From af989cc324f7e16c1812b69927792bc3452543c5 Mon Sep 17 00:00:00 2001
From: CrazyMax <1951866+crazy-max@users.noreply.github.com>
Date: Wed, 14 Jan 2026 10:56:14 +0100
Subject: [PATCH] oci: defaultPlatform function

Signed-off-by: CrazyMax <1951866+crazy-max@users.noreply.github.com>
---
 __tests__/oci/oci.test.ts | 24 +++++++++++++++++++-
 src/oci/oci.ts            | 48 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 71 insertions(+), 1 deletion(-)

diff --git a/__tests__/oci/oci.test.ts b/__tests__/oci/oci.test.ts
index 803db122..684f88fe 100644
--- a/__tests__/oci/oci.test.ts
+++ b/__tests__/oci/oci.test.ts
@@ -14,14 +14,17 @@
  * limitations under the License.
  */
 
-import {afterEach, describe, expect, test} from '@jest/globals';
+import {afterEach, describe, expect, jest, test} from '@jest/globals';
 import fs from 'fs';
 import os from 'os';
 import path from 'path';
 import * as rimraf from 'rimraf';
+import osm = require('os');
 
 import {OCI} from '../../src/oci/oci';
 
+import {Platform} from '../../src/types/oci/descriptor';
+
 const fixturesDir = path.join(__dirname, '..', '.fixtures');
 const tmpDir = fs.mkdtempSync(path.join(process.env.TEMP || os.tmpdir(), 'oci-oci-'));
 
@@ -29,6 +32,25 @@ afterEach(function () {
   rimraf.sync(tmpDir);
 });
 
+describe('defaultPlatform', () => {
+  test.each([
+    ['win32', 'x64', {architecture: 'amd64', os: 'windows'}],
+    ['win32', 'arm64', {architecture: 'arm64', os: 'windows'}],
+    ['darwin', 'x64', {architecture: 'amd64', os: 'darwin'}],
+    ['darwin', 'arm64', {architecture: 'arm64', os: 'darwin'}],
+    ['linux', 'ia32', {architecture: '386', os: 'linux'}],
+    ['linux', 'x64', {architecture: 'amd64', os: 'linux'}],
+    ['linux', 'arm64', {architecture: 'arm64', os: 'linux'}],
+    ['linux', 'ppc64', {architecture: 'ppc64le', os: 'linux'}],
+    ['linux', 's390x', {architecture: 's390x', os: 'linux'}]
+  ])('default platform for %s/%s', async (os: string, arch: string, expected: Platform) => {
+    jest.spyOn(osm, 'platform').mockImplementation(() => os as NodeJS.Platform);
+    jest.spyOn(osm, 'arch').mockImplementation(() => arch);
+    const res = OCI.defaultPlatform();
+    expect(res).toEqual(expected);
+  });
+});
+
 describe('loadArchive', () => {
   // prettier-ignore
   test.each(fs.readdirSync(path.join(fixturesDir, 'oci-archive')).filter(file => {
diff --git a/src/oci/oci.ts b/src/oci/oci.ts
index dd9a83b2..da888b48 100644
--- a/src/oci/oci.ts
+++ b/src/oci/oci.ts
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 import fs from 'fs';
+import os from 'os';
 import gunzip from 'gunzip-maybe';
 import * as path from 'path';
 import {Readable} from 'stream';
@@ -21,12 +22,59 @@ import * as tar from 'tar-stream';
 
 import {Archive, LoadArchiveOpts} from '../types/oci/oci';
 import {Index} from '../types/oci';
+import {Platform} from '../types/oci/descriptor';
 import {Manifest} from '../types/oci/manifest';
 import {Image} from '../types/oci/config';
 import {IMAGE_BLOBS_DIR_V1, IMAGE_INDEX_FILE_V1, IMAGE_LAYOUT_FILE_V1, ImageLayout} from '../types/oci/layout';
 import {MEDIATYPE_IMAGE_INDEX_V1, MEDIATYPE_IMAGE_MANIFEST_V1} from '../types/oci/mediatype';
 
 export class OCI {
+  public static defaultPlatform(): Platform {
+    const nodePlatform = os.platform();
+    const nodeArch = os.arch();
+
+    const goosMap: Record<string, string> = {
+      win32: 'windows',
+      sunos: 'solaris'
+      // others (linux, darwin, freebsd, openbsd, netbsd, aix, android) match Go already
+    };
+
+    const goArchMap: Record<string, string> = {
+      x64: 'amd64',
+      ia32: '386',
+      arm: 'arm',
+      arm64: 'arm64',
+      ppc64: 'ppc64le',
+      s390x: 's390x',
+      riscv64: 'riscv64',
+      loong64: 'loong64',
+      mips: 'mips',
+      mipsel: 'mipsle',
+      mips64: 'mips64',
+      mips64el: 'mips64le'
+    };
+
+    const goos = goosMap[nodePlatform] ?? nodePlatform;
+    const goarch = goArchMap[nodeArch] ?? nodeArch;
+
+    let variant: string | undefined;
+    if (goarch === 'arm') {
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      const armVersionRaw = (process.config.variables as any)?.arm_version;
+      const armVersion = Number(armVersionRaw);
+      // Go only recognizes v5/v6/v7 for GOARM. Do not emit v8+ (that would be arm64).
+      if ([5, 6, 7].includes(armVersion)) {
+        variant = `v${armVersion}`;
+      }
+    }
+
+    return {
+      architecture: goarch,
+      os: goos,
+      variant: variant
+    };
+  }
+
   public static loadArchive(opts: LoadArchiveOpts): Promise<Archive> {
     return new Promise<Archive>((resolve, reject) => {
       const tarex: tar.Extract = tar.extract();