Convert to OCI builder

.gitattributes

@@ -1,3 +1,4 @@
 **/*.txt  eol=lf
 Makefile  eol=lf
 hello.c   eol=lf
+/oci/*/**  linguist-generated

oci.sh

@@ -0,0 +1,205 @@
+#!/usr/bin/env bash
+set -Eeuo pipefail
+
+image="${1:-hello-world}"
+
+hash="sha256"
+
+self="$(basename "$BASH_SOURCE")"
+cd "$(dirname "$(readlink -f "$BASH_SOURCE")")"
+
+ociroot="./oci"
+blobs="$ociroot/blobs/$hash"
+
+rm -rf $ociroot
+
+mkdir -p $blobs
+
+toBlob() {
+    local content="$1"; shift
+
+    digest="$(echo -n $content | sha256sum | cut -d " " -f1)"
+    echo -n $content > "$blobs/$digest"
+    echo $digest
+}
+
+annotations() {
+    local os="$1"; shift
+    local arch="$1"; shift
+    local timestamp="$1"; shift
+    local revision="$1"; shift
+
+    jq -r -n --arg os $os --arg arch $arch --arg timestamp $timestamp --arg revision $revision '{
+        "com.docker.official-images.bashbrew.arch": $arch,
+        "org.opencontainers.image.base.name": "scratch",
+        "org.opencontainers.image.created": $timestamp,
+        "org.opencontainers.image.revision": $revision,
+        "org.opencontainers.image.source": "https://github.com/docker-library/hello-world.git#\($revision):\($arch)/hello-world",
+        "org.opencontainers.image.url": "https://hub.docker.com/_/hello-world",
+        "org.opencontainers.image.version": $os
+    } | tojson'
+}
+
+rootfs() {
+    local os="$1"; shift
+    local arch="$1"; shift
+
+    path="./$arch/hello-world"
+    tar -C $path -cf - hello > tmp.tar
+    digest="$(cat tmp.tar | sha256sum | cut -d " " -f1)"
+    mv tmp.tar "$blobs/$digest"
+    echo $digest
+}
+
+config() {
+    local digest="$1"; shift
+    local os="$1"; shift
+    local arch="$1"; shift
+    local timestamp="$1"; shift
+
+    configArch=""
+
+    case "$arch" in
+    arm64v8)
+        configArch="arm64"
+        ;;
+    arm32v*)
+        configArch="arm"
+        ;;
+    *)
+        configArch="$arch"
+        ;;
+    esac
+
+    content="$(jq -r -n --arg digest "$hash:$digest" --arg os $os --arg arch $configArch --arg timestamp $timestamp '{
+        config: {
+            Cmd: [
+                "/hello"
+            ],
+            Env: [
+                "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
+            ],
+            WorkingDir: "/"
+        },
+        os: $os,
+        architecture: $arch,
+        rootfs: {
+            diff_ids: [
+                $digest
+            ],
+            type: "layers"
+        },
+        "created": $timestamp,
+    } | tojson')"
+
+    toBlob $content
+}
+
+manifest() {
+    local configdigest="$1"; shift
+    local rootfsdigest="$1"; shift
+    local annotations="$1"; shift
+
+    configsize="$(wc -c "$blobs/$configdigest" | awk '{print $1}')"
+    rootfssize="$(wc -c "$blobs/$rootfsdigest" | awk '{print $1}')"
+
+    content="$(jq -r -n \
+        --arg configdigest "$hash:$configdigest" \
+        --arg configsize $configsize \
+        --arg rootfsdigest "$hash:$rootfsdigest" \
+        --arg rootfssize $rootfssize \
+        --argjson annotations $annotations \
+        '{
+        schemaVersion: 2,
+        mediaType: "application/vnd.oci.image.manifest.v1+json",
+        config: {
+            mediaType: "application/vnd.oci.image.config.v1+json",
+            digest: $configdigest,
+            size: $configsize | tonumber
+        },
+        layers: [
+            {
+                mediaType: "application/vnd.oci.image.layer.v1.tar",
+                digest: $rootfsdigest,
+                size: $rootfssize | tonumber
+            }
+        ],
+        annotations: $annotations
+    } | tojson')"
+
+    toBlob $content
+}
+
+indexdescriptor() {
+    local manifestdigest="$1"; shift
+    local os="$1"; shift
+    local arch="$1"; shift
+    local annotations="$1"; shift
+
+    manifestsize="$(wc -c "$blobs/$manifestdigest" | awk '{print $1}')"
+
+    platform=""
+
+    case "$arch" in
+    arm64v8)
+         platform=$(jq -r -n --arg os $os --arg arch "arm64" --arg variant "v8" '{
+            architecture: $arch,
+            os: $os,
+            variant: $variant
+        } | tojson')
+        ;;
+    arm32v*)
+        platform=$(jq -r -n --arg os $os --arg arch "arm" --arg variant "${arch/arm32/}" '{
+            architecture: $arch,
+            os: $os,
+            variant: $variant
+        } | tojson')
+        ;;
+    *)
+        platform=$(jq -r -n --arg os $os --arg arch $arch '{
+            architecture: $arch,
+            os: $os
+        } | tojson')
+        ;;
+    esac
+
+    jq -r -n \
+        --arg digest "$hash:$manifestdigest" \
+        --arg manifestsize $manifestsize \
+        --argjson platform $platform \
+        --argjson annotations $annotations \
+        '{
+        mediaType: "application/vnd.oci.image.manifest.v1+json",
+        digest: $digest,
+        size: $manifestsize | tonumber,
+        platform: $platform,
+        annotations: $annotations
+    } | tojson'
+}
+
+created="2025-01-21T23:32:32Z"
+
+arches=( *"/$image/hello" )
+
+manifests="[]"
+
+for path in "${arches[@]}"; do
+    os="linux"
+    arch="${path/\/hello\-world\/hello/}"
+
+    annotations=$(annotations $os $arch $created "foo")
+    rootfs=$(rootfs $os $arch)
+    config=$(config $rootfs $os $arch $created)
+    manifest=$(manifest $config $rootfs $annotations)
+    indexdescriptor=$(indexdescriptor $manifest $os $arch $annotations)
+
+    manifests=$(jq -r -n --argjson manifests $manifests --argjson manifest $indexdescriptor '$manifests  | . += [$manifest] | tojson')
+done
+
+# TODO: Windows
+
+jq -r -n --argjson manifests $manifests '{
+    schemaVersion: 2,
+    mediaType: "application/vnd.oci.image.index.v1+json",
+    manifests: $manifests
+}' > "$ociroot/index.json"