Simplify detection of Capsicum support.

This removes support for FreeBSD 10.0 and 10.1 which used
<sys/capability.h> instead of <sys/capsicum.h>. Support for
FreeBSD 10.1 ended on 2016-12-31. So now FreeBSD >= 10.2 is
required to enable Capsicum support.

This also removes support for Capsicum on Linux (libcaprights)
which seems to have been unmaintained since 2017 and Linux 4.11:
https://github.com/google/capsicum-linux

configure.ac

@@ -1051,12 +1051,12 @@ AM_CONDITIONAL([COND_CRC_CLMUL], [test "x$enable_clmul_crc" = xyes])
 # Check for sandbox support. If one is found, set enable_sandbox=found.
 AS_CASE([$enable_sandbox],
 	[auto | capsicum], [
-		AX_CHECK_CAPSICUM([enable_sandbox=found], [:])
+		AC_CHECK_FUNCS([cap_rights_limit], [enable_sandbox=found])
 	]
 )
 AS_CASE([$enable_sandbox],
 	[auto | pledge], [
-		AC_CHECK_FUNCS([pledge], [enable_sandbox=found ; break])
+		AC_CHECK_FUNCS([pledge], [enable_sandbox=found])
 	]
 )
 

m4/ax_check_capsicum.m4

@@ -1,85 +0,0 @@
-# -*- Autoconf -*-
-
-# SYNOPSIS
-#
-#   AX_CHECK_CAPSICUM([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
-#
-# DESCRIPTION
-#
-#   This macro searches for an installed Capsicum header and library,
-#   and if found:
-#     - AC_DEFINE([HAVE_CAPSICUM]) is called.
-#     - AC_DEFINE([HAVE_SYS_CAPSICUM_H]) is called if <sys/capsicum.h>
-#       is present (otherwise <sys/capability.h> must be used).
-#     - CAPSICUM_LIB is set to the -l option needed to link Capsicum support,
-#       and AC_SUBST([CAPSICUM_LIB]) is called.
-#     - The shell commands in ACTION-IF-FOUND are run. The default
-#       ACTION-IF-FOUND prepends ${CAPSICUM_LIB} into LIBS. If you don't
-#       want to modify LIBS and don't need to run any other commands either,
-#       use a colon as ACTION-IF-FOUND.
-#
-#   If Capsicum support isn't found:
-#     - The shell commands in ACTION-IF-NOT-FOUND are run. The default
-#       ACTION-IF-NOT-FOUND calls AC_MSG_WARN to print a warning that
-#       Capsicum support wasn't found.
-#
-#   You should use autoheader to include a definition for the symbols above
-#   in a config.h file.
-#
-#   Sample usage in a C/C++ source is as follows:
-#
-#     #ifdef HAVE_CAPSICUM
-#     # ifdef HAVE_SYS_CAPSICUM_H
-#     #  include <sys/capsicum.h>
-#     # else
-#     #  include <sys/capability.h>
-#     # endif
-#     #endif /* HAVE_CAPSICUM */
-#
-# LICENSE
-#
-#   Copyright (c) 2014 Google Inc.
-#   Copyright (c) 2015 Lasse Collin <lasse.collin@tukaani.org>
-#
-#   Copying and distribution of this file, with or without modification,
-#   are permitted in any medium without royalty provided the copyright
-#   notice and this notice are preserved.  This file is offered as-is,
-#   without any warranty.
-
-#serial 2
-
-AC_DEFUN([AX_CHECK_CAPSICUM], [
-# On FreeBSD >= 11.x and Linux, Capsicum is uses <sys/capsicum.h>.
-# If this header is found, it is assumed to be the right one.
-capsicum_header_found=no
-AC_CHECK_HEADERS([sys/capsicum.h], [capsicum_header_found=yes])
-if test "$capsicum_header_found" = no ; then
-    # On FreeBSD 10.x Capsicum uses <sys/capability.h>. Such a header exists
-    # on Linux too but it describes POSIX.1e capabilities. Look for the
-    # declaration of cap_rights_limit to check if <sys/capability.h> is
-    # a Capsicum header.
-    AC_CHECK_DECL([cap_rights_limit], [capsicum_header_found=yes], [],
-                  [#include <sys/capability.h>])
-fi
-
-capsicum_lib_found=no
-CAPSICUM_LIB=
-if test "$capsicum_header_found" = yes ; then
-    AC_LANG_PUSH([C])
-    # FreeBSD >= 10.x has Capsicum functions in libc.
-    AC_LINK_IFELSE([AC_LANG_CALL([], [cap_rights_limit])],
-                   [capsicum_lib_found=yes], [])
-    # Linux has Capsicum functions in libcaprights.
-    AC_CHECK_LIB([caprights], [cap_rights_limit],
-                 [CAPSICUM_LIB=-lcaprights
-                  capsicum_lib_found=yes], [])
-    AC_LANG_POP([C])
-fi
-AC_SUBST([CAPSICUM_LIB])
-
-if test "$capsicum_lib_found" = yes ; then
-    AC_DEFINE([HAVE_CAPSICUM], [1], [Define to 1 if Capsicum is available.])
-    m4_default([$1], [LIBS="${CAPSICUM_LIB} $LIBS"])
-else
-    m4_default([$2], [AC_MSG_WARN([Capsicum support not found])])
-fi])

src/xz/Makefile.am

@@ -53,7 +53,7 @@ xz_CPPFLAGS = \
 	-I$(top_srcdir)/src/liblzma/api \
 	-I$(top_builddir)/lib
 
-xz_LDADD = $(top_builddir)/src/liblzma/liblzma.la $(CAPSICUM_LIB)
+xz_LDADD = $(top_builddir)/src/liblzma/liblzma.la
 
 if COND_GNULIB
 xz_LDADD += $(top_builddir)/lib/libgnu.a

src/xz/file_io.c

@@ -29,12 +29,8 @@ static bool warn_fchown;
 #	include <utime.h>
 #endif
 
-#ifdef HAVE_CAPSICUM
-#	ifdef HAVE_SYS_CAPSICUM_H
-#		include <sys/capsicum.h>
-#	else
-#		include <sys/capability.h>
-#	endif
+#ifdef HAVE_CAP_RIGHTS_LIMIT
+#	include <sys/capsicum.h>
 #endif
 
 #include "tuklib_open_stdxxx.h"
@@ -214,8 +210,8 @@ io_sandbox_enter(int src_fd)
 	// characters have been loaded. This is needed at least with glibc.
 	tuklib_mbstr_width(dummy_str, NULL);
 
-#ifdef HAVE_CAPSICUM
-	// Capsicum needs FreeBSD 10.0 or later.
+#ifdef HAVE_CAP_RIGHTS_LIMIT
+	// Capsicum needs FreeBSD 10.2 or later.
 	cap_rights_t rights;
 
 	if (cap_enter())
@@ -266,7 +262,7 @@ io_sandbox_enter(int src_fd)
 	return;
 
 error:
-#ifdef HAVE_CAPSICUM
+#ifdef HAVE_CAP_RIGHTS_LIMIT
 	// If a kernel is configured without capability mode support or
 	// used in an emulator that does not implement the capability
 	// system calls, then the Capsicum system calls will fail and set

src/xz/private.h

@@ -52,7 +52,7 @@
 #	define STDERR_FILENO (fileno(stderr))
 #endif
 
-#if defined(HAVE_CAPSICUM) || defined(HAVE_PLEDGE)
+#if defined(HAVE_CAP_RIGHTS_LIMIT) || defined(HAVE_PLEDGE)
 #	define ENABLE_SANDBOX 1
 #endif