feat(GUI): spawn CLI directly from the AppImage in GNU/Linux (#775)

If we pass relative paths as arguments to the AppImage, they get
resolved from `/tmp/.mount_XXXXXX/usr`. We can exploit this to run the
Etcher CLI directly from the AppImage, rather than having to mount it
ourselves:

```sh
ELECTRON_RUN_AS_NODE=1 Etcher-linux-x64.AppImage bin/resources/app.asar [OPTIONS]
```

By using this little trick, we get rid of both our custom mounting logic
and the need of surrounding the command to run in single quotes,
therefore avoiding a whole new kind of escaping issues.

Since running the CLI directly from the AppImage means that the
`desktopintegration` will be ran for the CLI, we pass the `SKIP`
environment variable to avoid having it prompt the user for
installation.

We also updated the `desktopintegration` script to the latest version,
which reduces the amount of logging plus other minor fixes.

Fixes: https://github.com/resin-io/etcher/issues/637
Change-Type: patch
Changelog-Entry: Fix Etcher leaving zombie processes behind in GNU/Linux.
Signed-off-by: Juan Cruz Viotti <jviotti@openmailbox.org>

lib/src/child-writer/writer-proxy.js

@@ -22,6 +22,7 @@ const isElevated = Bluebird.promisify(require('is-elevated'));
 const ipc = require('node-ipc');
 const _ = require('lodash');
 const os = require('os');
+const path = require('path');
 const sudoPrompt = Bluebird.promisifyAll(require('sudo-prompt'));
 const EXIT_CODES = require('../exit-codes');
 const packageJSON = require('../../../package.json');
@@ -84,64 +85,27 @@ return isElevated().then((elevated) => {
         'env',
         'ELECTRON_RUN_AS_NODE=1',
         `IPC_SERVER_ID=${process.env.IPC_SERVER_ID}`,
-        `IPC_CLIENT_ID=${process.env.IPC_CLIENT_ID}`
+        `IPC_CLIENT_ID=${process.env.IPC_CLIENT_ID}`,
+
+        // This environment variable prevents the AppImages
+        // desktop integration script from presenting the
+        // "installation" dialog.
+        'SKIP=1'
 
       ];
 
-      // Executing a binary from inside an AppImage as other user
-      // (e.g: `root`) fails with a permission error because of a
-      // security measure imposed by FUSE.
-      //
-      // As a workaround, if we're inside an AppImage, we re-mount
-      // the same AppImage to another temporary location without
-      // FUSE, and re-call to writer proxy as `root` from there.
-
       if (process.env.APPIMAGE && process.env.APPDIR) {
-        const mountPoint = process.env.APPDIR + '-elevated';
 
-        // Translate the current arguments to
+        // Translate the current arguments to point to the AppImage
-        // point to the new mount location.
+        // Relative paths are resolved from `/tmp/.mount_XXXXXX/usr`
-        const translatedArguments = _.map(process.argv, (argv) => {
+        const translatedArguments = _.map(_.tail(process.argv), (argv) => {
-          return argv.replace(process.env.APPDIR, mountPoint);
+          return argv.replace(path.join(process.env.APPDIR, 'usr/'), '');
         });
 
-        // We wrap the command with `sh -c` since it seems
+        return commandPrefix
-        // the only way to effectively run many commands
+        .concat([ process.env.APPIMAGE ])
-        // with a graphical sudo interface,
-        return 'sh -c \'' + [
-
-          'mkdir',
-          '-p',
-          mountPoint,
-          '&&',
-          'mount',
-          '-o',
-          'loop',
-
-          // We re-mount the AppImage as "read-only", since `mount`
-          // will refuse to mount the same AppImage in two different
-          // locations otherwise.
-          '-o',
-          'ro',
-
-          process.env.APPIMAGE,
-          mountPoint,
-          '&&'
-        ]
-        .concat(commandPrefix)
         .concat(utils.escapeWhiteSpacesFromArguments(translatedArguments))
-        .concat([
+        .join(' ');
-          ';',
-
-          // We need to sleep for a little bit for `umount` to
-          // succeed, otherwise it complains with an `EBUSY` error.
-          'sleep',
-          '1',
-
-          ';',
-          'umount',
-          mountPoint
-        ]).join(' ') + '\'';
       }
 
       return commandPrefix.concat(

scripts/build/AppImages/desktopintegration

@@ -4,9 +4,23 @@
 # into the host system without special help from the host system.
 # If you want to use it, then place this in usr/bin/$APPNAME.wrapper
 # and set it as the Exec= line of the .desktop file in the AppImage.
-
+#
+# For example, to install the appropriate icons for Scribus,
+# put them into the AppDir at the following locations:
+#
+# ./usr/share/icons/default/128x128/apps/scribus.png
+# ./usr/share/icons/default/128x128/mimetypes/application-vnd.scribus.png
+#
+# Note that the filename application-vnd.scribus.png is derived from
+# and must be match MimeType=application/vnd.scribus; in scribus.desktop
+# (with "/" characters replaced by "-").
+#
+# Then, change Exec=scribus to Exec=scribus.wrapper and place the script
+# below in usr/bin/scribus.wrapper and make it executable.
+# When you run AppRun, then AppRun runs the wrapper script below
+# which in turn will run the main application.
+#
 # TODO:
-# Handle icons for mime types as well using xdg-icon-resource
 # Handle multiple versions of the same AppImage?
 # Handle removed AppImages? Currently we are just setting TryExec=
 # See http://specifications.freedesktop.org/thumbnail-spec/thumbnail-spec-latest.html#DELETE
@@ -21,33 +35,61 @@ if [ ! -z "$DEBUG" ] ; then
   set -x
 fi
 
+THIS="$0"
+args=("$@") # http://stackoverflow.com/questions/3190818/
+NUMBER_OF_ARGS="$#"
+
 # Please do not change $VENDORPREFIX as it will allow for desktop files
 # belonging to AppImages to be recognized by future AppImageKit components
 # such as desktop integration daemons
 VENDORPREFIX=appimagekit
 
-FILENAME=$(readlink -f "${0}")
+find-up () {
+  path="$(dirname "$(readlink -f "${THIS}")")"
+  while [[ "$path" != "" && ! -e "$path/$1" ]]; do
+    path=${path%/*}
+  done
+  # echo "$path"
+}
 
-echo $FILENAME
+if [ -z $APPDIR ] ; then
+  # Find the AppDir. It is the directory that contains AppRun.
+  # This assumes that this script resides inside the AppDir or a subdirectory.
+  # If this script is run inside an AppImage, then the AppImage runtime
+  # likely has already set $APPDIR
+  APPDIR=$(find-up "AppRun")
+fi
+
+# echo "$APPDIR"
+
+FILENAME="$(readlink -f "${THIS}")"
+
+# echo "$FILENAME"
 
 if [[ "$FILENAME" != *.wrapper ]] ; then
-  echo "$0 is not named correctly. It should be named \$Exec.wrapper"
+  echo "${THIS} is not named correctly. It should be named \$Exec.wrapper"
   exit 0
 fi
 
 BIN=$(echo "$FILENAME" | sed -e 's|.wrapper||g')
-if [[ ! -f $BIN ]] ; then
+if [[ ! -f "$BIN" ]] ; then
   echo "$BIN not found"
   exit 0
 fi
 
-ARGS=$@
-
 trap atexit EXIT
 
+# Note that the following handles 0, 1 or more arguments (file paths)
+# which can include blanks but uses a bashism; can the same be achieved
+# in POSIX-shell? (FIXME)
+# http://stackoverflow.com/questions/3190818
 atexit()
 {
-  exec $BIN $ARGS
+if [ $NUMBER_OF_ARGS -eq 0 ] ; then
+  exec "${BIN}"
+else
+  exec "${BIN}" "${args[@]}"
+fi
 }
 
 error()
@@ -69,13 +111,13 @@ yesno()
   TITLE=$1
   TEXT=$2
   if [ -x /usr/bin/zenity ] ; then
-    LD_LIBRARY_PATH="" zenity --question --title="$TITLE" --text="$TEXT" || exit 0
+    LD_LIBRARY_PATH="" zenity --question --title="$TITLE" --text="$TEXT" 2>/dev/null || exit 0
   elif [ -x /usr/bin/kdialog ] ; then
     LD_LIBRARY_PATH="" kdialog --caption "Disk auswerfen?" --title "$TITLE" -yesno "$TEXT" || exit 0
   elif [ -x /usr/bin/Xdialog ] ; then
     LD_LIBRARY_PATH="" Xdialog --title "$TITLE" --clear --yesno "$TEXT" 10 80 || exit 0
   else
-    echo "zenity, kdialog, Xdialog missing. Skipping $0."
+    echo "zenity, kdialog, Xdialog missing. Skipping ${THIS}."
     exit 0
   fi
 }
@@ -106,7 +148,7 @@ check_dep()
 {
   DEP=$1
   if [ -z $(which $DEP) ] ; then
-    echo "$DEP is missing. Skipping $0."
+    echo "$DEP is missing. Skipping ${THIS}."
     exit 0
   fi
 }
@@ -118,36 +160,41 @@ DIRNAME=$(dirname $FILENAME)
 check_dep desktop-file-validate
 check_dep update-desktop-database
 check_dep desktop-file-install
+check_dep xdg-icon-resource
+check_dep xdg-mime
+check_dep xdg-desktop-menu
 
-DESKTOPFILE=$(find ../ -name "*.desktop" | head -n 1)
+DESKTOPFILE=$(find "$APPDIR" -maxdepth 1 -name "*.desktop" | head -n 1)
-DESKTOPFILE_NAME=$(basename $DESKTOPFILE)
+# echo "$DESKTOPFILE"
+DESKTOPFILE_NAME=$(basename "${DESKTOPFILE}")
 
 if [ ! -f "$DESKTOPFILE" ] ; then
-  echo "Desktop file is missing. Please run $0 from within an AppImage."
+  echo "Desktop file is missing. Please run ${THIS} from within an AppImage."
   exit 0
 fi
 
 if [ -z "$APPIMAGE" ] ; then
-  echo "\$APPIMAGE is missing. Please run $0 from within an AppImage."
+  APPIMAGE="$APPDIR/AppRun"
-  exit 0
+  # Not running from within an AppImage; hence using the AppRun for Exec=
 fi
 
 # Construct path to the icon according to
 # http://specifications.freedesktop.org/thumbnail-spec/thumbnail-spec-latest.html
-ABS_APPIMAGE=$(readlink -e $APPIMAGE)
+ABS_APPIMAGE=$(readlink -e "$APPIMAGE")
 ICONURL="file://$ABS_APPIMAGE"
 MD5=$(echo -n $ICONURL | md5sum | cut -c -32)
 ICONFILE="$HOME/.cache/thumbnails/normal/$MD5.png"
 if [ ! -f "$ICONFILE" ] ; then
-  echo "$ICONFILE is missing. Please run $0 from within an AppImage."
+  echo "$ICONFILE is missing. Probably not running ${THIS} from within an AppImage."
-  exit 0
+  echo "Hence falling back to using .DirIcon"
+  ICONFILE="$APPDIR/.DirIcon"
 fi
 
 # $XDG_DATA_DIRS contains the default paths /usr/local/share:/usr/share
 # desktop file has to be installed in an applications subdirectory
 # of one of the $XDG_DATA_DIRS components
 if [ -z "$XDG_DATA_DIRS" ] ; then
-  echo "\$XDG_DATA_DIRS is missing. Please run $0 from within an AppImage."
+  echo "\$XDG_DATA_DIRS is missing. Please run ${THIS} from within an AppImage."
   exit 0
 fi
 
@@ -165,37 +212,56 @@ fi
 # and if so, whether it points to the same AppImage
 if [ -e "$DESTINATION_DIR_DESKTOP/$VENDORPREFIX-$DESKTOPFILE_NAME" ] ; then
   # echo "$DESTINATION_DIR_DESKTOP/$VENDORPREFIX-$DESKTOPFILE_NAME already there"
-  EXEC=$(grep "^Exec=" "$DESTINATION_DIR_DESKTOP/$VENDORPREFIX-$DESKTOPFILE_NAME" | head -n 1)
+  EXEC=$(grep "^Exec=" "$DESTINATION_DIR_DESKTOP/$VENDORPREFIX-$DESKTOPFILE_NAME" | head -n 1 | cut -d " " -f 1)
   # echo $EXEC
-  if [ "Exec=$APPIMAGE" == "$EXEC" ] ; then
+  if [ "Exec=\"$APPIMAGE\"" == "$EXEC" ] ; then
     exit 0
   fi
 fi
 
 # We ask the user only if we have found no reason to skip until here
 if [ -z "$SKIP" ] ; then
-  yesno "Install" "Should a desktop file for $APPIMAGE be installed?"
+  yesno "Install" "Would you like to integrate $APPIMAGE with your system?\n\nThis will add it to your applications menu and install icons.\nIf you don't do this you can still launch the application by double-clicking on the AppImage."
 fi
 
+APP=$(echo "$DESKTOPFILE_NAME" | sed -e 's/.desktop//g')
+
 # If the user has agreed, rewrite and install the desktop file, and the MIME information
 if [ -z "$SKIP" ] ; then
-  if [ -e ./share/mime/ ] ; then
+  # desktop-file-install is supposed to install .desktop files to the user's
-    find ./share/mime/ -type f -name *xml -exec xdg-mime install $SYSTEM_WIDE --novendor {} \;
-  fi
-  # desktop-file-install is supposed to install
-  # .desktop files to the user's
   # applications directory when run as a non-root user,
   # and to /usr/share/applications if run as root
   # but that does not really work for me...
-  echo desktop-file-install --rebuild-mime-info-cache \
+  #
-    --vendor=$VENDORPREFIX --set-key=Exec --set-value=$APPIMAGE \
+  # For Exec we must use quotes
-    --set-key=X-AppImage-Comment --set-value="Generated by $0" \
+  # For TryExec quotes is not supported, so, space must be replaced to \s
-    --set-icon=$ICONFILE --set-key=TryExec --set-value=$APPIMAGE $DESKTOPFILE \
+  # https://askubuntu.com/questions/175404/how-to-add-space-to-exec-path-in-a-thumbnailer-descrption/175567
-    --dir "$DESTINATION_DIR_DESKTOP"
   desktop-file-install --rebuild-mime-info-cache \
-    --vendor=$VENDORPREFIX --set-key=Exec --set-value=$APPIMAGE \
+    --vendor=$VENDORPREFIX --set-key=Exec --set-value="\"${APPIMAGE}\" %U" \
-    --set-key=X-AppImage-Comment --set-value="Generated by $0" \
+    --set-key=X-AppImage-Comment --set-value="Generated by ${THIS}" \
-    --set-icon=$ICONFILE --set-key=TryExec --set-value=$APPIMAGE $DESKTOPFILE \
+    --set-icon="$ICONFILE" --set-key=TryExec --set-value=${APPIMAGE// /\\s} "$DESKTOPFILE" \
     --dir "$DESTINATION_DIR_DESKTOP"
+  chmod a+x "$DESTINATION_DIR_DESKTOP/"*
+  RESOURCE_NAME=$(echo "$VENDORPREFIX-$DESKTOPFILE_NAME" | sed -e 's/.desktop//g')
+  # echo $RESOURCE_NAME
+
+  # Install the icon files for the application; TODO: scalable
+  ICONS=$(find "${APPDIR}/usr/share/icons/" -wholename "*/apps/${APP}.png" 2>/dev/null || true)
+  for ICON in $ICONS ; do
+    ICON_SIZE=$(echo "${ICON}" | rev | cut -d "/" -f 3 | rev | cut -d "x" -f 1)
+    xdg-icon-resource install --context apps --size ${ICON_SIZE} "${ICON}" "${RESOURCE_NAME}"
+  done
+
+  # Install mime type
+  find "${APPDIR}/usr/share/mime/" -type f -name *xml -exec xdg-mime install $SYSTEM_WIDE --novendor {} \; 2>/dev/null || true
+
+  # Install the icon files for the mime type; TODO: scalable
+  ICONS=$(find "${APPDIR}/usr/share/icons/" -wholename "*/mimetypes/*.png" 2>/dev/null || true)
+  for ICON in $ICONS ; do
+    ICON_SIZE=$(echo "${ICON}" | rev | cut -d "/" -f 3 | rev | cut -d "x" -f 1)
+    xdg-icon-resource install --context mimetypes --size ${ICON_SIZE} "${ICON}" $(basename $ICON | sed -e 's/.png//g')
+  done
+
   xdg-desktop-menu forceupdate
+  gtk-update-icon-cache # for MIME
 fi