mirror of
https://github.com/freebsd/freebsd-src
synced 2024-07-22 10:48:02 +00:00
kcmp: Add a manual page
Reviewed by: kib, emaste MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D43562
This commit is contained in:
parent
2e9b8c8c1e
commit
af0d437dd3
|
@ -215,6 +215,7 @@ MAN+= abort2.2 \
|
|||
ioctl.2 \
|
||||
issetugid.2 \
|
||||
jail.2 \
|
||||
kcmp.2 \
|
||||
kenv.2 \
|
||||
kill.2 \
|
||||
kldfind.2 \
|
||||
|
|
230
lib/libc/sys/kcmp.2
Normal file
230
lib/libc/sys/kcmp.2
Normal file
|
@ -0,0 +1,230 @@
|
|||
.\" SPDX-License-Identifier: BSD-2-Clause
|
||||
.\"
|
||||
.\" Copyright (c) 2024 The FreeBSD Foundation
|
||||
.\"
|
||||
.\" This documentation was written by
|
||||
.\" Mark Johnston <markj@FreeBSD.org> under sponsorship
|
||||
.\" from the FreeBSD Foundation.
|
||||
.\"
|
||||
.\" 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 AUTHORS 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 AUTHORS 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.
|
||||
.\"
|
||||
.Dd January 23, 2024
|
||||
.Dt KCMP 2
|
||||
.Os
|
||||
.Sh NAME
|
||||
.Nm kcmp
|
||||
.Nd compare two kernel objects
|
||||
.Sh LIBRARY
|
||||
.Lb libc
|
||||
.Sh SYNOPSIS
|
||||
.In unistd.h
|
||||
.Ft int
|
||||
.Fn kcmp "pid_t pid1" "pid_t pid2" "int type" "uintptr_t idx1" "uintptr_t idx2"
|
||||
.Sh DESCRIPTION
|
||||
The
|
||||
.Nm
|
||||
system call allows the caller to determine whether the two processes with
|
||||
PIDs
|
||||
.Fa pid1
|
||||
and
|
||||
.Fa pid2
|
||||
reference the same kernel object.
|
||||
The
|
||||
.Fa type
|
||||
parameter specifies the type of object, and
|
||||
.Fa idx1
|
||||
and
|
||||
.Fa idx2
|
||||
are identifiers which refer to some object in the context of process
|
||||
.Fa pid1
|
||||
and
|
||||
.Fa pid2 ,
|
||||
respectively.
|
||||
.Pp
|
||||
The following values for
|
||||
.Fa type
|
||||
may be specified:
|
||||
.Bl -tag -width KCMP_FILE
|
||||
.It Dv KCMP_FILE
|
||||
Compare two file descriptions referred to by file descriptors
|
||||
.Fa idx1
|
||||
and
|
||||
.Fa idx2 .
|
||||
They may be equivalent if, for example, one of the descriptors was
|
||||
created by applying
|
||||
.Xr dup 2
|
||||
to the other descriptor.
|
||||
.It Dv KCMP_FILEOBJ
|
||||
Perform a
|
||||
.Dq deep comparison
|
||||
of the file descriptions referred to by file descriptors
|
||||
.Fa idx1
|
||||
and
|
||||
.Fa idx2 .
|
||||
This tests whether the underlying object referred to by the file descriptions
|
||||
is the same.
|
||||
For example, if the same filesystem path is opened twice, the kernel will create
|
||||
two separate file descriptions to back the two file descriptors, but they will
|
||||
refer to the same underlying object, a
|
||||
.Xr vnode 9 .
|
||||
When compared using the
|
||||
.Dv KCMP_FILE
|
||||
type, these descriptors will be different, but using the
|
||||
.Dv KCMP_FILEOBJ
|
||||
type, they will be equal (assuming that the path was not unlinked in between
|
||||
the two opens).
|
||||
.It Dv KCMP_FILES
|
||||
Determine whether the two processes share the same file descriptor table.
|
||||
This will be the case if one of the processes was created by
|
||||
.Xr rfork 2
|
||||
without specifying the
|
||||
.Dv RFFDG
|
||||
flag.
|
||||
The
|
||||
.Fa idx1
|
||||
and
|
||||
.Fa idx2
|
||||
parameters are ignored.
|
||||
.It Dv KCMP_SIGHAND
|
||||
Determine whether the two processes share the same signal handler table.
|
||||
This will be the case if one of the processes was created using the
|
||||
.Dv RFSIGSHARE
|
||||
flag to
|
||||
.Xr rfork 2 .
|
||||
The
|
||||
.Fa idx1
|
||||
and
|
||||
.Fa idx2
|
||||
parameters are ignored.
|
||||
.It Dv KCMP_VM
|
||||
Determine whether the two processes share a virtual memory address space.
|
||||
This may be the case if one of the processes created the other using
|
||||
.Xr vfork 2
|
||||
or
|
||||
.Xr rfork 2
|
||||
with the
|
||||
.Dv RFMEM
|
||||
flag.
|
||||
The
|
||||
.Fa idx1
|
||||
and
|
||||
.Fa idx2
|
||||
parameters are ignored.
|
||||
.El
|
||||
The caller of
|
||||
.Nm
|
||||
must have permission to debug both processes, otherwise the system call
|
||||
will fail.
|
||||
.Sh RETURN VALUES
|
||||
If
|
||||
.Fa idx1
|
||||
and
|
||||
.Fa idx2
|
||||
refer to the same object,
|
||||
.Nm
|
||||
returns 0.
|
||||
If the object referred to by
|
||||
.Fa pid1
|
||||
and
|
||||
.Fa idx1
|
||||
is less or greater than the object referred to by
|
||||
.Fa pid2
|
||||
and
|
||||
.Fa idx2 ,
|
||||
.Nm
|
||||
returns the values 1 and 2, respectively.
|
||||
The order is defined internally by the kernel and is stable until the system
|
||||
reboots.
|
||||
If the two objects cannot be compared for some reason,
|
||||
.Nm
|
||||
returns 3.
|
||||
For example, if
|
||||
.Fa type
|
||||
is
|
||||
.Dv KCMP_FILEOBJ
|
||||
and
|
||||
.Fa idx1
|
||||
and
|
||||
.Fa idx2
|
||||
are different descriptor types, e.g., a socket and a file, then
|
||||
.Nm
|
||||
will return 3.
|
||||
.Pp
|
||||
If an error occurs, the value -1 is returned and the global variable
|
||||
.Va errno
|
||||
is set to indicate the error.
|
||||
.Sh ERRORS
|
||||
.Nm
|
||||
may fail with the following errors:
|
||||
.Bl -tag -width Er
|
||||
.It Bq Er ENODEV
|
||||
.Dv KCMP_FILEOBJ
|
||||
was specified and
|
||||
.Fa idx1
|
||||
refers to a file descriptor which does not implement a comparison operator.
|
||||
.It Bq Er EINVAL
|
||||
The value of
|
||||
.Fa type
|
||||
is invalid.
|
||||
.It Bq Er EBADF
|
||||
One of the file descriptors referred to by
|
||||
.Fa idx1
|
||||
or
|
||||
.Fa idx2
|
||||
is not valid.
|
||||
.It Bq Er ESRCH
|
||||
One of the processes referred to by
|
||||
.Fa pid1
|
||||
or
|
||||
.Fa pid2
|
||||
does not exist or is not visible (e.g., due to jail restrictions).
|
||||
.It Bq Er EPERM
|
||||
The caller does not have permission to access one of the processes referred to
|
||||
by
|
||||
.Fa pid1
|
||||
or
|
||||
.Fa pid2 .
|
||||
.El
|
||||
.Sh SEE ALSO
|
||||
.Xr dup 2 ,
|
||||
.Xr fcntl 2 ,
|
||||
.Xr fork 2 ,
|
||||
.Xr rfork 2 ,
|
||||
.Xr vfork 2
|
||||
.Sh STANDARDS
|
||||
The
|
||||
.Nm
|
||||
system call originated in Linux.
|
||||
This implementation aims to be source-compatible with the Linux implementation.
|
||||
.Fx
|
||||
implements only a subset of the possible values for
|
||||
.Fa type
|
||||
supported in Linux.
|
||||
More values may be added in the future.
|
||||
The
|
||||
.Dv KCMP_FILEOBJ
|
||||
type is a FreeBSD extension.
|
||||
.Sh HISTORY
|
||||
The
|
||||
.Nm
|
||||
function was introduced in
|
||||
.Fx 14.1 .
|
Loading…
Reference in a new issue