Security with Go

Copying a file

The following example uses the io.Copy() function to copy the contents from one reader to another writer:

package main 
 
import ( 
   "io" 
   "log" 
   "os" 
) 
 
func main() { 
   // Open original file 
   originalFile, err := os.Open("test.txt") 
   if err != nil { 
      log.Fatal(err) 
   } 
   defer originalFile.Close() 
 
   // Create new file 
   newFile, err := os.Create("test_copy.txt") 
   if err != nil { 
      log.Fatal(err) 
   } 
   defer newFile.Close() 
 
   // Copy the bytes to destination from source 
   bytesWritten, err := io.Copy(newFile, originalFile) 
   if err != nil { 
      log.Fatal(err) 
   } 
   log.Printf("Copied %d bytes.", bytesWritten) 
 
   // Commit the file contents 
   // Flushes memory to disk 
   err = newFile.Sync() 
   if err != nil { 
      log.Fatal(err) 
   }  
}