On Fri, Jan 8, 2016 at 8:41 PM, Nicolai Hess <[email protected]> wrote:

>
>
> 2016-01-09 0:12 GMT+01:00 Mariano Martinez Peck <[email protected]>:
>
>>
>> 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
>>
>
>
> no,  posix_spawn_file_actions_init is not supposed  allocate the structure.
>
> http://linux.die.net/man/3/posix_spawn_file_actions_init:
> "The *posix_spawn_file_actions_init*() function shall *initialize the
> object referenced*
>
>
>
Yeah, damn. And the following text may explain why it DOES work on OSX:

As an implementation detail, the externally visibily type
 *              posix_spawn_file_actions_t is defined to be a void *, and
 *              initialization involves allocation of a memory object.
 *              Subsequent changes to the spawn file actions may result in
 *              reallocation under the covers.


Extracted from
http://www.opensource.apple.com/source/Libc/Libc-583/sys/posix_spawn.c



> 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

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