vfs: make sure all 96 combinations of flags for Open work

vfs/make_open_tests.go

@@ -0,0 +1,228 @@
+// This makes the open test suite
+//
+// Run with go run make_open_tests.go | gofmt > open_test.go
+//
+//+build none
+
+// FIXME include read too?
+
+package main
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"strings"
+)
+
+// Interprets err into a vfs error
+func whichError(err error) string {
+	switch err {
+	case nil:
+		return "nil"
+	case io.EOF:
+		return "io.EOF"
+	}
+	s := err.Error()
+	switch {
+	case strings.Contains(s, "no such file or directory"):
+		return "ENOENT"
+	case strings.Contains(s, "bad file descriptor"):
+		return "EBADF"
+	case strings.Contains(s, "file exists"):
+		return "EEXIST"
+	}
+	log.Fatalf("Unknown error: %v", err)
+	return ""
+}
+
+// test Opening, reading and writing the file handle with the flags given
+func test(fileName string, flags int, mode string) {
+	// first try with file not existing
+	_, err := os.Stat(fileName)
+	if !os.IsNotExist(err) {
+		log.Fatalf("File must not exist")
+	}
+	f, openNonExistentErr := os.OpenFile(fileName, flags, 0666)
+
+	var readNonExistentErr error
+	var writeNonExistentErr error
+	if openNonExistentErr == nil {
+		// read some bytes
+		buf := []byte{0, 0}
+		_, readNonExistentErr = f.Read(buf)
+
+		// write some bytes
+		_, writeNonExistentErr = f.Write([]byte("hello"))
+
+		// close
+		err = f.Close()
+		if err != nil {
+			log.Fatalf("failed to close: %v", err)
+		}
+	}
+
+	// write the file
+	f, err = os.Create(fileName)
+	if err != nil {
+		log.Fatalf("failed to create: %v", err)
+	}
+	n, err := f.Write([]byte("hello"))
+	if n != 5 || err != nil {
+		log.Fatalf("failed to write n=%d: %v", n, err)
+	}
+	// close
+	err = f.Close()
+	if err != nil {
+		log.Fatalf("failed to close: %v", err)
+	}
+
+	// then open file and try with file existing
+
+	f, openExistingErr := os.OpenFile(fileName, flags, 0666)
+	var readExistingErr error
+	var writeExistingErr error
+	if openExistingErr == nil {
+		// read some bytes
+		buf := []byte{0, 0}
+		_, readExistingErr = f.Read(buf)
+
+		// write some bytes
+		n, writeExistingErr = f.Write([]byte("HEL"))
+
+		// close
+		err = f.Close()
+		if err != nil {
+			log.Fatalf("failed to close: %v", err)
+		}
+	}
+
+	// read the file
+	f, err = os.Open(fileName)
+	if err != nil {
+		log.Fatalf("failed to open: %v", err)
+	}
+	var buf = make([]byte, 64)
+	n, err = f.Read(buf)
+	if err != nil && err != io.EOF {
+		log.Fatalf("failed to read n=%d: %v", n, err)
+	}
+	err = f.Close()
+	if err != nil {
+		log.Fatalf("failed to close: %v", err)
+	}
+	contents := string(buf[:n])
+
+	// remove file
+	err = os.Remove(fileName)
+	if err != nil {
+		log.Fatalf("failed to remove: %v", err)
+	}
+
+	// output the struct
+	fmt.Printf(`{
+	flags: %s,
+	what: %q,
+	openNonExistentErr: %s,
+	readNonExistentErr: %s,
+	writeNonExistentErr: %s,
+	openExistingErr: %s,
+	readExistingErr: %s,
+	writeExistingErr: %s,
+	contents: %q,
+},`,
+		mode,
+		mode,
+		whichError(openNonExistentErr),
+		whichError(readNonExistentErr),
+		whichError(writeNonExistentErr),
+		whichError(openExistingErr),
+		whichError(readExistingErr),
+		whichError(writeExistingErr),
+		contents)
+}
+
+func main() {
+	fmt.Printf(`// data generated by go run make_open_tests.go | gofmt > open_test.go
+
+package vfs
+
+import (
+	"os"
+	"io"
+)
+
+// openTest describes a test of OpenFile
+type openTest struct{
+	flags int
+	what string
+	openNonExistentErr error
+	readNonExistentErr error
+	writeNonExistentErr error
+	openExistingErr error
+	readExistingErr error
+	writeExistingErr error
+	contents string
+}
+
+// openTests is a suite of tests for OpenFile with all possible
+// combination of flags.  This obeys Unix semantics even on Windows.
+var openTests = []openTest{
+`)
+	f, err := ioutil.TempFile("", "open-test")
+	if err != nil {
+		log.Fatal(err)
+	}
+	fileName := f.Name()
+	_ = f.Close()
+	err = os.Remove(fileName)
+	if err != nil {
+		log.Fatalf("failed to remove: %v", err)
+	}
+	for _, rwMode := range []int{os.O_RDONLY, os.O_WRONLY, os.O_RDWR} {
+		flags0 := rwMode
+		parts0 := []string{"os.O_RDONLY", "os.O_WRONLY", "os.O_RDWR"}[rwMode : rwMode+1]
+		for _, appendMode := range []int{0, os.O_APPEND} {
+			flags1 := flags0 | appendMode
+			parts1 := parts0
+			if appendMode != 0 {
+				parts1 = append(parts1, "os.O_APPEND")
+			}
+			for _, createMode := range []int{0, os.O_CREATE} {
+				flags2 := flags1 | createMode
+				parts2 := parts1
+				if createMode != 0 {
+					parts2 = append(parts2, "os.O_CREATE")
+				}
+				for _, exclMode := range []int{0, os.O_EXCL} {
+					flags3 := flags2 | exclMode
+					parts3 := parts2
+					if exclMode != 0 {
+						parts3 = append(parts2, "os.O_EXCL")
+					}
+					for _, syncMode := range []int{0, os.O_SYNC} {
+						flags4 := flags3 | syncMode
+						parts4 := parts3
+						if syncMode != 0 {
+							parts4 = append(parts4, "os.O_SYNC")
+						}
+						for _, truncMode := range []int{0, os.O_TRUNC} {
+							flags5 := flags4 | truncMode
+							parts5 := parts4
+							if truncMode != 0 {
+								parts5 = append(parts5, "os.O_TRUNC")
+							}
+							textMode := strings.Join(parts5, "|")
+							flags := flags5
+
+							test(fileName, flags, textMode)
+						}
+					}
+				}
+			}
+		}
+	}
+	fmt.Printf("\n}\n")
+}