Libguestfs - Nov 2021 - [PATCH libnbd] common/include/checked-overflow.h: Simplify

We don't need separate macros for size_t and uint64_t since the compiler
builtins are generic. If we need to port to a complier that does not have
generic builtins, it is likely that we can do this in a generic way.

Signed-off-by: Nir Soffer <nsoffer at redhat.com>
---
 common/include/checked-overflow.h | 18 ++++--------------
 common/utils/vector.c             | 10 +++++-----
 2 files changed, 9 insertions(+), 19 deletions(-)

diff --git a/common/include/checked-overflow.h
b/common/include/checked-overflow.h
index a84b82d..ddc4b48 100644
--- a/common/include/checked-overflow.h
+++ b/common/include/checked-overflow.h
@@ -46,24 +46,14 @@
 #error "this file may need to be ported to your compiler"
 #endif
 
-/* Add two uint64_t values.  *r = a + b
+/* Add two values.  *r = a + b
  * Returns true if overflow happened.
  */
-#define ADD_UINT64_T_OVERFLOW(a, b, r) __builtin_add_overflow((a), (b), (r))
+#define ADD_OVERFLOW(a, b, r) __builtin_add_overflow((a), (b), (r))
 
-/* Multiply two uint64_t values.  *r = a * b
+/* Multiply two values.  *r = a * b
  * Returns true if overflow happened.
  */
-#define MUL_UINT64_T_OVERFLOW(a, b, r) __builtin_mul_overflow((a), (b), (r))
-
-/* Add two size_t values.  *r = a + b
- * Returns true if overflow happened.
- */
-#define ADD_SIZE_T_OVERFLOW(a, b, r) __builtin_add_overflow((a), (b), (r))
-
-/* Multiply two size_t values.  *r = a * b
- * Returns true if overflow happened.
- */
-#define MUL_SIZE_T_OVERFLOW(a, b, r) __builtin_mul_overflow((a), (b), (r))
+#define MUL_OVERFLOW(a, b, r) __builtin_mul_overflow((a), (b), (r))
 
 #endif /* NBDKIT_CHECKED_OVERFLOW_H */
diff --git a/common/utils/vector.c b/common/utils/vector.c
index 550e624..ee75915 100644
--- a/common/utils/vector.c
+++ b/common/utils/vector.c
@@ -49,8 +49,8 @@ generic_vector_reserve (struct generic_vector *v, size_t n,
size_t itemsize)
    *   reqcap = v->cap + n
    *   reqbytes = reqcap * itemsize
    */
-  if (ADD_SIZE_T_OVERFLOW (v->cap, n, &reqcap) ||
-      MUL_SIZE_T_OVERFLOW (reqcap, itemsize, &reqbytes)) {
+  if (ADD_OVERFLOW (v->cap, n, &reqcap) ||
+      MUL_OVERFLOW (reqcap, itemsize, &reqbytes)) {
     errno = ENOMEM;
     return -1;
   }
@@ -60,9 +60,9 @@ generic_vector_reserve (struct generic_vector *v, size_t n,
size_t itemsize)
    *   newcap = v->cap + (v->cap + 1) / 2
    *   newbytes = newcap * itemsize
    */
-  if (ADD_SIZE_T_OVERFLOW (v->cap, 1, &t) ||
-      ADD_SIZE_T_OVERFLOW (v->cap, t/2, &newcap) ||
-      MUL_SIZE_T_OVERFLOW (newcap, itemsize, &newbytes) ||
+  if (ADD_OVERFLOW (v->cap, 1, &t) ||
+      ADD_OVERFLOW (v->cap, t/2, &newcap) ||
+      MUL_OVERFLOW (newcap, itemsize, &newbytes) ||
       newbytes < reqbytes) {
     /* If that either overflows or is less than the minimum requested,
      * fall back to the requested capacity.
-- 
2.31.1

On Wed, Nov 10, 2021 at 08:49:27PM +0200, Nir Soffer
wrote:
> We don't need separate macros for size_t and uint64_t since the
compiler
> builtins are generic. If we need to port to a complier that does not have
> generic builtins, it is likely that we can do this in a generic way.
> 
> Signed-off-by: Nir Soffer <nsoffer at redhat.com>
> ---
>  common/include/checked-overflow.h | 18 ++++--------------
>  common/utils/vector.c             | 10 +++++-----
>  2 files changed, 9 insertions(+), 19 deletions(-)
ACK.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org