recovery shell quality of life improvements

The recovery shell is quite powerful, but discoverability can be
limited. In an attempt to start fixing that, the following has been
done:

* Add a `help` alias and documentation page listing a few key things
  that can be done in the recovery shell.

* Enable tab completions for the following: set_ro_pool, set_rw_pool,
  mount_zfs, zfs-chroot/zfs_chroot

* Only source aliases/tab completions in interactive shells so that we
  don't impact the normal ZBM shell environment.

Closes #197

90zfsbootmenu/help-files/134/recovery-shell.pod

@@ -0,0 +1,31 @@
+NAME
+
+zfsbootmenu - Recovery Shell
+
+Common Commands
+
+zfsbootmenu
+  Launch the interactive boot environment menu.
+
+zfs-chroot zfs filesystem
+  Enter a chroot of the specified boot environment. The boot environment is mounted read/write if the zpool is imported read/write.
+
+set_rw_pool pool
+  Export, then re-import the pool read/write.
+
+set_ro_pool pool
+  Export, then re-import the pool read-only.
+
+mount_zfs zfs filesystem
+  Mount the filesystem at a unique location and print the mount point.
+
+help
+  View the online help system.
+
+logs
+  View warning/error/debug logs.
+
+AUTHOR
+
+ZFSBootMenu Team <https://github.com/zbm-dev/zfsbootmenu>
+

90zfsbootmenu/help-files/54/recovery-shell.pod

@@ -0,0 +1,35 @@
+NAME
+
+zfsbootmenu - Recovery Shell
+
+Common Commands
+
+zfsbootmenu
+  Launch the interactive boot environment menu.
+
+zfs-chroot zfs filesystem
+  Enter a chroot of the specified boot environment.
+  The boot environment is mounted read/write if the
+  zpool is imported read/write.
+
+set_rw_pool pool
+  Export, then re-import the pool read/write.
+
+set_ro_pool pool
+  Export, then re-import the pool read-only.
+
+mount_zfs zfs filesystem
+  Mount the filesystem at a unique location and print
+  the mount point.
+
+help
+  View the online help system.
+
+logs
+  View warning/error/debug logs.
+
+AUTHOR
+
+ZFSBootMenu Team
+<https://github.com/zbm-dev/zfsbootmenu>
+

90zfsbootmenu/help-files/94/recovery-shell.pod

@@ -0,0 +1,32 @@
+NAME
+
+zfsbootmenu - Recovery Shell
+
+Common Commands
+
+zfsbootmenu
+  Launch the interactive boot environment menu.
+
+zfs-chroot zfs filesystem
+  Enter a chroot of the specified boot environment. The boot environment is mounted read/write
+  if the zpool is imported read/write.
+
+set_rw_pool pool
+  Export, then re-import the pool read/write.
+
+set_ro_pool pool
+  Export, then re-import the pool read-only.
+
+mount_zfs zfs filesystem
+  Mount the filesystem at a unique location and print the mount point.
+
+help
+  View the online help system.
+
+logs
+  View warning/error/debug logs.
+
+AUTHOR
+
+ZFSBootMenu Team <https://github.com/zbm-dev/zfsbootmenu>
+

90zfsbootmenu/module-setup.sh

@@ -146,6 +146,7 @@ install() {
   _ret=0
   # shellcheck disable=SC2154
   inst_simple "${moddir}/zfsbootmenu-lib.sh" "/lib/zfsbootmenu-lib.sh" || _ret=$?
+  inst_simple "${moddir}/zfsbootmenu-completions.sh" "/lib/zfsbootmenu-completions.sh" || _ret=$?
   inst_simple "${moddir}/zfsbootmenu-init.sh" "/libexec/zfsbootmenu-init" || _ret=$?
   inst_simple "${moddir}/zfsbootmenu-preview.sh" "/libexec/zfsbootmenu-preview" || _ret=$?
   inst_simple "${moddir}/zfsbootmenu-input.sh" "/libexec/zfsbootmenu-input" || _ret=$?
@@ -317,12 +318,29 @@ EOF
   cat << EOF >> "${initdir}/etc/profile"
 [ -f /lib/zfsbootmenu-lib.sh ] && source /lib/zfsbootmenu-lib.sh
 [ -f /etc/zfsbootmenu.conf ] && source /etc/zfsbootmenu.conf
+
 export PATH=/usr/sbin:/usr/bin:/sbin:/bin
 export TERM=vt220
+
+zdebug "sourced /etc/profile"
+
+EOF
+
+  # Setup a default environment for all login shells
+  cat << EOF >> "${initdir}/.bashrc"
+[ -f /etc/profile ] && source /etc/profile
+[ -f /lib/zfsbootmenu-completions.sh ] && source /lib/zfsbootmenu-completions.sh
 export PS1="\033[0;33mzfsbootmenu\033[0m \w > "
+
 alias clear="tput clear"
 alias reset="tput reset"
 alias zbm="zfsbootmenu"
-alias logs="zlogtail -f"
+alias logs="ztrace"
+alias trace="ztrace"
+alias debug="ztrace"
+alias help="/libexec/zfsbootmenu-help -L recovery-shell"
+
+zdebug "sourced /.bashrc"
+
 EOF
 }

90zfsbootmenu/zfsbootmenu-completions.sh

@@ -0,0 +1,72 @@
+#!/bin/bash
+# shellcheck disable=SC2207
+
+# disabling this allows completions with the @ character
+shopt -u hostcomplete
+
+_zfs-chroot() {
+  local ZFS
+  COMPREPLY=()
+
+  [ "${#COMP_WORDS[@]}" != "2" ] && return
+
+  for SNAP in $( zfs list -H -o name -t snapshot ) ; do
+    ZFS+=("${SNAP}")
+  done
+
+  for FS in $( zfs list -H -o name ) ; do
+    ZFS+=("${FS}")
+  done
+
+  COMPREPLY=( $( compgen -W "${ZFS[*]}" -- "${COMP_WORDS[1]}" ) )
+}
+complete -F _zfs-chroot zfs-chroot
+complete -F _zfs-chroot zfs_chroot
+
+_set_rw_pool() {
+  local ZPOOL
+  COMPREPLY=()
+
+  [ "${#COMP_WORDS[@]}" != "2" ] && return
+
+  for POOL in $( zpool list -H -o name ) ; do
+    if ! is_writable "${POOL}" ; then
+      ZPOOL+=("${POOL}")
+    fi
+  done
+  COMPREPLY=( $( compgen -W "${ZPOOL[*]}" -- "${COMP_WORDS[1]}" ) )
+}
+complete -F _set_rw_pool set_rw_pool
+
+_set_ro_pool() {
+  local ZPOOL
+  COMPREPLY=()
+
+  [ "${#COMP_WORDS[@]}" != "2" ] && return
+
+  for POOL in $( zpool list -H -o name ) ; do
+    if is_writable "${POOL}" ; then
+      ZPOOL+=("${POOL}")
+    fi
+  done
+  COMPREPLY=( $( compgen -W "${ZPOOL[*]}" -- "${COMP_WORDS[1]}" ) )
+}
+complete -F _set_ro_pool set_ro_pool
+
+_mount_zfs() {
+  local ZFS
+  COMPREPLY=()
+
+  [ "${#COMP_WORDS[@]}" != "2" ] && return
+
+  for SNAP in $( zfs list -H -o name -t snapshot ) ; do
+    ZFS+=("${SNAP}")
+  done
+
+  for FS in $( zfs list -H -o name ) ; do
+    ZFS+=("${FS}")
+  done
+
+  COMPREPLY=( $( compgen -W "${ZFS[*]}" -- "${COMP_WORDS[1]}" ) )
+}
+complete -F _mount_zfs mount_zfs

90zfsbootmenu/zfsbootmenu-help.sh

@@ -28,13 +28,14 @@ help_pager() {
   SORTED+=("${FINAL}")
 
   printf '%s\n' "${SORTED[@]}" | ${FUZZYSEL} \
-    --prompt 'Topic >' \
+    --prompt 'Topic > ' \
     --with-nth=2.. \
     --bind pgup:preview-up,pgdn:preview-down \
     --preview="$0 -s {1}" \
     --preview-window="right:${PREVIEW_SIZE}:wrap" \
     --header="$( colorize green "[ESC]" ) $( colorize lightblue "back" )" \
     --tac \
+    --inline-info \
     --ansi
 }
 

90zfsbootmenu/zfsbootmenu-lib.sh

@@ -1710,6 +1710,33 @@ set_rw_pool() {
   return 1
 }
 
+# arg1: pool name
+# prints: nothing
+# returns: 0 on success, 1 on failure
+
+set_ro_pool() {
+  local pool ret
+
+  pool="${1}"
+  if [ -z "${pool}" ]; then
+    zerror "pool is undefined"
+    return 1
+  fi
+  zdebug "pool set to ${pool}"
+
+  if export_pool "${pool}" ; then
+    read_write='' import_pool "${pool}"
+    ret=$?
+
+    zdebug "import_pool: ${ret}"
+
+    return ${ret}
+  fi
+
+  return 1
+}
+
+
 # arg1: ZFS filesystem
 # prints: name of encryption root, if present
 # returns: 0 if system has an encryption root, 1 otherwise
@@ -2082,7 +2109,7 @@ zfs_chroot() {
 # returns: nothing
 
 emergency_shell() {
-  local message
+  local message skip mp fs
   message=${1:-unknown reason}
 
   tput clear
@@ -2091,7 +2118,17 @@ emergency_shell() {
 
   echo -n "Launching emergency shell: "
   echo -e "${message}\n"
-  /bin/bash -l
+
+  # -i (interactive) mode will source /.bashrc
+  /bin/bash -i
+
+  # shellcheck disable=SC2034
+  while read -r skip mp fs skip ; do
+    if [ "${fs}" == "zfs" ]; then
+      umount "${mp}"
+      zdebug "unmounting: ${mp}"
+    fi
+  done < /proc/self/mounts
 }
 
 # prints: nothing

90zfsbootmenu/zfsbootmenu.sh

@@ -299,7 +299,7 @@ while true; do
       # This will make all keys in the pool unavailable, but populate_be_list
       # should reload the missing keys in the next iteration, so why unlock here?
       if is_writable "${pool}"; then
-        export_pool "${pool}" && read_write='' import_pool "${pool}"
+        set_ro_pool "${pool}"
       else
         set_rw_pool "${pool}"
       fi

pod/online/recovery-shell.pod

@@ -0,0 +1,45 @@
+=pod
+
+=head1 NAME
+
+B<zfsbootmenu> - Recovery Shell
+
+=head1 Common Commands
+
+=over 2
+
+=item I<zfsbootmenu>
+
+Launch the interactive boot environment menu.
+
+=item I<zfs-chroot> B<zfs filesystem>
+
+Enter a chroot of the specified boot environment. The boot environment is mounted I<read/write> if the zpool is imported I<read/write>.
+
+=item I<set_rw_pool> B<pool>
+
+Export, then re-import the pool I<read/write>.
+
+=item I<set_ro_pool> B<pool>
+
+Export, then re-import the pool I<read-only>.
+
+=item I<mount_zfs> B<zfs filesystem>
+
+Mount the filesystem at a unique location and print the mount point.
+
+=item I<help>
+
+View the online help system.
+
+=item I<logs>
+
+View warning/error/debug logs.
+
+=back
+
+=head2 AUTHOR
+
+ZFSBootMenu Team L<https://github.com/zbm-dev/zfsbootmenu>
+
+=cut