How can one pull the (private) data of one's own Android app?

Attempting to pull a single file using

adb pull /data/data/com.corp.appName/files/myFile.txt myFile.txt

fails with

failed to copy '/data/data/com.corp.appName/files/myFile.txt myFile.txt' to 'myFile.txt': Permission denied

despite that USB debugging is enabled on the device.

We can go around the problem through the archaic route

adb shell
run-as com.corp.appName
cat files/myFile.txt > myFile.txt

but this is unwieldy for more than one file.

How can I pull the directory /data/data/com.corp.appName/files to my MacBook?

Doing this either directly or through a transit in `/storage/sdcard0/myDir (from where I can continue with Android File Transfer) is fine.

Additional Comment

It may be that just running

adb backup  -f myFiles com.corp.appName

will generate the files I am looking for. In that case I am looking for a way to untar/unzip the resulting backup!

Solution

adb backup will write an Android-specific archive:

adb backup  -f myAndroidBackup.ab  com.corp.appName

This archive can be converted to tar format using:

dd if=myAndroidBackup.ab bs=4K iflag=skip_bytes skip=24 | openssl zlib -d > myAndroidBackup.tar

Reference:

Search for "Update" at that link.

Alternatively, use Android backup extractor to extract files from the Android backup (.ab) file.