[src/trunk]: src/etc In rc.subr, add _have_rc_postprocessor function and use ...

[apb <apb%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/32f18dc30e82
branches:  trunk
changeset: 331025:32f18dc30e82
user:      apb <apb%NetBSD.org@localhost>
date:      Sun Jul 27 07:46:46 2014 +0000

description:
In rc.subr, add _have_rc_postprocessor function and use it instead of
inline tests like [ -n "${_rc_postprocessor_fd}" ]. The new function
performs a few new tests, including verifying that /etc/rc is still
running (using a new _rc_pid variable set by /etc/rc).

This is intended to deal with the case that a script run from /etc/rc
spawns a background process, then /etc/rc exits, but the background
process still has environment variables inherited from /etc/rc.

Fixes PR 46546.

diffstat:

 etc/rc      |   3 ++-
 etc/rc.subr |  49 +++++++++++++++++++++++++++++++++++++++----------
 2 files changed, 41 insertions(+), 11 deletions(-)

diffs (118 lines):

diff -r 3b088cf55e64 -r 32f18dc30e82 etc/rc
--- a/etc/rc    Sun Jul 27 04:46:48 2014 +0000
+++ b/etc/rc    Sun Jul 27 07:46:46 2014 +0000
@@ -1,6 +1,6 @@
 #!/bin/sh
 #
-# $NetBSD: rc,v 1.168 2014/04/09 12:45:05 apb Exp $
+# $NetBSD: rc,v 1.169 2014/07/27 07:46:46 apb Exp $
 #
 # rc --
 #      Run the scripts in /etc/rc.d with rcorder, and log output
@@ -84,6 +84,7 @@
        # with redirected output.
        #
        _rc_postprocessor_fd=9 ; export _rc_postprocessor_fd
+       _rc_pid=$$ ; export _rc_pid
        eval "exec ${_rc_postprocessor_fd}>&1"
 
        # Print a metadata line when we exit
diff -r 3b088cf55e64 -r 32f18dc30e82 etc/rc.subr
--- a/etc/rc.subr       Sun Jul 27 04:46:48 2014 +0000
+++ b/etc/rc.subr       Sun Jul 27 07:46:46 2014 +0000
@@ -1,4 +1,4 @@
-# $NetBSD: rc.subr,v 1.93 2014/07/22 17:11:09 wiz Exp $
+# $NetBSD: rc.subr,v 1.94 2014/07/27 07:46:46 apb Exp $
 #
 # Copyright (c) 1997-2011 The NetBSD Foundation, Inc.
 # All rights reserved.
@@ -786,6 +786,35 @@
 }
 
 #
+# _have_rc_postprocessor
+#      Test whether the current script is running in a context that
+#      was invoked from /etc/rc with a postprocessor.
+#
+#      If the test fails, some variables may be unset to make
+#      such tests more efficient in future.
+#
+_have_rc_postprocessor()
+{
+       # Cheap tests that fd and pid are set, fd is writable.
+       [ -n "${_rc_postprocessor_fd}" ] || return 1
+       [ -n "${_rc_pid}" ] || return 1
+       eval ": >&${_rc_postprocessor_fd}" 2>/dev/null || return 1
+
+       # More expensive test that pid is running.
+       # Unset _rc_pid if this fails.
+       kill -0 "${_rc_pid}" 2>/dev/null \
+       || { unset _rc_pid; return 1; }
+
+       # More expensive test that pid appears to be
+       # a shell running an rc script.
+       # Unset _rc_pid if this fails.
+       expr "$(ps -p "${_rc_pid}" -o command=)" : ".*sh .*/rc.*" >/dev/null \
+       || { unset _rc_pid; return 1; }
+
+       return 0
+}
+
+#
 # run_rc_script file arg
 #      Start the script `file' with `arg', and correctly handle the
 #      return value from the script.  If `file' ends with `.sh', it's
@@ -794,9 +823,8 @@
 #      executable run as a child process.
 #
 #      If `file' contains "KEYWORD: interactive" and if we are
-#      running inside /etc/rc with postprocessing (as signified by
-#      _rc_postprocessor_fd being defined) then the script's stdout
-#      and stderr are redirected to $_rc_original_stdout_fd and
+#      running inside /etc/rc with postprocessing, then the script's
+#      stdout and stderr are redirected to $_rc_original_stdout_fd and
 #      $_rc_original_stderr_fd, so the output will be displayed on the
 #      console but not intercepted by /etc/rc's postprocessor.
 #
@@ -816,7 +844,7 @@
        eval unset ${_arg}_cmd ${_arg}_precmd ${_arg}_postcmd
 
        _must_redirect=false
-       if [ -n "${_rc_postprocessor_fd}" ] \
+       if _have_rc_postprocessor \
            && _has_rcorder_keyword interactive $_file
        then
                _must_redirect=true
@@ -1114,7 +1142,7 @@
        # _rc_postprocessor fd, if defined, is the fd to which we must
        # print, prefixing the output with $_rc_metadata_prefix.
        #
-       if [ -n "$_rc_postprocessor_fd" ]; then
+       if _have_rc_postprocessor; then
                command printf "%s%s\n" "$rc_metadata_prefix" "$1" \
                        >&${_rc_postprocessor_fd}
        fi
@@ -1154,10 +1182,11 @@
 #
 print_rc_normal()
 {
-       # If _rc_postprocessor_fd is defined, then it is the fd
-       # to which we must print; otherwise print to stdout.
+       # print to stdout or _rc_postprocessor_fd, depending on
+       # whether not we have an rc postprocessor.
        #
-       local fd="${_rc_postprocessor_fd:-1}"
+       local fd=1
+       _have_rc_postprocessor && fd="${_rc_postprocessor_fd}"
        case "$1" in
        "-n")
                command printf "%s" "$2" >&${fd}
@@ -1186,7 +1215,7 @@
 #
 no_rc_postprocess()
 {
-       if [ -n "${_rc_postprocessor_fd}" ]; then
+       if _have_rc_postprocessor; then
                "$@" >&${_rc_original_stdout_fd} 2>&${_rc_original_stderr_fd}
        else
                "$@"