Subversion Repositories openrisc

// Copyright 2010 The Go Authors.  All rights reserved.

// Use of this source code is governed by a BSD-style

// license that can be found in the LICENSE file.

// +build darwin freebsd linux netbsd openbsd

// Unix environment variables.

package syscall

import "sync"

var (

        // envOnce guards initialization by copyenv, which populates env.

        envOnce sync.Once

        // envLock guards env and envs.

        envLock sync.RWMutex

        // env maps from an environment variable to its first occurrence in envs.

        env map[string]int

        // envs is provided by the runtime. elements are expected to be

        // of the form "key=value".

        Envs []string

)

// setenv_c is provided by the runtime, but is a no-op if cgo isn't

// loaded.

func setenv_c(k, v string)

func copyenv() {

        env = make(map[string]int)

        for i, s := range Envs {

                for j := 0; j < len(s); j++ {

                        if s[j] == '=' {

                                key := s[:j]

                                if _, ok := env[key]; !ok {

                                        env[key] = i

                                }

                                break

                        }

                }

        }

}

func Getenv(key string) (value string, found bool) {

        envOnce.Do(copyenv)

        if len(key) == 0 {

                return "", false

        }

        envLock.RLock()

        defer envLock.RUnlock()

        i, ok := env[key]

        if !ok {

                return "", false

        }

        s := Envs[i]

        for i := 0; i < len(s); i++ {

                if s[i] == '=' {

                        return s[i+1:], true

                }

        }

        return "", false

}

func Setenv(key, value string) error {

        envOnce.Do(copyenv)

        if len(key) == 0 {

                return EINVAL

        }

        envLock.Lock()

        defer envLock.Unlock()

        i, ok := env[key]

        kv := key + "=" + value

        if ok {

                Envs[i] = kv

        } else {

                i = len(Envs)

                Envs = append(Envs, kv)

        }

        env[key] = i

        setenv_c(key, value)

        return nil

}

func Clearenv() {

        envOnce.Do(copyenv) // prevent copyenv in Getenv/Setenv

        envLock.Lock()

        defer envLock.Unlock()

        env = make(map[string]int)

        Envs = []string{}

        // TODO(bradfitz): pass through to C

}

func Environ() []string {

        envOnce.Do(copyenv)

        envLock.RLock()

        defer envLock.RUnlock()

        a := make([]string, len(Envs))

        copy(a, Envs)

        return a

}