Index: include/unistd.h =================================================================== RCS file: /usr/cvs/src/include/unistd.h,v retrieving revision 1.80 diff -u -r1.80 unistd.h --- include/unistd.h 14 Dec 2006 21:42:03 -0000 1.80 +++ include/unistd.h 9 Jan 2008 21:49:24 -0000 @@ -480,6 +480,7 @@ void endusershell(void); int exect(const char *, char * const *, char * const *); int execvP(const char *, const char *, char * const *); +int feature_present(const char *); char *fflagstostr(u_long); int getdomainname(char *, int); int getgrouplist(const char *, gid_t, gid_t *, int *); Index: lib/libc/gen/Makefile.inc =================================================================== RCS file: /usr/cvs/src/lib/libc/gen/Makefile.inc,v retrieving revision 1.129 diff -u -r1.129 Makefile.inc --- lib/libc/gen/Makefile.inc 8 Jan 2008 21:58:13 -0000 1.129 +++ lib/libc/gen/Makefile.inc 9 Jan 2008 21:49:24 -0000 @@ -10,7 +10,7 @@ clock.c closedir.c confstr.c \ crypt.c ctermid.c daemon.c devname.c dirname.c disklabel.c \ dlfcn.c dlfunc.c drand48.c erand48.c err.c errlst.c errno.c \ - exec.c fmtcheck.c fmtmsg.c fnmatch.c \ + exec.c feature_present.c fmtcheck.c fmtmsg.c fnmatch.c \ fpclassify.c frexp.c fstab.c ftok.c fts.c ftw.c \ getbootfile.c getbsize.c \ getcap.c getcwd.c getdomainname.c getgrent.c getgrouplist.c \ @@ -45,7 +45,8 @@ basename.3 check_utility_compat.3 clock.3 \ confstr.3 ctermid.3 daemon.3 devname.3 directory.3 dirname.3 \ dladdr.3 dlinfo.3 dllockinit.3 dlopen.3 \ - err.3 exec.3 fmtcheck.3 fmtmsg.3 fnmatch.3 fpclassify.3 frexp.3 \ + err.3 exec.3 \ + feature_present.3 fmtcheck.3 fmtmsg.3 fnmatch.3 fpclassify.3 frexp.3 \ ftok.3 fts.3 ftw.3 \ getbootfile.3 getbsize.3 getcap.3 getcontext.3 getcwd.3 \ getdiskbyname.3 getdomainname.3 getfsent.3 \ Index: lib/libc/gen/feature_present.3 =================================================================== RCS file: lib/libc/gen/feature_present.3 diff -N lib/libc/gen/feature_present.3 --- /dev/null 1 Jan 1970 00:00:00 -0000 +++ lib/libc/gen/feature_present.3 9 Jan 2008 21:49:43 -0000 @@ -0,0 +1,72 @@ +.\" Copyright (c) 2008 Yahoo!, Inc. +.\" All rights reserved. +.\" Written by: John Baldwin +.\" +.\" 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. Neither the name of the author nor the names of any co-contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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. +.\" +.\" $FreeBSD$ +.\" +.Dd January 8, 2008 +.Dt feature_present 3 +.Os +.Sh NAME +.Nm feature_present +.Nd query presence of a kernel feature +.Sh LIBRARY +.Lb libc +.Sh SYNOPSIS +.In unistd.h +.Ft int +.Fn feature_present "const char *feature" +.Sh DESCRIPTION +The +.Fn feature_present +function provides a method for an application to determine if a specific +kernel feature is present in the currently running kernel. +The +.Fa feature +argument specifies the name of the feature to check. +The +.Fn feature_present +function will return 1 if the specified feature is present, +otherwise it will return 0. +If the +.Fn feature_present +function is not able to determine the presence of +.Fa feature +due to an internal error it will return 0. +.Sh RETURN VALUES +If +.Fa feature +is present then 1 is returned; +otherwise 0 is returned. +.Sh SEE ALSO +.Xr sysconf 3 , +.Xr sysctl 3 +.Sh HISTORY +The +.Fn feature_present +function first appeared in +.Fx 8.0 . Index: lib/libc/gen/feature_present.c =================================================================== RCS file: lib/libc/gen/feature_present.c diff -N lib/libc/gen/feature_present.c --- /dev/null 1 Jan 1970 00:00:00 -0000 +++ lib/libc/gen/feature_present.c 9 Jan 2008 21:49:43 -0000 @@ -0,0 +1,62 @@ +/*- + * Copyright (c) 2008 Yahoo!, Inc. + * All rights reserved. + * Written by: John Baldwin + * + * 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. Neither the name of the author nor the names of any co-contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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. + */ + +#include +__FBSDID("$FreeBSD$"); + +#include +#include +#include +#include + +/* + * Returns true if the named feature is present in the currently + * running kernel. A feature's presence is indicated by an integer + * sysctl node called kern.feature. that is non-zero. + */ +int +feature_present(const char *feature) +{ + char *mib; + size_t len; + int i; + + if (asprintf(&mib, "kern.features.%s", feature) < 0) + return (0); + len = sizeof(i); + if (sysctlbyname(mib, &i, &len, NULL, 0) < 0) { + free(mib); + return (0); + } + free(mib); + if (len != sizeof(i)) + return (0); + return (i != 0); +}