add workflow to compute and publish the fuzz coverage

Author: lucasbalieiro

.github/workflows/coverage.yaml

@@ -0,0 +1,85 @@
+name: Fuzz Coverage
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - "corpus/**"
+
+  schedule:
+    - cron: "0 3 * * *"  # Daily at 03:00 UTC
+  workflow_dispatch:
+
+permissions:
+  contents: write
+  pages: write
+  id-token: write
+
+jobs:
+  coverage:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout corpus repo
+        uses: actions/checkout@v4
+
+      - name: Checkout fuzz targets repo
+        uses: actions/checkout@v4
+        with:
+          repository: stratum-mining/stratum
+          path: stratum 
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@nightly
+        with:
+          profile: minimal
+          toolchain: nightly
+          override: true
+          components: llvm-tools-preview
+
+      - name: Add Rust LLVM tools to PATH
+        run: |
+          LLVM_TOOLS=$(rustc +nightly --print sysroot)/lib/rustlib/$(rustc --print host-tuple)/bin
+          echo "$LLVM_TOOLS" >> $GITHUB_PATH
+          ls -al "$LLVM_TOOLS" 
+
+      - name: Install cargo-fuzz
+        run: cargo install cargo-fuzz
+
+      - name: Copy corpus into fuzz targets repo
+        run: |
+          mkdir -p stratum/fuzz/corpus
+          mv corpus/* stratum/fuzz/corpus
+
+      - name: Run fuzz coverage
+        run: |
+          chmod +x ./scripts/fuzz_coverage.sh
+          cp ./scripts/fuzz_coverage.sh stratum/fuzz_coverage.sh
+          cd stratum/
+          ls fuzz/
+          ./fuzz_coverage.sh
+
+      - name: Move coverage results into this repo
+        run: |
+          rm -rf coverage
+          mkdir -p coverage
+          cp -r stratum/coverage_html coverage/
+
+      - name: Upload pages artifact
+        uses: actions/upload-pages-artifact@v3
+        with:
+          path: coverage/coverage_html
+
+  deploy:
+    needs: coverage
+    runs-on: ubuntu-latest
+    environment:
+      name: github-pages
+      url: ${{ steps.deploy.outputs.page_url }}
+
+    steps:
+      - name: Deploy to GitHub Pages
+        id: deploy
+        uses: actions/deploy-pages@v4
+

scripts/fuzz_coverage.sh

@@ -0,0 +1,98 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+############################################
+# Tools must be available directly in PATH:
+#   llvm-profdata
+#   llvm-cov
+############################################
+
+PROJECT_ROOT="$(pwd)"
+HOST_TARGET=$(rustc +nightly --print host-tuple)
+
+echo "[+] Project root: $PROJECT_ROOT"
+echo "[+] Host target: $HOST_TARGET"
+
+############################################
+# 1. Run coverage for all fuzz targets
+############################################
+
+echo "[+] Running fuzz coverage"
+for target in $(cargo +nightly fuzz list); do
+    echo "   → $target"
+    cargo +nightly fuzz coverage "$target"
+done
+
+############################################
+# 2. Merge all .profdata
+############################################
+
+echo "[+] Merging coverage profiles"
+llvm-profdata merge -sparse \
+    fuzz/coverage/*/coverage.profdata \
+    -o fuzz/coverage/merged.profdata
+
+############################################
+# 3. Collect fuzz target coverage binaries
+############################################
+
+echo "[+] Collecting fuzz binaries"
+
+OBJECTS=""
+FIRST_TARGET=""
+
+for target in $(cargo fuzz list); do
+    BIN="target/$HOST_TARGET/coverage/$HOST_TARGET/release/$target"
+
+    if [ ! -f "$BIN" ]; then
+        echo "ERROR: expected binary not found: $BIN"
+        exit 1
+    fi
+
+    if [ -z "$FIRST_TARGET" ]; then
+        FIRST_TARGET="$BIN"
+    else
+        OBJECTS="$OBJECTS -object $BIN"
+    fi
+done
+
+############################################
+# 4. Filtering rules:
+#    - ignore stdlib (/rustc/…)
+#    - ignore crates.io (~/.cargo/registry/…)
+#    - ignore everything outside the project dir
+############################################
+
+IGNORE_FLAGS=(
+    "-ignore-filename-regex=/.*/rustc/.*"
+    "-ignore-filename-regex=/.cargo/registry/.*"
+    "-ignore-filename-regex=^/(?!${PROJECT_ROOT}).*$"
+)
+
+############################################
+# 5. Generate text summary
+############################################
+
+echo "[+] Generating text summary"
+llvm-cov report \
+    "${IGNORE_FLAGS[@]}" \
+    -instr-profile=fuzz/coverage/merged.profdata \
+    $FIRST_TARGET $OBJECTS \
+    > coverage_summary.txt
+
+############################################
+# 6. Generate HTML report
+############################################
+
+echo "[+] Generating HTML report"
+llvm-cov show \
+    "${IGNORE_FLAGS[@]}" \
+    -instr-profile=fuzz/coverage/merged.profdata \
+    $FIRST_TARGET $OBJECTS \
+    -format=html \
+    -output-dir=coverage_html
+
+echo "[✓] Done!"
+echo "HTML → coverage_html/index.html"
+echo "TXT  → coverage_summary.txt"
+