github.com/goproxy0/go@v0.0.0-20171111080102-49cc0c489d2c/src/cmd/go/internal/base/env.go (about)

     1  // Copyright 2017 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  package base
     6  
     7  import "strings"
     8  
     9  // EnvForDir returns a copy of the environment
    10  // suitable for running in the given directory.
    11  // The environment is the current process's environment
    12  // but with an updated $PWD, so that an os.Getwd in the
    13  // child will be faster.
    14  func EnvForDir(dir string, base []string) []string {
    15  	// Internally we only use rooted paths, so dir is rooted.
    16  	// Even if dir is not rooted, no harm done.
    17  	return MergeEnvLists([]string{"PWD=" + dir}, base)
    18  }
    19  
    20  // MergeEnvLists merges the two environment lists such that
    21  // variables with the same name in "in" replace those in "out".
    22  // This always returns a newly allocated slice.
    23  func MergeEnvLists(in, out []string) []string {
    24  	out = append([]string(nil), out...)
    25  NextVar:
    26  	for _, inkv := range in {
    27  		k := strings.SplitAfterN(inkv, "=", 2)[0]
    28  		for i, outkv := range out {
    29  			if strings.HasPrefix(outkv, k) {
    30  				out[i] = inkv
    31  				continue NextVar
    32  			}
    33  		}
    34  		out = append(out, inkv)
    35  	}
    36  	return out
    37  }