Relicense under Apache-2.0 OR MIT. (#844)

* Switch to standard copyright headers with Apache-2.0 OR MIT.

* Add formatting check to the CI.

* Switch to an `AUTHORS` file.

* Switch to Apache 2.0 and MIT license files.

* Add a source of truth for licenses in the workspace `Cargo.toml`.

* Add cargo formatting.

* Add Apache 2.0 / MIT license info to the readme files.

* Remove outdated license info for `resvg` tests.

* Add changelog entry.

* Update `explorer-thumbnailer` install script publisher.

.github/copyright.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+
+# If there are new files with headers that can't match the conditions here,
+# then the files can be ignored by an additional glob argument via the -g flag.
+# For example:
+#   -g "!src/special_file.rs"
+#   -g "!src/special_directory"
+
+# Check all the standard Rust source files
+output=$(rg "^// Copyright (19|20)[\d]{2} (.+ and )?the Resvg Authors( and .+)?$\n^// SPDX-License-Identifier: Apache-2\.0 OR MIT$\n\n" --files-without-match --multiline -g "*.{rs,c,cpp,h}" .)
+
+if [ -n "$output" ]; then
+	echo -e "The following files lack the correct copyright header:\n"
+	echo $output
+	echo -e "\n\nPlease add the following header:\n"
+	echo "// Copyright $(date +%Y) the Resvg Authors"
+	echo "// SPDX-License-Identifier: Apache-2.0 OR MIT"
+	echo -e "\n... rest of the file ...\n"
+	exit 1
+fi
+
+echo "All files have correct copyright headers."
+exit 0

.github/workflows/main.yml

@@ -6,6 +6,30 @@ env:
   CARGO_TERM_COLOR: always
 
 jobs:
+  fmt:
+    name: formatting
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      # TODO: Enable this when more of the Linebender CI has been applied.
+      #- name: install stable toolchain
+      #  uses: dtolnay/rust-toolchain@master
+      #  with:
+      #    toolchain: ${{ env.RUST_STABLE_VER }}
+      #    components: rustfmt
+
+      - name: cargo fmt
+        run: cargo fmt --all --check
+
+      - name: install ripgrep
+        run: |
+          sudo apt update
+          sudo apt install ripgrep
+
+      - name: check copyright headers
+        run: bash .github/copyright.sh
+
   build:
     runs-on: ubuntu-latest
     steps:

AUTHORS

@@ -0,0 +1,8 @@
+# This is the list of Resvg's significant contributors.
+#
+# This does not necessarily list everyone who has contributed code,
+# especially since many employees of one corporation may be contributing.
+# To see the full list of contributors, see the revision history in
+# source control.
+Yevhenii Reizner
+Laurenz Stampfl

CHANGELOG.md

@@ -7,6 +7,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 This changelog also contains important changes in dependencies.
 
 ## [Unreleased]
+### Changed
+- License to `Apache-2.0 OR MIT`.
+  See [resvg#838](https://github.com/linebender/resvg/issues/838) for more information.
 
 ## [0.44.0] - 2024-09-28
 ### Added