block: Introduce qemu_try_blockalign()

This function returns NULL instead of aborting when an allocation fails.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>

block.c

@@ -5258,6 +5258,19 @@ void *qemu_blockalign(BlockDriverState *bs, size_t size)
     return qemu_memalign(bdrv_opt_mem_align(bs), size);
 }
 
+void *qemu_try_blockalign(BlockDriverState *bs, size_t size)
+{
+    size_t align = bdrv_opt_mem_align(bs);
+
+    /* Ensure that NULL is never returned on success */
+    assert(align > 0);
+    if (size == 0) {
+        size = align;
+    }
+
+    return qemu_try_memalign(align, size);
+}
+
 /*
  * Check if all memory in this vector is sector aligned.
  */

include/block/block.h

@@ -455,6 +455,7 @@ void bdrv_img_create(const char *filename, const char *fmt,
 size_t bdrv_opt_mem_align(BlockDriverState *bs);
 void bdrv_set_guest_block_size(BlockDriverState *bs, int align);
 void *qemu_blockalign(BlockDriverState *bs, size_t size);
+void *qemu_try_blockalign(BlockDriverState *bs, size_t size);
 bool bdrv_qiov_is_aligned(BlockDriverState *bs, QEMUIOVector *qiov);
 
 struct HBitmapIter;

include/qemu/osdep.h

@@ -95,6 +95,7 @@ typedef signed int              int_fast16_t;
 #define qemu_printf printf
 
 int qemu_daemon(int nochdir, int noclose);
+void *qemu_try_memalign(size_t alignment, size_t size);
 void *qemu_memalign(size_t alignment, size_t size);
 void *qemu_anon_ram_alloc(size_t size);
 void qemu_vfree(void *ptr);

util/oslib-posix.c

@@ -94,7 +94,7 @@ void *qemu_oom_check(void *ptr)
     return ptr;
 }
 
-void *qemu_memalign(size_t alignment, size_t size)
+void *qemu_try_memalign(size_t alignment, size_t size)
 {
     void *ptr;
 
@@ -106,19 +106,23 @@ void *qemu_memalign(size_t alignment, size_t size)
     int ret;
     ret = posix_memalign(&ptr, alignment, size);
     if (ret != 0) {
-        fprintf(stderr, "Failed to allocate %zu B: %s\n",
-                size, strerror(ret));
-        abort();
+        errno = ret;
+        ptr = NULL;
     }
 #elif defined(CONFIG_BSD)
-    ptr = qemu_oom_check(valloc(size));
+    ptr = valloc(size);
 #else
-    ptr = qemu_oom_check(memalign(alignment, size));
+    ptr = memalign(alignment, size);
 #endif
     trace_qemu_memalign(alignment, size, ptr);
     return ptr;
 }
 
+void *qemu_memalign(size_t alignment, size_t size)
+{
+    return qemu_oom_check(qemu_try_memalign(alignment, size));
+}
+
 /* alloc shared memory pages */
 void *qemu_anon_ram_alloc(size_t size)
 {

util/oslib-win32.c

@@ -50,18 +50,23 @@ void *qemu_oom_check(void *ptr)
     return ptr;
 }
 
-void *qemu_memalign(size_t alignment, size_t size)
+void *qemu_try_memalign(size_t alignment, size_t size)
 {
     void *ptr;
 
     if (!size) {
         abort();
     }
-    ptr = qemu_oom_check(VirtualAlloc(NULL, size, MEM_COMMIT, PAGE_READWRITE));
+    ptr = VirtualAlloc(NULL, size, MEM_COMMIT, PAGE_READWRITE);
     trace_qemu_memalign(alignment, size, ptr);
     return ptr;
 }
 
+void *qemu_memalign(size_t alignment, size_t size)
+{
+    return qemu_oom_check(qemu_try_memalign(alignment, size));
+}
+
 void *qemu_anon_ram_alloc(size_t size)
 {
     void *ptr;