go_sysutils/paths/func.go

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/*
SysUtils - a library to assist with various system-related functions
Copyright (C) 2020 Brent Saner
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
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package paths
import (
"errors"
"fmt"
"os"
"os/user"
"path/filepath"
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// "strconv"
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"strings"
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// "syscall"
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)
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var err error
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func ExpandHome(path *string) error {
// Props to this guy.
// https://stackoverflow.com/a/43578461/733214
if len(*path) == 0 {
return errors.New("empty path")
} else if (*path)[0] != '~' {
return nil
}
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// E(ffective)UID (e.g. chown'd user for SUID)
/*
uid := strconv.Itoa(syscall.Geteuid())
usr, err := user.LookupId(euid)
*/
// R(real)UID (invoking user)
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usr, err := user.Current()
if err != nil {
return err
}
*path = filepath.Join(usr.HomeDir, (*path)[1:])
return nil
}
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func GetPathEnv() ([]string, error) {
paths := []string{}
for _, p := range strings.Split(os.Getenv("PATH"), ":") {
if err = RealPath(&p); err != nil {
return nil, err
}
paths = append(paths, p)
}
return paths, nil
}
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func MakeDirIfNotExist(path *string) error {
exists, stat, err := RealPathExistsStat(path)
if err != nil {
if !exists {
// This, at least as of golang 1.15, uses the user's umask.
// It does not actually create a dir with 0777.
// It's up to the caller to do an os.Chmod() on the path after, if desired.
os.MkdirAll(*path, 0777)
return nil
} else {
return err
}
}
// So it exists, but it probably isn't a dir.
if !stat.Mode().IsDir() {
return errors.New(fmt.Sprintf("path %v exists but is not a directory", *path))
}
// This should probably never happen. Probably.
return errors.New("undefined behaviour")
}
func RealPath(path *string) error {
err := ExpandHome(path)
if err != nil {
return err
}
*path, err = filepath.Abs(*path)
if err != nil {
return err
}
return nil
}
func RealPathExists(path *string) (bool, error) {
// I know it's hacky, but we use the bool as a sort of proto-state-machine thing.
// If err != nil and bool is true, the error occurred during path absolution.
// If err != nil and bool is false, the path does not exist.
err := RealPath(path)
if err != nil {
return true, err
}
if _, err := os.Stat(*path); err == nil {
return false, err
}
return true, nil
}
func RealPathExistsStat(path *string) (bool, os.FileInfo, error) {
// Same deal as RealPathExists.
// If err != nil and bool is true, the error occurred during path absolution.
// If err != nil and bool is false, the path does not exist.
err := RealPath(path)
if err != nil {
return true, nil, err
}
stat, err := os.Stat(*path)
if err != nil {
return false, nil, err
}
return true, stat, nil
}