go_sysutils/envs/funcs.go

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package envs
import (
`bytes`
`errors`
`fmt`
`io/ioutil`
`os`
`reflect`
`strings`
`sync`
`r00t2.io/goutils/multierr`
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`r00t2.io/goutils/structutils`
`r00t2.io/sysutils/errs`
`r00t2.io/sysutils/internal`
`r00t2.io/sysutils/paths`
)
// GetEnvMap returns a map of all environment variables. All values are strings.
func GetEnvMap() (envVars map[string]string) {
var envList []string = os.Environ()
envVars = envListToMap(envList)
return
}
/*
GetEnvMapNative returns a map of all environment variables, but attempts to "nativize" them.
All values are interfaces. It is up to the caller to typeswitch them to proper types.
Note that the PATH/Path environment variable (for *Nix and Windows, respectively) will be
a []string (as per GetPathEnv). No other env vars, even if they contain os.PathListSeparator,
will be transformed to a slice or the like.
If an error occurs during parsing the path env var, it will be rendered as a string.
All number types will attempt to be their 64-bit version (i.e. int64, uint64, float64, etc.).
If a type cannot be determined for a value, its string form will be used
(as it would be found in GetEnvMap).
*/
func GetEnvMapNative() (envMap map[string]interface{}) {
var stringMap map[string]string = GetEnvMap()
envMap = nativizeEnvMap(stringMap)
return
}
/*
GetFirst gets the first instance if populated/set occurrence of varNames.
For example, if you have three potential env vars, FOO, FOOBAR, FOOBARBAZ,
and want to follow the logic flow of:
1.) Check if FOO is set. If not,
2.) Check if FOOBAR is set. If not,
3.) Check if FOOBARBAZ is set.
Then this would be specified as:
GetFirst([]string{"FOO", "FOOBAR", "FOOBARBAZ"})
If val is "" and ok is true, this means that one of the specified variable names IS
set but is set to an empty value. If ok is false, none of the specified variables
are set.
It is a thin wrapper around GetFirstWithRef.
*/
func GetFirst(varNames []string) (val string, ok bool) {
val, ok, _ = GetFirstWithRef(varNames)
return
}
/*
GetFirstWithRef behaves exactly like GetFirst, but with an additional returned value, idx,
which specifies the index in varNames in which a set variable was found. e.g. if:
GetFirstWithRef([]string{"FOO", "FOOBAR", "FOOBAZ"})
is called and FOO is not set but FOOBAR is, idx will be 1.
If ok is false, idx will always be -1 and should be ignored.
*/
func GetFirstWithRef(varNames []string) (val string, ok bool, idx int) {
idx = -1
for i, vn := range varNames {
if HasEnv(vn) {
ok = true
idx = i
val = os.Getenv(vn)
return
}
}
return
}
// GetPathEnv returns a slice of the PATH variable's items.
func GetPathEnv() (pathList []string, err error) {
var pathVar string = internal.GetPathEnvName()
pathList = make([]string, 0)
for _, p := range strings.Split(os.Getenv(pathVar), string(os.PathListSeparator)) {
if err = paths.RealPath(&p); err != nil {
return
}
pathList = append(pathList, p)
}
return
}
/*
GetPidEnvMap will only work on *NIX-like systems with procfs.
It gets the environment variables of a given process' PID.
*/
func GetPidEnvMap(pid uint32) (envMap map[string]string, err error) {
var envBytes []byte
var envList []string
var envArr [][]byte
var procPath string
var exists bool
envMap = make(map[string]string, 0)
procPath = fmt.Sprintf("/proc/%v/environ", pid)
if exists, err = paths.RealPathExists(&procPath); err != nil {
return
}
if !exists {
err = errors.New(fmt.Sprintf("information for pid %v does not exist", pid))
return
}
if envBytes, err = ioutil.ReadFile(procPath); err != nil {
return
}
envArr = bytes.Split(envBytes, []byte{0x0})
envList = make([]string, len(envArr))
for idx, b := range envArr {
envList[idx] = string(b)
}
envMap = envListToMap(envList)
return
}
/*
GetPidEnvMapNative, like GetEnvMapNative, returns a map of all environment variables, but attempts to "nativize" them.
All values are interfaces. It is up to the caller to typeswitch them to proper types.
See the documentation for GetEnvMapNative for details.
*/
func GetPidEnvMapNative(pid uint32) (envMap map[string]interface{}, err error) {
var stringMap map[string]string
if stringMap, err = GetPidEnvMap(pid); err != nil {
return
}
envMap = nativizeEnvMap(stringMap)
return
}
/*
HasEnv is much like os.LookupEnv, but only returns a boolean for
if the environment variable key exists or not.
This is useful anywhere you may need to set a boolean in a func call
depending on the *presence* of an env var or not.
*/
func HasEnv(key string) (envIsSet bool) {
_, envIsSet = os.LookupEnv(key)
return
}
/*
Interpolate takes one of:
- a string (pointer only)
- a struct (pointer only)
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- a map (applied to both keys *and* values)
- a slice
and performs variable substitution on strings from environment variables.
It supports both UNIX/Linux/POSIX syntax formats (e.g. $VARNAME, ${VARNAME}) and,
if on Windows, it *additionally* supports the EXPAND_SZ format (e.g. %VARNAME%).
For structs, the tag name used can be changed by setting the StructTagInterpolate
variable in this submodule; the default is `envsub`.
If the tag value is "-", the field will be skipped.
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For map fields within structs etc., the default is to apply interpolation to both keys and values.
All other tag value(s) are ignored.
For maps and slices, Interpolate will recurse into values (e.g. [][]string will work as expected).
If s is nil, no interpolation will be performed. No error will be returned.
If s is not a valid/supported type, no interpolation will be performed. No error will be returned.
*/
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func Interpolate[T any](s T) (err error) {
var ptrVal reflect.Value
var ptrType reflect.Type
var ptrKind reflect.Kind
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var sVal reflect.Value = reflect.ValueOf(s)
var sType reflect.Type = sVal.Type()
var kind reflect.Kind = sType.Kind()
switch kind {
case reflect.Ptr:
if sVal.IsNil() || sVal.IsZero() || !sVal.IsValid() {
return
}
ptrVal = sVal.Elem()
ptrType = ptrVal.Type()
ptrKind = ptrType.Kind()
if ptrKind == reflect.String {
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err = interpolateStringReflect(ptrVal)
} else {
// Otherwise, it should be a struct ptr.
if ptrKind != reflect.Struct {
return
}
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err = interpolateStruct(ptrVal)
}
case reflect.Map:
if sVal.IsNil() || sVal.IsZero() || !sVal.IsValid() {
return
}
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err = interpolateMap(sVal)
case reflect.Slice:
if sVal.IsNil() || sVal.IsZero() || !sVal.IsValid() {
return
}
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err = interpolateSlice(sVal)
/*
case reflect.Struct:
if sVal.IsZero() || !sVal.IsValid() {
return
}
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err = interpolateStruct(sVal)
*/
}
return
}
/*
InterpolateString takes (a pointer to) a struct or string and performs variable substitution on it
from environment variables.
It supports both UNIX/Linux/POSIX syntax formats (e.g. $VARNAME, ${VARNAME}) and,
if on Windows, it *additionally* supports the EXPAND_SZ format (e.g. %VARNAME%).
If s is nil, nothing will be done and err will be ErrNilPtr.
This is a standalone function that is much more performant than Interpolate
at the cost of rigidity.
*/
func InterpolateString(s *string) (err error) {
var newStr string
if s == nil {
err = errs.ErrNilPtr
return
}
if newStr, err = interpolateString(*s); err != nil {
return
}
*s = newStr
return
}
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// interpolateMap is used by Interpolate for maps. v should be a reflect.Value of a map.
func interpolateMap(v reflect.Value) (err error) {
var kVal reflect.Value
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var vVal reflect.Value
var newMap reflect.Value
var wg sync.WaitGroup
var numJobs int
var errChan chan error
var doneChan chan bool = make(chan bool, 1)
var mErr *multierr.MultiError = multierr.NewMultiError(nil)
var t reflect.Type = v.Type()
var kind reflect.Kind = t.Kind()
if kind != reflect.Map {
err = errs.ErrBadType
return
}
if v.IsNil() || v.IsZero() || !v.IsValid() {
return
}
numJobs = v.Len()
errChan = make(chan error, numJobs)
wg.Add(numJobs)
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newMap = reflect.MakeMap(v.Type())
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for _, kVal = range v.MapKeys() {
vVal = v.MapIndex(kVal)
go func(key, val reflect.Value) {
var mapErr error
var newKey reflect.Value
var newVal reflect.Value
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newKey = reflect.New(key.Type()).Elem()
newVal = reflect.New(val.Type()).Elem()
newKey.Set(key.Convert(newKey.Type()))
newVal.Set(val.Convert(newVal.Type()))
defer wg.Done()
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// key
if key.Kind() == reflect.String {
if mapErr = interpolateStringReflect(newKey); mapErr != nil {
errChan <- mapErr
return
}
} else {
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if mapErr = interpolateValue(newKey); mapErr != nil {
errChan <- mapErr
return
}
}
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// value
if val.Kind() == reflect.String {
if mapErr = interpolateStringReflect(newVal); mapErr != nil {
errChan <- mapErr
return
}
} else {
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if mapErr = interpolateValue(newVal); mapErr != nil {
errChan <- mapErr
return
}
}
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newMap.SetMapIndex(newKey.Convert(key.Type()), newVal.Convert(key.Type()))
}(kVal, vVal)
}
go func() {
wg.Wait()
close(errChan)
doneChan <- true
}()
<-doneChan
for i := 0; i < numJobs; i++ {
if err = <-errChan; err != nil {
mErr.AddError(err)
err = nil
}
}
if !mErr.IsEmpty() {
err = mErr
return
}
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v.Set(newMap.Convert(v.Type()))
return
}
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// interpolateSlice is used by Interpolate for slices and arrays. v should be a reflect.Value of a slice/array.
func interpolateSlice(v reflect.Value) (err error) {
var wg sync.WaitGroup
var errChan chan error
var numJobs int
var doneChan chan bool = make(chan bool, 1)
var mErr *multierr.MultiError = multierr.NewMultiError(nil)
var t reflect.Type = v.Type()
var kind reflect.Kind = t.Kind()
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switch kind {
case reflect.Slice:
if v.IsNil() || v.IsZero() || !v.IsValid() {
return
}
case reflect.Array:
if v.IsZero() || !v.IsValid() {
return
}
default:
err = errs.ErrBadType
return
}
numJobs = v.Len()
errChan = make(chan error, numJobs)
wg.Add(numJobs)
for i := 0; i < v.Len(); i++ {
go func(idx int) {
var sErr error
defer wg.Done()
if v.Index(idx).Kind() == reflect.String {
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if sErr = interpolateStringReflect(v.Index(idx)); sErr != nil {
errChan <- sErr
return
}
} else {
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if sErr = interpolateValue(v.Index(idx)); sErr != nil {
errChan <- sErr
return
}
}
}(i)
}
go func() {
wg.Wait()
close(errChan)
doneChan <- true
}()
<-doneChan
for i := 0; i < numJobs; i++ {
if err = <-errChan; err != nil {
mErr.AddError(err)
err = nil
}
}
if !mErr.IsEmpty() {
err = mErr
return
}
return
}
// interpolateStringReflect is used for structs/nested strings using reflection.
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func interpolateStringReflect(v reflect.Value) (err error) {
var strVal string
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if v.Kind() != reflect.String {
err = errs.ErrBadType
return
}
if strVal, err = interpolateString(v.String()); err != nil {
return
}
v.Set(reflect.ValueOf(strVal).Convert(v.Type()))
return
}
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// interpolateStruct is used by Interpolate for structs. v should be a reflect.Value of a struct.
func interpolateStruct(v reflect.Value) (err error) {
var field reflect.StructField
var fieldVal reflect.Value
var wg sync.WaitGroup
var errChan chan error
var numJobs int
var doneChan chan bool = make(chan bool, 1)
var mErr *multierr.MultiError = multierr.NewMultiError(nil)
var t reflect.Type = v.Type()
var kind reflect.Kind = t.Kind()
if kind != reflect.Struct {
err = errs.ErrBadType
return
}
numJobs = v.NumField()
wg.Add(numJobs)
errChan = make(chan error, numJobs)
for i := 0; i < v.NumField(); i++ {
field = t.Field(i)
fieldVal = v.Field(i)
go func(f reflect.StructField, fv reflect.Value) {
var fErr error
defer wg.Done()
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if fErr = interpolateStructField(f, fv); fErr != nil {
errChan <- fErr
return
}
}(field, fieldVal)
}
go func() {
wg.Wait()
close(errChan)
doneChan <- true
}()
<-doneChan
for i := 0; i < numJobs; i++ {
if err = <-errChan; err != nil {
mErr.AddError(err)
err = nil
}
}
if !mErr.IsEmpty() {
err = mErr
return
}
return
}
// interpolateStructField interpolates a struct field.
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func interpolateStructField(field reflect.StructField, v reflect.Value) (err error) {
var parsedTagOpts map[string]bool
if !v.CanSet() {
return
}
// Skip if explicitly instructed to do so.
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parsedTagOpts = structutils.TagToBoolMap(field, StructTagInterpolate, structutils.TagMapTrim)
if parsedTagOpts["-"] {
return
}
if v.Kind() == reflect.Ptr {
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err = interpolateStructField(field, v.Elem())
} else {
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err = interpolateValue(v)
}
return
}
// interpolateValue is a dispatcher for a reflect value.
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func interpolateValue(v reflect.Value) (err error) {
var kind reflect.Kind = v.Kind()
switch kind {
case reflect.Ptr:
if v.IsNil() || v.IsZero() || !v.IsValid() {
return
}
v = v.Elem()
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if err = interpolateValue(v); err != nil {
return
}
case reflect.String:
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if err = interpolateStringReflect(v); err != nil {
return
}
return
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case reflect.Slice, reflect.Array:
if err = interpolateSlice(v); err != nil {
}
case reflect.Map:
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if err = interpolateMap(v); err != nil {
return
}
case reflect.Struct:
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if err = interpolateStruct(v); err != nil {
return
}
}
return
}