fix: bug with prs from forks returning incorrect set of changed files

src/commitSha.ts

@@ -86,15 +86,27 @@ export interface DiffResult {
   initialCommit?: boolean
 }
 
-export const getSHAForNonPullRequestEvent = async (
-  inputs: Inputs,
-  env: Env,
-  workingDirectory: string,
-  isShallow: boolean,
-  hasSubmodule: boolean,
-  gitFetchExtraArgs: string[],
+interface SHAForNonPullRequestEvent {
+  inputs: Inputs
+  env: Env
+  workingDirectory: string
+  isShallow: boolean
+  hasSubmodule: boolean
+  gitFetchExtraArgs: string[]
   isTag: boolean
-): Promise<DiffResult> => {
+  remoteName: string
+}
+
+export const getSHAForNonPullRequestEvent = async ({
+  inputs,
+  env,
+  workingDirectory,
+  isShallow,
+  hasSubmodule,
+  gitFetchExtraArgs,
+  isTag,
+  remoteName
+}: SHAForNonPullRequestEvent): Promise<DiffResult> => {
   let targetBranch = env.GITHUB_REF_NAME
   let currentBranch = targetBranch
   let initialCommit = false
@@ -122,8 +134,8 @@ export const getSHAForNonPullRequestEvent = async (
             '-u',
             '--progress',
             `--deepen=${inputs.fetchDepth}`,
-            'origin',
-            `+refs/heads/${sourceBranch}:refs/remotes/origin/${sourceBranch}`
+            remoteName,
+            `+refs/heads/${sourceBranch}:refs/remotes/${remoteName}/${sourceBranch}`
           ]
         })
       } else {
@@ -134,8 +146,8 @@ export const getSHAForNonPullRequestEvent = async (
             '-u',
             '--progress',
             `--deepen=${inputs.fetchDepth}`,
-            'origin',
-            `+refs/heads/${targetBranch}:refs/remotes/origin/${targetBranch}`
+            remoteName,
+            `+refs/heads/${targetBranch}:refs/remotes/${remoteName}/${targetBranch}`
           ]
         })
       }
@@ -307,14 +319,23 @@ export const getSHAForNonPullRequestEvent = async (
   }
 }
 
-export const getSHAForPullRequestEvent = async (
-  inputs: Inputs,
-  env: Env,
-  workingDirectory: string,
-  isShallow: boolean,
-  hasSubmodule: boolean,
+interface SHAForPullRequestEvent {
+  inputs: Inputs
+  workingDirectory: string
+  isShallow: boolean
+  hasSubmodule: boolean
   gitFetchExtraArgs: string[]
-): Promise<DiffResult> => {
+  remoteName: string
+}
+
+export const getSHAForPullRequestEvent = async ({
+  inputs,
+  workingDirectory,
+  isShallow,
+  hasSubmodule,
+  gitFetchExtraArgs,
+  remoteName
+}: SHAForPullRequestEvent): Promise<DiffResult> => {
   let targetBranch = github.context.payload.pull_request?.base?.ref
   const currentBranch = github.context.payload.pull_request?.head?.ref
   if (inputs.sinceLastRemoteCommit) {
@@ -330,7 +351,7 @@ export const getSHAForPullRequestEvent = async (
           ...gitFetchExtraArgs,
           '-u',
           '--progress',
-          'origin',
+          remoteName,
           `pull/${github.context.payload.pull_request?.number}/head:${currentBranch}`
         ]
       })
@@ -343,8 +364,8 @@ export const getSHAForPullRequestEvent = async (
             '-u',
             '--progress',
             `--deepen=${inputs.fetchDepth}`,
-            'origin',
-            `+refs/heads/${currentBranch}*:refs/remotes/origin/${currentBranch}*`
+            remoteName,
+            `+refs/heads/${currentBranch}*:refs/remotes/${remoteName}/${currentBranch}*`
           ]
         })
       }
@@ -364,8 +385,8 @@ export const getSHAForPullRequestEvent = async (
             '-u',
             '--progress',
             `--deepen=${inputs.fetchDepth}`,
-            'origin',
-            `+refs/heads/${targetBranch}:refs/remotes/origin/${targetBranch}`
+            remoteName,
+            `+refs/heads/${targetBranch}:refs/remotes/${remoteName}/${targetBranch}`
           ]
         })
 
@@ -427,10 +448,7 @@ export const getSHAForPullRequestEvent = async (
     }
   }
 
-  if (
-    !github.context.payload.pull_request?.base?.ref ||
-    github.context.payload.pull_request?.head?.repo?.fork === true
-  ) {
+  if (!github.context.payload.pull_request?.base?.ref) {
     diff = '..'
   }
 
@@ -492,7 +510,8 @@ export const getSHAForPullRequestEvent = async (
       } else {
         previousSha = await getRemoteBranchHeadSha({
           cwd: workingDirectory,
-          branch: targetBranch
+          branch: targetBranch,
+          remoteName
         })
 
         if (!previousSha) {
@@ -521,8 +540,8 @@ export const getSHAForPullRequestEvent = async (
                 '-u',
                 '--progress',
                 `--deepen=${inputs.fetchDepth}`,
-                'origin',
-                `+refs/heads/${targetBranch}:refs/remotes/origin/${targetBranch}`
+                remoteName,
+                `+refs/heads/${targetBranch}:refs/remotes/${remoteName}/${targetBranch}`
               ]
             })
 

src/main.ts

@@ -23,6 +23,7 @@ import {
   hasLocalGitDirectory,
   isRepoShallow,
   recoverDeletedFiles,
+  setForkRemote,
   setOutput,
   submoduleExists,
   updateGitGlobalConfig,
@@ -65,8 +66,15 @@ const getChangedFilesFromLocalGitHistory = async ({
 
   const isShallow = await isRepoShallow({cwd: workingDirectory})
   const hasSubmodule = await submoduleExists({cwd: workingDirectory})
-  let gitFetchExtraArgs = ['--no-tags', '--prune', '--recurse-submodules']
+  let gitFetchExtraArgs = ['--no-tags', '--prune']
+
+  if (hasSubmodule) {
+    gitFetchExtraArgs.push('--recurse-submodules')
+  }
+
   const isTag = env.GITHUB_REF?.startsWith('refs/tags/')
+  const isFork = github.context.payload.pull_request?.head.repo.fork || false
+  let remoteName = 'origin'
   const outputRenamedFilesAsDeletedAndAdded =
     inputs.outputRenamedFilesAsDeletedAndAdded
   let submodulePaths: string[] = []
@@ -79,33 +87,39 @@ const getChangedFilesFromLocalGitHistory = async ({
     gitFetchExtraArgs = ['--prune', '--no-recurse-submodules']
   }
 
+  if (isFork) {
+    await setForkRemote({cwd: workingDirectory})
+    remoteName = 'fork'
+  }
+
   let diffResult: DiffResult
 
   if (!github.context.payload.pull_request?.base?.ref) {
     core.info(`Running on a ${github.context.eventName || 'push'} event...`)
-    diffResult = await getSHAForNonPullRequestEvent(
+    diffResult = await getSHAForNonPullRequestEvent({
       inputs,
       env,
       workingDirectory,
       isShallow,
       hasSubmodule,
       gitFetchExtraArgs,
-      isTag
-    )
+      isTag,
+      remoteName
+    })
   } else {
     core.info(
       `Running on a ${github.context.eventName || 'pull_request'} (${
         github.context.payload.action
       }) event...`
     )
-    diffResult = await getSHAForPullRequestEvent(
+    diffResult = await getSHAForPullRequestEvent({
       inputs,
-      env,
       workingDirectory,
       isShallow,
       hasSubmodule,
-      gitFetchExtraArgs
-    )
+      gitFetchExtraArgs,
+      remoteName
+    })
   }
 
   if (diffResult.initialCommit) {

src/utils.ts

@@ -685,14 +685,16 @@ export const isInsideWorkTree = async ({
 
 export const getRemoteBranchHeadSha = async ({
   cwd,
-  branch
+  branch,
+  remoteName
 }: {
   cwd: string
   branch: string
+  remoteName: string
 }): Promise<string> => {
   const {stdout} = await exec.getExecOutput(
     'git',
-    ['rev-parse', `origin/${branch}`],
+    ['rev-parse', `${remoteName}/${branch}`],
     {
       cwd,
       silent: !core.isDebug()
@@ -742,6 +744,24 @@ export const getParentSha = async ({cwd}: {cwd: string}): Promise<string> => {
   return stdout.trim()
 }
 
+export const setForkRemote = async ({cwd}: {cwd: string}): Promise<void> => {
+  if (github.context.payload.repository?.fork) {
+    await exec.getExecOutput(
+      'git',
+      [
+        'remote',
+        'set-url',
+        'fork',
+        github.context.payload.repository?.clone_url
+      ],
+      {
+        cwd,
+        silent: !core.isDebug()
+      }
+    )
+  }
+}
+
 export const verifyCommitSha = async ({
   sha,
   cwd,