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package main
import (
"fmt"
"io"
"os"
"path/filepath"
"github.com/matryer/try"
)
// IsDir returns whether the path is a directory.
func IsDir(dir string) bool {
info, err := os.Lstat(dir)
return err == nil && info.Mode().IsDir() && info.Mode()&os.ModeSymlink == 0
}
// SameFile returns true if the two file paths specify the same path.
// While Linux is case-preserving case-sensitive (and therefore a string comparison will work),
// Windows is case-preserving case-insensitive; we use os.SameFile() to work cross-platform.
func SameFile(filename1 string, filename2 string) (bool, error) {
fi1, err := os.Stat(filename1)
if err != nil {
return false, err
}
fi2, err := os.Stat(filename2)
if err != nil {
return false, err
}
return os.SameFile(fi1, fi2), nil
}
func openInputFile(input string) (io.ReadCloser, error) {
var r *os.File
if input == "" {
r = os.Stdin
} else {
err := try.Do(func(attempt int) (bool, error) {
var ferr error
r, ferr = os.Open(input)
return attempt < 5, ferr
})
if err != nil {
return nil, fmt.Errorf("open input file %q: %w", input, err)
}
}
return r, nil
}
func openInputFiles(filenames []string, sep []byte) (*concatFileReader, error) {
return newConcatFileReader(filenames, openInputFile, sep)
}
func openOutputFile(output string) (*os.File, error) {
var w *os.File
if output == "" {
w = os.Stdout
} else {
dir := filepath.Dir(output)
if err := os.MkdirAll(dir, 0777); err != nil {
return nil, fmt.Errorf("creating directory %q: %w", dir, err)
}
err := try.Do(func(attempt int) (bool, error) {
var ferr error
w, ferr = os.OpenFile(output, os.O_WRONLY|os.O_TRUNC|os.O_CREATE, 0666)
return attempt < 5, ferr
})
if err != nil {
return nil, fmt.Errorf("open output file %q: %w", output, err)
}
}
return w, nil
}
func createSymlink(input, output string) error {
if _, err := os.Stat(output); err == nil {
if err = os.Remove(output); err != nil {
return err
}
}
if err := os.MkdirAll(filepath.Dir(output), 0777); err != nil {
return err
}
if err := os.Symlink(input, output); err != nil {
return err
}
return nil
}
type concatFileReader struct {
filenames []string
sep []byte
opener func(string) (io.ReadCloser, error)
cur io.ReadCloser
sepLeft int
}
func newConcatFileReader(filenames []string, opener func(string) (io.ReadCloser, error), sep []byte) (*concatFileReader, error) {
var cur io.ReadCloser
if 0 < len(filenames) {
var filename string
filename, filenames = filenames[0], filenames[1:]
var err error
if cur, err = opener(filename); err != nil {
return nil, err
}
}
return &concatFileReader{filenames, sep, opener, cur, 0}, nil
}
func (r *concatFileReader) Read(p []byte) (int, error) {
m := r.writeSep(p) // write remaining separator
if r.cur == nil {
return m, io.EOF
}
n, err := r.cur.Read(p[m:])
n += m
// current reader is finished, load in the new reader
if err == io.EOF {
if err := r.cur.Close(); err != nil {
return n, err
}
r.cur = nil
if 0 < len(r.filenames) {
var filename string
filename, r.filenames = r.filenames[0], r.filenames[1:]
if r.cur, err = r.opener(filename); err != nil {
return n, err
}
r.sepLeft = len(r.sep)
// if previous read returned (0, io.EOF), read from the new reader
if n == 0 {
return r.Read(p)
}
n += r.writeSep(p[n:])
}
}
return n, err
}
func (r *concatFileReader) writeSep(p []byte) int {
if 0 < r.sepLeft {
m := copy(p, r.sep[len(r.sep)-r.sepLeft:])
r.sepLeft -= m
return m
}
return 0
}
func (r *concatFileReader) Close() error {
if r.cur != nil {
return r.cur.Close()
}
return nil
}
|
