Mariano,
if you followed the approach I described recently you wouldn't be
having these problems. Instead, the system would be generating the
information you need to know about sizes for you automatically. Eventually
you're going to have to grasp the nettle of how to import platform-specific
information such as structure sizes, values of $defines, layout of structs,
etc, etc. I presented a straightforward approach but you've yet to comment
on it.
On Sat, Jan 9, 2016 at 4:54 AM, Mariano Martinez Peck <[email protected]
> wrote:
> Hi Ben, allf
>
> Ok, I can also confirm that doing ExternalAddress allocate: 76 does work
> in Linux. And yes, since it's opaque I don't have to map it and just
> allocating the correct size is enough.
> I expect this would work in all GNU libc (glibc) based UNIXses.
> Esteban, well, I thought the init function would do both, allocate and
> init, but in glibc it seems it only init. In OSX it seems it does both. But
> from the API point of view it's not explicit that they should allocate the
> space.
>
> Anyway, I think we get this working this time. Thanks all for the help.
>
> Now the problem I am facing (in Linux) is that my none blocking pipes do
> not seem to be none blocking or either feof() call is not working as
> expected. Ok, I have to deal with this one now.
>
> Thanks!!
>
>
> On Sat, Jan 9, 2016 at 9:44 AM, Ben Coman <[email protected]> wrote:
>
>> On Sat, Jan 9, 2016 at 12:15 PM, Ben Coman <[email protected]> wrote:
>> > On Sat, Jan 9, 2016 at 7:12 AM, Mariano Martinez Peck
>> > <[email protected]> wrote:
>> >>
>> >> On Jan 8, 2016 4:13 PM, "Ben Coman" <[email protected]> wrote:
>> >>>
>> >>> On Sat, Jan 9, 2016 at 2:04 AM, Mariano Martinez Peck
>> >>> <[email protected]> wrote:
>> >>> > Hi guys,
>> >>> >
>> >>> > I wonder if someone could give me a hand to find out why a FFI
>> calling I
>> >>> > am
>> >>> > doing is crashing. In OSX it works correct but I am testing in
>> CentOS
>> >>> > and it
>> >>> > fails. I wonder if it also crashes in other Linuxes too.
>> >>>
>> >>> I only had enough time to run it a few time so you know it also
>> >>> crashes in Debian Jessie 32-bit. There were no debug logs. I got
>> >>> these sorts of messages...
>> >>>
>> >>
>> >> Thanks!
>> >>
>> >>> *** Error in `/home/ben/tst/pharo-vm/pharo': free(): invalid next size
>> >>> (fast): 0x08841a70 ***
>> >>>
>> >>> pharo: malloc.c:3695: _int_malloc: Assertion `(unsigned long) (size)
>> >>> >= (unsigned long) (nb)' failed.
>> >>> *** Error in `/home/ben/tst/pharo-vm/pharo': malloc(): memory
>> >>> corruption: 0x0984c1e0 ***
>> >>>
>> >>>
>> >>> Searching github for "posix_spawn_file_actions_init "
>> >>> (https://git.io/vuSPL)
>> >>> I see a lot a function definitions of the form...
>> >>> int posix_spawn_file_actions_init(posix_spawn_file_actions_t *fa)
>> >>> {
>> >>> fa->__actions = 0;
>> >>> return 0;
>> >>> }
>> >>>
>> >>> ...so it seems you need to first allocate the space for the struct and
>> >>> then pass the address of that.
>> >>
>> >> I thought the same. But I also read in glibc that that the init and
>> destroy
>> >> would free and alloc exactly so that you don't have to do it.
>> >>
>> >> In fact, the structure is known to be opaque. I cannot rely in what I
>> see in
>> >> internet since each os may have a different.
>> >>
>> >> And I cant get the size of it from ffi so I cannot allocate
>> accurately. I
>> >> think I am screw. I don't want to go to plugin side grrr ..
>> >>
>> >> And osx does work.
>> >>
>> >> I think I will try against glibc rather than libc.
>> >>
>> >> Another idea?
>> >>
>> >>> {
>> >>> int __allocated;
>> >>> int __used;
>> >>> struct __spawn_action *__actions;
>> >>> int __pad[16];
>> >>> } posix_spawn_file_actions_t;
>> >>> // http://linux.die.net/include/spawn.h
>> >>>
>> >>
>> >> But that's opaque right? I cannot rely on that
>> >
>> > Your ExternalAddress use only allocates 4 bytes for the pointer. You
>> > need to also allocate the space for the structure. I guess these may
>> > need separate ExternalXXX objects, but just as hack experiment I find
>> > below that n:=68 crashes and n:=69 its fine.
>>
>> Whoops, I missed that the space for the struct seems actually
>> allocated by ExternalAddress. Doh! there it is staring at me with the
>> #allocate: message. So I guess a separate ExternalXXX object isn't
>> required.
>>
>> >
>> > | posixSpawnFileActionsT n |
>> > n := 68. "n := 69"
>> > posixSpawnFileActionsT := ExternalAddress allocate: n.
>> > OSSUnixSubprocess new primitivePosixSpawnFileActionsInit:
>> > posixSpawnFileActionsT.
>> > posixSpawnFileActionsT free.
>> >
>> >
>> > In trying to understand this I found an interesting article...
>> > http://www.catb.org/esr/structure-packing/
>> > What I don't know is for a 32-bit OS on a 64-bit machine, is my
>> > pointer 4 or 8 bytes?
>> > Assuming 4 I derive the structure size for my 32-bit system is...
>> > 4 int __allocated;
>> > 4 int __used;
>> > 4 struct __spawn_action *__actions;
>> > 64 int __pad[16];
>> > 76 posix_spawn_file_actions_t;
>> >
>> > 76 - 68 = 8 is an interesting round number, but I can't quite reason it
>> out.
>>
>> btw I confirmed *my* structure size by compiling and running...
>> #include <stdio.h>
>> #include <spawn.h>
>> posix_spawn_file_actions_t tst;
>> int main()
>> {
>> printf("-->sizeof=%d\n", sizeof(posix_spawn_file_actions_t));
>> }
>>
>> -->sizeof=76
>>
>> cheers -ben
>>
>> > With FFI how to you allocate some external memory and then get a
>> > pointer to it to pass to primitivePosixSpawnFileActionsInit ?
>> >
>> > cheers -ben
>> >
>> >>> > I am using latest Pharo 5.0 with Spur. To reproduce:
>> >>> >
>> >>> > 1) Get latest Pharo 5.0 and Spur via:
>> >>> > wget -O- get.pharo.org/alpha+vm | bash
>> >>> >
>> >>> > 2) Inside Pharo, load my prototype tool:
>> >>> >
>> >>> > Gofer it
>> >>> > package: 'OSSubprocess';
>> >>> > url: 'http://smalltalkhub.com/mc/marianopeck/OSSubprocess/main';
>> >>> > load.
>> >>> >
>> >>> > 3) This is the code I am executing and it's crashing:
>> >>> >
>> >>> > | posixSpawnFileActionsT | posixSpawnFileActionsT := ExternalAddress
>> >>> > allocate: 4. OSSUnixSubprocess new
>> primitivePosixSpawnFileActionsInit:
>> >>> > posixSpawnFileActionsT. posixSpawnFileActionsT free.
>> >>> > 4) The primitive is as simple as:
>> >>> >
>> >>> > primitivePosixSpawnFileActionsInit: aPosixSpawnFileActionsT
>> >>> > ^ self ffiCall: #( int posix_spawn_file_actions_init(void*
>> >>> > aPosixSpawnFileActionsT) ) module: LibC
>> >>> >
>> >>> > I have no idea what I am doing wrong. And again, this works on OSX.
>> The
>> >>> > function I am calling is: int
>> >>> > posix_spawn_file_actions_init(posix_spawn_file_actions_t
>> *file_actions);
>> >>> > as
>> >>> > you can read in [1]
>> >>> >
>> >>> > Below is the stacktrace I get the Linux terminal.
>> >>> >
>> >>> > Any hint is greatly appreciated.
>> >>> >
>> >>> > Thanks,
>> >>> >
>> >>> >
>> >>> > [1]
>> >>> >
>> >>> >
>> http://pubs.opengroup.org/onlinepubs/9699919799/functions/posix_spawn_file_actions_destroy.html
>> >>>
>>
>>
>
>
> --
> Mariano
> http://marianopeck.wordpress.com
>
--
_,,,^..^,,,_
best, Eliot
