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Diffstat (limited to 'lib/libc/sys/pdfork.2')
-rw-r--r-- | lib/libc/sys/pdfork.2 | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/lib/libc/sys/pdfork.2 b/lib/libc/sys/pdfork.2 new file mode 100644 index 0000000..3f36e88 --- /dev/null +++ b/lib/libc/sys/pdfork.2 @@ -0,0 +1,182 @@ +.\" +.\" Copyright (c) 2009-2010 Robert N. M. Watson +.\" All rights reserved. +.\" +.\" This software was developed at the University of Cambridge Computer +.\" Laboratory with support from a grant from Google, Inc. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" $FreeBSD$ +.\" +.Dd August 16, 2011 +.Dt PDFORK 2 +.Os +.Sh NAME +.Nm pdfork , +.Nm pdgetpid , +.Nm pdkill , +.Nm pdwait4 +.Nd System calls to manage process descriptors +.Sh LIBRARY +.Lb libc +.Sh SYNOPSIS +.In sys/procdesc.h +.Ft int +.Fn pdfork "int *fdp" "int flags" +.Ft int +.Fn pdgetpid "int fd" "pid_t *pidp" +.Ft int +.Fn pdkill "int fd" "int signum" +.Ft int +.Fn pdwait4 "int fd" "int *status" "int options" "struct rusage *rusage" +.Sh DESCRIPTION +Process descriptors are special file descriptors that represent processes, +and are created using +.Fn pdfork , +a variant of +.Xr fork 2 , +which, if successful, returns a process descriptor in the integer pointed to +by +.Fa pidp . +Processes created via +.Fn pdfork +will not cause +.Dv SIGCHLD +on termination. +.Fn pdfork +can accept the flags: +.Bl -tag -width ".Dv PD_DAEMON" +.It Dv PD_DAEMON +Instead of the default terminate-on-close behaviour, allow the process to +live until it is explicitly killed with +.Xr kill 2 . +.Pp +This option is not permitted in Capsicum capability mode (see +.Xr cap_enter 2 ) . +.El +.Pp +.Fn pdgetpid +queries the process ID (PID) if the process descriptor +.Fa fd . +.Pp +.Fn pdkill +is functionally identical to +.Xr kill 2 , +except that it accepts a process descriptor, +.Fa fd , +rather than a PID. +.Pp +.Fn pdwait4 +behaves identially to +.Xr wait4 2 , +but operates with respect to a process descriptor argument rather than a PID. +.Pp +The following system calls also have effects specific to process descriptors: +.Pp +.Xr fstat 2 +queries status of a process descriptor; currently only the +.Fa st_mode , +.Fa st_birthtime , +.Fa st_atime , +.Fa st_ctime +and +.Fa st_mtime +fields are defined. If the owner read, write, and execute bits are set then the +process represented by the process descriptor is still alive. +.Pp +.Xr poll 2 +and +.Xr select 2 +allow waiting for process state transitions; currently only +.Dv POLLHUP +is defined, and will be raised when the process dies. +.Pp +.Xr close 2 +will close the process descriptor unless +.Dv PD_DAEMON +is set; if the process is still alive and this is +the last reference to the process descriptor, the process will be terminated +with the signal +.Dv SIGKILL . +.Sh RETURN VALUES +.Fn pdfork +returns a PID, 0 or -1, as +.Xr fork 2 +does. +.Pp +.Fn pdgetpid +and +.Fn pdkill +return 0 on success and -1 on failure. +.Pp +.Fn pdwait4 +returns a PID on success and -1 on failure. +.Sh ERRORS +These functions may return the same error numbers as their PID-based equivalents +(e.g. +.Fn pdfork +may return the same error numbers as +.Xr fork 2 ) , +with the following additions: +.Bl -tag -width Er +.It Bq Er EINVAL +The signal number given to +.Fn pdkill +is invalid. +.It Bq Er ENOTCAPABLE +The process descriptor being operated on has insufficient rights (e.g. +.Dv CAP_PDKILL +for +.Fn pdkill ) . +.El +.Sh SEE ALSO +.Xr close 2 , +.Xr fork 2 , +.Xr fstat 2 , +.Xr kill 2 , +.Xr poll 2 , +.Xr wait4 2 +.Sh HISTORY +The +.Fn pdfork , +.Fn pdgetpid , +.Fn pdkill +and +.Fn pdwait4 +system calls first appeared in +.Fx 9.0 . +.Pp +Support for process descriptors mode was developed as part of the +.Tn TrustedBSD +Project. +.Sh AUTHORS +.An -nosplit +These functions and the capability facility were created by +.An "Robert N. M. Watson" Aq rwatson@FreeBSD.org +and +.An "Jonathan Anderson" Aq jonathan@FreeBSD.org +at the University of Cambridge Computer Laboratory with support from a grant +from Google, Inc. +.Sh BUGS +.Fn pdwait4 +has not yet been implemented. |