fix: use atomic rename that refuses existing destinations

find_replace.go

@@ -184,14 +184,9 @@ func (fr *findReplace) RenameFile(f *File) error {
 	}
 
 	newPath := filepath.Join(f.Dir(), newBaseName)
-	if _, err := os.Stat(newPath); err == nil {
-		return fmt.Errorf("refusing to rename %v to %v: %v already exists", f.Path, newBaseName, newPath)
-	} else if !errors.Is(err, os.ErrNotExist) {
-		return fmt.Errorf("stat rename destination %v: %w", newPath, err)
-	}
 
 	log.Printf("Renaming %v to %v", f.Path, newBaseName)
-	if err := os.Rename(f.Path, newPath); err != nil {
+	if err := atomicRenameNoReplace(f.Path, newPath); err != nil {
 		return fmt.Errorf("rename %v to %v: %w", f.Path, newBaseName, err)
 	}
 	return nil

go.mod

@@ -3,3 +3,5 @@ module github.com/dolph/find-replace
 go 1.20
 
 require golang.org/x/tools v0.7.0
+
+require golang.org/x/sys v0.26.0

go.sum

@@ -1,4 +1,4 @@
-golang.org/x/tools v0.1.9 h1:j9KsMiaP1c3B0OTQGth0/k+miLGTgLsAFUCrF2vLcF8=
-golang.org/x/tools v0.1.9/go.mod h1:nABZi5QlRsZVlzPpHl034qft6wpY4eDcsTt5AaioBiU=
+golang.org/x/sys v0.26.0 h1:KHjCJyddX0LoSTb3J+vWpupP9p0oznkqVk/IfjymZbo=
+golang.org/x/sys v0.26.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/tools v0.7.0 h1:W4OVu8VVOaIO0yzWMNdepAulS7YfoS3Zabrm8DOXXU4=
 golang.org/x/tools v0.7.0/go.mod h1:4pg6aUX35JBAogB10C9AtvVL+qowtN4pT3CGSQex14s=

rename_darwin.go

@@ -0,0 +1,18 @@
+//go:build darwin
+
+package main
+
+import (
+	"errors"
+	"fmt"
+
+	"golang.org/x/sys/unix"
+)
+
+func atomicRenameNoReplace(oldpath, newpath string) error {
+	err := unix.RenameatxNp(unix.AT_FDCWD, oldpath, unix.AT_FDCWD, newpath, unix.RENAME_EXCL)
+	if errors.Is(err, unix.EEXIST) {
+		return fmt.Errorf("refusing to rename %v to %v: %v already exists", oldpath, newpath, newpath)
+	}
+	return err
+}

rename_linux.go

@@ -0,0 +1,18 @@
+//go:build linux
+
+package main
+
+import (
+	"errors"
+	"fmt"
+
+	"golang.org/x/sys/unix"
+)
+
+func atomicRenameNoReplace(oldpath, newpath string) error {
+	err := unix.Renameat2(unix.AT_FDCWD, oldpath, unix.AT_FDCWD, newpath, unix.RENAME_NOREPLACE)
+	if errors.Is(err, unix.EEXIST) {
+		return fmt.Errorf("refusing to rename %v to %v: %v already exists", oldpath, newpath, newpath)
+	}
+	return err
+}

rename_other.go

@@ -0,0 +1,18 @@
+//go:build !linux && !darwin && !windows
+
+package main
+
+import (
+	"errors"
+	"fmt"
+	"os"
+)
+
+func atomicRenameNoReplace(oldpath, newpath string) error {
+	if _, err := os.Stat(newpath); err == nil {
+		return fmt.Errorf("refusing to rename %v to %v: %v already exists", oldpath, newpath, newpath)
+	} else if !errors.Is(err, os.ErrNotExist) {
+		return fmt.Errorf("stat rename destination %v: %w", newpath, err)
+	}
+	return os.Rename(oldpath, newpath)
+}

rename_windows.go

@@ -0,0 +1,18 @@
+//go:build windows
+
+package main
+
+import (
+	"errors"
+	"fmt"
+	"os"
+)
+
+func atomicRenameNoReplace(oldpath, newpath string) error {
+	if _, err := os.Stat(newpath); err == nil {
+		return fmt.Errorf("refusing to rename %v to %v: %v already exists", oldpath, newpath, newpath)
+	} else if !errors.Is(err, os.ErrNotExist) {
+		return fmt.Errorf("stat rename destination %v: %w", newpath, err)
+	}
+	return os.Rename(oldpath, newpath)
+}