Re: [PATCH 4/9] util/oslib-win32: Return NULL on qemu_try_memalign() with zero size

[Richard Henderson]

On 2/26/22 08:07, Peter Maydell wrote:

Currently if qemu_try_memalign() is asked to allocate 0 bytes, we assert.
Instead return NULL; this is in line with the posix_memalign() API,
and is valid to pass to _aligned_free() (which will do nothing).

This change is a preparation for sharing the qemu_try_memalign()
code between Windows and POSIX -- at the moment only the Windows
version has the assert that size != 0.

Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
---
  util/oslib-win32.c | 7 +++++--
  1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/util/oslib-win32.c b/util/oslib-win32.c
index 05857414695..8c1c64719d7 100644
--- a/util/oslib-win32.c
+++ b/util/oslib-win32.c
@@ -48,13 +48,16 @@ void *qemu_try_memalign(size_t alignment, size_t size)
  {
      void *ptr;

- g_assert(size != 0);

      if (alignment < sizeof(void *)) {
          alignment = sizeof(void *);
      } else {
          g_assert(is_power_of_2(alignment));
      }
-    ptr = _aligned_malloc(size, alignment);
+    if (size) {
+        ptr = _aligned_malloc(size, alignment);
+    } else {
+        ptr = NULL;
+    }

Oh, should we set errno to something here?
Otherwise a random value will be used by qemu_memalign.


r~

      trace_qemu_memalign(alignment, size, ptr);
      return ptr;
  }