Re: misc/46546: powerd script fails due to spurious environment variable

[Alan Barrett <apb%cequrux.com@localhost>]

The following reply was made to PR misc/46546; it has been noted by GNATS.

From: Alan Barrett <apb%cequrux.com@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: misc/46546: powerd script fails due to spurious environment
 variable
Date: Fri, 25 Jul 2014 18:39:35 +0200

 --bAmEntskrkuBymla
 Content-Type: text/plain; charset=us-ascii; format=flowed
 Content-Disposition: inline
 
 Please try the attached patch, which attempts to notice when a process that 
 was started under control of /etc/rc no longer has access to /etc/rc's output 
 postprocessor (which will be the case for daemons launched from rc.d scripts).
 
 --apb (Alan Barrett)
 
 --bAmEntskrkuBymla
 Content-Type: text/plain; charset=us-ascii
 Content-Disposition: attachment; filename="pr46546.patch"
 
 Index: etc/rc
 ===================================================================
 --- etc/rc     9 Apr 2014 12:45:05 -0000       1.168
 +++ etc/rc     25 Jul 2014 12:35:33 -0000
 @@ -84,6 +84,7 @@ rc_real_work()
        # 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
 Index: etc/rc.subr
 ===================================================================
 --- etc/rc.subr        17 Dec 2012 18:17:27 -0000      1.92
 +++ etc/rc.subr        25 Jul 2014 14:45:13 -0000
 @@ -786,6 +786,35 @@ $command $rc_flags $command_args"
  }
  
  #
 +# _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 @@ $command $rc_flags $command_args"
  #     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 @@ run_rc_script()
        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 @@ print_rc_metadata()
        # _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 @@ _flush_rc_output()
  #
  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 @@ print_rc_normal()
  #
  no_rc_postprocess()
  {
 -      if [ -n "${_rc_postprocessor_fd}" ]; then
 +      if _have_rc_postprocessor; then
                "$@" >&${_rc_original_stdout_fd} 2>&${_rc_original_stderr_fd}
        else
                "$@"
 
 --bAmEntskrkuBymla--