[make-initrd] [PATCH v6 16/22] bootchain-core: new logic of the daemon main loop

["Leonid Krivoshein" <klark.devel@gmail.com>]

- Adds the ability to overload the boot chain new steps;
- Limits the number of repeated runs of steps-scripts to five;
- Adds a switch for allow/disallow to retry steps-scripts;
- Introduces the difference between the modes "NATIVE"
  and "COMPATIBILITY" with the pipeline;
- Offers a new way of ending the daemon main loop;
- Saves the names of the steps taken.

See README.md for more details.

Signed-off-by: Leonid Krivoshein <klark.devel@gmail.com>
---
 features/bootchain-core/README.md             | 62 +++++++++++++
 .../data/bin/bootchain-sh-functions           |  2 +
 features/bootchain-core/data/sbin/chaind      | 91 ++++++++++++++-----
 3 files changed, 131 insertions(+), 24 deletions(-)

diff --git a/features/bootchain-core/README.md b/features/bootchain-core/README.md
index db73c0a..bde5c9b 100644
--- a/features/bootchain-core/README.md
+++ b/features/bootchain-core/README.md
@@ -54,6 +54,11 @@ us to optimize fill in `initramfs` only which we are need.
   Such pseudo-steps allow you to control, basically, the internal state of the
   daemon and should not be taken into account in the boot chain, as if they are
   hidden.
+- The `chaind` daemon allows you to overload the chain with a new set of steps,
+  thanks to this, you can change the logic of work "on the fly", support loops
+  and conditional jumps, in text dialogs it is an opportunity to go back.
+- Keeps records of the steps taken at least once and allows you to prevent their
+  re-launch.
 - `bootchain-sh-functions` extends the API of the original `pipeline-sh-functions`,
   see the details in the corresponding section.
 - Via resolve_target() supports not only forward, but also reverse addressing,
@@ -68,6 +73,11 @@ us to optimize fill in `initramfs` only which we are need.
   of the previous step through symbolic links to mount points inside initramfs,
   outside the tree the results of the steps, which provides, if necessary, the
   overlap mounting mechanism inherent in the program `propagator`.
+- Along with the NATIVE mode of operation, the `chaind` daemon can work in
+  COMPATIBILITY WITH `pipeline`. In the NATIVE mode of operation, the daemon
+  imposes another an approach to processing the status code of the completed
+  step and the method of premature completion of the boot chain, see the details
+  in the corresponding section.
 - The daemon can be configured when building initramfs via the included file
   configurations of `/etc/sysconfig/bootchain`, and not only through boot
   parameters, see the details in the corresponding section.
@@ -81,6 +91,50 @@ Despite the differences, `chaind` is backward compatible with previously
 written steps for the `pipelined` daemon and does not require changes for
 configurations with `root=pipeline`.
 
+## Features of the pipelined work
+
+If the step-script will be finished with code of status 2, the original daemon
+`pipelined` will understand it like a must to stop chains and finish work.
+(meaning that system is ready to go stage2). If the step-script does not
+process this code from an external command, and stage2 is not ready to work
+yet, a situation with premature termination of the daemon will arise.
+
+If the step-script will be finished with non-null code of status (different
+from 2), daemon `pipelined` will understand it like a fail and will repeat this
+failure-step with pause in one second in infinity cycle (until common timeout
+rootdelay=180). But, sometimes repeat steps are unnecessary because the
+situation is incorrigible and repeating will just waste of time and make a
+system log is filling up. But the daemon `pipelined` don't know how to work
+with this situations.
+
+## New approach in chaind daemon
+
+For steps-scripts are suggested before finish work with code of status 0 call
+break_bc_loop() for tell to the daemon about ready stage2 and needed finish
+work this daemon after the current step.In case of a failure in the step-by-step
+scenario, the daemon can repeat it, but no more than four times with a pause of
+two seconds. In order for a failure in the step-by-step scenario to lead to an
+immediate shutdown of the daemon, it is necessary to use the internal step
+`noretry`.
+
+## Daemon operation mode
+
+### NATIVE mode of operation
+
+NATIVE mode is activated by the `root=bootchain` parameter. In this mode, the
+daemon will perceive the status code 2 from the step script in the same way as
+any other non-zero code and then act according to the internal state: if
+repetitions are allowed, the step script will be called again with a pause
+of 2 seconds, but no more than four times. If repetitions are prohibited,
+the daemon itself will immediately terminate.
+
+### Pipeline COMPATIBILITY mode
+
+Compatibility mode is activated by the `root=pipeline` parameter. In this mode,
+the daemon behaves the same as the original `pipelined`, except that it limits
+the number of re-runs of the failed step. He perceives the status code 2 not as
+a failure, but as a command to end the main daemon cycle.
+
 ## Configuration
 
 The configuration is defined in the file `/etc/sysconfig/bootchain` when
@@ -109,6 +163,14 @@ addressing, as if they are hidden.
   on the <OUT> of the previous step from the <IN> of the next step, which can
   be useful, for example, when we don`t want the results of the `waitdev` step
   to be used in the next step, `localdev`, which primarily looks at them.
+- `noretry` - prohibits the following steps from ending with a non-zero return
+  code, what will lead to the immediate shutdown of the daemon in case of a
+  script failure any next step. By default, the steps are allowed to fail,
+  the daemon will try to restart them again four times with a pause of two
+  seconds.
+- `retry` - allows all subsequent steps to be completed with a non-zero return
+  code, which will lead to their starting five times, in total. This mode of
+  operation of the daemon operates by default.
 
 ## External elements of the bootchain (steps-scripts)
 
diff --git a/features/bootchain-core/data/bin/bootchain-sh-functions b/features/bootchain-core/data/bin/bootchain-sh-functions
index d1d0cef..8c5a2f2 100644
--- a/features/bootchain-core/data/bin/bootchain-sh-functions
+++ b/features/bootchain-core/data/bin/bootchain-sh-functions
@@ -17,9 +17,11 @@ message_time=1
 if [ "${ROOT-}" = pipeline ]; then
 	BC_LOGFILE="${BC_LOGFILE:-/var/log/pipelined.log}"
 	mntdir="${mntdir:-/dev/pipeline}"
+	pipeline_mode=1
 else
 	BC_LOGFILE="${BC_LOGFILE:-/var/log/chaind.log}"
 	mntdir="${mntdir:-/dev/bootchain}"
+	pipeline_mode=
 fi
 
 BC_NEXTCHAIN=/.initrd/bootchain/bootchain.next
diff --git a/features/bootchain-core/data/sbin/chaind b/features/bootchain-core/data/sbin/chaind
index 5623a37..4c9ebaa 100755
--- a/features/bootchain-core/data/sbin/chaind
+++ b/features/bootchain-core/data/sbin/chaind
@@ -2,7 +2,11 @@
 
 . bootchain-sh-functions
 
+bcretry=1
 pidfile="/var/run/$PROG.pid"
+chainsteps="$BOOTCHAIN"
+stepnum=0
+prevdir=
 
 
 exit_handler()
@@ -39,11 +43,7 @@ run mkdir -p -- "$mntdir" "$BC_PASSED"
 mountpoint -q -- "$mntdir" ||
 	run mount -t tmpfs tmpfs "$mntdir" ||:
 
-stepnum=0
-chainsteps="$BOOTCHAIN"
-datadir=
-destdir=
-
+rc=0
 while [ -n "$chainsteps" ]; do
 	name="${chainsteps%%,*}"
 	exe="$handlerdir/$name"
@@ -54,53 +54,96 @@ while [ -n "$chainsteps" ]; do
 		prevdir=
 		message "[0] Step '$name' has been passed"
 
+	elif [ "$name" = retry ]; then
+		chainsteps="${chainsteps#$name}"
+		chainsteps="${chainsteps#,}"
+		bcretry=1
+		message "subsequent steps will restart after failure"
+
+	elif [ "$name" = noretry ]; then
+		chainsteps="${chainsteps#$name}"
+		chainsteps="${chainsteps#,}"
+		bcretry=0
+		message "daemon will be stopped immediately after any step failure"
+
 	elif [ -x "$exe" ]; then
 		assign "callnum" "\${callnum_$name:-0}"
 		datadir="$mntdir/src/step$stepnum"
 		destdir="$mntdir/dst/step$stepnum"
 
-		[ "$stepnum" != 0 ] ||
-			prevdir=""
-
 		run mkdir -p -- "$datadir" "$destdir"
 
-		if ! mountpoint -q "$destdir"; then
+		if mountpoint -q -- "$destdir" ||
+			[ -s "$destdir/DEVNAME" ] ||
+			[ -b "$destdir/dev" ] ||
+			[ -c "$destdir/dev" ]
+		then
+			message "[$callnum] Handler: $exe skipped"
+		else
 			message "[$callnum] Handler: $exe"
 
 			export name callnum datadir destdir prevdir
 
+			for try in 1 2 3 4 5; do
 				[ -z "$BC_DEBUG" ] ||
 					run "$handlerdir/debug" ||:
 				rc=0
 				run "$exe" ||
 					rc=$?
-
-			if [ "$rc" != 0 ]; then
-				[ "$rc" != 2 ] ||
+				[ "$rc" != 0 ] ||
 					break
-				message "[$callnum] Handler failed (rc=$rc)"
-				sleep 1
-				continue
-			fi
-		else
-			message "[$callnum] Handler: $exe skipped"
+				[ "$rc" != 2 ] || [ -z "$pipeline_mode" ] ||
+					break 2
+				message "[$callnum] Handler failed (rc=$rc, try=$try)"
+				[ ! -f "$BC_PASSED/$PROG" ] ||
+					break 2
+				[ "$bcretry" != 0 ] ||
+					break
+				sleep 2
+			done
+
+			[ -r "$BC_NEXTCHAIN" ] ||
+				run touch "$BC_PASSED/$name"
+			[ ! -f "$BC_PASSED/$PROG" ] ||
+				break
+			[ "$rc" = 0 ] ||
+				break
 		fi
 
-		prevdir="$destdir"
+		if [ ! -r "$BC_NEXTCHAIN" ]; then
+			callnum=$((1 + $callnum))
+			assign "callnum_$name" "\$callnum"
+			eval "export callnum_$name"
+		fi
 
-		callnum=$(($callnum + 1))
-		eval "callnum_$name=\"\$callnum\""
+		stepnum=$((1 + $stepnum))
+		prevdir="$(readlink-e "$destdir" 2>/dev/null ||:)"
 	fi
 
-	chainsteps="${chainsteps#$name}"
-	chainsteps="${chainsteps#,}"
+	if [ ! -r "$BC_NEXTCHAIN" ]; then
+		chainsteps="${chainsteps#$name}"
+		chainsteps="${chainsteps#,}"
+	else
+		debug "chain will be reloaded by $BC_NEXTCHAIN:"
+		fdump "$BC_NEXTCHAIN"
+		. "$BC_NEXTCHAIN"
+		run rm -f -- "$BC_NEXTCHAIN"
+	fi
 
-	stepnum=$(($stepnum + 1))
+	debug "remaining steps: $chainsteps"
 done
 
 [ -z "$chainsteps" ] ||
 	message "remaining steps after breaking loop: $chainsteps"
 
+if [ "$rc" = 2 ] && [ -n "$pipeline_mode" ]; then
+	debug "finishing in pipeline mode"
+elif [ "$rc" = 0 ] && [ -f "$BC_PASSED/$PROG" ]; then
+	debug "finishing in bootchain mode"
+else
+	fatal "daemon terminated incorrectly (rc=$rc)"
+fi
+
 if [ -z "$BC_DEBUG" ]; then
 	grep -qs " $mntdir/" /proc/mounts ||
 		run umount -- "$mntdir" &&
-- 
2.24.1