Check that fs is case-sensitive

main.go

@@ -11,6 +11,7 @@ import (
 	"os"
 	"os/exec"
 	"os/user"
+	"path/filepath"
 	"runtime/debug"
 	"strconv"
 	"time"
@@ -92,6 +93,37 @@ func (lw *LevelWriter) WriteLevel(l zerolog.Level, p []byte) (n int, err error)
 	return len(p), nil
 }
 
+func isFsCaseInsensitive(dir string) (yes bool, err error) {
+	pathLowercase := filepath.Join(dir, "file")
+	fLowercase, err := os.Create(pathLowercase)
+	if err != nil {
+		return
+	}
+	defer fLowercase.Close()
+	defer os.Remove(pathLowercase)
+
+	pathUppercase := filepath.Join(dir, "FILE")
+	fUppercase, err := os.Create(pathUppercase)
+	if err != nil {
+		return
+	}
+	defer fUppercase.Close()
+	defer os.Remove(pathUppercase)
+
+	statLowercase, err := fLowercase.Stat()
+	if err != nil {
+		return
+	}
+
+	statUppercase, err := fUppercase.Stat()
+	if err != nil {
+		return
+	}
+
+	yes = os.SameFile(statLowercase, statUppercase)
+	return
+}
+
 var tempDirBase string
 
 var consoleWriter, fileWriter LevelWriter
@@ -163,6 +195,15 @@ func main() {
 		log.Debug().Msgf("%v", buildInfo.Settings)
 	}
 
+	path := filepath.Join(usr.HomeDir, ".out-of-tree")
+	yes, err := isFsCaseInsensitive(path)
+	if err != nil {
+		log.Fatal().Err(err).Msg(path)
+	}
+	if yes {
+		log.Warn().Msg("case-insensitive file system not supported")
+	}
+
 	_, err = exec.LookPath(cli.ContainerRuntime)
 	if err != nil {
 		if cli.ContainerRuntime == "podman" { // default value