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+.\" 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. All advertising materials mentioning features or use of this software
+.\"    must display the following acknowledgement:
+.\"	This product includes software developed by the University of
+.\"	California, Berkeley and its contributors.
+.\" 4. 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
+.\"
+.Dd April 19, 1994
+.Dt KVM_OPEN 3
+.Os
+.Sh NAME
+.Nm kvm_open ,
+.Nm kvm_openfiles ,
+.Nm kvm_close
+.Nd initialize kernel virtual memory access
+.Sh SYNOPSIS
+.Fd #include <fcntl.h>
+.Fd #include <kvm.h>
+.br
+.Ft kvm_t *
+.Fn kvm_open "const char *execfile" "const char *corefile" "char *swapfile" "int flags" "const char *errstr"
+.Ft kvm_t *
+.Fn kvm_openfiles "const char *execfile" "const char *corefile" "char *swapfile" "int flags" "char *errbuf"
+.Ft int
+.Fn kvm_close "kvm_t *kd"
+.Sh DESCRIPTION
+The functions
+.Fn kvm_open
+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
+.Fa execfile
+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,
+which is indicated by
+.Dv _PATH_UNIX
+in <paths.h>.
+.Pp
+.Fa corefile 
+is the kernel memory device file.  It can be either /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 <paths.h> is used.
+.Pp
+.Fa swapfile
+should indicate the swap device.  If
+.Dv NULL ,
+.Dv _PATH_DRUM
+from <paths.h> is used.
+.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
+There are two open routines which differ only with respect to 
+the error mechanism.
+One provides backward compatibility with the SunOS kvm library, while the
+other provides an improved error reporting framework.
+.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 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_openfiles
+function provides BSD 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_openfiles
+will place any error message in the
+.Fa errbuf
+argument.  This buffer should be _POSIX2_LINE_MAX characters large (from
+<limits.h>).
+.Sh RETURN VALUES
+The
+.Fn kvm_open
+and 
+.Fn kvm_openfiles
+functions both 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_openfiles
+writes the error message into 
+.Fa errbuf .
+.Pp
+The
+.Fn kvm_close
+function returns 0 on success and -1 on failure.
+.Sh BUGS
+There should not be two open calls.  The ill-defined error semantics
+of the Sun library and the desire to have a backward-compatible library
+for BSD left little choice.
+.Sh SEE ALSO
+.Xr open 2 ,
+.Xr kvm 3 ,
+.Xr kvm_getargv 3 ,
+.Xr kvm_getenvv 3 ,
+.Xr kvm_geterr 3 ,
+.Xr kvm_getprocs 3 ,
+.Xr kvm_nlist 3 ,
+.Xr kvm_read 3 ,
+.Xr kvm_write 3