From 7f1dd6c2b4c63ca5207ad33d9aeb97733c344984 Mon Sep 17 00:00:00 2001
From: Arran Ubels <arran4@gmail.com>
Date: Sun, 9 Oct 2022 17:02:31 +1100
Subject: [PATCH 1/3] Tests

---
 .github/workflows/test.yml | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 .github/workflows/test.yml

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 0000000..a882731
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,28 @@
+on: [push, pull_request]
+name: Test
+jobs:
+  test:
+    strategy:
+      matrix:
+        go-version: [1.19.x]
+        os: [ubuntu-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+    - name: Install Go
+      uses: actions/setup-go@v2
+      with:
+        go-version: ${{ matrix.go-version }}
+    - name: Checkout code
+      uses: actions/checkout@v2
+    - name: Cache-Go
+      uses: actions/cache@v1
+      with:
+        path: |
+          ~/go/pkg/mod              # Module download cache
+          ~/.cache/go-build         # Build cache (Linux)
+          ~/Library/Caches/go-build # Build cache (Mac)
+        key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
+        restore-keys: |
+          ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
+    - name: Test
+      run: go test ./...

From 9b1b3b6784241cf6ce02f406ec8997be11f06f14 Mon Sep 17 00:00:00 2001
From: Arran Ubels <arran4@gmail.com>
Date: Sun, 9 Oct 2022 17:12:21 +1100
Subject: [PATCH 2/3] Valid header logic.

---
 entity.go           | 3 +++
 textproto/header.go | 9 +++++++++
 2 files changed, 12 insertions(+)

diff --git a/entity.go b/entity.go
index a0858e5..b52e08f 100644
--- a/entity.go
+++ b/entity.go
@@ -141,6 +141,9 @@ func ReadWithOptions(r io.Reader, opts *ReadOptions) (*Entity, error) {
 	if err != nil {
 		return nil, err
 	}
+	if !h.Valid() {
+		return nil, nil
+	}
 
 	lr.N = math.MaxInt64
 
diff --git a/textproto/header.go b/textproto/header.go
index 10c04f3..eace386 100644
--- a/textproto/header.go
+++ b/textproto/header.go
@@ -226,6 +226,11 @@ func (h *Header) Len() int {
 	return len(h.l)
 }
 
+// Valid returns if the data structure is valid, if it was initialized correctly
+func (h *Header) Valid() bool {
+	return h.l != nil && h.m != nil
+}
+
 // Map returns all header fields as a map.
 //
 // This function is provided for interoperability with the standard library.
@@ -533,6 +538,10 @@ func ReadHeader(r *bufio.Reader) (Header, error) {
 
 	for {
 		kv, err := readContinuedLineSlice(r)
+		if kv == nil && len(fs) == 0 {
+			// Construct an invalid header.
+			return Header{}, err
+		}
 		if len(kv) == 0 {
 			return newHeader(fs), err
 		}

From 88d073923c5eb7fcecf8a6600bcede22cf8b94b7 Mon Sep 17 00:00:00 2001
From: Arran Ubels <arran4@gmail.com>
Date: Sun, 9 Oct 2022 17:13:33 +1100
Subject: [PATCH 3/3] Another build system is in place.

---
 .github/workflows/test.yml | 28 ----------------------------
 1 file changed, 28 deletions(-)
 delete mode 100644 .github/workflows/test.yml

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
deleted file mode 100644
index a882731..0000000
--- a/.github/workflows/test.yml
+++ /dev/null
@@ -1,28 +0,0 @@
-on: [push, pull_request]
-name: Test
-jobs:
-  test:
-    strategy:
-      matrix:
-        go-version: [1.19.x]
-        os: [ubuntu-latest]
-    runs-on: ${{ matrix.os }}
-    steps:
-    - name: Install Go
-      uses: actions/setup-go@v2
-      with:
-        go-version: ${{ matrix.go-version }}
-    - name: Checkout code
-      uses: actions/checkout@v2
-    - name: Cache-Go
-      uses: actions/cache@v1
-      with:
-        path: |
-          ~/go/pkg/mod              # Module download cache
-          ~/.cache/go-build         # Build cache (Linux)
-          ~/Library/Caches/go-build # Build cache (Mac)
-        key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
-        restore-keys: |
-          ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
-    - name: Test
-      run: go test ./...