[Github] Make unprivileged-download-artifact download multiple artifacts

This is designed to allow a workflow (e.g., premerge) upload comments
across multiple jobs. Subsequent PRs will wire this up within the
issue-write workflow to support reading comments from multiple files.

Reviewers: tstellar, cmtice

Reviewed By: cmtice

Pull Request: llvm/llvm-project#170216

Author: boomanaiden154

.github/workflows/test-unprivileged-download-artifact.yml

@@ -21,15 +21,23 @@ jobs:
     if: github.repository_owner == 'llvm'
     runs-on: ubuntu-24.04
     steps:
-      - name: Create Test File
+      - name: Create Test Files
         run: |
-          echo "test" > comment
-      - name: Upload Test File
+          echo "foo" > comment1
+          echo "bar" > comment2
+      - name: Upload Test File 1
         uses: actions/upload-artifact@330a01c490aca151604b8cf639adc76d48f6c5d4 # v5.0.0
         with:
-          name: workflow-args
+          name: artifact-name-1
           path: |
-            comment
+            comment1
+      - name: Upload Test File 2
+        uses: actions/upload-artifact@330a01c490aca151604b8cf639adc76d48f6c5d4 # v5.0.0
+        with:
+          name: artifact-name-2
+          path: |
+            comment2
+        
 
   test-download:
     name: Test Unprivileged Download Artifact
@@ -47,8 +55,10 @@ jobs:
         id: download-artifact
         with:
           run-id: ${{ github.run_id }}
-          artifact-name: workflow-args
+          artifact-name: artifact-name-
       - name: Assert That Contents are the Same
         run: |
-          cat comment
-          [[ "$(cat comment)" == "test" ]]
+          cat comment1
+          [[ "$(cat comment1)" == "foo" ]]
+          cat comment2
+          [[ "$(cat comment2)" == "bar" ]]

.github/workflows/unprivileged-download-artifact/action.yml

@@ -19,9 +19,9 @@ outputs:
       The filename of the downloaded artifact or the empty string if the
       artifact was not found.
     value: ${{ steps.download-artifact.outputs.filename }}
-  artifact-id:
+  artifact-ids:
     description: "The id of the artifact being downloaded."
-    value: ${{ steps.artifact-url.outputs.id }}
+    value: ${{ steps.artifact-url.outputs.ids }}
 
 
 runs:
@@ -36,46 +36,67 @@ runs:
             response = await github.rest.actions.listArtifactsForRepo({
               owner: context.repo.owner,
               repo: context.repo.repo,
-              name: "${{ inputs.artifact-name }}"
             })
           } else {
             response = await github.rest.actions.listWorkflowRunArtifacts({
               owner: context.repo.owner,
               repo: context.repo.repo,
               run_id: "${{ inputs.run-id }}",
-              name: "${{ inputs.artifact-name }}"
             })
           }
 
           console.log(response)
 
+          artifacts_to_download = []
           for (artifact of response.data.artifacts) {
+            if (artifact.name.startsWith("${{ inputs.artifact-name }}")) {
+              artifacts_to_download.push(artifact)
+            }
+          }
+
+          for (artifact of artifacts_to_download) {
             console.log(artifact);
           }
 
-          if (response.data.artifacts.length == 0) {
-            console.log("Could not find artifact ${{ inputs.artifact-name }} for workflow run ${{ inputs.run-id }}")
+          if (artifacts_to_download.length == 0) {
+            console.log("Could not find artifacts starting with name ${{ inputs.artifact-name }} for workflow run ${{ inputs.run-id }}")
             return;
           }
 
-          const url_response = await github.rest.actions.downloadArtifact({
-            owner: context.repo.owner,
-            repo: context.repo.repo,
-            artifact_id: response.data.artifacts[0].id,
-            archive_format: "zip"
-          })
+          artifact_ids = []
+          artifact_urls = []
+          artifact_names = []
+          for (artifact_to_download of artifacts_to_download) {
+            const url_response = await github.rest.actions.downloadArtifact({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              artifact_id: artifact_to_download.id,
+              archive_format: "zip"
+            })
+
+            artifact_ids.push(artifact_to_download.id)
+            artifact_urls.push('"' + url_response.url + '"')
+            artifact_names.push('"' + artifact_to_download.name + '"')
+          }
 
-          core.setOutput("url", url_response.url);
-          core.setOutput("id", response.data.artifacts[0].id);
+          core.setOutput("urls", artifact_urls.join(" "));
+          core.setOutput("ids", artifact_ids.join(" "));
+          core.setOutput("names", artifact_names.join(" "));
 
     - shell: bash
-      if: steps.artifact-url.outputs.url != ''
+      if: steps.artifact-url.outputs.urls != ''
       id: download-artifact
       run: |
-        curl -L -o ${{ inputs.artifact-name }}.zip "${{ steps.artifact-url.outputs.url }}"
-        echo "filename=${{ inputs.artifact-name }}.zip" >> $GITHUB_OUTPUT
+        artifact_urls=(${{ steps.artifact-url.outputs.urls }})
+        artifact_names=(${{ steps.artifact-url.outputs.names }})
+        for i in "${!artifact_urls[@]}"; do
+          curl -L -o "${artifact_names[$i]}.zip" "${artifact_urls[$i]}"
+        done
 
     - shell: bash
-      if: steps.download-artifact.outputs.filename != ''
+      if: steps.artifact-url.outputs.names != ''
       run: |
-        unzip ${{ steps.download-artifact.outputs.filename }}
+        artifact_names=(${{ steps.artifact-url.outputs.names }})
+        for name in "${artifact_names[@]}"; do
+          unzip "${name}.zip"
+        done