Date: Tue, 21 Mar 2017 19:02:17 +0000 (UTC) From: Ngie Cooper <ngie@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r315686 - head/lib/libkvm Message-ID: <201703211902.v2LJ2HZL068540@repo.freebsd.org>
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Author: ngie Date: Tue Mar 21 19:02:17 2017 New Revision: 315686 URL: https://svnweb.freebsd.org/changeset/base/315686 Log: kvm_geterr: handle `kd` == NULL in a deterministic/graceful manner 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 Modified: head/lib/libkvm/kvm.c head/lib/libkvm/kvm_geterr.3 Modified: head/lib/libkvm/kvm.c ============================================================================== --- head/lib/libkvm/kvm.c Tue Mar 21 18:02:14 2017 (r315685) +++ head/lib/libkvm/kvm.c Tue Mar 21 19:02:17 2017 (r315686) @@ -66,9 +66,14 @@ static char sccsid[] = "@(#)kvm.c 8.2 (B SET_DECLARE(kvm_arch, struct kvm_arch); +static char _kd_is_null[] = ""; + char * kvm_geterr(kvm_t *kd) { + + if (kd == NULL) + return (_kd_is_null); return (kd->errbuf); } Modified: head/lib/libkvm/kvm_geterr.3 ============================================================================== --- head/lib/libkvm/kvm_geterr.3 Tue Mar 21 18:02:14 2017 (r315685) +++ head/lib/libkvm/kvm_geterr.3 Tue Mar 21 19:02:17 2017 (r315686) @@ -32,7 +32,7 @@ .\" @(#)kvm_geterr.3 8.1 (Berkeley) 6/4/93 .\" $FreeBSD$ .\" -.Dd June 4, 1993 +.Dd March 21, 2017 .Dt KVM_GETERR 3 .Os .Sh NAME @@ -54,6 +54,15 @@ library call did not produce an error. The string returned is stored in memory owned by .Xr kvm 3 so the message should be copied out and saved elsewhere if necessary. +.Sh RETURN VALUES +The function +.Fn kvm_geterr +will return "" if +.Fa kd +is +.Dv NULL +or an error has not been captured for +.Fa kd . .Sh SEE ALSO .Xr kvm 3 , .Xr kvm_close 3 ,
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