From 2ddad4401e17fa807e8a3c4bd289ccdd993f0868 Mon Sep 17 00:00:00 2001
From: CrazyMax <1951866+crazy-max@users.noreply.github.com>
Date: Wed, 27 May 2026 17:01:22 +0200
Subject: [PATCH] uninstall current emulators

Signed-off-by: CrazyMax <1951866+crazy-max@users.noreply.github.com>
---
 .github/workflows/ci.yml  | 20 ++++++++++++++++++++
 README.md                 |  1 +
 __tests__/context.test.ts |  6 ++++++
 action.yml                |  4 ++++
 src/context.ts            |  2 ++
 src/main.ts               | 12 ++++++++++++
 6 files changed, 45 insertions(+)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index cdde4bd..46c043a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -125,3 +125,23 @@ jobs:
         uses: ./
         with:
           image: ${{ matrix.image }}
+
+  reset:
+    runs-on: ubuntu-latest
+    steps:
+      -
+        name: Checkout
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+      -
+        name: Install multiarch/qemu-user-static
+        run: |
+          docker run --rm --privileged multiarch/qemu-user-static --reset -p yes -c yes
+      -
+        name: Set up QEMU
+        id: qemu
+        uses: ./
+        with:
+          reset: true
+      -
+        name: Available platforms
+        run: echo ${{ steps.qemu.outputs.platforms }}
diff --git a/README.md b/README.md
index 07613b5..4c7d47e 100644
--- a/README.md
+++ b/README.md
@@ -86,6 +86,7 @@ The following inputs can be used as `step.with` keys:
 |---------------|--------|-------------------------------------------------------------------------------|----------------------------------------------------|
 | `image`       | String | [`tonistiigi/binfmt:latest`](https://hub.docker.com/r/tonistiigi/binfmt/tags) | QEMU static binaries Docker image                  |
 | `platforms`   | String | `all`                                                                         | Platforms to install (e.g., `arm64,riscv64,arm`)   |
+| `reset`       | Bool   | `false`                                                                       | Uninstall current emulators before installation    |
 | `cache-image` | Bool   | `true`                                                                        | Cache binfmt image to GitHub Actions cache backend |
 
 ### outputs
diff --git a/__tests__/context.test.ts b/__tests__/context.test.ts
index b00addf..994aefe 100644
--- a/__tests__/context.test.ts
+++ b/__tests__/context.test.ts
@@ -17,11 +17,13 @@ describe('getInputs', () => {
     [
       0,
       new Map<string, string>([
+        ['reset', 'false'],
         ['cache-image', 'true'],
       ]),
       {
         image: 'docker.io/tonistiigi/binfmt:latest',
         platforms: 'all',
+        reset: false,
         cacheImage: true,
       }
     ],
@@ -30,11 +32,13 @@ describe('getInputs', () => {
       new Map<string, string>([
         ['image', 'docker/binfmt:latest'],
         ['platforms', 'arm64,riscv64,arm'],
+        ['reset', 'false'],
         ['cache-image', 'false'],
       ]),
       {
         image: 'docker/binfmt:latest',
         platforms: 'arm64,riscv64,arm',
+        reset: false,
         cacheImage: false,
       }
     ],
@@ -42,11 +46,13 @@ describe('getInputs', () => {
       2,
       new Map<string, string>([
         ['platforms', 'arm64, riscv64, arm '],
+        ['reset', 'false'],
         ['cache-image', 'true'],
       ]),
       {
         image: 'docker.io/tonistiigi/binfmt:latest',
         platforms: 'arm64,riscv64,arm',
+        reset: false,
         cacheImage: true,
       }
     ]
diff --git a/action.yml b/action.yml
index 137a741..c338686 100644
--- a/action.yml
+++ b/action.yml
@@ -15,6 +15,10 @@ inputs:
     description: 'Platforms to install (e.g. arm64,riscv64,arm)'
     default: 'all'
     required: false
+  reset:
+    description: 'Uninstall current emulators before installation'
+    default: 'false'
+    required: false
   cache-image:
     description: 'Cache binfmt image to GitHub Actions cache backend'
     default: 'true'
diff --git a/src/context.ts b/src/context.ts
index 45a56e2..97e5178 100644
--- a/src/context.ts
+++ b/src/context.ts
@@ -4,6 +4,7 @@ import {Util} from '@docker/actions-toolkit/lib/util.js';
 export interface Inputs {
   image: string;
   platforms: string;
+  reset: boolean;
   cacheImage: boolean;
 }
 
@@ -11,6 +12,7 @@ export function getInputs(): Inputs {
   return {
     image: core.getInput('image') || 'docker.io/tonistiigi/binfmt:latest',
     platforms: Util.getInputList('platforms').join(',') || 'all',
+    reset: core.getBooleanInput('reset'),
     cacheImage: core.getBooleanInput('cache-image')
   };
 }
diff --git a/src/main.ts b/src/main.ts
index 5802fb9..bac0626 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -44,6 +44,18 @@ actionsToolkit.run(
       });
     });
 
+    if (input.reset) {
+      await core.group(`Uninstalling current emulators`, async () => {
+        await Docker.getExecOutput(['run', '--rm', '--privileged', input.image, '--uninstall', 'qemu-*'], {
+          ignoreReturnCode: true
+        }).then(res => {
+          if (res.stderr.length > 0 && res.exitCode != 0) {
+            throw new Error(res.stderr.match(/(.*)\s*$/)?.[0]?.trim() ?? 'unknown error');
+          }
+        });
+      });
+    }
+
     await core.group(`Installing QEMU static binaries`, async () => {
       await Docker.getExecOutput(['run', '--rm', '--privileged', input.image, '--install', input.platforms], {
         ignoreReturnCode: true