Fix update-efiboot-image loop device leak

If update-efiboot-image exits abnormally or is terminated
from an external signal, it has been observed to leave
dangling mounts and/or fails to release the loop device.
Over time, all loop devices can be consumed on the build host.

This update adds an exit handler to ensure release of the
mount and loop device.

Closes-Bug: 1896822
Change-Id: I1891df134ae583750ca1d4858bdc2402e6a67ff6
Signed-off-by: Scott Little <scott.little@windriver.com>

build-tools/update-efiboot-image

@@ -15,6 +15,59 @@
 
 MY_YUM_CONF=""
 
+# Several commands may need to be executed with sudo if we're not using
+# udev.  Use a variable to hold the optional "sudo" part
+if [ 0${BUILD_ISO_USE_UDEV} -eq 1 ]; then
+    SUDOPREFIX=""
+else
+    SUDOPREFIX="sudo"
+fi
+
+function env_check {
+    for VAR_TO_CHECK in $@; do
+        if [ -z "${!VAR_TO_CHECK}" ]; then
+            echo "Required environment variable is missing: $VAR_TO_CHECK"
+            exit 1
+        fi
+    done
+}
+
+env_check MY_REPO MY_WORKSPACE BSP_FILES_PATH
+
+# Cleanup function that will release all mounts and loop devices
+function finish {
+    if [ -z "$LOOP" ] && [ ! -z "$SETUP_RET" ]; then
+        if [ 0${BUILD_ISO_USE_UDEV} -eq 1 ]; then
+            LOOP=$(echo $SETUP_RET | awk '{print $5;}' | sed -e 's/\.//g')
+        else
+            LOOP=$(echo $SETUP_RET)
+        fi
+    fi
+
+    if [ ! -z "$LOOP" ]; then
+        if [ 0${BUILD_ISO_USE_UDEV} -eq 1 ]; then
+            udisksctl unmount -b $LOOP
+        else
+            sudo umount $LOOP
+        fi
+        echo $(date) Unmounted $LOOP. $? | tee --append $MOUNT_LOG_FILE
+
+        if [ 0${BUILD_ISO_USE_UDEV} -eq 1 ]; then
+            CLEANUP_RET=$(udisksctl loop-delete -b $LOOP)
+        else
+            CLEANUP_RET=$(sudo losetup -d $LOOP)
+        fi
+        echo $(date) Released loop device $LOOP. $CLEANUP_RET | tee --append $MOUNT_LOG_FILE
+    fi
+
+
+    if [ ! -z "$EFI_MOUNT" ] && [ -d "$EFI_MOUNT" ]; then
+        ${SUDOPREFIX} rmdir $EFI_MOUNT
+        echo $(date) Deleted mount point $EFI_MOUNT | tee --append $MOUNT_LOG_FILE
+    fi
+
+}
+
 function setup_env_vars  {
     mkdir -p $MY_WORKSPACE/export/
 
@@ -67,7 +120,22 @@ printf "  Calling $0\n"
 setup_env_vars
 
 printf "  Calling $(basename $0)\n"
+
+mkdir -p $OUTPUT_DIR
+if [ $? -ne 0 ]; then
+   printf "  Error: failed to create directory '$OUTPUT_DIR'.\n"
+   exit 1
+fi
+
 MOUNT_LOG_FILE=$OUTPUT_DIR/mounts_used.log
+touch $MOUNT_LOG_FILE
+if [ $? -ne 0 ]; then
+   printf "  Error: Failed to create log file '$MOUNT_LOG_FILE'.\n"
+   exit 1
+fi
+
+# Register our cleanup function
+trap finish EXIT
 
 # Clear old image file
 printf "  Delete old efiboot.img file\n"
@@ -83,25 +151,25 @@ printf "  Replacing the efiboot.img grub.cfg file with the Titanium Cloud one\n"
 # This is controlled via env variable
 
 if [ 0${BUILD_ISO_USE_UDEV} -eq 1 ]; then
-    RET=$(udisksctl loop-setup -f $OUTPUT_DIR/efiboot.img --no-user-interaction)
+    SETUP_RET=$(udisksctl loop-setup -f $OUTPUT_DIR/efiboot.img --no-user-interaction)
     if [ $? -ne 0 ]; then
       printf "  Error: failed udev loop-setup command.\n"
       exit 1
     fi
-    LOOP=$(echo $RET | awk '{print $5;}' | sed -e 's/\.//g')
+    LOOP=$(echo $SETUP_RET | awk '{print $5;}' | sed -e 's/\.//g')
 else
     # no udev - use losetup command
     # retcode is the lo device used
-    RET=$(sudo losetup --show -f $OUTPUT_DIR/efiboot.img)
+    SETUP_RET=$(sudo losetup --show -f $OUTPUT_DIR/efiboot.img)
-    if [ -z "$RET" ] ; then
+    if [ -z "$SETUP_RET" ] ; then
       printf "  Error: failed sudo losetup command.\n"
       exit 1
     fi
 
     # Save the loop device used into a file
-    echo $(date) $RET >> $MOUNT_LOG_FILE
+    echo $(date) $SETUP_RET >> $MOUNT_LOG_FILE
 
-    LOOP=$(echo $RET)
+    LOOP=$(echo $SETUP_RET)
     if [ -z $LOOP ] ; then
       printf "  Error: failed losetup  command.\n"
       exit 1
@@ -122,14 +190,6 @@ if [ -z $EFI_MOUNT ] ; then
   exit 1
 fi
 
-# Several commands may need to be executed with sudo if we're not using
-# udev.  Use a variable to hold the optional "sudo" part
-if [ 0${BUILD_ISO_USE_UDEV} -eq 1 ]; then
-    SUDOPREFIX=""
-else
-    SUDOPREFIX="sudo"
-fi
-
 # Update the vanilla UEFI Centos grub.cfg with the Titanium Cloud version
 ${SUDOPREFIX} cp "$BSP_FILES_PATH/grub.cfg"  "$EFI_MOUNT/EFI/BOOT/grub.cfg"
 
@@ -170,15 +230,4 @@ rm -rf $TMPDIR
 ${SUDOPREFIX} mkdir -p $EFI_MOUNT/CERTS
 ${SUDOPREFIX} cp $INTERNAL_REPO_ROOT/build-tools/certificates/* $EFI_MOUNT/CERTS
 
-# Cleanup mounts
-if [ 0${BUILD_ISO_USE_UDEV} -eq 1 ]; then
-    udisksctl unmount -b $LOOP
-    RET=$(udisksctl loop-delete -b $LOOP)
-else
-    sudo umount $LOOP
-    RET=$(sudo losetup -d $LOOP)
-fi
-
-echo $(date) Deleted $LOOP. $RET >> $MOUNT_LOG_FILE
-${SUDOPREFIX} rmdir $EFI_MOUNT
 exit 0