github.com/razvanm/vanadium-go-1.3@v0.0.0-20160721203343-4a65068e5915/src/runtime/env_posix.go (about) 1 // Copyright 2012 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 // +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris windows 6 7 package runtime 8 9 import "unsafe" 10 11 func environ() []string 12 13 func getenv(s *byte) *byte { 14 val := gogetenv(gostringnocopy(s)) 15 if val == "" { 16 return nil 17 } 18 // Strings found in environment are NUL-terminated. 19 return &bytes(val)[0] 20 } 21 22 func gogetenv(key string) string { 23 env := environ() 24 if env == nil { 25 gothrow("getenv before env init") 26 } 27 for _, s := range environ() { 28 if len(s) > len(key) && s[len(key)] == '=' && s[:len(key)] == key { 29 return s[len(key)+1:] 30 } 31 } 32 return "" 33 } 34 35 var _cgo_setenv uintptr // pointer to C function 36 var _cgo_unsetenv uintptr // pointer to C function 37 38 // Update the C environment if cgo is loaded. 39 // Called from syscall.Setenv. 40 func syscall_setenv_c(k string, v string) { 41 if _cgo_setenv == 0 { 42 return 43 } 44 arg := [2]unsafe.Pointer{cstring(k), cstring(v)} 45 asmcgocall(unsafe.Pointer(_cgo_setenv), unsafe.Pointer(&arg)) 46 } 47 48 // Update the C environment if cgo is loaded. 49 // Called from syscall.unsetenv. 50 func syscall_unsetenv_c(k string) { 51 if _cgo_unsetenv == 0 { 52 return 53 } 54 arg := [1]unsafe.Pointer{cstring(k)} 55 asmcgocall(unsafe.Pointer(_cgo_unsetenv), unsafe.Pointer(&arg)) 56 } 57 58 func cstring(s string) unsafe.Pointer { 59 p := make([]byte, len(s)+1) 60 sp := (*_string)(unsafe.Pointer(&s)) 61 memmove(unsafe.Pointer(&p[0]), unsafe.Pointer(sp.str), uintptr(len(s))) 62 return unsafe.Pointer(&p[0]) 63 }