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Updates to match new libzip version + potential fix #125

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merged 3 commits into from
Feb 8, 2023

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@grendello grendello commented Feb 2, 2023

A handful of changes for new libzip:

  • Update various enums to add new members from libzip 1.9.2
  • Add support for entry and archive comments
  • Set default values for various methods to match the upstream defaults
  • Stop using deprecated upstream functions

Implement a possible fix for the dreaded "cannot open file as zip archive" error we
sometimes see on CI. The error is caused by invalid content of the APK we generate
while building a Xamarin.Android app. During that process we open a ZIP archive
created by the Android SDK aapt2 utility and we append our content to it. In most
cases it works fine, but sometimes (we have no repro for this) the appended content
is invalid. What we see is that where there should be the content (compressed data
stream) of the first file we append to the original archive, there instead is a
copy of that original archive's central directory.

The issue may be caused by incorrect handling of the ZIP_SOURCE_SEEK_WRITE command
passed to our stream/source handler. Attempt to fix it by implementing the command
in the manner similar to that found in libzip itself.

Also some additions to the API as well as fixed a handful of compile
warnings
New minor version because of the new versions of native libraries
@grendello grendello marked this pull request as ready for review February 8, 2023 17:49
@grendello grendello changed the title [WIP] Updates for the newer libzip version Updates to match new libzip version + potential fix Feb 8, 2023
@dellis1972 dellis1972 merged commit f7dd2fb into main Feb 8, 2023
@grendello grendello deleted the updates-and-fixes branch February 8, 2023 18:31
grendello added a commit to grendello/xamarin-android-tools that referenced this pull request Feb 27, 2023
Context: dotnet/android-libzipsharp#125

The new LibZipSharp version potentially fixes the issue we see
from time to time on Ci, when an attempt to process a zip archive
(APK, in our case) ends with an error when trying to open the
archive.
dellis1972 pushed a commit to dotnet/android-tools that referenced this pull request Feb 27, 2023
Context: dotnet/android-libzipsharp#125

The new LibZipSharp version potentially fixes the issue we see
from time to time on Ci, when an attempt to process a zip archive
(APK, in our case) ends with an error when trying to open the
archive.
jonpryor pushed a commit to dotnet/android that referenced this pull request Feb 28, 2023
…7759)

Fixes? #6067

Context: https://gist.github.com/grendello/55b9a74c80c611dd48b726ee6f16d3c9
Context: dotnet/android-libzipsharp#125

Context: #7622

Changes: http://github.com/xamarin/monodroid/compare/50faac94c6a0c27864564829ac83f3988c82f8ef...602aca98245744882a129206b79b5a5e093dae44

  * xamarin/monodroid@602aca982: Bump androidtools for new LibZipSharp (xamarin/monodroid#1287)
  * xamarin/monodroid@1f52d5873: [tools/msbuild] Deploy *resources.dll from PackageReference (xamarin/monodroid#1276)

Changes: xamarin/androidtools@f11d163...c0bcb66

  * xamarin/androidtools@c0bcb66: Bump xamarin-android-tools for new LibZipSharp (xamarin/androidtools#377)

Changes: dotnet/android-tools@099fd95...dbe42bf

  * dotnet/android-tools@dbe42bf: Bump LibZipSharp version (dotnet/android-tools#204)

Sometimes in our tests we see an error from LibZipSharp which claims
a file cannot be opened as a valid ZIP archive:

	error ANDZA0000: Unable to open '…/example.apk' as zip archive

The reason for this is ZIP format corruption happening sometimes in
the `<BuildApk/>` task.

The way the process works is that we first run `aapt2` to produce
an APK archive named `packaged_resources`, which we then copy to the
destination APK (using standard `File.Copy()`) and open it to append
our content.  The first item we always append is the `classes.dex`
file which is also the **only** corrupted entry in the broken APK
files.

ZIP files contain two records describing each entry in the archive:

 1. in the Central Directory (located at the end of the file)

 2. local header in the ZIP data stream, offset of which is contained
    in the above Central Directory record.

After close examination, it appears that the broken APK files contain
(1) for `classes.dex` but not (2).  Instead of (2) we see a *copy*
of `packaged_resource` package's Central Directory record:

	% zipinfo -vv example.apk
	…
	Central directory entry #9:
	---------------------------

	  There are an extra 2 bytes preceding this file.

	  classes.dex

	  offset of local header from start of archive:   21680
	…

In particular, "There are an extra 2 bytes preceding this file" is a
sign that something "isn't right".  If we use `hexdump` to look at
the 128 bytes starting at offset 21680:

	% hexdump -C -s 21680 -n 128 example.apk 
	000054b0  50 4b 01 02 00 00 00 00  00 00 08 00 00 00 21 00  |PK............!.|
	000054c0  5e b2 00 5e cc 03 00 00  5c 0b 00 00 13 00 00 00  |^..^....\.......|
	000054d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 41 6e  |..............An|
	000054e0  64 72 6f 69 64 4d 61 6e  69 66 65 73 74 2e 78 6d  |droidManifest.xm|
	000054f0  6c 50 4b 01 02 00 00 00  00 00 00 00 00 00 00 21  |lPK............!|
	00005500  00 5c 71 d9 26 d2 05 00  00 d2 05 00 00 1d 00 00  |.\q.&...........|
	00005510  00 00 00 00 00 00 00 00  00 00 00 fd 03 00 00 72  |...............r|
	00005520  65 73 2f 64 72 61 77 61  62 6c 65 2d 6d 64 70 69  |es/drawable-mdpi|

we see that it starts with "PK", the common magic signature for zip
archives, and the following bytes { 0x1 0x2 } indicate that this is a
*central directory* entry, while it *should* be { 0x3, 0x4 } for a
*local header* entry.

The corruption may be caused by invalid stream position after we open
the `packaged_resources` copy and append `classes.dex` entry to it;
see dotnet/android-libzipsharp#125 for details.

We believe that the changes to `ZipArchive.stream_callback()` in
dotnet/android-libzipsharp#125 alongside additional calls to `Flush()` after
adding `classex.dex` **may** fix the problem.

If it doesn't, we should consider copying data from
`packaged_resources` to the final APK entry by entry by decompressing
them from the original archive and adding them to the destination one.
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