54fc00f7f9
Don't segfault in kvm_close(3) if provided a NULL pointer. Instead, return -1 and set errno to EINVAL. Document this new behavior explicitly. MFC after: 1 week Reviewed by: vangyzen Sponsored by: Dell EMC Isilon Differential Revision: D10065
272 lines
6.7 KiB
Groff
272 lines
6.7 KiB
Groff
.\" Copyright (c) 1992, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" This code is derived from software developed by the Computer Systems
|
|
.\" Engineering group at Lawrence Berkeley Laboratory under DARPA contract
|
|
.\" BG 91-66 and contributed to Berkeley.
|
|
.\"
|
|
.\" 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.
|
|
.\" 3. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
|
|
.\"
|
|
.\" @(#)kvm_open.3 8.3 (Berkeley) 4/19/94
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd March 20, 2017
|
|
.Dt KVM_OPEN 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm kvm_open ,
|
|
.Nm kvm_open2 ,
|
|
.Nm kvm_openfiles ,
|
|
.Nm kvm_close
|
|
.Nd initialize kernel virtual memory access
|
|
.Sh LIBRARY
|
|
.Lb libkvm
|
|
.Sh SYNOPSIS
|
|
.In fcntl.h
|
|
.In kvm.h
|
|
.Ft kvm_t *
|
|
.Fn kvm_open "const char *execfile" "const char *corefile" "const char *swapfile" "int flags" "const char *errstr"
|
|
.Ft kvm_t *
|
|
.Fo kvm_open2
|
|
.Fa "const char *execfile"
|
|
.Fa "const char *corefile"
|
|
.Fa "int flags"
|
|
.Fa "char *errbuf"
|
|
.Fa "int (*resolver)(const char *name, kvaddr_t *addr)"
|
|
.Fc
|
|
.Ft kvm_t *
|
|
.Fn kvm_openfiles "const char *execfile" "const char *corefile" "const char *swapfile" "int flags" "char *errbuf"
|
|
.Ft int
|
|
.Fn kvm_close "kvm_t *kd"
|
|
.Sh DESCRIPTION
|
|
The functions
|
|
.Fn kvm_open ,
|
|
.Fn kvm_open2 ,
|
|
and
|
|
.Fn kvm_openfiles
|
|
return a descriptor used to access kernel virtual memory
|
|
via the
|
|
.Xr kvm 3
|
|
library routines.
|
|
Both active kernels and crash dumps are accessible
|
|
through this interface.
|
|
.Pp
|
|
The
|
|
.Fa execfile
|
|
argument is the executable image of the kernel being examined.
|
|
This file must contain a symbol table.
|
|
If this argument is
|
|
.Dv NULL ,
|
|
the currently running system is assumed,
|
|
as determined from
|
|
.Xr getbootfile 3 .
|
|
.Pp
|
|
The
|
|
.Fa corefile
|
|
argument is the kernel memory device file.
|
|
It can be either
|
|
.Pa /dev/mem
|
|
or a crash dump core generated by
|
|
.Xr savecore 8 .
|
|
If
|
|
.Fa corefile
|
|
is
|
|
.Dv NULL ,
|
|
the default indicated by
|
|
.Dv _PATH_MEM
|
|
from
|
|
.In paths.h
|
|
is used.
|
|
It can also be set to a special value
|
|
.Pa /dev/null
|
|
by utilities like
|
|
.Xr ps 1
|
|
that do not directly access kernel memory.
|
|
.Pp
|
|
The
|
|
.Fa swapfile
|
|
argument is currently unused.
|
|
.Pp
|
|
The
|
|
.Fa flags
|
|
argument indicates read/write access as in
|
|
.Xr open 2
|
|
and applies only to the core file.
|
|
Only
|
|
.Dv O_RDONLY ,
|
|
.Dv O_WRONLY ,
|
|
and
|
|
.Dv O_RDWR
|
|
are permitted.
|
|
.Pp
|
|
The
|
|
.Nm kvm
|
|
library provides two different error reporting mechanisms.
|
|
One provides backward compatibility with the SunOS kvm library, while the
|
|
other provides an improved error reporting framework.
|
|
The mechanism used by a descriptor is determined by the function used to
|
|
open the descriptor.
|
|
.Pp
|
|
The
|
|
.Fn kvm_open
|
|
function is the Sun kvm compatible open call.
|
|
Here, the
|
|
.Fa errstr
|
|
argument indicates how errors should be handled.
|
|
If it is
|
|
.Dv NULL ,
|
|
no errors are reported and the application cannot know the
|
|
specific nature of the failed kvm call.
|
|
If it is not
|
|
.Dv NULL ,
|
|
errors are printed to
|
|
.Dv stderr
|
|
with
|
|
.Fa errstr
|
|
prepended to the message, as in
|
|
.Xr perror 3 .
|
|
Normally, the name of the program is used here.
|
|
The string is assumed to persist at least until the corresponding
|
|
.Fn kvm_close
|
|
call.
|
|
.Pp
|
|
The
|
|
.Fn kvm_open2
|
|
and
|
|
.Fn kvm_openfiles
|
|
functions provide
|
|
.Bx
|
|
style error reporting.
|
|
Here, error messages are not printed out by the library.
|
|
Instead, the application obtains the error message
|
|
corresponding to the most recent kvm library call using
|
|
.Fn kvm_geterr
|
|
(see
|
|
.Xr kvm_geterr 3 ) .
|
|
The results are undefined if the most recent kvm call did not produce
|
|
an error.
|
|
Since
|
|
.Fn kvm_geterr
|
|
requires a kvm descriptor, but the open routines return
|
|
.Dv NULL
|
|
on failure,
|
|
.Fn kvm_geterr
|
|
cannot be used to get the error message if open fails.
|
|
Thus,
|
|
.Fn kvm_open2
|
|
and
|
|
.Fn kvm_openfiles
|
|
will place any error message in the
|
|
.Fa errbuf
|
|
argument.
|
|
This buffer should be _POSIX2_LINE_MAX characters large (from
|
|
<limits.h>).
|
|
.Pp
|
|
The
|
|
.Fa resolver
|
|
argument points to a function used by the
|
|
.Nm kvm
|
|
library to map symbol names to kernel virtual addresses.
|
|
When the
|
|
.Fa resolver
|
|
function is called,
|
|
.Fa name
|
|
specifies the requested symbol name.
|
|
If the function is able to resolve the name to an address,
|
|
the address should be set in
|
|
.Fa addr
|
|
and the function should return zero.
|
|
If the function is not able to resolve the name to an address,
|
|
it should return a non-zero value.
|
|
When opening a native kernel image,
|
|
.Fa resolver
|
|
may be set to
|
|
.Dv NULL
|
|
to use an internal function to resolve symbol names.
|
|
Non-native kernel images
|
|
.Pq such as when cross-debugging a crash dump
|
|
require a valid
|
|
.Fa resolver .
|
|
.Sh RETURN VALUES
|
|
The
|
|
.Fn kvm_open ,
|
|
.Fn kvm_open2 ,
|
|
and
|
|
.Fn kvm_openfiles
|
|
functions return a descriptor to be used
|
|
in all subsequent kvm library calls.
|
|
The library is fully re-entrant.
|
|
On failure,
|
|
.Dv NULL
|
|
is returned, in which case
|
|
.Fn kvm_open2
|
|
and
|
|
.Fn kvm_openfiles
|
|
write the error message into
|
|
.Fa errbuf .
|
|
.Pp
|
|
.Rv -std kvm_close
|
|
.Sh ERRORS
|
|
The
|
|
.Fn kvm_close
|
|
function may fail and set the global variable
|
|
.Va errno
|
|
for any of the errors specified for
|
|
.Xr close 2 .
|
|
.Pp
|
|
The
|
|
.Fn kvm_close
|
|
function may also fail and set
|
|
.Va errno
|
|
if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EINVAL
|
|
The value passed via
|
|
.Fa kd
|
|
was
|
|
.Dv NULL .
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr close 2 ,
|
|
.Xr open 2 ,
|
|
.Xr kvm 3 ,
|
|
.Xr kvm_getargv 3 ,
|
|
.Xr kvm_getenvv 3 ,
|
|
.Xr kvm_geterr 3 ,
|
|
.Xr kvm_getprocs 3 ,
|
|
.Xr kvm_native 3 ,
|
|
.Xr kvm_nlist 3 ,
|
|
.Xr kvm_read 3 ,
|
|
.Xr kvm_write 3 ,
|
|
.Xr kmem 4 ,
|
|
.Xr mem 4
|
|
.Sh BUGS
|
|
There should not be three open calls.
|
|
The ill-defined error semantics
|
|
of the Sun library and the desire to have a backward-compatible library
|
|
for
|
|
.Bx
|
|
left little choice.
|