From 44525d25a24f47137a1141249c3f625dfcec7ab5 Mon Sep 17 00:00:00 2001
From: peak-stephen <121192940+peak-stephen@users.noreply.github.com>
Date: Sun, 15 Jan 2023 21:58:18 +0100
Subject: [PATCH 1/2] Do not try to hash non-regular files

If the build context directory contains named pipes, unix sockets, or
other special files, the provider will try to read them and hang.
---
 cmd/pulumi-resource-docker-buildkit/main.go | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/cmd/pulumi-resource-docker-buildkit/main.go b/cmd/pulumi-resource-docker-buildkit/main.go
index 4551796..745b9ba 100644
--- a/cmd/pulumi-resource-docker-buildkit/main.go
+++ b/cmd/pulumi-resource-docker-buildkit/main.go
@@ -475,9 +475,12 @@ func hashContext(contextPath string, dockerfile string) (string, error) {
 		if err != nil {
 			return fmt.Errorf("determining mode for %q: %w", path, err)
 		}
-		err = ch.hashPath(path, info.Mode())
-		if err != nil {
-			return fmt.Errorf("hashing %q: %w", path, err)
+		mode := info.Mode()
+		if mode.IsRegular() || mode == fs.ModeSymlink {
+			err = ch.hashPath(path, info.Mode())
+			if err != nil {
+				return fmt.Errorf("hashing %q: %w", path, err)
+			 }
 		}
 		return nil
 	})

From 3220455989134111b59642bab213ed9f37ad3069 Mon Sep 17 00:00:00 2001
From: peak-stephen <121192940+peak-stephen@users.noreply.github.com>
Date: Sun, 15 Jan 2023 22:57:39 +0100
Subject: [PATCH 2/2] Improve hashing of symlinks

---
 cmd/pulumi-resource-docker-buildkit/main.go | 42 ++++++++++++---------
 1 file changed, 25 insertions(+), 17 deletions(-)

diff --git a/cmd/pulumi-resource-docker-buildkit/main.go b/cmd/pulumi-resource-docker-buildkit/main.go
index 745b9ba..54ae401 100644
--- a/cmd/pulumi-resource-docker-buildkit/main.go
+++ b/cmd/pulumi-resource-docker-buildkit/main.go
@@ -397,19 +397,30 @@ func newContextHash(contextPath string) *contextHash {
 }
 
 func (ch *contextHash) hashPath(path string, fileMode fs.FileMode) error {
-	f, err := os.Open(filepath.Join(ch.contextPath, path))
-	if err != nil {
-		return fmt.Errorf("open %s: %w", path, err)
-	}
-	defer f.Close()
-	h := sha256.New()
-	_, err = io.Copy(h, f)
-	if err != nil {
-		return fmt.Errorf("read %s: %w", path, err)
-	}
 	ch.input.Write([]byte(path))
 	ch.input.Write([]byte(fileMode.String()))
-	ch.input.Write(h.Sum(nil))
+
+	fullpath := filepath.Join(ch.contextPath, path)
+	if fileMode.IsRegular() {
+		f, err := os.Open(fullpath)
+		if err != nil {
+			return fmt.Errorf("open %s: %w", path, err)
+		}
+		defer f.Close()
+		h := sha256.New()
+		_, err = io.Copy(h, f)
+		if err != nil {
+			return fmt.Errorf("read %s: %w", path, err)
+		}
+		ch.input.Write(h.Sum(nil))
+	} else if fileMode&fs.ModeSymlink != 0 {
+		dest, err := os.Readlink(fullpath)
+		if err != nil {
+			return fmt.Errorf("readlink %s:")
+		}
+		ch.input.Write([]byte(dest))
+	}
+
 	ch.input.WriteByte(0)
 	return nil
 }
@@ -475,12 +486,9 @@ func hashContext(contextPath string, dockerfile string) (string, error) {
 		if err != nil {
 			return fmt.Errorf("determining mode for %q: %w", path, err)
 		}
-		mode := info.Mode()
-		if mode.IsRegular() || mode == fs.ModeSymlink {
-			err = ch.hashPath(path, info.Mode())
-			if err != nil {
-				return fmt.Errorf("hashing %q: %w", path, err)
-			 }
+		err = ch.hashPath(path, info.Mode())
+		if err != nil {
+			return fmt.Errorf("hashing %q: %w", path, err)
 		}
 		return nil
 	})