new toy to play with

diff --git a/eclass/check-reqs.eclass b/eclass/check-reqs.eclass
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+# Copyright 1999-2004 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+# $Header: /var/cvsroot/gentoo-x86/eclass/check-reqs.eclass,v 1.1 2004/11/19 20:57:31 ciaranm Exp $
+#
+# Original Author: Ciaran McCreesh <ciaranm@gentoo.org>
+#
+# This eclass provides a uniform way of handling ebuilds which have very high
+# build requirements in terms of memory or disc space. It provides a function
+# which should usually be called during pkg_setup().
+#
+# From a user perspective, the variable BUILDREQS_ACTION can be set to:
+#    * "warn" (default), which will display a warning and wait for 15s
+#    * "error", which will make the ebuild error out
+#    * "ignore", which will not take any action
+# The chosen action only happens when the system's resources are detected
+# correctly and only if they are below the threshold specified by the package.
+#
+# For ebuild authors: only use this eclass if you reaaalllllly have stupidly
+# high build requirements. At an absolute minimum, you shouldn't be using this
+# unless the ebuild needs >256MBytes RAM or >1GByte temporary or install space.
+# The code should look something like:
+#
+# pkg_setup() {
+#     # values in MBytes
+#
+#     # need this much memory (does *not* check swap)
+#     BUILDREQS_MEMORY="256"
+#
+#     # need this much temporary build space
+#     BUILDREQS_DISK_BUILD="2048"
+#
+#     # install will need this much space in /usr
+#     BUILDREQS_DISK_USR="1024"
+#
+#     # install will need this much space in /var
+#     BUILDREQS_DISK_VAR="1024"
+#
+#     # go!
+#     check_reqs
+# }
+#
+# You should *not* override the user's BUILDREQS_ACTION setting, nor should you
+# attempt to provide a value if it is unset. Note that the environment variables
+# are used rather than parameters for a few reasons:
+#   * easier to do if use blah ; then things
+#   * we might add in additional requirements things later
+# If you don't specify a value for, say, BUILDREQS_MEMORY, then the test is not
+# carried out.
+#
+# These checks should probably mostly work on non-Linux, and they should
+# probably degrade gracefully if they don't. Probably.
+
+inherit eutils
+
+ECLASS=check-reqs
+INHERITED="$INHERITED $ECLASS"
+
+check_reqs() {
+       [ -n "$1" ] && die "Usage: check_reqs"
+
+       export BUILDREQS_NEED_SLEEP="" BUILDREQS_NEED_DIE=""
+       if [ "$BUILDREQS_ACTION" != "ignore" ] ; then
+               [ -n "$BUILDREQS_MEMORY" ] && check_build_memory
+               [ -n "$BUILDREQS_DISK_BUILD" ] && check_build_disk \
+                       "${PORTAGE_TMPDIR}" "\${PORTAGE_TMPDIR}" "${BUILDREQS_DISK_BUILD}"
+               [ -n "$BUILDREQS_DISK_USR" ] && check_build_disk \
+                       "${ROOT}/usr"  "\${ROOT}/usr" "${BUILDREQS_DISK_USR}"
+               [ -n "$BUILDREQS_DISK_VAR" ] && check_build_disk \
+                       "${ROOT}/var"  "\${ROOT}/var" "${BUILDREQS_DISK_VAR}"
+       fi
+
+       if [ -n "${BUILDREQS_NEED_SLEEP}" ] ; then
+               echo
+               ewarn "Bad things may happen! You may abort the build by pressing ctrl+c in"
+               ewarn "the next 15 seconds."
+               ewarn " "
+               einfo "To make this kind of warning a fatal error, add a line to /etc/make.conf"
+               einfo "setting BUILDREQS_ACTION=\"error\". To skip build requirements checking,"
+               einfo "set BUILDREQS_ACTION=\"ignore\"."
+               epause 15
+       fi
+
+       if [ -n "${BUILDREQS_NEED_DIE}" ] ; then
+               eerror "Bailing out as specified by BUILDREQS_ACTION"
+               die "Build requirements not met"
+       fi
+}
+
+# internal use only!
+check_build_memory() {
+       [ -n "$1" ] && die "Usage: check_build_memory"
+       check_build_msg_begin "${BUILDREQS_MEMORY}" "MBytes" "RAM"
+       if [ -r /proc/meminfo ] ; then
+               actual_memory=$(sed -n -e '/MemTotal:/s/^[^:]*: *\([0-9]\+\) kB/\1/p' \
+                       /proc/meminfo)
+       else
+               actual_memory=$(sysctl hw.physmem 2>/dev/null )
+               [ "$?" == "0" ] &&
+                       actual_memory=$(echo $actual_memory | sed -e 's/^[^:=]*[:=]//' )
+       fi
+       if [ -n "${actual_memory}" ] ; then
+               if [ ${actual_memory} -lt $((1024 * ${BUILDREQS_MEMORY})) ] ; then
+                       eend 1
+                       check_build_msg_ick "${BUILDREQS_MEMORY}" "MBytes" "RAM"
+               else
+                       eend 0
+               fi
+       else
+               eend 1
+               ewarn "Couldn't determine amount of memory, skipping ..."
+       fi
+}
+
+# internal use only!
+check_build_disk() {
+       [ -z "$3" ] && die "Usage: check_build_disk where name needed"
+       check_build_msg_begin "${3}" "MBytes" \
+                       "disk space at ${2}"
+       actual_space=$(df -Pm ${1} 2>/dev/null | sed -n \
+                       '$s/\(\S\+\s\+\)\{3\}\([0-9]\+\).*/\2/p' 2>/dev/null )
+       if [ "$?" == "0" ] && [ -n "${actual_space}" ] ; then
+               if [ ${actual_space} -lt ${3} ] ; then
+                       eend 1
+                       check_build_msg_ick "${3}" "MBytes" \
+                                       "disk space at ${2}"
+               else
+                       eend 0
+               fi
+       else
+               eend 1
+               ewarn "Couldn't figure out disk space, skipping ..."
+       fi
+}
+
+# internal use only!
+check_build_msg_begin() {
+       ebegin "Checking for at least ${1}${2} ${3}"
+}
+
+# internal use only!
+check_build_msg_skip() {
+       ewarn "Skipping check for at least ${1}${2} ${3}"
+}
+
+# internal use only!
+check_build_msg_ick() {
+       if [ "${BUILDREQS_ACTION}" == "error" ] ; then
+               eerror "Don't have at least ${1}${2} ${3}"
+               echo
+               export BUILDREQS_NEED_DIE="yes"
+       else
+               ewarn "Don't have at least ${1}${2} ${3}"
+               echo
+               export BUILDREQS_NEED_SLEEP="yes"
+       fi
+}
+