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fileinfo_unix.go
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fileinfo_unix.go
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// Copyright 2017 the u-root Authors. All rights reserved
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build !plan9
// +build !plan9
package ls
import (
"fmt"
"os"
"os/user"
"regexp"
"strconv"
"strings"
"syscall"
"time"
humanize "github.com/dustin/go-humanize"
"golang.org/x/sys/unix"
)
// Matches characters which would interfere with ls's formatting.
var unprintableRe = regexp.MustCompile("[[:cntrl:]\n]")
// FileInfo holds file metadata.
//
// Since `os.FileInfo` is an interface, it is difficult to tweak some of its
// internal values. For example, replacing the starting directory with a dot.
// `extractImportantParts` populates our own struct which we can modify at will
// before printing.
type FileInfo struct {
Name string
Mode os.FileMode
Rdev uint64
UID, GID uint32
Size int64
MTime time.Time
SymlinkTarget string
}
// FromOSFileInfo converts os.FileInfo to an ls.FileInfo.
func FromOSFileInfo(path string, fi os.FileInfo) FileInfo {
var link string
s := fi.Sys().(*syscall.Stat_t)
if fi.Mode()&os.ModeType == os.ModeSymlink {
if l, err := os.Readlink(path); err != nil {
link = err.Error()
} else {
link = l
}
}
return FileInfo{
Name: fi.Name(),
Mode: fi.Mode(),
Rdev: uint64(s.Rdev),
UID: s.Uid,
GID: s.Gid,
Size: fi.Size(),
MTime: fi.ModTime(),
SymlinkTarget: link,
}
}
// PrintableName returns a printable file name.
func (fi FileInfo) PrintableName() string {
return unprintableRe.ReplaceAllLiteralString(fi.Name, "?")
}
// Without this cache, `ls -l` is orders of magnitude slower.
var (
uidCache = map[uint32]string{}
gidCache = map[uint32]string{}
)
// Convert uid to username, or return uid on error.
func lookupUserName(id uint32) string {
if s, ok := uidCache[id]; ok {
return s
}
s := fmt.Sprint(id)
if u, err := user.LookupId(s); err == nil {
s = u.Username
}
uidCache[id] = s
return s
}
// Convert gid to group name, or return gid on error.
func lookupGroupName(id uint32) string {
if s, ok := gidCache[id]; ok {
return s
}
s := fmt.Sprint(id)
if g, err := user.LookupGroupId(s); err == nil {
s = g.Name
}
gidCache[id] = s
return s
}
// Stringer provides a consistent way to format FileInfo.
type Stringer interface {
// FileString formats a FileInfo.
FileString(fi FileInfo) string
}
// NameStringer is a Stringer implementation that just prints the name.
type NameStringer struct{}
// FileString implements Stringer.FileString and just returns fi's name.
func (ns NameStringer) FileString(fi FileInfo) string {
return fi.PrintableName()
}
// QuotedStringer is a Stringer that returns the file name surrounded by qutoes
// with escaped control characters.
type QuotedStringer struct{}
// FileString returns the name surrounded by quotes with escaped control characters.
func (qs QuotedStringer) FileString(fi FileInfo) string {
return fmt.Sprintf("%#v", fi.Name)
}
// LongStringer is a Stringer that returns the file info formatted in `ls -l`
// long format.
type LongStringer struct {
Human bool
Name Stringer
}
// FileString implements Stringer.FileString.
func (ls LongStringer) FileString(fi FileInfo) string {
// Golang's FileMode.String() is almost sufficient, except we would
// rather use b and c for devices.
replacer := strings.NewReplacer("Dc", "c", "D", "b")
// Ex: crw-rw-rw- root root 1, 3 Feb 6 09:31 null
pattern := "%[1]s\t%[2]s\t%[3]s\t%[4]d, %[5]d\t%[7]v\t%[8]s"
if fi.Mode&os.ModeDevice == 0 && fi.Mode&os.ModeCharDevice == 0 {
// Ex: -rw-rw---- myuser myuser 1256 Feb 6 09:31 recipes.txt
pattern = "%[1]s\t%[2]s\t%[3]s\t%[6]s\t%[7]v\t%[8]s"
}
var size string
if ls.Human {
size = humanize.Bytes(uint64(fi.Size))
} else {
size = strconv.FormatInt(fi.Size, 10)
}
s := fmt.Sprintf(pattern,
replacer.Replace(fi.Mode.String()),
lookupUserName(fi.UID),
lookupGroupName(fi.GID),
unix.Major(fi.Rdev),
unix.Minor(fi.Rdev),
size,
fi.MTime.Format("Jan _2 15:04"),
ls.Name.FileString(fi))
if fi.Mode&os.ModeType == os.ModeSymlink {
s += fmt.Sprintf(" -> %v", fi.SymlinkTarget)
}
return s
}