From 7803305f1afd9476e372c0d9c5c4357153bd3a73 Mon Sep 17 00:00:00 2001
From: Koichi Murase <myoga.murase@gmail.com>
Date: Sun, 12 Mar 2023 20:10:03 +0900
Subject: [PATCH] lib: add "util.bgproc" for "ble/util/bgproc"

---
 GNUmakefile        |   1 +
 contrib            |   2 +-
 docs/ChangeLog.md  |   4 +-
 lib/util.bgproc.sh | 460 +++++++++++++++++++++++++++++++++++++++++++++
 make_command.sh    |   1 +
 note.txt           |  98 ++++++++++
 src/util.sh        |  14 +-
 7 files changed, 575 insertions(+), 5 deletions(-)
 create mode 100644 lib/util.bgproc.sh

diff --git a/GNUmakefile b/GNUmakefile
index beccf5e0..790ab87f 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -98,6 +98,7 @@ outfiles += $(OUTDIR)/lib/test-decode.sh
 outfiles += $(OUTDIR)/lib/test-edit.sh
 outfiles += $(OUTDIR)/lib/test-syntax.sh
 outfiles += $(OUTDIR)/lib/test-complete.sh
+outfiles += $(OUTDIR)/lib/util.bgproc.sh
 $(OUTDIR)/lib/%.sh: lib/%.sh | $(OUTDIR)/lib
 	cp -p $< $@
 $(OUTDIR)/lib/%.txt: lib/%.txt | $(OUTDIR)/lib
diff --git a/contrib b/contrib
index b4978f81..bfc1670e 160000
--- a/contrib
+++ b/contrib
@@ -1 +1 @@
-Subproject commit b4978f8126bcd478e5fb5657be7806e2a672b217
+Subproject commit bfc1670e9ca473af6db1eb7b5ccabda44dd896e5
diff --git a/docs/ChangeLog.md b/docs/ChangeLog.md
index 3a9e3731..d77b4ada 100644
--- a/docs/ChangeLog.md
+++ b/docs/ChangeLog.md
@@ -138,7 +138,8 @@
 - decode: accept isolated <kbd>ESC \<char\></kbd> (requested by mozirilla213) `#D2004` d7210494
 - sabbrev: add widget `magic-slash` to approximate Zsh named directories (motivated by mozirilla213) `#D2008` e6b9581c
 - sabbrev: support inline and linewise sabbre with `ble-sabbrev -il` `#D2012` 56208534
-- complete: add `bleopt complete_source_sabbrev_{opts,ignore}` (motivated by mozirilla213) `#D2013` f95eb0cc `#D2016` xxxxxxxx
+- complete: add `bleopt complete_source_sabbrev_{opts,ignore}` (motivated by mozirilla213) `#D2013` f95eb0cc `#D2016` 45c76746
+- util.bgproc: separate `ble/util/bgproc` from `histdb` (motivated by bkerin) `#D2017` xxxxxxxx
 
 ## Changes
 
@@ -615,6 +616,7 @@
   - histdb: fix `.timeout` not set for background `sqlite3` `#D1982` 20b42fa
   - histdb: suppress color codes in the default `histdb_remarks` `#D1968` 20b42fa
   - histdb: disable timeout of background processes in Bash 3.2 `#D1992` 20b42fa
+  - histdb: rewrite to use `ble/util/bgproc` `#D2017` xxxxxxxx
 - integration: move `fzf` and `bash-preexec` integrations to subdir `#D1939` 86d9467
 
 <!---------------------------------------------------------------------------->
diff --git a/lib/util.bgproc.sh b/lib/util.bgproc.sh
new file mode 100644
index 00000000..24f97d81
--- /dev/null
+++ b/lib/util.bgproc.sh
@@ -0,0 +1,460 @@
+# -*- mode: sh; mode: sh-bash -*-
+
+## @fn ble/util/bgproc#open prefix command [opts]
+##   Start a session for a background process.  The session can be closed by
+##   calling "ble/util/bgproc#close PREFIX".  The background process is usually
+##   started on the start of the session and terminated on closing the session.
+##   In addition, if requested, the background process can be stopped and
+##   started any time in the session.  If the background process is stopped
+##   when it is needed, it is automatically restarted.  If "timeout=TIMEOUT" is
+##   specified in OPTS, the background process is automatically stopped where
+##   there is no access for the time duration specified by TIMEOUT.
+##
+##   @param[in] prefix
+##     This names the identifier of the bgproc.  This is actually used as the
+##     prefix of the array names used to store the information of the created
+##     bgproc, so the value needs to be a valid variable name.
+##
+##     When the bgproc is successfully created, the following array elements
+##     are set, (where PREFIX in the variable name is replaced by the value of
+##     prefix).
+##
+##     @var PREFIX_bgproc[0]       ... fd_response
+##     @var PREFIX_bgproc[1]       ... fd_request
+##     @var PREFIX_bgproc[2]       ... command
+##     @var PREFIX_bgproc[3]       ... opts
+##     @var PREFIX_bgproc[4]       ... bgpid
+##     @var PREFIX_bgproc_fname[0] ... fname_response
+##     @var PREFIX_bgproc_fname[1] ... fname_request
+##     @var PREFIX_bgproc_fname[2] ... fname_run_pid
+##
+##     To send strings to stdin of the background process, one can write to the
+##     file descriptor ${PREFIX_bgproc[1]}.  To read strings coming from stdout
+##     of the background process, one can read from the file descriptor
+##     ${PREFIX_bgproc[0]}.
+##
+##     When any of "timeout=TIMEOUT", "deferred", and "restart" are specified
+##     to OPTS, one should call "ble/util/bgproc#use PREFIX" just before
+##     directly accesssing the file descriptors ${PREFIX_bgproc[0]} and
+##     ${PREFIX_bgproc[1]} to ensure that the background process is running.
+##     Or, one can use a shorthand "ble/util/bgproc#post PREFIX STRING" to
+##     ensure the background process and write STRING to it.  Immediately after
+##     "ble/util/bgproc#post PREFIX STRING", one do not need to call
+##     "ble/util/bgproc#use PREFIX" to read from ${PREFIX_bgproc[0]}.
+##
+##   @param[in] command
+##     The command to execute.
+##
+##     Note: If the command wants to access the variable names "bgproc" and
+##     "bgproc_fname" defined outside the command, please save the values in
+##     other names of variables before calling "ble/util/bgproc#open" and
+##     access those alternative variables from inside the command.  The
+##     variable names "bgproc" and "bgproc_fname" are hidden by the local
+##     variables used by ble/util/bgproc itself.
+##
+##   @param[in,opt] opts
+##     A colon-separated list of options.  The following options can be
+##     specified.
+##
+##     deferred
+##       When this option is specified, the background process is initially not
+##       started.  It will be started when it is first required.
+##
+##     restart
+##       When this option is specified, if the background process died
+##       unexpectedly, the background process will be restarted when it becomes
+##       necessary.
+##
+##       Note: Even if this option is unspecified, the background process that
+##       was intensiontally stopped will be always restarted when it becomes
+##       necessary.  This option only affects the case that the background
+##       process exited or died outside the management of bgproc.
+##
+##     timeout=TIMEOUT
+##       When this option is specified, the background process is stopped when
+##       there are no access to the background process for the time duration
+##       specified by TIMEOUT.  The unit of TIMEOUT is millisecond.
+##
+##     owner-close-on-unload
+##       This option suppresses the automatic call of "ble/util/bgproc#close"
+##       from the "unload" blehook.  This option is useful when another
+##       "unload" blehook needs to access to this bgproc.  When this option is
+##       specified, another "unload" blehook needs to manually call
+##       "ble/util/bgproc#close" for this bgproc.  If "ble/util/bgproc#close"
+##       is not called, the background process may be forcibly terminated by
+##       the final cleaup stage of ble.sh session.
+##
+##     no-close-on-unload
+##       This option suppresses the automatic call of "ble/util/bgproc#close"
+##       and any cleanups of the background process, so that the background
+##       process survives after Bash terminates or ble.sh has been unloaded.
+##
+##       Note: Nevertheless, file descriptors at the side of the parent shell
+##       will be closed on the termination of the parent shell, which can cause
+##       SIGPIPE write error or EOF read error in the background process.
+##
+##     kill-timeout=TIMEOUT
+##       This option specifies the timeout after the attempt of stopping the
+##       background process in unit of millisecond.  The default is 10000 (10
+##       seconds).  If the background process does not terminate within the
+##       timeout after closing the file descriptors at the side of the parent
+##       shell, the background process will receive SIGTERM.  If it does not
+##       terminate even after sending SIGTERM, it will then receive SIGKILL
+##       after additional 10 seconds.
+##
+##   @exit 0 if the background process is successfully started or "deferred" is
+##   specified to OPTS.  2 if an invalid prefix value is specified.  3 if the
+##   system does not support named pipes.  1 if the background process failed
+##   to be started.
+##
+## @fn ble/util/bgproc/onstart:PREFIX
+##   When this function is defined, this function is called after the new
+##   background process is created.
+##
+## @fn ble/util/bgproc/onstop:PREFIX
+##   When this function is defined, this function is called before the
+##   background process is stopped.
+##
+##   The application can send an intruction to terminate the background process
+##   in this hook (in case that the background process does not automatically
+##   end on the close of the file descriptors, or the file descriptors can be
+##   shared with other background subshells).  Note that the background process
+##   will receive SIGTERM or SIGKILL if it does not terminate within the
+##   timeout specified by kill-timeout=TIMEOUT.
+##
+## @fn ble/util/bgproc/onclose:PREFIX
+##   When this function is defined, this function is called before the bgproc
+##   session is closed.
+##
+## @fn ble/util/bgproc/ontimeout:PREFIX
+##   When this function is defined, this function is called before the timeout
+##   specified by "timeout=TIMEOUT" in OPTS.  If this function exits with
+##   non-zero status, the timeout is canceled.
+##
+function ble/util/bgproc#open {
+  if ! ble/string#match "$1" '^[_a-zA-Z][_a-zA-Z0-9]*$'; then
+    ble/util/print "$FUNCNAME: $1: invalid prefix value." >&2
+    return 2
+  fi
+
+  # If there is an existing bgproc on the same prefix, close it first.
+  ble/util/bgproc#close "$1"
+
+  local -a bgproc=()
+  bgproc[0]=
+  bgproc[1]=
+  bgproc[2]=$2
+  bgproc[3]=${3-}
+
+  local -a bgproc_fname=()
+  bgproc_fname[0]=$_ble_base_run/$$.util.bgproc.$1.response.pipe
+  bgproc_fname[1]=$_ble_base_run/$$.util.bgproc.$1.request.pipe
+  bgproc_fname[2]=$_ble_base_run/$$.util.bgproc.$1.pid
+
+  ble/util/save-vars "${1}_" bgproc bgproc_fname
+
+  [[ :${bgproc[3]}: == *:deferred:* ]] || ble/util/bgproc#start "$1"; local ext=$?
+  if ((ext!=0)); then
+    builtin eval -- "${1}_bgproc=() ${1}_bgproc_fname=()"
+  fi
+  return "$ext"
+}
+
+## @fn ble/util/bgproc#alive prefix
+##   Test if the bgproc session is active.
+##
+##   @param[in] prefix
+##     The name to identify the bgproc.
+##
+function ble/util/bgproc#opened {
+  local bgpid_ref=${1}_bgproc[0]
+  [[ ${!bgpid_ref+set} ]] || return 2
+}
+
+## @fn ble/util/bgproc/.alive
+##   @var[in] bgproc
+function ble/util/bgproc/.alive {
+  [[ ${bgproc[4]-} ]] && kill -0 "${bgproc[4]}" 2>/dev/null
+}
+
+## @fn ble/util/bgproc/.exec
+##   @var[in] bgproc
+function ble/util/bgproc/.exec {
+  # Note: We need to specify the redirections for ${bgproc[0]} and ${bgproc[1]}
+  # on "builtin eval" because of a bash-3.0 bug.  In Bash 3.0, the redirections
+  # are not properly set up if one uses a function definition of the form
+  # "function fname { } redirections".
+  builtin eval -- "${bgproc[2]}" <&"${bgproc[1]}" >&"${bgproc[0]}"
+}
+
+## @fn ble/util/bgproc/.mkfifo
+##   @var[in] bgproc_fname
+function ble/util/bgproc/.mkfifo {
+  local -a pipe_remove=() pipe_create=()
+  local i
+  for i in 0 1; do
+    [[ -p ${bgproc_fname[i]} ]] && continue
+    ble/array#push pipe_create "${bgproc_fname[i]}"
+    if [[ -e ${bgproc_fname[i]} || -h ${bgproc_fname[i]} ]]; then
+      ble/array#push pipe_remove "${bgproc_fname[i]}"
+    fi
+  done
+  ((${#pipe_remove[@]}==0)) || ble/bin/rm -f "${pipe_remove[@]}" 2>/dev/null
+  ((${#pipe_create[@]}==0)) || ble/bin/mkfifo "${pipe_create[@]}" 2>/dev/null
+}
+
+## @fn ble/util/bgproc#start prefix
+##   Start the background process.  This runs the command specified to
+##   "ble/util/bgproc#open".
+##
+##   @param[in] prefix
+##     The name to identify the bgproc.
+##
+##   @exit 0 if the background process is successfully started or was already
+##   running.  2 if the PREFIX does not corresponds to an existing bgproc.  3
+##   if the system does not support the named pipes.  1 if the background
+##   process failed to be started.
+##
+function ble/util/bgproc#start {
+  local bgproc bgproc_fname
+  ble/util/restore-vars "${1}_" bgproc bgproc_fname
+  if ((!${#bgproc[@]})); then
+    ble/util/print "$FUNCNAME: $1: not an existing bgproc name." >&2
+    return 2
+  fi
+
+  if ble/util/bgproc/.alive; then
+    # The background process is already running
+    return 0
+  fi
+  [[ ! ${bgproc[0]-} ]] || ble/fd#close 'bgproc[0]'
+  [[ ! ${bgproc[1]-} ]] || ble/fd#close 'bgproc[1]'
+
+  # Note: mkfifo may fail in MSYS-1
+  local _ble_local_ext=0
+  if ble/util/bgproc/.mkfifo &&
+    ble/fd#alloc 'bgproc[0]' '<> "${bgproc_fname[0]}"' &&
+    ble/fd#alloc 'bgproc[1]' '<> "${bgproc_fname[1]}"'
+  then
+    # Note: We want to assign a new process group to the background process
+    # without affecting the job table of the main shell so use the subshell
+    # `(...)'.  The process group is later used to kill the process tree in
+    # stopping the background process.  Note that the command substitutions
+    # $(...) do not create a new process group even if we specify `set -m' so
+    # cannot be used for the present purpose.
+    ble/util/assign 'bgproc[4]' '(set -m; ble/util/bgproc/.exec __ble_suppress_joblist__ >/dev/null & ble/util/print "$!")'
+
+    if ble/util/bgproc/.alive; then
+      [[ :${bgproc[3]}: == *:no-close-on-unload:* ]] ||
+        ble/util/print "-${bgproc[4]}" >| "${bgproc_fname[2]}"
+      [[ :${bgproc[3]}: == *:no-close-on-unload:* || :${bgproc[3]}: == *:owner-close-on-unload:* ]] ||
+        blehook unload!="ble/util/bgproc#close $1"
+      ble/util/bgproc#keepalive "$1"
+    else
+      builtin unset -v 'bgproc[4]'
+      _ble_local_ext=1
+    fi
+  else
+    _ble_local_ext=3
+  fi
+
+  if ((_ble_local_ext!=0)); then
+    [[ ! ${bgproc[0]-} ]] || ble/fd#close 'bgproc[0]'
+    [[ ! ${bgproc[1]-} ]] || ble/fd#close 'bgproc[1]'
+    bgproc[0]=
+    bgproc[1]=
+    builtin unset -v 'bgproc[4]'
+  fi
+
+  ble/util/save-vars "${1}_" bgproc bgproc_fname
+
+  if ((_ble_local_ext==0)); then
+    ble/function#try ble/util/bgproc/onstart:"$1"
+  fi
+  return "$_ble_local_ext"
+}
+
+function ble/util/bgproc#stop/.wait {
+  local pid=$1 msec=$2
+  while
+    kill -0 "$pid" 2>/dev/null || return 0
+    ((msec>0))
+  do
+    ble/util/msleep "$((msec>1000?1000:msec))"
+    ((msec-=1000))
+  done
+  return 1
+}
+function ble/util/bgproc#stop/.kill {
+  local pid=$1 i close_timeout=$2
+  ble/util/bgproc#stop/.wait "$pid" "$close_timeout" && return 0
+  kill -- "$pid"
+  ble/util/bgproc#stop/.wait "$pid" 10000 && return 0
+  kill -9 "$pid"
+}
+
+## @fn ble/util/bgproc#stop prefix
+##   Stop the background process.
+##
+##   @param[in] prefix
+##     The name to identify the bgproc.
+##
+function ble/util/bgproc#stop {
+  local prefix=$1
+  ble/util/idle.cancel "ble/util/bgproc#keepalive/.timeout $prefix"
+
+  local bgproc bgproc_fname
+  ble/util/restore-vars "${prefix}_" bgproc bgproc_fname
+  if ((!${#bgproc[@]})); then
+    ble/util/print "$FUNCNAME: $prefix: not an existing bgproc name." >&2
+    return 2
+  fi
+
+  [[ ${bgproc[4]-} ]] || return 1
+
+  if ble/is-function ble/util/bgproc/onstop:"$prefix" && ble/util/bgproc/.alive; then
+    ble/util/bgproc/onstop:"$prefix"
+  fi
+
+  ble/fd#close 'bgproc[0]'
+  ble/fd#close 'bgproc[1]'
+  >| "${bgproc_fname[2]}"
+
+  # When the background process is active, kill the process after waiting for
+  # the time specified by kill-timeout.
+  if ble/util/bgproc/.alive; then
+    local ret close_timeout=10000
+    if ble/opts#extract-last-optarg "${bgproc[3]}" kill-timeout; then
+      close_timeout=$ret
+    fi
+    (ble/util/bgproc#stop/.kill "-${bgproc[4]}" "$close_timeout" </dev/null &>/dev/null & disown)
+  fi
+
+  builtin eval -- "${prefix}_bgproc[0]="
+  builtin eval -- "${prefix}_bgproc[1]="
+  builtin unset -v "${prefix}_bgproc[4]"
+  return 0
+}
+
+## @fn ble/util/bgproc#alive prefix
+##   Test if the background process is currently running.
+##
+##   @param[in] prefix
+##     The name to identify the bgproc.
+##
+function ble/util/bgproc#alive {
+  local bgpid_ref=${1}_bgproc[4]
+  [[ ${!bgpid_ref-} ]] || return 2
+  kill -0 "${!bgpid_ref}" 2>/dev/null
+}
+
+function ble/util/bgproc#keepalive/.timeout {
+  local prefix=$1
+
+  # Call ble/util/bgproc/ontimeout:PREFIX if any
+  if ble/is-function ble/util/bgproc/ontimeout:"$prefix"; then
+    if ! ble/util/bgproc/ontimeout:"$prefix"; then
+      ble/util/bgproc#keepalive "$prefix"
+      return 0
+    fi
+  fi
+
+  ble/util/bgproc#stop "$prefix"
+}
+
+## @fn ble/util/bgproc#keepalive prefix
+##   Rest the timeout to stop the background process.
+##
+##   @param[in] prefix
+##     The name to identify the bgproc.
+##
+function ble/util/bgproc#keepalive {
+  local prefix=$1 bgproc
+  ble/util/restore-vars "${prefix}_" bgproc
+  ((${#bgproc[@]})) || return 2
+  ble/util/bgproc/.alive || return 1
+
+  local timeout_proc="ble/util/bgproc#keepalive/.timeout $1"
+  ble/util/idle.cancel "$timeout_proc"
+  ble/opts#extract-last-optarg "${bgproc[3]}" timeout || return 0; local bgproc_timeout=$ret
+  if ((bgproc_timeout>0)); then
+    ble/util/idle.push --sleep="$bgproc_timeout" "$timeout_proc"
+  fi
+  return 0
+}
+
+_ble_util_bgproc_onclose_processing=
+## @fn ble/util/bgproc#close prefix
+##   Close the bgproc session.
+##
+##   @param[in] prefix
+##     The name to identify the bgproc.
+##
+function ble/util/bgproc#close {
+  # If the bgproc does not exist, do nothing.
+  ble/util/bgproc#opened "$1" || return 2
+
+  local prefix=${1}
+  blehook unload-="ble/util/bgproc#close $prefix"
+  ble/util/idle.cancel "ble/util/bgproc#keepalive/.timeout $prefix"
+
+  # When the callback function "ble/util/bgproc/onclose:PREFIX" is defined, we
+  # call the function before starting the closing process.  However, we skip
+  # this if the present call of "ble/util/bgproc#close" is already from inside
+  # the callback, we skip it to avoid the infinite recursion.
+  if ble/is-function ble/util/bgproc/onclose:"$prefix"; then
+    if [[ :${_ble_util_bgproc_onclose_processing-}: != *:"$prefix":* ]]; then
+      local _ble_util_bgproc_onclose_processing=${_ble_util_bgproc_onclose_processing-}:$prefix
+      ble/util/bgproc/onclose:"$prefix"
+    fi
+  fi
+
+  ble/util/bgproc#stop "$prefix"
+  builtin eval -- "${prefix}_bgproc=() ${prefix}_bgproc_fname=()"
+}
+
+## @fn ble/util/bgproc#use prefix
+##   Ensure the file descriptors to be ready for uses.  When the background
+##   process is temporarily stopped, this will restart the background process.
+##   When the background process was terminated unexpectedly and "restart" is
+##   specified to the bgproc's OPTS, this will also restart the background
+##   process.
+##
+##   @param[in] prefix
+##     The name to identify the bgproc.
+##
+##   @exit 0 if the background process is ready.  2 if the specified PREFIX
+##   does not correspond to an existing bgproc.  3 if the system does not seem
+##   to support named pipes.  1 if the background process was stopped and
+##   failed to restart it.
+##
+function ble/util/bgproc#use {
+  local bgproc
+  ble/util/restore-vars "${1}_" bgproc
+  if ((!${#bgproc[@]})); then
+    ble/util/print "$FUNCNAME: $1: not an existing bgproc name." >&2
+    return 2
+  fi
+
+  if [[ ! ${bgproc[4]-} ]]; then
+    # The background process has been stopped intenstionally.  We automatically
+    # restart the background process in this case.
+    ble/util/bgproc#start "$1" || return "$?"
+  elif ! kill -0 "${bgproc[4]-}"; then
+    # The background process died unexpectedly
+    if [[ :${bgproc[3]-}: == *:restart:* ]]; then
+      ble/util/bgproc#start "$1" || return "$?"
+    else
+      return 1
+    fi
+  else
+    ble/util/bgproc#keepalive "$1"
+    return 0
+  fi
+}
+
+function ble/util/bgproc#post {
+  ble/util/bgproc#use "$1" || return "$?"
+  local fd1_ref=${1}_bgproc[1]
+  ble/util/print "$2" >&"${!fd1_ref}"
+}
diff --git a/make_command.sh b/make_command.sh
index d32e4379..041d03b8 100755
--- a/make_command.sh
+++ b/make_command.sh
@@ -1132,6 +1132,7 @@ function sub:scan/a.txt {
   grc --color --exclude={test,ext,./lib/test-\*.sh,./make_command.sh,\*.md} --exclude=check-mem.sh '[/[:space:]<>"'\''][a-z]\.txt|/dev/(pts/|pty)[0-9]*|/dev/tty' |
     sed -E 'h;s/'"$_make_rex_escseq"'//g
       \Z^\./memo/Zd
+      \Zgithub302-perlre-server\.bashZd
     s/^[^:]*:[0-9]+:[[:space:]]*//
       \Z^[[:space:]]*#Zd
       \ZDEBUG_LEAKVARZd
diff --git a/note.txt b/note.txt
index f85cea74..01ed2c12 100644
--- a/note.txt
+++ b/note.txt
@@ -623,6 +623,11 @@ bashbug 算術式周りのバグと注意点
     $ bash-3.1 -c '((a?(b=123):c?(d=321):1))'
     bash-3.1: ((: a?(b=123):c?(d=321):1: syntax error in expression (error token is "?(d=321):1")
 
+  * bash-3.0
+
+    D1956: 関数定義の一番外側でリダイレクトしてもリダイレクトされない。例えば、
+    function func { ls -l /proc/$BASHPID/fd/{0..2}; } <&"$fd0" >&"$fd1"
+
 bash 配列の宣言に関する仕様・バグと注意点
 
   * arr=(1 2 3) func の形式で配列をシェル関数に渡そうとすると、
@@ -1237,6 +1242,10 @@ bash_tips
 
     6 ble-update で更新の必要がなかった時に内部的に使用 (由来: ACK = 6)
 
+    2 コマンドの使い方が異なる
+
+    3 ble/util/bgproc は named pipes がシステムでサポートされていない時に 3 を返す。
+
 2017-10-18
 
   * ble-decode: widget に関して [#M0007]
@@ -6624,6 +6633,95 @@ bash_tips
     Done (実装ログ)
 -------------------------------------------------------------------------------
 
+2023-03-12
+
+  * bgproc: histdb から切り離して再利用可能にする (motivated by bkerin) [#D2017]
+    https://lists.gnu.org/archive/html/help-bash/2023-03/msg00068.html
+    https://github.com/akinomyoga/ble.sh/issues/302#issuecomment-1462977627
+
+    * done: ble/opts#has バグ修正。影響は cmdspec_opts の plus-options だけの様だ。
+      全然判定できていなかった。常にほぼ false になっていたと思われる。
+
+    * done: ble/util/bgproc 既に開いている prefix を指定した場合は以前のものは
+      削除する。
+
+    * done: 複数のプロセスが走っている場合に対応できる様にプロセスグループを作
+      らせる事にする。set -m を実行すれば良い。
+
+      * done: 実は負の引数を kill -0 に渡すことでプロセスグループの何れかのプロ
+        セスが残っているかどうかを判定することができると分かった → これを利用
+        して改めて kill 部分の処理を作り直した。
+
+      * done: どうやらコマンド置換の中でやるとプロセスグループが作られない様だ。
+        なので bgpid=$(set -m; bgproc & echo "$!") ではなくて ble/util/assign
+        bgpid '(set -m; ...)' とする必要がある。
+
+        一方で、そもそもコマンド置換にしていた理由はあったのだったか。もし別の
+        理由があったのであればそれについても () で壊れないか確認する必要がある。
+        調べてみるとコマンド置換を使っていたのは最初からで (#D1925) 特に考察は
+        していない様に見える。取り敢えず普通のプロセス置換にしても大丈夫。
+
+        修正した。
+
+    * done: EXIT (もしくは internal_EXIT) に自動で登録する?
+
+      →と思ったが単なる close ではなくて EXIT の時に特別の処理をしたい時に
+      EXIT もしくは internal_EXIT を設定していると、期せずして先に bgproc#close
+      されてしまって後処理ができなくなってしまう。
+
+      a うーん。後処理を行いたい場合の為に internal_EXIT に登録しない設定を作る?
+
+        特に指定しない場合に自動で終了処理を追加するとしても、internal_EXIT で
+        呼び出して良いのだろうか。他の EXIT 処理が bgproc を利用したいという場
+        合に問題が起こる可能性がある。という事を考えると、EXIT の方に登録するべ
+        き? 然し EXIT の方に登録したとしても呼び出しの順序によって変なことが起
+        こる可能性がある。
+
+      b reject: bgproc/onclose:prefix の中で EXIT 処理を実装してもらう
+
+        別の方法として bgproc#close の中で終了処理としての close なのか一時的な
+        close なのかを判定して各自処理を切り替える方針で実装してもらう? しかし
+        これだと bgproc が生きていても死んでいても実行するべき処理の場合に困る。
+        単に bgproc#close からの呼び出しを期待していると bgproc が走っていない
+        場合にその処理が呼び出されなくなってしまう。それに分かりにくい。
+
+      取り敢えず owner-close-on-exit と no-close-on-exit を opts として指定可能
+      にすることにした。
+
+    * fixed: unload の時にも同様に呼び出すべきなのではないか? というか寧ろ今ま
+      で EXIT でやっていたのは unload でやるべきだったのではないか。
+
+      →histdb と bgproc の両方を EXIT ではなく unload を使う様に変更した。
+
+    * done: close-callback は関数に置き換えるべきなのでは? 結局 bgproc#close を
+      呼び出す必要があるのであれば、opts の中に直接コマンドを記述するよりはちゃ
+      んとした関数を定義して関数名を close-callback に指定することになるが、そ
+      うであるのならば最初から関数名を ble/util/bgproc/close:_ble_histdb 等に固
+      定してそれを直接呼び出す様にした方がわかりやすい。
+
+      また callback の中で ble/util/bgproc#close を呼び出すのも一見して無限ルー
+      プになるのでインターフェイスとして分かりにくい。それよりは単に close 直前
+      の終端処理として呼び出す様にするのが良い気がする。それでも
+      ble/util/bgproc#close を入れ子で呼び出した時の対策は今のまま残しておく事
+      にする。
+
+    * done: request を送る機能 & 死んでいたら再始動する機能
+
+      timeout でデータを削除してしまうと restart 時に問題なのでは? なので
+      timeout 時には [4] だけ消す事にする? timeout で終了した場合と期せず終了し
+      てしまった場合は区別するべき。
+
+      適当にいい加減な bgproc を作って動作確認した。取り敢えず簡単な使い道の範
+      囲ではちゃんと動いている様である。
+
+      また help-bash で提供されていた例に関しても cotnrib/config/github302 に実
+      装してみて動作確認した。動いている気がする。
+
+    面倒なので取り敢えずこれで push する事にする。何れにしても histdb は未だ実
+    験中でドキュメントにも記していないし、また例として実装した perlre-server も
+    help-bash / GitHub #302 の為の例に過ぎないので寧ろテストしてもらうぐらいで
+    良い。
+
 2023-03-10
 
   * complete: complete_source_sabbrev_ignore が動いていない [#D2016]
diff --git a/src/util.sh b/src/util.sh
index f957337a..92030173 100644
--- a/src/util.sh
+++ b/src/util.sh
@@ -417,9 +417,11 @@ function ble/util/restore-vars {
   local __ble_name __ble_prefix=$1; shift
   for __ble_name; do
     if ble/is-array "$__ble_prefix$__ble_name"; then
-      builtin eval "$__ble_name=(\"\${$__ble_prefix$__ble_name[@]}\")"
+      # Note: bash-4.2 以下では set -u で空配列に対する "${arr[@]}" が失敗す
+      # るので ${arr[@]+"${arr[@]}"} とする。
+      builtin eval "$__ble_name=(\${$__ble_prefix$__ble_name[@]+\"\${$__ble_prefix$__ble_name[@]}\"})"
     else
-      builtin eval "$__ble_name=\"\$$__ble_prefix$__ble_name\""
+      builtin eval "$__ble_name=\"\${$__ble_prefix$__ble_name-}\""
     fi
   done
 }
@@ -1378,7 +1380,7 @@ function ble/path#contains {
 
 ## @fn ble/opts#has opts key
 function ble/opts#has {
-  local rex=':'$2'[=[]'
+  local rex=':'$2'[=:]'
   [[ :$1: =~ $rex ]]
 }
 ## @fn ble/opts#remove opts value
@@ -2195,6 +2197,12 @@ function ble/util/assign/.rmtmp {
 }
 if ((_ble_bash>=40000)); then
   # mapfile の方が read より高速
+  #
+  # @remarks 将来的に ${ ...; } に切り替えることになった時に set -m でプロセス
+  #   グループが作られるかどうかについて確認が必要。util.broc.sh では «
+  #   ble/util/assign bgpid '(set -m; command & echo "$!")' » でプロセスグルー
+  #   プが作られる事を想定している。例えば $(...) はプロセスグループが作られな
+  #   いので使えない。
   function ble/util/assign {
     local _ble_local_tmpfile; ble/util/assign/.mktmp
     builtin eval -- "$2" >| "$_ble_local_tmpfile"