Date: Fri, 17 Mar 2000 19:29:32 +0100 (CET) From: mikko@dynas.se To: FreeBSD-gnats-submit@freebsd.org Subject: bin/17437: pthread_atfork() missing from libc_r Message-ID: <200003171829.TAA17749@shiba.d.home.dynas.se>
next in thread | raw e-mail | index | archive | help
>Number: 17437 >Category: bin >Synopsis: pthread_atfork() missing from libc_r >Confidential: no >Severity: serious >Priority: high >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Fri Mar 17 10:30:02 PST 2000 >Closed-Date: >Last-Modified: >Originator: Mikko Työläjärvi >Release: FreeBSD 5.0-CURRENT i386 >Organization: >Environment: FreeBSD [345].x >Description: While porting some code using pthreads to FreeBSD, I noticed to my surprise that pthread_atfork() was nowhere to be found, and there did not seem to be any PRs related to the function. So either I am the only one using pthread_atfork(), or it has fallen out of the standard... Most other systems (Solaris, AIX, HP-UX, IRIX and Linux) has the function, and it is documented at: <http://www.opengroup.org/onlinepubs/007908799/xsh/pthread_atfork.html>; Enough complaining. Unless I have seriously misunderstood the workings of libc_r, the patch below should bring pthread_atfork() to FreeBSD (applies against -CURRENT, March 16). It works for me. Someone may want to turn the man-page into proper English too... Regards, /Mikko >How-To-Repeat: Compile anything that uses pthread_atfork()... >Fix: --- lib/libc_r/uthread/Makefile.inc.org Thu Mar 16 22:31:06 2000 +++ lib/libc_r/uthread/Makefile.inc Thu Mar 16 22:31:42 2000 @@ -6,6 +6,7 @@ SRCS+= \ uthread_accept.c \ uthread_aio_suspend.c \ + uthread_atfork.c \ uthread_attr_destroy.c \ uthread_attr_init.c \ uthread_attr_getdetachstate.c \ --- lib/libc_r/man/pthread_atfork.3.orig Fri Mar 17 19:01:53 2000 +++ lib/libc_r/man/pthread_atfork.3 Fri Mar 17 19:01:47 2000 @@ -0,0 +1,73 @@ +.\" +.\" "THE BEER-WARE LICENSE" (Revision 42m): +.\" <mikko@dynas.se> wrote this file. As long as you retain this notice you +.\" can do whatever you want with this stuff. If we meet some day, and you think +.\" this stuff is worth it, you can buy me a beer in return. Mikko Työläjärvi +.\" +.\" $FreeBSD$ +.\" +.Dd March 16, 2000 +.Dt PTHREAD_ATFORK 3 +.Os BSD 4 +.Sh NAME +.Nm pthread_atfork +.Nd register fork handlers +.Sh SYNOPSIS +.Fd #include <pthread.h> +.Ft int +.Fn pthread_atfork "void (*prepare)(void)" "void (*parent)(void)" "void (*child)(void)" +.Sh DESCRIPTION +The +.Fn pthread_atfork +function registers fork handlers to be called before and after +.Fn fork . +Handlers are run in the context of the thread that calls +.Fn fork . +.Pp +The +.Fa prepare +handlers are invoked before fork processing. The +.Fa parent +and +.Fa child +handlers are invoked after fork processing, in the parent and child +processes respectively. +Handlers will be called in the parent process even when the +.Fn fork +operation fails. +.Pp +Any number of handlers can be registered by +.Fn pthread_atfork . +Function pointers that are NULL will be ignored. +The +.Fa Parent +and +.Fa child +handlers are called in the order that they were registered. The +.Fn prepare +handlers are called in the reverse order. +.Pp +.Sh RETURN VALUES +If successful, the +.Fn pthread_atfork +function will return zero. +Otherwise an error number will be returned to +indicate the error. +.Sh ERRORS +.Fn pthread_atfork +will fail if: +.Bl -tag -width Er +.It Bq Er ENOMEM +The process cannot allocate enough memory to register another set of +handlers. +.El +.Pp +.Sh SEE ALSO +.Xr fork 2 , +.Xr atexit 3 +.Sh STANDARDS +.Fn pthread_atfork +conforms to ISO/IEC 9945-1 ANSI/IEEE +.Pq Dq Tn POSIX +.\" XXX: Dunno -- someone will have to check the exact details: +Std 1003.1 Second Edition 1996-07-12. --- lib/libc_r/man/Makefile.inc.org Fri Mar 17 18:42:54 2000 +++ lib/libc_r/man/Makefile.inc Fri Mar 17 18:42:31 2000 @@ -4,7 +4,8 @@ .PATH: ${.CURDIR}/man -MAN3+= pthread_cancel.3 \ +MAN3+= pthread_atfork.3 \ + pthread_cancel.3 \ pthread_cleanup_pop.3 \ pthread_cleanup_push.3 \ pthread_cond_broadcast.3 \ --- include/pthread.h.org Thu Mar 16 22:29:54 2000 +++ include/pthread.h Thu Mar 16 22:37:37 2000 @@ -303,6 +303,9 @@ int pthread_attr_setfloatstate __P((pthread_attr_t *, int)); int pthread_attr_getfloatstate __P((pthread_attr_t *, int *)); + +int pthread_atfork __P((void (*prepare)(void), + void (*parent)(void), void (*child)(void))); __END_DECLS #endif --- lib/libc_r/uthread/pthread_private.h.org Thu Mar 16 22:30:22 2000 +++ lib/libc_r/uthread/pthread_private.h Fri Mar 17 16:26:21 2000 @@ -999,6 +999,16 @@ #define _FD_UNLOCK(_fd,_type) _thread_fd_unlock(_fd, _type) #endif +/* Atfork handlers */ +#define ATFORK_PREPARE 0 +#define ATFORK_PARENT 1 +#define ATFORK_CHILD 2 + +typedef struct atfork_data { + struct atfork_data *next, *prev; + void (*funcs[3])(void); +} atfork_data; + /* * Function prototype definitions. */ @@ -1060,6 +1070,7 @@ void _thread_enter_cancellation_point(void); void _thread_leave_cancellation_point(void); void _thread_cancellation_point(void); +atfork_data *_thread_atfork_list(void); /* #include <signal.h> */ int _thread_sys_sigaction(int, const struct sigaction *, struct sigaction *); --- lib/libc_r/uthread/uthread_atfork.c.org Fri Mar 17 18:37:07 2000 +++ lib/libc_r/uthread/uthread_atfork.c Fri Mar 17 18:27:19 2000 @@ -0,0 +1,56 @@ +/* + * "THE BEER-WARE LICENSE" (Revision 42m): + * <mikko@dynas.se> wrote this file. As long as you retain this notice you + * can do whatever you want with this stuff. If we meet some day, and you think + * this stuff is worth it, you can buy me a beer in return. Mikko Työläjärvi + * + * $FreeBSD$ + */ + +#include <errno.h> +#include <stdlib.h> +#ifdef _THREAD_SAFE +#include <pthread.h> +#include "pthread_private.h" + +static atfork_data *atfork_list = NULL; +static spinlock_t atfork_lock = _SPINLOCK_INITIALIZER; + +int +pthread_atfork(void (*prepare)(void), + void (*parent)(void), + void (*child)(void)) +{ + atfork_data *ap; + + if (prepare == NULL && parent == NULL && child == NULL) + return 0; + + if ((ap = malloc(sizeof(atfork_data))) == NULL) + return ENOMEM; + + ap->funcs[ATFORK_PREPARE] = prepare; + ap->funcs[ATFORK_PARENT] = parent; + ap->funcs[ATFORK_CHILD] = child; + + _SPINLOCK(&atfork_lock); + if ((ap->next = atfork_list) != NULL) + atfork_list->prev = ap; + atfork_list = ap; + _SPINUNLOCK(&atfork_lock); + + return 0; +} + +atfork_data * +_thread_atfork_list(void) +{ + atfork_data *ap; + + _SPINLOCK(&atfork_lock); + ap = atfork_list; + _SPINUNLOCK(&atfork_lock); + + return ap; +} +#endif --- lib/libc_r/uthread/uthread_fork.c.org Fri Mar 17 18:12:22 2000 +++ lib/libc_r/uthread/uthread_fork.c Fri Mar 17 18:10:23 2000 @@ -47,6 +47,16 @@ pid_t ret; pthread_t pthread; pthread_t pthread_save; + atfork_data *ap, *alist; + + /* Run any registered "prepare" callbacks: */ + alist = _thread_atfork_list(); + for (ap = alist; ap != NULL; ap = ap->next) { + if (ap->funcs[ATFORK_PREPARE] != NULL) + ap->funcs[ATFORK_PREPARE](); + if (ap->next == NULL) + break; + } /* * Defer signals to protect the scheduling queues from access @@ -216,6 +226,15 @@ * Undefer and handle pending signals, yielding if necessary: */ _thread_kern_sig_undefer(); + + /* + * Run any parent/child callbacks matching the "prepare" callbacks + * from function entry, in reverse order: + */ + i = ret ? ATFORK_PARENT : ATFORK_CHILD; + for (; ap != NULL; ap = (ap != alist) ? ap->prev : NULL) + if (ap->funcs[i] != NULL) + ap->funcs[i](); /* Return the process ID: */ return (ret); >Release-Note: >Audit-Trail: >Unformatted: To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200003171829.TAA17749>