On 05/31/2018 05:58 PM, Frediano Ziglio wrote:
According to C standard the size of a structure without fields is
not defined (see
https://stackoverflow.com/questions/21851930/size-of-empty-structure-in-c-and-c).
As use almost use GCC we used these structures having 0-size. This is
As we almost only use GCC ...
.. currently these structures are of size 0.
This can become a problem ... if 2 sides ...
usually not a problem however can became a problem if 2 side talking
side -> sides
a given protocol uses these structures.
uses -> use
To avoid such possible mismatch (for instance having one side C and the
other C++ which define these structure as having 1 as size) add an
define -> defines, structure -> structures
empty (0-size array) field.
Although a 0-size array is not considered also that portable we use
extensively this feature with different compiler never encountering
compiler -> compilers
issues.
Signed-off-by: Frediano Ziglio <fziglio@xxxxxxxxxx>
Ack.
I tested it with a following simple program, f.c,
(building it with gcc and g++):
---
#include <stdio.h>
#include <spice/vd_agent.h>
int main()
{
printf("sizeof(VDAgentClipboardRelease)=%lu\n",
sizeof(VDAgentClipboardRelease));
return 0;
}
---
Uri.
I should have checked before sending.
---
spice/vd_agent.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/spice/vd_agent.h b/spice/vd_agent.h
index 7109ede..dda7044 100644
--- a/spice/vd_agent.h
+++ b/spice/vd_agent.h
@@ -234,6 +234,7 @@ typedef struct SPICE_ATTR_PACKED VDAgentClipboardRelease
{
uint8_t selection;
uint8_t __reserved[sizeof(uint32_t) - 1 * sizeof(uint8_t)];
#endif
+ uint8_t dummy_empty_field[0]; /* C/C++ compatibility */
} VDAgentClipboardRelease;
typedef struct SPICE_ATTR_PACKED VDAgentMaxClipboard {
Frediano
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