Hi Mark,
You are correct. The "packed" attribute was not working properly in Sun
Studio 12. It has been fixed in Sun Studio 12.1 (C version 5.10).
--Dave
Mark Maule wrote:
Hi all:
It seems like __attribute__((__packed__)) is not packing correctly, or at least
not in the same way as #pragma pack in compiler version 0x590. Is this a bug,
or am I doing something wrong?
thanks
Mark
Given this program:
#include <unistd.h>
#include <stdio.h>
#include <stddef.h>
struct foo_unpacked {
uint32_t f1;
uint64_t f2;
uint32_t f3;
uint64_t f4;
};
struct foo_packed_attribute {
uint32_t f1;
uint64_t f2;
uint32_t f3;
uint64_t f4;
} __attribute((__packed__));
#pragma pack(1)
struct foo_packed_pragma {
uint32_t f1;
uint64_t f2;
uint32_t f3;
uint64_t f4;
};
#pragma pack()
#define DUMP_STRUCT(s) \
printf("sizeof(" #s ")=%d\n", sizeof(s)); \
printf("offsetof f1=%d\n", offsetof(s, f1)); \
printf("offsetof f2=%d\n", offsetof(s, f2)); \
printf("offsetof f3=%d\n", offsetof(s, f3)); \
printf("offsetof f4=%d\n", offsetof(s, f4));
int
main(int argc, char **argv)
{
printf("__SUNPRO_C=%x\n", __SUNPRO_C);
DUMP_STRUCT(struct foo_unpacked);
DUMP_STRUCT(struct foo_packed_attribute);
DUMP_STRUCT(struct foo_packed_pragma);
}
I get this output:
psg-solaris-01$ cc -m64 -o foo foo.c
psg-solaris-01$ ./foo
__SUNPRO_C=590
sizeof(struct foo_unpacked)=32
offsetof f1=0
offsetof f2=8
offsetof f3=16
offsetof f4=24
sizeof(struct foo_packed_attribute)=32
offsetof f1=0
offsetof f2=8
offsetof f3=16
offsetof f4=24
sizeof(struct foo_packed_pragma)=24
offsetof f1=0
offsetof f2=4
offsetof f3=12
offsetof f4=16
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