github.com/paketo-buildpacks/libpak@v1.70.0/internal/entry_writer.go (about) 1 /* 2 * Copyright 2018-2020 the original author or authors. 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * https://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package internal 18 19 import ( 20 "fmt" 21 "io" 22 "os" 23 "path/filepath" 24 ) 25 26 const ModeExecutable = 0100 27 28 type EntryWriter struct{} 29 30 func (e EntryWriter) Write(source string, destination string) error { 31 p := filepath.Dir(destination) 32 if err := os.MkdirAll(p, 0755); err != nil { 33 return fmt.Errorf("unable to create destination directory %s\n%w", p, err) 34 } 35 36 s, err := os.Lstat(source) 37 if err != nil { 38 return fmt.Errorf("unable to stat file %s\n%w", source, err) 39 } 40 41 if s.Mode()&os.ModeSymlink != 0 { 42 target, err := os.Readlink(source) 43 if err != nil { 44 return fmt.Errorf("unable to read link %s\n%w", source, err) 45 } 46 47 if err := os.Symlink(target, destination); err != nil { 48 return fmt.Errorf("unable to create link %s\n%w", destination, err) 49 } 50 51 return nil 52 } 53 54 var perm os.FileMode 55 if s.Mode()&ModeExecutable == ModeExecutable { 56 perm = 0755 57 } else { 58 perm = 0644 59 } 60 61 in, err := os.OpenFile(source, os.O_RDONLY, 0) 62 if err != nil { 63 return fmt.Errorf("unable to open source file %s\n%w", source, err) 64 } 65 defer in.Close() 66 67 out, err := os.OpenFile(destination, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, perm) 68 if err != nil { 69 return fmt.Errorf("unable to open destination file %s\n%w", destination, err) 70 } 71 defer out.Close() 72 73 if _, err := io.Copy(out, in); err != nil { 74 return fmt.Errorf("unable to copy %s to %s\n%w", source, destination, err) 75 } 76 77 return nil 78 }