1.\" Copyright (c) 1992, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software developed by the Computer Systems 5.\" Engineering group at Lawrence Berkeley Laboratory under DARPA contract 6.\" BG 91-66 and contributed to Berkeley. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. All advertising materials mentioning features or use of this software 17.\" must display the following acknowledgement: 18.\" This product includes software developed by the University of 19.\" California, Berkeley and its contributors. 20.\" 4. Neither the name of the University nor the names of its contributors 21.\" may be used to endorse or promote products derived from this software 22.\" without specific prior written permission. 23.\" 24.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34.\" SUCH DAMAGE. 35.\" 36.\" @(#)kvm_open.3 8.3 (Berkeley) 4/19/94 37.\" $FreeBSD$ 38.\" 39.Dd April 19, 1994 40.Dt KVM_OPEN 3 41.Os 42.Sh NAME 43.Nm kvm_open , 44.Nm kvm_openfiles , 45.Nm kvm_close 46.Nd initialize kernel virtual memory access 47.Sh LIBRARY 48.Lb libkvm 49.Sh SYNOPSIS 50.In fcntl.h 51.In kvm.h 52.Ft kvm_t * 53.Fn kvm_open "const char *execfile" "const char *corefile" "const char *swapfile" "int flags" "const char *errstr" 54.Ft kvm_t * 55.Fn kvm_openfiles "const char *execfile" "const char *corefile" "const char *swapfile" "int flags" "char *errbuf" 56.Ft int 57.Fn kvm_close "kvm_t *kd" 58.Sh DESCRIPTION 59The functions 60.Fn kvm_open 61and 62.Fn kvm_openfiles 63return a descriptor used to access kernel virtual memory 64via the 65.Xr kvm 3 66library routines. Both active kernels and crash dumps are accessible 67through this interface. 68.Pp 69.Fa execfile 70is the executable image of the kernel being examined. 71This file must contain a symbol table. 72If this argument is 73.Dv NULL , 74the currently running system is assumed, 75as determined from 76.Xr getbootfile 3 . 77.Pp 78.Fa corefile 79is the kernel memory device file. It can be either /dev/mem 80or a crash dump core generated by 81.Xr savecore 8 . 82If 83.Fa corefile 84is 85.Dv NULL , 86the default indicated by 87.Dv _PATH_MEM 88from <paths.h> is used. 89.Pp 90The 91.Fa swapfile 92argument is currently unused. 93.Pp 94The 95.Fa flags 96argument indicates read/write access as in 97.Xr open 2 98and applies only to the core file. 99Only 100.Dv O_RDONLY , 101.Dv O_WRONLY , 102and 103.Dv O_RDWR 104are permitted. 105.Pp 106There are two open routines which differ only with respect to 107the error mechanism. 108One provides backward compatibility with the SunOS kvm library, while the 109other provides an improved error reporting framework. 110.Pp 111The 112.Fn kvm_open 113function is the Sun kvm compatible open call. Here, the 114.Fa errstr 115argument indicates how errors should be handled. If it is 116.Dv NULL , 117no errors are reported and the application cannot know the 118specific nature of the failed kvm call. 119If it is not 120.Dv NULL , 121errors are printed to stderr with 122.Fa errstr 123prepended to the message, as in 124.Xr perror 3 . 125Normally, the name of the program is used here. 126The string is assumed to persist at least until the corresponding 127.Fn kvm_close 128call. 129.Pp 130The 131.Fn kvm_openfiles 132function provides 133.Bx 134style error reporting. 135Here, error messages are not printed out by the library. 136Instead, the application obtains the error message 137corresponding to the most recent kvm library call using 138.Fn kvm_geterr 139(see 140.Xr kvm_geterr 3 ) . 141The results are undefined if the most recent kvm call did not produce 142an error. 143Since 144.Fn kvm_geterr 145requires a kvm descriptor, but the open routines return 146.Dv NULL 147on failure, 148.Fn kvm_geterr 149cannot be used to get the error message if open fails. 150Thus, 151.Fn kvm_openfiles 152will place any error message in the 153.Fa errbuf 154argument. This buffer should be _POSIX2_LINE_MAX characters large (from 155<limits.h>). 156.Sh RETURN VALUES 157The 158.Fn kvm_open 159and 160.Fn kvm_openfiles 161functions both return a descriptor to be used 162in all subsequent kvm library calls. 163The library is fully re-entrant. 164On failure, 165.Dv NULL 166is returned, in which case 167.Fn kvm_openfiles 168writes the error message into 169.Fa errbuf . 170.Pp 171The 172.Fn kvm_close 173function returns 0 on success and -1 on failure. 174.Sh BUGS 175There should not be two open calls. The ill-defined error semantics 176of the Sun library and the desire to have a backward-compatible library 177for 178.Bx 179left little choice. 180.Sh SEE ALSO 181.Xr open 2 , 182.Xr kvm 3 , 183.Xr kvm_getargv 3 , 184.Xr kvm_getenvv 3 , 185.Xr kvm_geterr 3 , 186.Xr kvm_getprocs 3 , 187.Xr kvm_nlist 3 , 188.Xr kvm_read 3 , 189.Xr kvm_write 3 190