pp.platform

#@ $pp_platform: set to the platform identifier (eg, "aix", "linux" etc.)
pp_platform=

#@ pp_set_platform(): sets the $pp_platform variable
#   If --platform is provided, use that and check in the $pp_platforms list
#   Otherwise probe each backend to see if it recognises `uname -s`
#   Uses the $pp_platforms global variable.
pp_set_platform () {
    if test -n "$pp_opt_platform"; then
	pp_contains "$pp_platforms" "$pp_opt_platform" ||
		pp_die "$pp_opt_platform: unknown platform"
	pp_platform="$pp_opt_platform"
    else
	uname_s=`uname -s 2>/dev/null`
	pp_platform=
	for p in $pp_platforms; do
	    pp_debug "probing for platform $p"
	    if eval pp_backend_${p}_detect "$uname_s"; then
		pp_platform="$p"
		break;
	    fi
	done
	test -z "$pp_platform" &&
		pp_die "cannot detect platform (supported: $pp_platforms)"
    fi
    pp_debug "pp_platform = $pp_platform"
}