COR-181 - Take zlib from the mailcore2 release instead of S3

[dbezverkhnii]

Build-Zip.ps1 fetched zlib.zip from the spark-prebuilt-binaries S3 bucket, authenticating with SPARK_PREBUILT_KEY and throwing when it was unset. That was the last thing in the Spark Windows build still reaching for AWS: mailcore2 moved off it in readdle/mailcore2#104, and removing the secret from the spark-core-mono workflows made this script fail.

The same zlib binary now travels as a public asset on the mailcore2 windows-prebuilt release — mailcore2-windows-deps-1.zip, the very archive mailcore2 itself builds against. Downloading it takes no credential.

Why the swap is exact

Zip/minizip/CMakeLists.txt consumes zlib_DIR as ${zlib_DIR}/include, ${zlib_DIR}/lib, and ${zlib_DIR}/lib64/zlib.{dll,pdb,lib,exp}. The archive carries all four under mailcore2-windows-deps/zlib/, the same layout zlib-win32-1 always had — mailcore2 reads include and lib64 from that exact directory. Only the path changes; the bytes and the CMake contract do not.

Notes

• Both copies of the script are updated — build-scripts/Windows-5.10/ and the legacy build-scripts/Windows/ — so nothing in this repository reads SPARK_PREBUILT_KEY any more.
• The unpack clears any tree a previous archive left, so stale files cannot be picked up.
• Consumers pin this repository by tag (spark-core-mono pins 2.1.1.5), so nothing changes for anyone until a new tag is cut and that pin is bumped.

Verification

Confirmed by inspection and by downloading the asset anonymously; the archive contains the four required paths. Not yet run on a Windows machine — the real check is a spark-core-mono CD run against a new tag, which needs this merged and tagged first.

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Note

Low Risk
Build-script-only change for Windows Zip dependencies; removes a secret requirement but relies on a public third-party release URL and correct archive layout.

Overview
Windows Zip builds no longer download zlib.zip from Spark’s S3 bucket or require SPARK_PREBUILT_KEY. Both build-scripts/Windows-5.10/Build-Zip.ps1 and build-scripts/Windows/Build-Zip.ps1 now pull the public mailcore2-windows-deps-1.zip from the mailcore2 windows-prebuilt GitHub release and point zlib_DIR at mailcore2-windows-deps/zlib (same include/lib/lib64 layout minizip’s CMake already expects).

The setup step downloads the new archive, removes any prior mailcore2-windows-deps tree before unpacking (so stale files aren’t reused), then expands into the dependencies folder. Only the source URL and paths change; the zlib binary and CMake contract stay aligned with mailcore2.

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[dbezverkhnii]

Closing: we decided to keep SPARK_PREBUILT_KEY for Zip and leave zlib on S3 for now. COR-181 scoped the AWS removal to mailcore2 only.

Leaving the branch in place — the swap is verified (the zlib in mailcore2-windows-deps-1.zip is byte-identical to the one the MailCore prebuilt ships), so this can be reopened as is if we revisit.