code: mafs

ref: 56bd332994102b4e194819abb5e087a8895452f9
dir: /tests/testpkdstruct.c/

#include <u.h>
#include <libc.h>

typedef unsigned char u8;
typedef unsigned short u16;
typedef unsigned int u32;
typedef unsigned long long u64;

typedef	struct	Spanid	Spanid;
typedef	struct	Tag	Tag;

/*
	this program shows inconsistent behaviour when returning packed structs.
	Everything works fine if the Tag is defined with this definition.
	Bottom line: Cannot count on return values of packed structures.
struct Tag
{
	u8 type;
	u64 path;
};

 */

#pragma pack on
struct Tag
{
	u64 path;	/* Qid.path, unique identifier */
	u8 type;	/* Tmagic, Tdentry, Tdata, Tindn */
};
struct Spanid	/* Spanid identifier */
{
	u16 len;	/* number of blocks */
	u64 blkno;	/* starting block number */
	Tag;
//	Tag1;
};
#pragma pack off

Spanid t[10] = {0};

void
save(void)
{
	t[0].blkno = 888888;
	t[0].len = 9;
	t[0].type = 9;
	t[0].path = 789789;
}

Spanid
get(int i)
{
	print("get	t[i] blkno %llud len %d"
			" type %d path %llud\n",
			t[i].blkno, t[i].len,
			t[i].type, t[i].path);
	return t[i];
}

void
put(Spanid s)
{
	print("put	s blkno %llud len %d\n", s.blkno, s.len);
	t[1].blkno = s.blkno;
	t[1].len = s.len;
}

void
main(int, void**)
{
	Spanid s;

	save();
	s = get(0);
	print("	blkno %llud len %d"
			" type %d path %llud\n",
			s.blkno, s.len,
			s.type, s.path);

	s.blkno = 77777;
	s.len = 8;
	put(s);
	s.len = 10;
	s = get(1);
	print("	blkno %llud len %d\n", s.blkno, s.len);
	exits(0);
}