479
Author: Florian Weimer <fweimer@redhat.com>
Date:   Sat Dec 15 18:58:09 2018 +0100

    support: Do not require overflow builtin in support/blob_repeat.c
    
    It is only available in GCC 5 and later.
    
    Tested-by: Romain Naour <romain.naour@gmail.com>

diff --git a/ChangeLog b/ChangeLog
index 3dd9054..90e9f8f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2018-12-15  Florian Weimer  <fweimer@redhat.com>
+
+	* support/blob_repeat.c (check_mul_overflow_size_t): New function.
+	(minimum_stride_size): Use it.
+	(support_blob_repeat_allocate): Likewise.
+
 2018-12-14  Joseph Myers  <joseph@codesourcery.com>
 
 	* sysdeps/x86/fpu/bits/mathinline.h (asinh): Remove inline
diff --git a/support/blob_repeat.c b/support/blob_repeat.c
index 16c1e44..718846d 100644
--- a/support/blob_repeat.c
+++ b/support/blob_repeat.c
@@ -34,6 +34,26 @@
    optimization because mappings carry a lot of overhead.  */
 static const size_t maximum_small_size = 4 * 1024 * 1024;
 
+/* Set *RESULT to LEFT * RIGHT.  Return true if the multiplication
+   overflowed.  See <malloc/malloc-internal.h>.  */
+static inline bool
+check_mul_overflow_size_t (size_t left, size_t right, size_t *result)
+{
+#if __GNUC__ >= 5
+  return __builtin_mul_overflow (left, right, result);
+#else
+  /* size_t is unsigned so the behavior on overflow is defined.  */
+  *result = left * right;
+  size_t half_size_t = ((size_t) 1) << (8 * sizeof (size_t) / 2);
+  if (__glibc_unlikely ((left | right) >= half_size_t))
+    {
+      if (__glibc_unlikely (right != 0 && *result / right != left))
+        return true;
+    }
+  return false;
+#endif
+}
+
 /* Internal helper for fill.  */
 static void
 fill0 (char *target, const char *element, size_t element_size,
@@ -118,8 +138,8 @@ minimum_stride_size (size_t page_size, size_t element_size)
      common multiple, it appears only once.  Therefore, shift one
      factor.  */
   size_t multiple;
-  if (__builtin_mul_overflow (page_size >> common_zeros, element_size,
-                              &multiple))
+  if (check_mul_overflow_size_t (page_size >> common_zeros, element_size,
+                                 &multiple))
     return 0;
   return multiple;
 }
@@ -255,7 +275,7 @@ support_blob_repeat_allocate (const void *element, size_t element_size,
                               size_t count)
 {
   size_t total_size;
-  if (__builtin_mul_overflow (element_size, count, &total_size))
+  if (check_mul_overflow_size_t (element_size, count, &total_size))
     {
       errno = EOVERFLOW;
       return (struct support_blob_repeat) { 0 };

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog             |    6 ++++++
 support/blob_repeat.c |   26 +++++++++++++++++++++++---
 2 files changed, 29 insertions(+), 3 deletions(-)


hooks/post-receive
-- 
GNU C Library master sources



More information about the Glibc-cvs mailing list