scripts: fix find_block false positives /dev/log/kernel and /dev/BOOT

- try /dev/block first with full depth to catch all platform/soc variations to the by-name directory, and the new dynamic partition /dev/block/mapper
- next try uevent for block devices as before
- lastly try /dev with maxdepth 1 (immediate directory) to find /dev/bootimg, /dev/recovery, etc. while avoiding /dev/log/kernel
- move bootimg higher in the list than boot so /dev/bootimg gets found first and avoids /dev/BOOT
- recovery_a/_b now also exists
- minor touch-ups for readability and consistency

Fixes #2720

scripts/util_functions.sh

@@ -170,24 +170,33 @@ recovery_cleanup() {
 
 # find_block [partname...]
 find_block() {
+  local BLOCK DEV DEVICE DEVNAME PARTNAME UEVENT
   for BLOCK in "$@"; do
-    DEVICE=`find /dev \( -type b -o -type c -o -type l \) -iname $BLOCK | head -n 1` 2>/dev/null
+    DEVICE=`find /dev/block \( -type b -o -type c -o -type l \) -iname $BLOCK | head -n 1` 2>/dev/null
     if [ ! -z $DEVICE ]; then
       readlink -f $DEVICE
       return 0
     fi
   done
   # Fallback by parsing sysfs uevents
-  for uevent in /sys/dev/block/*/uevent; do
-    local DEVNAME=`grep_prop DEVNAME $uevent`
-    local PARTNAME=`grep_prop PARTNAME $uevent`
+  for UEVENT in /sys/dev/block/*/uevent; do
+    DEVNAME=`grep_prop DEVNAME $UEVENT`
+    PARTNAME=`grep_prop PARTNAME $UEVENT`
     for BLOCK in "$@"; do
-      if [ "`toupper $BLOCK`" = "`toupper $PARTNAME`" ]; then
+      if [ "$(toupper $BLOCK)" = "$(toupper $PARTNAME)" ]; then
         echo /dev/block/$DEVNAME
         return 0
       fi
     done
   done
+  # Look just in /dev in case we're dealing with MTD/NAND without /dev/block devices/links
+  for DEV in "$@"; do
+    DEVICE=`find /dev \( -type b -o -type c -o -type l \) -maxdepth 1 -iname $DEV | head -n 1` 2>/dev/null
+    if [ ! -z $DEVICE ]; then
+      readlink -f $DEVICE
+      return 0
+    fi
+  done
   return 1
 }
 
@@ -370,11 +379,11 @@ get_flags() {
 find_boot_image() {
   BOOTIMAGE=
   if $RECOVERYMODE; then
-    BOOTIMAGE=`find_block recovery_ramdisk$SLOT recovery sos`
+    BOOTIMAGE=`find_block recovery_ramdisk$SLOT recovery$SLOT sos`
   elif [ ! -z $SLOT ]; then
     BOOTIMAGE=`find_block ramdisk$SLOT recovery_ramdisk$SLOT boot$SLOT`
   else
-    BOOTIMAGE=`find_block ramdisk recovery_ramdisk kern-a android_boot kernel boot lnx bootimg boot_a`
+    BOOTIMAGE=`find_block ramdisk recovery_ramdisk kern-a android_boot kernel bootimg boot lnx boot_a`
   fi
   if [ -z $BOOTIMAGE ]; then
     # Lets see what fstabs tells me