[Kobo] Restart KOReader after a crash (#5328)

* Restart KOReader after a crash, after showing a fancy crash recap screen (our very own Gray Screen of Death!).

Kobo only, because it's possibly the platform where getting booted out
of KOReader is the most annoying.

Keeps track of crashes, to be able to give up after a while, in order to
avoid boot loops in the unlikely event of a crash loop on startup.

Adds a dev option to *always* exit KOReader after the crash screen.

frontend/apps/filemanager/filemanagermenu.lua

@@ -304,6 +304,22 @@ function FileManagerMenu:setUpdateItemTable()
             end,
         })
     end
+    --- @note Currently, only Kobo has a fancy crash display (#5328)
+    if Device:isKobo() then
+        table.insert(self.menu_items.developer_options.sub_item_table, {
+            text = _("Always abort on crash"),
+            checked_func = function()
+                return G_reader_settings:isTrue("dev_abort_on_crash")
+            end,
+            callback = function()
+                G_reader_settings:flipNilOrFalse("dev_abort_on_crash")
+                local InfoMessage = require("ui/widget/infomessage")
+                UIManager:show(InfoMessage:new{
+                    text = _("This will take effect on next restart."),
+                })
+            end,
+        })
+    end
     if not Device.should_restrict_JIT then
         table.insert(self.menu_items.developer_options.sub_item_table, {
             text = _("Disable C blitter"),

platform/kobo/koreader.sh

@@ -43,7 +43,7 @@ ko_update_check() {
             ./fbink -q -y -6 -pm "Update successful :)"
             ./fbink -q -y -5 -pm "KOReader will start momentarily . . ."
         else
-            # Huh ho...
+            # Uh oh...
             ./fbink -q -y -6 -pmh "Update failed :("
             ./fbink -q -y -5 -pm "KOReader may fail to function properly!"
         fi
@@ -155,7 +155,7 @@ case "${ORIG_FB_BPP}" in
     16) ;;
     32) ;;
     *)
-        # Hu oh? Don't do anything...
+        # Uh oh? Don't do anything...
         unset ORIG_FB_BPP
         ;;
 esac
@@ -196,15 +196,103 @@ if [ -e crash.log ]; then
     mv -f crash.log.new crash.log
 fi
 
+CRASH_COUNT=0
+CRASH_TS=0
+CRASH_PREV_TS=0
+# Because we *want* an initial fbdepth pass ;).
 RETURN_VALUE=85
-while [ $RETURN_VALUE -eq 85 ]; do
-    # Do an update check now, so we can actually update KOReader via the "Restart KOReader" menu entry ;).
-    ko_update_check
-    # Do the fb depth switch, unless it's been disabled
-    ko_do_fbdepth
+while [ $RETURN_VALUE -ne 0 ]; do
+    # 85 is what we return when asking for a KOReader restart
+    if [ $RETURN_VALUE -eq 85 ]; then
+        # Do an update check now, so we can actually update KOReader via the "Restart KOReader" menu entry ;).
+        ko_update_check
+        # Do or double-check the fb depth switch, or restore original bitdepth if requested
+        ko_do_fbdepth
+    fi
 
     ./reader.lua "${args}" >>crash.log 2>&1
     RETURN_VALUE=$?
+
+    # Did we crash?
+    if [ $RETURN_VALUE -ne 0 ] && [ $RETURN_VALUE -ne 85 ]; then
+        # Increment the crash counter
+        CRASH_COUNT=$((CRASH_COUNT + 1))
+        CRASH_TS=$(date +'%s')
+        # Reset it to a first crash if it's been a while since our last crash...
+        if [ $((CRASH_TS - CRASH_PREV_TS)) -ge 20 ]; then
+            CRASH_COUNT=1
+        fi
+
+        # Check if the user requested to always abort on crash
+        if grep -q '\["dev_abort_on_crash"\] = true' 'settings.reader.lua' 2>/dev/null; then
+            ALWAYS_ABORT="true"
+            # In which case, make sure we pause on *every* crash
+            CRASH_COUNT=1
+        else
+            ALWAYS_ABORT="false"
+        fi
+
+        # Show a fancy bomb on screen
+        viewWidth=600
+        viewHeight=800
+        FONTH=16
+        eval "$(./fbink -e | tr ';' '\n' | grep -e viewWidth -e viewHeight -e FONTH | tr '\n' ';')"
+        # Compute margins & sizes relative to the screen's resolution, so we end up with a similar layout, no matter the device.
+        # Height @ ~56.7%, w/ a margin worth 1.5 lines
+        bombHeight=$((viewHeight/2 + viewHeight/15))
+        bombMargin=$((FONTH + FONTH/2))
+        # With a little notice at the top of the screen, on a big gray screen of death ;).
+        ./fbink -q -b -c -B GRAY9 -m -y 1 "Don't Panic! (Crash n°${CRASH_COUNT} -> ${RETURN_VALUE})"
+        if [ ${CRASH_COUNT} -eq 1 ]; then
+            # Warn that we're waiting on a tap to continue...
+            ./fbink -q -b -O -m -y 2 "Tap the screen to continue."
+        fi
+        # U+1F4A3, the hard way, because we can't use \u or \U escape sequences...
+        # shellcheck disable=SC2039
+        ./fbink -q -b -O -m -t regular=./fonts/freefont/FreeSerif.ttf,px=${bombHeight},top=${bombMargin} $'\xf0\x9f\x92\xa3'
+        # And then print the tail end of the log on the bottom of the screen...
+        crashLog="$(tail -n 25 crash.log | sed -e 's/\t/    /g')"
+        # The idea for the margins being to leave enough room for an fbink -Z bar, small horizontal margins, and a font size based on what 6pt looked like @ 265dpi
+        ./fbink -q -b -O -t regular=./fonts/droid/DroidSansMono.ttf,top=$((viewHeight/2 + FONTH * 2 + FONTH/2)),left=$((viewWidth/60)),right=$((viewWidth/60)),px=$((viewHeight/64)) "${crashLog}"
+        # So far, we hadn't triggered an actual screen refresh, do that now, to make sure everything is bundled in a single flashing refresh.
+        ./fbink -q -f -s top=0,left=0
+        # Cue a lemming's faceplant sound effect!
+
+        echo "!!!!" >>crash.log 2>&1
+        echo "Uh oh, something went awry... (Crash n°${CRASH_COUNT}: $(date +'%x @ %X'))" >>crash.log 2>&1
+        if [ $CRASH_COUNT -lt 5 ] && [ "${ALWAYS_ABORT}" = "false" ]; then
+            echo "Attempting to restart KOReader . . ." >>crash.log 2>&1
+            echo "!!!!" >>crash.log 2>&1
+        fi
+
+        # Pause a bit if it's the first crash in a while, so that it actually has a chance of getting noticed ;).
+        if [ ${CRASH_COUNT} -eq 1 ]; then
+            # NOTE: We don't actually care about what read read, we're just using it as a fancy sleep ;).
+            #       i.e., we pause either until the 15s timeout, or until the user touches the screen.
+            # shellcheck disable=SC2039
+            read -r -t 15 </dev/input/event1
+        fi
+        # Cycle the last crash timestamp
+        CRASH_PREV_TS=${CRASH_TS}
+
+        # But if we've crashed more than 5 consecutive times, exit, because we wouldn't want to be stuck in a loop...
+        # NOTE: No need to check for ALWAYS_ABORT, CRASH_COUNT will always be 1 when it's true ;).
+        if [ $CRASH_COUNT -ge 5 ]; then
+            echo "Too many consecutive crashes, aborting . . ." >>crash.log 2>&1
+            echo "!!!! ! !!!!" >>crash.log 2>&1
+            break
+        fi
+
+        # If the user requested to always abort on crash, do so.
+        if [ "${ALWAYS_ABORT}" = "true" ]; then
+            echo "Aborting . . ." >>crash.log 2>&1
+            echo "!!!! ! !!!!" >>crash.log 2>&1
+            break
+        fi
+    else
+        # Reset the crash counter if that was a sane exit/restart
+        CRASH_COUNT=0
+    fi
 done
 
 # Restore original fb bitdepth if need be...