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 69The 70.Fa execfile 71argument is the executable image of the kernel being examined. 72This file must contain a symbol table. 73If this argument is 74.Dv NULL , 75the currently running system is assumed, 76as determined from 77.Xr getbootfile 3 . 78.Pp 79The 80.Fa corefile 81argument is the kernel memory device file. It can be either /dev/mem 82or a crash dump core generated by 83.Xr savecore 8 . 84If 85.Fa corefile 86is 87.Dv NULL , 88the default indicated by 89.Dv _PATH_MEM 90from <paths.h> is used. 91.Pp 92The 93.Fa swapfile 94argument is currently unused. 95.Pp 96The 97.Fa flags 98argument indicates read/write access as in 99.Xr open 2 100and applies only to the core file. 101Only 102.Dv O_RDONLY , 103.Dv O_WRONLY , 104and 105.Dv O_RDWR 106are permitted. 107.Pp 108There are two open routines which differ only with respect to 109the error mechanism. 110One provides backward compatibility with the SunOS kvm library, while the 111other provides an improved error reporting framework. 112.Pp 113The 114.Fn kvm_open 115function is the Sun kvm compatible open call. Here, the 116.Fa errstr 117argument indicates how errors should be handled. If it is 118.Dv NULL , 119no errors are reported and the application cannot know the 120specific nature of the failed kvm call. 121If it is not 122.Dv NULL , 123errors are printed to 124.Dv stderr 125with 126.Fa errstr 127prepended to the message, as in 128.Xr perror 3 . 129Normally, the name of the program is used here. 130The string is assumed to persist at least until the corresponding 131.Fn kvm_close 132call. 133.Pp 134The 135.Fn kvm_openfiles 136function provides 137.Bx 138style error reporting. 139Here, error messages are not printed out by the library. 140Instead, the application obtains the error message 141corresponding to the most recent kvm library call using 142.Fn kvm_geterr 143(see 144.Xr kvm_geterr 3 ) . 145The results are undefined if the most recent kvm call did not produce 146an error. 147Since 148.Fn kvm_geterr 149requires a kvm descriptor, but the open routines return 150.Dv NULL 151on failure, 152.Fn kvm_geterr 153cannot be used to get the error message if open fails. 154Thus, 155.Fn kvm_openfiles 156will place any error message in the 157.Fa errbuf 158argument. This buffer should be _POSIX2_LINE_MAX characters large (from 159<limits.h>). 160.Sh RETURN VALUES 161The 162.Fn kvm_open 163and 164.Fn kvm_openfiles 165functions both return a descriptor to be used 166in all subsequent kvm library calls. 167The library is fully re-entrant. 168On failure, 169.Dv NULL 170is returned, in which case 171.Fn kvm_openfiles 172writes the error message into 173.Fa errbuf . 174.Pp 175The 176.Fn kvm_close 177function returns 0 on success and -1 on failure. 178.Sh BUGS 179There should not be two open calls. The ill-defined error semantics 180of the Sun library and the desire to have a backward-compatible library 181for 182.Bx 183left little choice. 184.Sh SEE ALSO 185.Xr open 2 , 186.Xr kvm 3 , 187.Xr kvm_getargv 3 , 188.Xr kvm_getenvv 3 , 189.Xr kvm_geterr 3 , 190.Xr kvm_getprocs 3 , 191.Xr kvm_nlist 3 , 192.Xr kvm_read 3 , 193.Xr kvm_write 3 194