1 // Copyright 2011 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // Plan 9 environment variables. 6 7 package syscall 8 9 import ( 10 "errors" 11 ) 12 13 var ( 14 errZeroLengthKey = errors.New("zero length key") 15 errShortWrite = errors.New("i/o count too small") 16 ) 17 18 func readenv(key string) (string, error) { 19 fd, err := open("/env/"+key, O_RDONLY) 20 if err != nil { 21 return "", err 22 } 23 defer Close(fd) 24 l, _ := Seek(fd, 0, 2) 25 Seek(fd, 0, 0) 26 buf := make([]byte, l) 27 n, err := Read(fd, buf) 28 if err != nil { 29 return "", err 30 } 31 if n > 0 && buf[n-1] == 0 { 32 buf = buf[:n-1] 33 } 34 return string(buf), nil 35 } 36 37 func writeenv(key, value string) error { 38 fd, err := create("/env/"+key, O_RDWR, 0666) 39 if err != nil { 40 return err 41 } 42 defer Close(fd) 43 b := []byte(value) 44 n, err := Write(fd, b) 45 if err != nil { 46 return err 47 } 48 if n != len(b) { 49 return errShortWrite 50 } 51 return nil 52 } 53 54 func Getenv(key string) (value string, found bool) { 55 if len(key) == 0 { 56 return "", false 57 } 58 v, err := readenv(key) 59 if err != nil { 60 return "", false 61 } 62 return v, true 63 } 64 65 func Setenv(key, value string) error { 66 if len(key) == 0 { 67 return errZeroLengthKey 68 } 69 err := writeenv(key, value) 70 if err != nil { 71 return err 72 } 73 return nil 74 } 75 76 func Clearenv() { 77 RawSyscall(SYS_RFORK, RFCENVG, 0, 0) 78 } 79 80 func Unsetenv(key string) error { 81 if len(key) == 0 { 82 return errZeroLengthKey 83 } 84 Remove("/env/" + key) 85 return nil 86 } 87 88 func Environ() []string { 89 fd, err := open("/env", O_RDONLY) 90 if err != nil { 91 return nil 92 } 93 defer Close(fd) 94 files, err := readdirnames(fd) 95 if err != nil { 96 return nil 97 } 98 ret := make([]string, 0, len(files)) 99 100 for _, key := range files { 101 v, err := readenv(key) 102 if err != nil { 103 continue 104 } 105 ret = append(ret, key+"="+v) 106 } 107 return ret 108 } 109
