From 6b502613f5df4b20e530612bc75f4e25399b07bd Mon Sep 17 00:00:00 2001
From: tannevaled <tannevaled@users.noreply.github.com>
Date: Mon, 1 Jun 2026 08:45:22 +0200
Subject: [PATCH] new(jmacd/xdelta): VCDIFF (RFC 3284) delta compression
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Joshua MacDonald's xdelta3 — the most widely used VCDIFF
implementation outside Google's now-archived open-vcdiff. Used by
Chromium auto-update channels and many embedded firmware delta
pipelines. C autotools build, GPL-2.0+.

Upstream is dormant (last push 2020) but unarchived; the algorithm
and CLI surface are RFC-stable.

Builds from the modern xdelta3/ subdir; the older xdelta1/ proto
is left out (1998 historical only).

Test: round-trip encode/decode with a small source/target pair.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
---
 projects/github.com/jmacd/xdelta/package.yml | 57 ++++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 projects/github.com/jmacd/xdelta/package.yml

diff --git a/projects/github.com/jmacd/xdelta/package.yml b/projects/github.com/jmacd/xdelta/package.yml
new file mode 100644
index 0000000000..3fe434cca1
--- /dev/null
+++ b/projects/github.com/jmacd/xdelta/package.yml
@@ -0,0 +1,57 @@
+# xdelta3 — open-source VCDIFF (RFC 3284) delta compression by Joshua MacDonald.
+#
+# The most widely used VCDIFF implementation outside Google's own
+# open-vcdiff (which is archived as of 2023-08). xdelta is what
+# Chromium auto-update uses for some delta channels, what many
+# embedded firmware update pipelines run, and the canonical
+# alternative reference for the format.
+#
+# Upstream is dormant since 2020 but the project is not archived;
+# the algorithm and CLI surface are RFC-stable. C autotools build,
+# GPL-2.0+.
+#
+# This packages the modern v3 line (`xdelta3/`). The older `xdelta1/`
+# subdir is left out — that's the 1998 prototype, of historical
+# interest only.
+
+distributable:
+  url: https://github.com/jmacd/xdelta/archive/refs/tags/v{{version}}.tar.gz
+  strip-components: 1
+
+versions:
+  # Upstream publishes git tags but ZERO GitHub Releases. Use /tags.
+  github: jmacd/xdelta/tags
+
+platforms:
+  - linux/x86-64
+  - linux/aarch64
+  - darwin/x86-64
+  - darwin/aarch64
+
+build:
+  working-directory: xdelta3
+  dependencies:
+    gnu.org/autoconf: '*'
+    gnu.org/automake: '*'
+    gnu.org/libtool: '*'
+    gnu.org/make: '*'
+    freedesktop.org/pkg-config: '*'
+    linux:
+      gnu.org/gcc: '*'
+  script:
+    - autoreconf -fi
+    - ./configure --prefix={{prefix}}
+    - make --jobs {{ hw.concurrency }}
+    - make install
+
+provides:
+  - bin/xdelta3
+
+test:
+  # Round-trip: source → delta → reconstructed-target; verify identity.
+  - run: |
+      printf 'the quick brown fox jumps over the lazy dog\n' > source.txt
+      printf 'the quick brown FOX jumps over the lazy DOG\n' > target.txt
+      xdelta3 -e -s source.txt target.txt delta.vcdiff
+      xdelta3 -d -s source.txt delta.vcdiff out.txt
+      diff -q target.txt out.txt