Re: compat linux pipe2() circus

2011-09-20 Thread Mark Kettenis 
 Date: Tue, 20 Sep 2011 01:41:35 +0300
 From: Paul Irofti p...@irofti.net
 
 Linux keeps surprising me everytime!
 
 This time its their pipe2 system call which adds flags to the pipe call.
 Its the unix-ish way apparently to turn pipes into files on a kernel
 filesystem, or so they claim.
 
 Anywho, this fixes glibc pipe2 system calls by wrapping against the
 regular pipe systemcall if no flags are set and by signaling we don't
 support that if they are.
 
 Okay?
 
 
 Index: linux_ipc.c
 ===
 RCS file: /cvs/src/sys/compat/linux/linux_ipc.c,v
 retrieving revision 1.11
 diff -u -p -r1.11 linux_ipc.c
 --- linux_ipc.c   5 Sep 2009 10:28:43 -   1.11
 +++ linux_ipc.c   19 Sep 2011 22:37:33 -
 @@ -719,3 +719,21 @@ linux_shmctl(p, v, retval)
   }
  }
  #endif /* SYSVSHM */
 +
 +int
 +linux_sys_pipe2(struct proc *p, void *v, register_t *retval)
 +{
 + struct linux_sys_pipe2_args *uap = v;
 + struct sys_pipe_args pargs;
 +
 + /*
 +  * We don't really support pipe2, but glibc falls back to pipe
 +  * we return signal that.
 +  * /
 + if (SCARG(uap, flags) != 0)
 + return ENOSYS;

Don't unimplemented system calls return ENOSYS already?  Then the
comment makes no sense.  Because if glibc falls back on pipe if pipe2
fails, you don't need this code at all.

 +
 + /* If no flag is set then the this is a plain pipe call. */
 + SCARG(pargs, fdp) = SCARG(uap, fdp);
 + return sys_pipe(p, pargs, retval);
 +}

Re: compat linux pipe2() circus

2011-09-20 Thread Ariane van der Steldt 
On Tue, Sep 20, 2011 at 09:47:45AM +0200, Mark Kettenis wrote:
  Date: Tue, 20 Sep 2011 01:41:35 +0300
  From: Paul Irofti p...@irofti.net
  
  Linux keeps surprising me everytime!
  
  This time its their pipe2 system call which adds flags to the pipe call.
  Its the unix-ish way apparently to turn pipes into files on a kernel
  filesystem, or so they claim.
  
  Anywho, this fixes glibc pipe2 system calls by wrapping against the
  regular pipe systemcall if no flags are set and by signaling we don't
  support that if they are.
  
  Okay?
  
  
  Index: linux_ipc.c
  ===
  RCS file: /cvs/src/sys/compat/linux/linux_ipc.c,v
  retrieving revision 1.11
  diff -u -p -r1.11 linux_ipc.c
  --- linux_ipc.c 5 Sep 2009 10:28:43 -   1.11
  +++ linux_ipc.c 19 Sep 2011 22:37:33 -
  @@ -719,3 +719,21 @@ linux_shmctl(p, v, retval)
  }
   }
   #endif /* SYSVSHM */
  +
  +int
  +linux_sys_pipe2(struct proc *p, void *v, register_t *retval)
  +{
  +   struct linux_sys_pipe2_args *uap = v;
  +   struct sys_pipe_args pargs;
  +
  +   /*
  +* We don't really support pipe2, but glibc falls back to pipe
  +* we return signal that.
  +* /
  +   if (SCARG(uap, flags) != 0)
  +   return ENOSYS;
 
 Don't unimplemented system calls return ENOSYS already?  Then the
 comment makes no sense.  Because if glibc falls back on pipe if pipe2
 fails, you don't need this code at all.

The comment is wrong.
Glibc invokes the pipe2 syscall when the pipe() function is called.
Linux does still have the regular pipe() system call, it's a wrapper
around pipe2 (ofcourse that doesn't help us if glibc doesn't use it).

  +
  +   /* If no flag is set then the this is a plain pipe call. */
  +   SCARG(pargs, fdp) = SCARG(uap, fdp);
  +   return sys_pipe(p, pargs, retval);
  +}
 

The comment should change, but I'm fine with the code.
-- 
Ariane

compat linux pipe2() circus

2011-09-19 Thread Paul Irofti 
Linux keeps surprising me everytime!

This time its their pipe2 system call which adds flags to the pipe call.
Its the unix-ish way apparently to turn pipes into files on a kernel
filesystem, or so they claim.

Anywho, this fixes glibc pipe2 system calls by wrapping against the
regular pipe systemcall if no flags are set and by signaling we don't
support that if they are.

Okay?


Index: linux_ipc.c
===
RCS file: /cvs/src/sys/compat/linux/linux_ipc.c,v
retrieving revision 1.11
diff -u -p -r1.11 linux_ipc.c
--- linux_ipc.c 5 Sep 2009 10:28:43 -   1.11
+++ linux_ipc.c 19 Sep 2011 22:37:33 -
@@ -719,3 +719,21 @@ linux_shmctl(p, v, retval)
}
 }
 #endif /* SYSVSHM */
+
+int
+linux_sys_pipe2(struct proc *p, void *v, register_t *retval)
+{
+   struct linux_sys_pipe2_args *uap = v;
+   struct sys_pipe_args pargs;
+
+   /*
+* We don't really support pipe2, but glibc falls back to pipe
+* we return signal that.
+* /
+   if (SCARG(uap, flags) != 0)
+   return ENOSYS;
+
+   /* If no flag is set then the this is a plain pipe call. */
+   SCARG(pargs, fdp) = SCARG(uap, fdp);
+   return sys_pipe(p, pargs, retval);
+}
Index: linux_syscall.h
===
RCS file: /cvs/src/sys/compat/linux/linux_syscall.h,v
retrieving revision 1.66
diff -u -p -r1.66 linux_syscall.h
--- linux_syscall.h 19 Sep 2011 14:33:40 -  1.66
+++ linux_syscall.h 19 Sep 2011 22:37:34 -
@@ -1,10 +1,10 @@
-/* $OpenBSD: linux_syscall.h,v 1.66 2011/09/19 14:33:40 pirofti Exp $  
*/
+/* $OpenBSD$   */
 
 /*
  * System call numbers.
  *
  * DO NOT EDIT-- this file is automatically generated.
- * created fromOpenBSD: syscalls.master,v 1.62 2011/09/18 02:23:18 
pirofti Exp 
+ * created fromOpenBSD: syscalls.master,v 1.63 2011/09/19 14:33:14 
pirofti Exp 
  */
 
 /* syscall: syscall ret: int args: */
@@ -747,5 +747,8 @@
 
 /* syscall: get_robust_list ret: int args: int struct 
linux_robust_list_head ** size_t * */
 #defineLINUX_SYS_get_robust_list   312
+
+/* syscall: pipe2 ret: int args: int * int */
+#defineLINUX_SYS_pipe2 331
 
 #defineLINUX_SYS_MAXSYSCALL338
Index: linux_syscallargs.h
===
RCS file: /cvs/src/sys/compat/linux/linux_syscallargs.h,v
retrieving revision 1.68
diff -u -p -r1.68 linux_syscallargs.h
--- linux_syscallargs.h 19 Sep 2011 14:33:40 -  1.68
+++ linux_syscallargs.h 19 Sep 2011 22:37:35 -
@@ -1,10 +1,10 @@
-/* $OpenBSD: linux_syscallargs.h,v 1.68 2011/09/19 14:33:40 pirofti Exp $  
*/
+/* $OpenBSD$   */
 
 /*
  * System call argument lists.
  *
  * DO NOT EDIT-- this file is automatically generated.
- * created fromOpenBSD: syscalls.master,v 1.62 2011/09/18 02:23:18 
pirofti Exp 
+ * created fromOpenBSD: syscalls.master,v 1.63 2011/09/19 14:33:14 
pirofti Exp 
  */
 
 #ifdef syscallarg
@@ -610,6 +610,11 @@ struct linux_sys_get_robust_list_args {
syscallarg(size_t *) len;
 };
 
+struct linux_sys_pipe2_args {
+   syscallarg(int *) fdp;
+   syscallarg(int) flags;
+};
+
 /*
  * System call prototypes.
  */
@@ -876,3 +881,4 @@ int linux_sys_clock_gettime(struct proc 
 intlinux_sys_clock_getres(struct proc *, void *, register_t *);
 intlinux_sys_set_robust_list(struct proc *, void *, register_t *);
 intlinux_sys_get_robust_list(struct proc *, void *, register_t *);
+intlinux_sys_pipe2(struct proc *, void *, register_t *);
Index: linux_syscalls.c
===
RCS file: /cvs/src/sys/compat/linux/linux_syscalls.c,v
retrieving revision 1.66
diff -u -p -r1.66 linux_syscalls.c
--- linux_syscalls.c19 Sep 2011 14:33:40 -  1.66
+++ linux_syscalls.c19 Sep 2011 22:37:35 -
@@ -1,10 +1,10 @@
-/* $OpenBSD: linux_syscalls.c,v 1.66 2011/09/19 14:33:40 pirofti Exp $ 
*/
+/* $OpenBSD$   */
 
 /*
  * System call names.
  *
  * DO NOT EDIT-- this file is automatically generated.
- * created fromOpenBSD: syscalls.master,v 1.62 2011/09/18 02:23:18 
pirofti Exp 
+ * created fromOpenBSD: syscalls.master,v 1.63 2011/09/19 14:33:14 
pirofti Exp 
  */
 
 char *linux_syscallnames[] = {
@@ -359,7 +359,7 @@ char *linux_syscallnames[] = {
#328 (unimplemented eventfd2),/* 328 = unimplemented 
eventfd2 */
#329 (unimplemented epoll_create1),   /* 329 = unimplemented 
epoll_create1 */
#330 (unimplemented dup3),/* 330 = unimplemented dup3 */
-   #331 (unimplemented pipe2),   /* 331 = unimplemented pipe2 */
+   pipe2,/* 331 = pipe2 */
#332 (unimplemented inotify_init1),   /* 332 = unimplemented 
inotify_init1 */
#333 (unimplemented preadv),

Re: compat linux pipe2() circus

2011-09-19 Thread Joerg Sonnenberger 
On Tue, Sep 20, 2011 at 01:41:35AM +0300, Paul Irofti wrote:
 This time its their pipe2 system call which adds flags to the pipe call.
 Its the unix-ish way apparently to turn pipes into files on a kernel
 filesystem, or so they claim.

No, the idea is to make it possible to set O_CLOEXEC atomically. Of
course, the pipe2 system call as implemented in Linux is kind of messed
up, since the flag attribute applies to both sides of the pipe. The use
cases of pipes that don't involve exec are limited (using pipes to
terminate poll/select loops from signal handles, communication between a
fork'd hord of children), so I am kind of waiting for pipe3 to appear...

Joerg

Re: compat linux pipe2() circus

2011-09-19 Thread Matthew Dempsky 
On Mon, Sep 19, 2011 at 4:22 PM, Joerg Sonnenberger
jo...@britannica.bec.de wrote:
 No, the idea is to make it possible to set O_CLOEXEC atomically. Of
 course, the pipe2 system call as implemented in Linux is kind of messed
 up, since the flag attribute applies to both sides of the pipe.

If you need O_CLOEXEC, you want it to apply to both fds anyway, even
if you plan on passing one fd to a child process.  You just turn the
appropriate cloexec flag back off after calling fork(2).