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7d0a282a12
Return a NUL string instead of just working by accident with kvm_geterr(3) when MALLOC_PRODUCTION is disabled (I didn't confirm the MALLOC_PRODUCTION being enabled path). Document the new explicit return behavior for kvm_geterr(3), as well as the previous implicit behavior, i.e., the buffer attached to returned via kvm_geterr(3) would be empty if a previous error hadn't been stored in `kd`. Differential Revision: D10022 MFC after: 1 week Reviewed by: vangyzen Sponsored by: Dell EMC Isilon
88 lines
3.0 KiB
Groff
88 lines
3.0 KiB
Groff
.\" Copyright (c) 1992, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software developed by the Computer Systems
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.\" Engineering group at Lawrence Berkeley Laboratory under DARPA contract
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.\" BG 91-66 and contributed to Berkeley.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)kvm_geterr.3 8.1 (Berkeley) 6/4/93
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.\" $FreeBSD$
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.\"
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.Dd March 21, 2017
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.Dt KVM_GETERR 3
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.Os
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.Sh NAME
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.Nm kvm_geterr
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.Nd get error message on kvm descriptor
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.Sh LIBRARY
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.Lb libkvm
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.Sh SYNOPSIS
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.In kvm.h
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.Ft char *
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.Fn kvm_geterr "kvm_t *kd"
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.Sh DESCRIPTION
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This function returns a string describing the most recent error condition
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on the descriptor
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.Fa kd .
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The results are undefined if the most recent
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.Xr kvm 3
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library call did not produce an error.
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The string returned is stored in memory owned by
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.Xr kvm 3
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so the message should be copied out and saved elsewhere if necessary.
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.Sh RETURN VALUES
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The function
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.Fn kvm_geterr
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will return "" if
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.Fa kd
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is
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.Dv NULL
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or an error has not been captured for
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.Fa kd .
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.Sh SEE ALSO
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.Xr kvm 3 ,
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.Xr kvm_close 3 ,
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.Xr kvm_getargv 3 ,
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.Xr kvm_getenvv 3 ,
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.Xr kvm_getprocs 3 ,
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.Xr kvm_nlist 3 ,
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.Xr kvm_open 3 ,
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.Xr kvm_openfiles 3 ,
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.Xr kvm_read 3 ,
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.Xr kvm_write 3
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.Sh BUGS
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This routine cannot be used to access error conditions due to a failed
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.Fn kvm_openfiles
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call, since failure is indicated by returning a
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.Dv NULL
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descriptor.
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Therefore, errors on open are output to the special error buffer
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passed to
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.Fn kvm_openfiles .
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This option is not available to
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.Fn kvm_open .
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