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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
// load default environment variables (from $VESPA_HOME/conf/vespa/default-env.txt)
// Author: arnej
package vespa
import (
"bufio"
"fmt"
"os"
"strings"
)
// backwards-compatible parsing of default-env.txt
func LoadDefaultEnv() error {
return loadDefaultEnvTo(new(osEnvReceiver))
}
// parse default-env.txt, then dump export statements for "sh" to stdout
func ExportDefaultEnvToSh() error {
holder := newShellEnvExporter()
err := loadDefaultEnvTo(holder)
holder.overrideVar("VESPA_HOME", FindHome())
holder.overrideVar("VESPA_USER", FindVespaUser())
holder.dump()
return err
}
type loadEnvReceiver interface {
fallbackVar(varName, varVal string)
overrideVar(varName, varVal string)
unsetVar(varName string)
}
type osEnvReceiver struct {
}
func (p *osEnvReceiver) fallbackVar(varName, varVal string) {
if os.Getenv(varName) == "" {
os.Setenv(varName, varVal)
}
}
func (p *osEnvReceiver) overrideVar(varName, varVal string) {
os.Setenv(varName, varVal)
}
func (p *osEnvReceiver) unsetVar(varName string) {
os.Unsetenv(varName)
}
func loadDefaultEnvTo(r loadEnvReceiver) error {
const defEnvTxt = "/conf/vespa/default-env.txt"
vespaHome := FindHome()
f, err := os.Open(vespaHome + defEnvTxt)
if err != nil {
return err
}
defer f.Close()
scanner := bufio.NewScanner(f)
for scanner.Scan() {
line := scanner.Text()
if strings.HasPrefix(line, "#") {
continue
}
fields := nSpacedFields(line, 3)
action := fields[0]
if action == "" {
continue
}
varName := fields[1]
varVal := fields[2]
if !isValidShellVariableName(varName) {
err = fmt.Errorf("Not a valid environment variable name: '%s'", varName)
continue
}
if strings.HasPrefix(varVal, `"`) && strings.HasSuffix(varVal, `"`) {
varVal = varVal[1 : len(varVal)-1]
}
switch action {
case "override":
r.overrideVar(varName, varVal)
case "fallback":
r.fallbackVar(varName, varVal)
case "unset":
r.unsetVar(varName)
default:
err = fmt.Errorf("unknown action '%s'", action)
}
}
if err == nil {
err = scanner.Err()
}
return err
}
// borrowed some code from strings.Fields() implementation:
func nSpacedFields(s string, n int) []string {
var asciiSpace = [256]uint8{'\t': 1, '\n': 1, '\v': 1, '\f': 1, '\r': 1, ' ': 1}
a := make([]string, n)
na := 0
fieldStart := 0
i := 0
// Skip spaces in the front of the input.
for i < len(s) && asciiSpace[s[i]] != 0 {
i++
}
fieldStart = i
for i < len(s) && na+1 < n {
if asciiSpace[s[i]] == 0 {
i++
continue
}
a[na] = s[fieldStart:i]
na++
i++
// Skip spaces in between fields.
for i < len(s) && asciiSpace[s[i]] != 0 {
i++
}
fieldStart = i
}
// ignore trailing spaces
for i = len(s); i > fieldStart && asciiSpace[s[i-1]] != 0; i-- {
}
a[na] = s[fieldStart:i]
return a
}
// pretty strict for now, can be more lenient if needed
func isValidShellVariableName(s string) bool {
for i := 0; i < len(s); i++ {
b := s[i]
switch {
case (b >= 'A' && b <= 'Z'): // ok
case (b >= 'a' && b <= 'z'): // ok
case (b >= '0' && b <= '9'): // ok
case b == '_': // ok
default:
return false
}
}
return len(s) > 0
}
type shellEnvExporter struct {
exportVars map[string]string
unsetVars map[string]string
}
func newShellEnvExporter() *shellEnvExporter {
return &shellEnvExporter{
exportVars: make(map[string]string),
unsetVars: make(map[string]string),
}
}
func (p *shellEnvExporter) fallbackVar(varName, varVal string) {
if os.Getenv(varName) == "" || p.unsetVars[varName] != "" {
delete(p.unsetVars, varName)
p.exportVars[varName] = shellQuote(varVal)
}
}
func (p *shellEnvExporter) overrideVar(varName, varVal string) {
delete(p.unsetVars, varName)
p.exportVars[varName] = shellQuote(varVal)
}
func (p *shellEnvExporter) unsetVar(varName string) {
delete(p.exportVars, varName)
p.unsetVars[varName] = "unset"
}
func shellQuote(s string) string {
l := 0
nq := false
for _, ch := range s {
switch {
case (ch >= 'A' && ch <= 'Z') ||
(ch >= 'a' && ch <= 'z') ||
(ch >= '0' && ch <= '9'):
l++
case ch == '_' || ch == ' ':
l++
nq = true
case ch == '\'' || ch == '\\':
l = l + 4
nq = true
default:
l++
nq = true
}
}
if nq {
l = l + 2
}
res := make([]rune, l)
i := 0
if nq {
res[i] = '\''
i++
}
for _, ch := range s {
if ch == '\'' || ch == '\\' {
res[i] = '\''
i++
res[i] = '\\'
i++
res[i] = ch
i++
res[i] = '\''
} else {
res[i] = ch
}
i++
}
if nq {
res[i] = '\''
i++
}
if i != l {
err := fmt.Errorf("expected length %d but was %d", l, i)
panic(err)
}
return string(res)
}
func (p *shellEnvExporter) dump() {
for vn, vv := range p.exportVars {
fmt.Printf("%s=%s\n", vn, vv)
fmt.Printf("export %s\n", vn)
}
for vn, _ := range p.unsetVars {
fmt.Printf("unset %s\n", vn)
}
}
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