engine.#Source: Fix relative path support

Fixes #1492

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

plan/task/source.go

@@ -4,8 +4,8 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"io/fs"
 	"os"
+	"strings"
 
 	"github.com/moby/buildkit/client/llb"
 	"github.com/rs/zerolog/log"
@@ -22,22 +22,27 @@ type sourceTask struct {
 }
 
 func (c *sourceTask) PreRun(ctx context.Context, pctx *plancontext.Context, v *compiler.Value) error {
-	path, err := v.Lookup("path").String()
+	origPath, err := v.Lookup("path").String()
 	if err != nil {
 		return err
 	}
 
-	if !fs.ValidPath(path) {
-		return fmt.Errorf("invalid path %q", path)
+	absPath, err := v.Lookup("path").AbsPath()
+	if err != nil {
+		return err
 	}
 
-	absPath, err := v.Lookup("path").AbsPath()
+	location, err := v.Lookup("path").Dirname()
 	if err != nil {
 		return err
 	}
 
-	if _, err := os.Stat(path); errors.Is(err, os.ErrNotExist) {
-		return fmt.Errorf("path %q does not exist", path)
+	if !strings.HasPrefix(absPath, location) {
+		return fmt.Errorf("path %q is not relative", origPath)
+	}
+
+	if _, err := os.Stat(absPath); errors.Is(err, os.ErrNotExist) {
+		return fmt.Errorf("path %q does not exist", origPath)
 	}
 
 	pctx.LocalDirs.Add(absPath)

tests/tasks.bats

@@ -137,6 +137,7 @@ setup() {
     cd "$TESTDIR"/tasks/source
     "$DAGGER" --europa up ./source.cue
     "$DAGGER" --europa up ./source_include_exclude.cue
+    "$DAGGER" --europa up ./source_relative.cue
 
     run "$DAGGER" --europa up ./source_invalid_path.cue
     assert_failure

tests/tasks/dockerfile/cue.mod/pkg/.gitignore

@@ -1,5 +1,5 @@
 # generated by dagger
+dagger.lock
 alpha.dagger.io
 dagger.io
-dagger.lock
 universe.dagger.io

tests/tasks/source/source.cue

@@ -25,18 +25,18 @@ engine.#Plan & {
 
 		verifyHello: engine.#ReadFile & {
 			input: source.output
-			path:  "/hello.txt"
+			path:  "/world.txt"
 		} & {
 			// assert result
-			contents: "hello\n"
+			contents: "world\n"
 		}
 
 		verifyWorld: engine.#ReadFile & {
-			input: source.output
-			path:  "/world.txt"
+			input: exec.output
+			path:  "/test.txt"
 		} & {
 			// assert result
-			contents: "world\n"
+			contents: "hello world"
 		}
 	}
 }

tests/tasks/source/source_invalid_path.cue

@@ -11,7 +11,7 @@ engine.#Plan & {
 		}
 
 		source: engine.#Source & {
-			path: ".."
+			path: "testdata/../.."
 		}
 	}
 }

tests/tasks/source/source_relative.cue

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"dagger.io/dagger/engine"
+)
+
+engine.#Plan & {
+	actions: {
+		image: engine.#Pull & {
+			source: "alpine:3.15.0@sha256:e7d88de73db3d3fd9b2d63aa7f447a10fd0220b7cbf39803c803f2af9ba256b3"
+		}
+
+		source: engine.#Source & {
+			path: "./testdata"
+		}
+
+		verifyHello: engine.#ReadFile & {
+			input: source.output
+			path:  "/world.txt"
+		} & {
+			// assert result
+			contents: "world\n"
+		}
+	}
+}

tests/tasks/source/testdata/world.txt

@@ -0,0 +1 @@
+world