Native localtime() segfaults

Question

I seem to be doing something wrong in this attempt to expose the localtime functionality in Perl 6:

use NativeCall;
my class TimeStruct is repr<CStruct> {
    has int32 $!tm_sec;
    has int32 $!tm_min;
    has int32 $!tm_hour;
    has int32 $!tm_mday;
    has int32 $!tm_mon;
    has int32 $!tm_year;
    has int32 $!tm_wday;
    has int32 $!tm_yday;
    has int32 $!tm_isdst;
    has Str   $!tm_zone;
    has long  $!tm_gmtoff;
}

sub localtime(uint32 $epoch --> TimeStruct) is native {*}
dd localtime(time);  # segfault

Running under perl6-lldb-m, I get:

Process 82758 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x5ae5dda1)
    frame #0: 0x00007fffe852efb4 libsystem_c.dylib`_st_localsub + 13
libsystem_c.dylib`_st_localsub:
->  0x7fffe852efb4 <+13>: movq   (%rdi), %rax
    0x7fffe852efb7 <+16>: movq   %rax, -0x20(%rbp)
    0x7fffe852efbb <+20>: movq   0x8e71d3e(%rip), %rbx     ; lclptr
    0x7fffe852efc2 <+27>: testq  %rbx, %rbx
Target 0: (moar) stopped.

Any obvious things I'm doing wrong here?

UPDATE: the final working solution:

class TimeStruct is repr<CStruct> {
    has int32 $.tm_sec;    # *must* be public attributes
    has int32 $.tm_min;
    has int32 $.tm_hour;
    has int32 $.tm_mday;
    has int32 $.tm_mon;
    has int32 $.tm_year;
    has int32 $.tm_wday;
    has int32 $.tm_yday;
    has int32 $.tm_isdst;
    has long  $.tm_gmtoff; # these two were
    has Str   $.time_zone; # in the wrong order
}

sub localtime(int64 $epoch is rw --> TimeStruct) is native {*}

my int64 $epoch = time;  # needs a separate definition somehow
dd localtime($epoch);

Answer 1

localtime() expects a pointer of type time_t* as argument. Assuming time_t and uint32_t are compatible types on your particular platform,

sub localtime(uint32 $epoch is rw --> TimeStruct) is native {*}
my uint32 $t = time;
dd localtime($t);

should do it (though you won't get to see anything unless you make your attributes public).

I'm a bit surprised that your time_t isn't a 64-bit type, and having just googled apple time.h, I also suspect the last two attributes in your struct declaration are in the wrong order...