From 399644e47874bff147afb19c89228901ac39340e Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Mon, 15 Apr 2024 21:40:15 +0200 Subject: Adding upstream version 6.05.01. Signed-off-by: Daniel Baumann --- man3/pthread_atfork.3 | 108 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 108 insertions(+) create mode 100644 man3/pthread_atfork.3 (limited to 'man3/pthread_atfork.3') diff --git a/man3/pthread_atfork.3 b/man3/pthread_atfork.3 new file mode 100644 index 0000000..1bcfc7e --- /dev/null +++ b/man3/pthread_atfork.3 @@ -0,0 +1,108 @@ +.\" Copyright (C) 2017 Michael Kerrisk +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH pthread_atfork 3 2023-03-30 "Linux man-pages 6.05.01" +.SH NAME +pthread_atfork \- register fork handlers +.SH LIBRARY +POSIX threads library +.RI ( libpthread ", " \-lpthread ) +.SH SYNOPSIS +.nf +.B #include +.PP +.BI "int pthread_atfork(void (*" prepare ")(void), void (*" parent ")(void)," +.BI " void (*" child ")(void));" +.fi +.SH DESCRIPTION +The +.BR pthread_atfork () +function registers fork handlers that are to be executed when +.BR fork (2) +is called by any thread in a process. +The handlers are executed in the context of the thread that calls +.BR fork (2). +.PP +Three kinds of handler can be registered: +.IP \[bu] 3 +.I prepare +specifies a handler that is executed in the parent process before +.BR fork (2) +processing starts. +.IP \[bu] +.I parent +specifies a handler that is executed in the parent process after +.BR fork (2) +processing completes. +.IP \[bu] +.I child +specifies a handler that is executed in the child process after +.BR fork (2) +processing completes. +.PP +Any of the three arguments may be NULL if no handler is needed +in the corresponding phase of +.BR fork (2) +processing. +.SH RETURN VALUE +On success, +.BR pthread_atfork () +returns zero. +On error, it returns an error number. +.BR pthread_atfork () +may be called multiple times by a process +to register additional handlers. +The handlers for each phase are called in a specified order: the +.I prepare +handlers are called in reverse order of registration; the +.I parent +and +.I child +handlers are called in the order of registration. +.SH ERRORS +.TP +.B ENOMEM +Could not allocate memory to record the fork handler list entry. +.SH STANDARDS +POSIX.1-2008. +.SH HISTORY +POSIX.1-2001. +.SH NOTES +When +.BR fork (2) +is called in a multithreaded process, +only the calling thread is duplicated in the child process. +The original intention of +.BR pthread_atfork () +was to allow the child process to be returned to a consistent state. +For example, at the time of the call to +.BR fork (2), +other threads may have locked mutexes that are visible in the +user-space memory duplicated in the child. +Such mutexes would never be unlocked, +since the threads that placed the locks are not duplicated in the child. +The intent of +.BR pthread_atfork () +was to provide a mechanism whereby the application (or a library) +could ensure that mutexes and other process and thread state would be +restored to a consistent state. +In practice, this task is generally too difficult to be practicable. +.PP +After a +.BR fork (2) +in a multithreaded process returns in the child, +the child should call only async-signal-safe functions (see +.BR signal\-safety (7)) +until such time as it calls +.BR execve (2) +to execute a new program. +.PP +POSIX.1 specifies that +.BR pthread_atfork () +shall not fail with the error +.BR EINTR . +.SH SEE ALSO +.BR fork (2), +.BR atexit (3), +.BR pthreads (7) -- cgit v1.2.3