On Sat, Jan 9, 2016 at 8:54 PM, Mariano Martinez Peck <marianopeck@gmail.com> 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.
Its probably not 76 bytes in 64-bit though. Can someone on 64-bit report the result of my little C-code sample. Probably its okay initially to waste a few bytes on 32-bit until we have something to calculate these at runtime (btw, what is the current state/plans for such a feature).
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.
Do you have any code samples? Sounds like an interesting thing to have a look at. cheers -ben
Thanks!!
On Sat, Jan 9, 2016 at 9:44 AM, Ben Coman <btc@openinworld.com> wrote:
On Sat, Jan 9, 2016 at 12:15 PM, Ben Coman <btc@openinworld.com> wrote:
On Sat, Jan 9, 2016 at 7:12 AM, Mariano Martinez Peck <marianopeck@gmail.com> wrote:
On Jan 8, 2016 4:13 PM, "Ben Coman" <btc@openinworld.com> wrote:
On Sat, Jan 9, 2016 at 2:04 AM, Mariano Martinez Peck <marianopeck@gmail.com> 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_a...
-- Mariano http://marianopeck.wordpress.com