illumos gate

Using a 64bit libipadm (#13863) breaks ipadm_addr_info().

libipadm uses a door to get the address information from ipmgmtd, which is a 32bit process. The data passed through the door is a ipmgmt_get_rval_t followed by a packed nvlist. The definition of ipmgmt_get_rval_t in ipadm_ipmgmt.h is as follows:

typedef struct ipmgmt_get_rval_s {
    int32_t        ir_err;
    size_t    ir_nvlsize;
    /* packed nvl follows */
} ipmgmt_get_rval_t;

Obviously size_t is 4 bytes in a 32bit process and 8 bytes in a 64bit process. Additionally, 64bit compiler will usually add 4 bytes of padding between ir_err and ir_nvlsize to align the latter to a 64bit boundary. Hence the 64bit libipadm will misinterpret what the 32bit ipmgmtd is sending, confusing nvlist_unpack() which is subsequently called. It works the other way around, but only by accident.

This can be fixed easily by changing the definition like this:

typedef struct ipmgmt_get_rval_s {
    int64_t        ir_err;
    uint64_t    ir_nvlsize;
    /* packed nvl follows */
} ipmgmt_get_rval_t;

Testing: I rebuilt both 32bit and 64bit libipadm and a 32bit ipmgmtd with this change. The problem observed previously disappeared.