Currently qemu_try_memalign()'s behaviour if asked to allocate
0 bytes is rather variable:
* on Windows, we will assert
* on POSIX platforms, we get the underlying behaviour of
the posix_memalign() or equivalent function, which may be
either "return a valid non-NULL pointer" or "return NULL"
Explictly check for 0 byte allocations, so we get consistent
behaviour across platforms. We handle them by incrementing the size
so that we return a valid non-NULL pointer that can later be passed
to qemu_vfree(). This is permitted behaviour for the
posix_memalign() API and is the most usual way that underlying
malloc() etc implementations handle a zero-sized allocation request,
because it won't trip up calling code that assumes NULL means an
error. (This includes our own qemu_memalign(), which will abort on
NULL.)
This change is a preparation for sharing the qemu_try_memalign() code
between Windows and POSIX.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
util/oslib-posix.c | 3 +++
util/oslib-win32.c | 4 +++-
2 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index 0278902ee79..f7e22f4ff9b 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -209,6 +209,9 @@ void *qemu_try_memalign(size_t alignment, size_t size)
g_assert(is_power_of_2(alignment));
}
+ if (size == 0) {
+ size++;
+ }
#if defined(CONFIG_POSIX_MEMALIGN)
int ret;
ret = posix_memalign(&ptr, alignment, size);
diff --git a/util/oslib-win32.c b/util/oslib-win32.c
index 05857414695..8c28d70904d 100644
--- a/util/oslib-win32.c
+++ b/util/oslib-win32.c
@@ -48,12 +48,14 @@ void *qemu_try_memalign(size_t alignment, size_t size)
{
void *ptr;
- g_assert(size != 0);