How to patch an application in emulator/device similar to how Google Play is doing with “Smart app updates”?

问题

Is it possible to achieve locally (using adb or other ways) what Google Play is doing in "Smart app updates" ?

What I want to do is to create a binary diff on the PC (using some command line tools) and then deploy the diff to simulator/device using Android tools (adb, shell, etc).

I am aware of https://android.stackexchange.com/questions/36421/what-is-the-applypatch-tool-and-how-does-one-use-it which doesn't provide any info about HOW to actually create and apply patches, just WHAT adb shell applypatch is.

I tried to take a quick look at the C++ Android implementation code here which does the patching: https://android.googlesource.com/platform/bootable/recovery/+/master/applypatch/main.cpp#167

So far I created a binary diff using bsdiff, which apparently uses same algorithm with what Google Play and Android is using. But I don't know how to actually apply the patch.

EDIT: To clarify, here's a good example:

I have com.appv1.apk on my PC and also installed on the device/emulator.
I have com.appv2.apk on my PC.
Using bsdiff I create the binary diff between com.appv1.apk and com.appv2.apk called let's say diff.bin

Now, what is the actual adb command I need to run to deploy diff.binon the device/emulator such that after deploying the diff, com.appv1.apk on the device/emulator becomes com.appv2.apk ?

回答1:

I would say that between the usage print out:

usage: applypatch [-b <bonus-file>] <src-file> <tgt-file> <tgt-sha1> <tgt-size> [<src-sha1>:<patch> ...]
   or  applypatch -c <file> [<sha1> ...]
   or  applypatch -s <bytes>
   or  applypatch -l

Filenames may be of the form
  MTD:<partition>:<len_1>:<sha1_1>:<len_2>:<sha1_2>:...
to specify reading from or writing to an MTD partition.

and the comments below:

// This program applies binary patches to files in a way that is safe
// (the original file is not touched until we have the desired
// replacement for it) and idempotent (it's okay to run this program
// multiple times).
//
// - if the sha1 hash of <tgt-file> is <tgt-sha1>, does nothing and exits
//   successfully.
//
// - otherwise, if no <src-sha1>:<patch> is provided, flashes <tgt-file> with
//   <src-file>. <tgt-file> must be a partition name, while <src-file> must
//   be a regular image file. <src-file> will not be deleted on success.
//
// - otherwise, if the sha1 hash of <src-file> is <src-sha1>, applies the
//   bsdiff <patch> to <src-file> to produce a new file (the type of patch
//   is automatically detected from the file header).  If that new
//   file has sha1 hash <tgt-sha1>, moves it to replace <tgt-file>, and
//   exits successfully.  Note that if <src-file> and <tgt-file> are
//   not the same, <src-file> is NOT deleted on success.  <tgt-file>
//   may be the string "-" to mean "the same as src-file".
//
// - otherwise, or if any error is encountered, exits with non-zero
//   status.
//
// <src-file> (or <file> in check mode) may refer to an EMMC partition
// to read the source data.  See the comments for the
// LoadPartitionContents() function for the format of such a filename.

it is pretty straight-forward.

So the basic command to patch com.appv1.apk with diff.bin and save the result to the com.appv2.apk would be:

applypatch com.appv1.apk com.appv2.apk <com.appv2.apk SHA1> <com.appv2.apk size> <com.appv1.apk SHA1>:diff.bin

来源：https://stackoverflow.com/questions/39513048/how-to-patch-an-application-in-emulator-device-similar-to-how-google-play-is-doi

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