fix(vcs): address review findings on PR #88

Findings addressed:
- F1/G1: Add doc comment to GetAllFilesInPath documenting fail-fast contract
- F2/G2: Add explicit backslash-prefix guard to skip '\ No newline' markers
- F3: Add comment explaining position > 0 guard (skip lines before first hunk)
- F4: Refactor parseHunkNewStart to use strconv.Atoi instead of per-char concat
- F5: Add error propagation tests (ListContents, GetFileContent, nested, ctx cancel)
- F6: Wrap errors.ErrUnsupported in DismissReview for programmatic checking
- S1: Add ctx.Err() checks + max file count/byte constants with clear errors
- S2: Addressed by S1 — input bounds are now enforced via the same constants

gitea/client.go

@@ -835,7 +835,7 @@ func (c *Client) ResolveComment(ctx context.Context, owner, repo string, comment
 // DismissReview dismisses a review on a pull request.
 // This is a stub for the vcs.Reviewer interface; full implementation is Phase 2.
 func (c *Client) DismissReview(ctx context.Context, owner, repo string, number int, reviewID int64, message string) error {
-	return fmt.Errorf("DismissReview: not implemented")
+	return fmt.Errorf("DismissReview: %w", errors.ErrUnsupported)
 }
 
 // GetFileContentAtRef fetches a file at a specific ref from a repo.

vcs/util.go

@@ -3,39 +3,82 @@ package vcs
 import (
 	"context"
 	"fmt"
+	"strconv"
 	"strings"
 )
 
+const (
+	// maxFilesInPath is the maximum number of files GetAllFilesInPath will fetch.
+	// Prevents unbounded resource consumption on very large directory trees.
+	maxFilesInPath = 10000
+
+	// maxTotalBytesInPath is the maximum total bytes GetAllFilesInPath will accumulate.
+	// Prevents memory exhaustion when fetching large repositories.
+	maxTotalBytesInPath = 100 * 1024 * 1024 // 100 MB
+)
+
 // GetAllFilesInPath recursively fetches all file contents under a path using the
 // provided FileReader. Returns a map of filepath -> content for all files found.
 // If the path points to an empty directory, returns an empty map.
+//
+// This function uses fail-fast error handling: any error from ListContents or
+// GetFileContent aborts the entire traversal and returns the error immediately.
+// This differs from gitea.Client.GetAllFilesInPath, which logs errors and continues.
+// The fail-fast contract ensures callers can trust that a nil error means all files
+// were successfully fetched.
+//
+// Resource limits: the traversal is bounded by maxFilesInPath (file count) and
+// maxTotalBytesInPath (total accumulated bytes). The context is checked before each
+// recursive call and file fetch to respect cancellation.
 func GetAllFilesInPath(ctx context.Context, client FileReader, owner, repo, path string) (map[string]string, error) {
 	results := make(map[string]string)
+	totalBytes := 0
 
-	entries, err := client.ListContents(ctx, owner, repo, path)
+	var walk func(string) error
+	walk = func(dir string) error {
+		if err := ctx.Err(); err != nil {
+			return fmt.Errorf("context cancelled during traversal: %w", err)
+		}
+
+		entries, err := client.ListContents(ctx, owner, repo, dir)
 		if err != nil {
-		return nil, fmt.Errorf("list contents %q: %w", path, err)
+			return fmt.Errorf("list contents %q: %w", dir, err)
 		}
 
 		for _, entry := range entries {
-		switch entry.Type {
+			if err := ctx.Err(); err != nil {
-		case "file":
+				return fmt.Errorf("context cancelled during traversal: %w", err)
-			content, err := client.GetFileContent(ctx, owner, repo, entry.Path, "")
-			if err != nil {
-				return nil, fmt.Errorf("get file %q: %w", entry.Path, err)
-			}
-			results[entry.Path] = content
-		case "dir":
-			subResults, err := GetAllFilesInPath(ctx, client, owner, repo, entry.Path)
-			if err != nil {
-				return nil, fmt.Errorf("recurse into %q: %w", entry.Path, err)
-			}
-			for k, v := range subResults {
-				results[k] = v
-			}
-		}
 			}
 
+			switch entry.Type {
+			case "file":
+				if len(results) >= maxFilesInPath {
+					return fmt.Errorf("exceeded max file count (%d) in path %q", maxFilesInPath, path)
+				}
+
+				content, err := client.GetFileContent(ctx, owner, repo, entry.Path, "")
+				if err != nil {
+					return fmt.Errorf("get file %q: %w", entry.Path, err)
+				}
+
+				totalBytes += len(content)
+				if totalBytes > maxTotalBytesInPath {
+					return fmt.Errorf("exceeded max total bytes (%d) in path %q", maxTotalBytesInPath, path)
+				}
+
+				results[entry.Path] = content
+			case "dir":
+				if err := walk(entry.Path); err != nil {
+					return err
+				}
+			}
+		}
+		return nil
+	}
+
+	if err := walk(path); err != nil {
+		return nil, err
+	}
 	return results, nil
 }
 
@@ -92,6 +135,12 @@ func BuildLineToPositionMap(diff string) map[string]map[int]int {
 			continue
 		}
 
+		// Skip "\ No newline at end of file" markers — these are git diff
+		// metadata and not part of the file content.
+		if strings.HasPrefix(line, `\`) {
+			continue
+		}
+
 		// Process diff content lines
 		if strings.HasPrefix(line, "+") {
 			position++
@@ -101,7 +150,10 @@ func BuildLineToPositionMap(diff string) map[string]map[int]int {
 			position++
 			// Deletion lines don't map to new line numbers
 		} else if strings.HasPrefix(line, " ") {
-			// Context line (space-prefixed)
+			// Context line (space-prefixed).
+			// Only map if position > 0, which means we've seen a hunk header.
+			// Lines before the first hunk header (position == 0) are not part
+			// of any diff hunk and should be skipped.
 			if position > 0 {
 				position++
 				result[currentFile][newLine] = position
@@ -123,23 +175,19 @@ func parseHunkNewStart(hunkLine string) int {
 	}
 	rest := hunkLine[plusIdx+1:]
 
-	// Read digits until comma or space
+	// Find the end of the number (first non-digit after +)
-	var numStr string
+	endIdx := 0
-	for _, ch := range rest {
+	for endIdx < len(rest) && rest[endIdx] >= '0' && rest[endIdx] <= '9' {
-		if ch >= '0' && ch <= '9' {
+		endIdx++
-			numStr += string(ch)
-		} else {
-			break
-		}
 	}
 
-	if numStr == "" {
+	if endIdx == 0 {
 		return 1
 	}
 
-	n := 0
+	n, err := strconv.Atoi(rest[:endIdx])
-	for _, ch := range numStr {
+	if err != nil {
-		n = n*10 + int(ch-'0')
+		return 1
 	}
 	return n
 }

vcs/util_test.go

@@ -2,6 +2,7 @@ package vcs_test
 
 import (
 	"context"
+	"strings"
 	"fmt"
 	"testing"
 
@@ -248,3 +249,83 @@ func TestBuildLineToPositionMap(t *testing.T) {
 		}
 	})
 }
+
+func TestGetAllFilesInPath_ErrorPropagation(t *testing.T) {
+	ctx := context.Background()
+
+	t.Run("ListContents error propagates", func(t *testing.T) {
+		client := &mockFileReader{
+			contents: map[string][]vcs.ContentEntry{
+				// "src" not in map, so ListContents will fail
+			},
+		}
+		_, err := vcs.GetAllFilesInPath(ctx, client, "owner", "repo", "src")
+		if err == nil {
+			t.Fatal("expected error, got nil")
+		}
+		if !strings.Contains(err.Error(), "list contents") {
+			t.Errorf("expected error about list contents, got: %v", err)
+		}
+	})
+
+	t.Run("GetFileContent error propagates", func(t *testing.T) {
+		client := &mockFileReader{
+			contents: map[string][]vcs.ContentEntry{
+				"src": {
+					{Name: "main.go", Path: "src/main.go", Type: "file"},
+				},
+			},
+			files: map[string]string{
+				// "src/main.go" not in files map, so GetFileContent will fail
+			},
+		}
+		_, err := vcs.GetAllFilesInPath(ctx, client, "owner", "repo", "src")
+		if err == nil {
+			t.Fatal("expected error, got nil")
+		}
+		if !strings.Contains(err.Error(), "get file") {
+			t.Errorf("expected error about get file, got: %v", err)
+		}
+	})
+
+	t.Run("nested ListContents error propagates", func(t *testing.T) {
+		client := &mockFileReader{
+			contents: map[string][]vcs.ContentEntry{
+				"src": {
+					{Name: "pkg", Path: "src/pkg", Type: "dir"},
+				},
+				// "src/pkg" not in map, so recursive ListContents will fail
+			},
+		}
+		_, err := vcs.GetAllFilesInPath(ctx, client, "owner", "repo", "src")
+		if err == nil {
+			t.Fatal("expected error, got nil")
+		}
+		if !strings.Contains(err.Error(), "list contents") {
+			t.Errorf("expected error about list contents, got: %v", err)
+		}
+	})
+
+	t.Run("cancelled context propagates", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		cancel() // Cancel immediately
+
+		client := &mockFileReader{
+			contents: map[string][]vcs.ContentEntry{
+				"src": {
+					{Name: "main.go", Path: "src/main.go", Type: "file"},
+				},
+			},
+			files: map[string]string{
+				"src/main.go": "package main",
+			},
+		}
+		_, err := vcs.GetAllFilesInPath(ctx, client, "owner", "repo", "src")
+		if err == nil {
+			t.Fatal("expected error from cancelled context, got nil")
+		}
+		if !strings.Contains(err.Error(), "context cancelled") {
+			t.Errorf("expected context cancellation error, got: %v", err)
+		}
+	})
+}