1package util
  2
  3import (
  4	"errors"
  5	"io"
  6	"os"
  7	"path/filepath"
  8	"strconv"
  9	"sync"
 10	"time"
 11
 12	"github.com/go-git/go-billy/v5"
 13)
 14
 15// RemoveAll removes path and any children it contains. It removes everything it
 16// can but returns the first error it encounters. If the path does not exist,
 17// RemoveAll returns nil (no error).
 18func RemoveAll(fs billy.Basic, path string) error {
 19	fs, path = getUnderlyingAndPath(fs, path)
 20
 21	if r, ok := fs.(removerAll); ok {
 22		return r.RemoveAll(path)
 23	}
 24
 25	return removeAll(fs, path)
 26}
 27
 28type removerAll interface {
 29	RemoveAll(string) error
 30}
 31
 32func removeAll(fs billy.Basic, path string) error {
 33	// This implementation is adapted from os.RemoveAll.
 34
 35	// Simple case: if Remove works, we're done.
 36	err := fs.Remove(path)
 37	if err == nil || errors.Is(err, os.ErrNotExist) {
 38		return nil
 39	}
 40
 41	// Otherwise, is this a directory we need to recurse into?
 42	dir, serr := fs.Stat(path)
 43	if serr != nil {
 44		if errors.Is(serr, os.ErrNotExist) {
 45			return nil
 46		}
 47
 48		return serr
 49	}
 50
 51	if !dir.IsDir() {
 52		// Not a directory; return the error from Remove.
 53		return err
 54	}
 55
 56	dirfs, ok := fs.(billy.Dir)
 57	if !ok {
 58		return billy.ErrNotSupported
 59	}
 60
 61	// Directory.
 62	fis, err := dirfs.ReadDir(path)
 63	if err != nil {
 64		if errors.Is(err, os.ErrNotExist) {
 65			// Race. It was deleted between the Lstat and Open.
 66			// Return nil per RemoveAll's docs.
 67			return nil
 68		}
 69
 70		return err
 71	}
 72
 73	// Remove contents & return first error.
 74	err = nil
 75	for _, fi := range fis {
 76		cpath := fs.Join(path, fi.Name())
 77		err1 := removeAll(fs, cpath)
 78		if err == nil {
 79			err = err1
 80		}
 81	}
 82
 83	// Remove directory.
 84	err1 := fs.Remove(path)
 85	if err1 == nil || errors.Is(err1, os.ErrNotExist) {
 86		return nil
 87	}
 88
 89	if err == nil {
 90		err = err1
 91	}
 92
 93	return err
 94
 95}
 96
 97// WriteFile writes data to a file named by filename in the given filesystem.
 98// If the file does not exist, WriteFile creates it with permissions perm;
 99// otherwise WriteFile truncates it before writing.
100func WriteFile(fs billy.Basic, filename string, data []byte, perm os.FileMode) (err error) {
101	f, err := fs.OpenFile(filename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, perm)
102	if err != nil {
103		return err
104	}
105	defer func() {
106		if f != nil {
107			err1 := f.Close()
108			if err == nil {
109				err = err1
110			}
111		}
112	}()
113
114	n, err := f.Write(data)
115	if err == nil && n < len(data) {
116		err = io.ErrShortWrite
117	}
118
119	return nil
120}
121
122// Random number state.
123// We generate random temporary file names so that there's a good
124// chance the file doesn't exist yet - keeps the number of tries in
125// TempFile to a minimum.
126var rand uint32
127var randmu sync.Mutex
128
129func reseed() uint32 {
130	return uint32(time.Now().UnixNano() + int64(os.Getpid()))
131}
132
133func nextSuffix() string {
134	randmu.Lock()
135	r := rand
136	if r == 0 {
137		r = reseed()
138	}
139	r = r*1664525 + 1013904223 // constants from Numerical Recipes
140	rand = r
141	randmu.Unlock()
142	return strconv.Itoa(int(1e9 + r%1e9))[1:]
143}
144
145// TempFile creates a new temporary file in the directory dir with a name
146// beginning with prefix, opens the file for reading and writing, and returns
147// the resulting *os.File. If dir is the empty string, TempFile uses the default
148// directory for temporary files (see os.TempDir). Multiple programs calling
149// TempFile simultaneously will not choose the same file. The caller can use
150// f.Name() to find the pathname of the file. It is the caller's responsibility
151// to remove the file when no longer needed.
152func TempFile(fs billy.Basic, dir, prefix string) (f billy.File, err error) {
153	// This implementation is based on stdlib ioutil.TempFile.
154	if dir == "" {
155		dir = getTempDir(fs)
156	}
157
158	nconflict := 0
159	for i := 0; i < 10000; i++ {
160		name := filepath.Join(dir, prefix+nextSuffix())
161		f, err = fs.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600)
162		if errors.Is(err, os.ErrExist) {
163			if nconflict++; nconflict > 10 {
164				randmu.Lock()
165				rand = reseed()
166				randmu.Unlock()
167			}
168			continue
169		}
170		break
171	}
172	return
173}
174
175// TempDir creates a new temporary directory in the directory dir
176// with a name beginning with prefix and returns the path of the
177// new directory. If dir is the empty string, TempDir uses the
178// default directory for temporary files (see os.TempDir).
179// Multiple programs calling TempDir simultaneously
180// will not choose the same directory. It is the caller's responsibility
181// to remove the directory when no longer needed.
182func TempDir(fs billy.Dir, dir, prefix string) (name string, err error) {
183	// This implementation is based on stdlib ioutil.TempDir
184
185	if dir == "" {
186		dir = getTempDir(fs.(billy.Basic))
187	}
188
189	nconflict := 0
190	for i := 0; i < 10000; i++ {
191		try := filepath.Join(dir, prefix+nextSuffix())
192		err = fs.MkdirAll(try, 0700)
193		if errors.Is(err, os.ErrExist) {
194			if nconflict++; nconflict > 10 {
195				randmu.Lock()
196				rand = reseed()
197				randmu.Unlock()
198			}
199			continue
200		}
201		if errors.Is(err, os.ErrNotExist) {
202			if _, err := os.Stat(dir); errors.Is(err, os.ErrNotExist) {
203				return "", err
204			}
205		}
206		if err == nil {
207			name = try
208		}
209		break
210	}
211	return
212}
213
214func getTempDir(fs billy.Basic) string {
215	ch, ok := fs.(billy.Chroot)
216	if !ok || ch.Root() == "" || ch.Root() == "/" || ch.Root() == string(filepath.Separator) {
217		return os.TempDir()
218	}
219
220	return ".tmp"
221}
222
223type underlying interface {
224	Underlying() billy.Basic
225}
226
227func getUnderlyingAndPath(fs billy.Basic, path string) (billy.Basic, string) {
228	u, ok := fs.(underlying)
229	if !ok {
230		return fs, path
231	}
232	if ch, ok := fs.(billy.Chroot); ok {
233		path = fs.Join(ch.Root(), path)
234	}
235
236	return u.Underlying(), path
237}
238
239// ReadFile reads the named file and returns the contents from the given filesystem.
240// A successful call returns err == nil, not err == EOF.
241// Because ReadFile reads the whole file, it does not treat an EOF from Read
242// as an error to be reported.
243func ReadFile(fs billy.Basic, name string) ([]byte, error) {
244	f, err := fs.Open(name)
245	if err != nil {
246		return nil, err
247	}
248
249	defer f.Close()
250
251	var size int
252	if info, err := fs.Stat(name); err == nil {
253		size64 := info.Size()
254		if int64(int(size64)) == size64 {
255			size = int(size64)
256		}
257	}
258
259	size++ // one byte for final read at EOF
260	// If a file claims a small size, read at least 512 bytes.
261	// In particular, files in Linux's /proc claim size 0 but
262	// then do not work right if read in small pieces,
263	// so an initial read of 1 byte would not work correctly.
264
265	if size < 512 {
266		size = 512
267	}
268
269	data := make([]byte, 0, size)
270	for {
271		if len(data) >= cap(data) {
272			d := append(data[:cap(data)], 0)
273			data = d[:len(data)]
274		}
275
276		n, err := f.Read(data[len(data):cap(data)])
277		data = data[:len(data)+n]
278
279		if err != nil {
280			if errors.Is(err, io.EOF) {
281				err = nil
282			}
283
284			return data, err
285		}
286	}
287}