dev: add doc about internal package extracted from Go (#3204)

Author: ldez

.golangci.yml

@@ -138,9 +138,8 @@ issues:
 
 run:
   timeout: 5m
-  go: '1.17' # TODO(ldez): we force to use an old version of Go for the CI and the tests.
   skip-dirs:
-    - test/testdata_etc
-    - internal/cache
-    - internal/renameio
-    - internal/robustio
+    - test/testdata_etc # test files
+    - internal/cache # extracted from Go code
+    - internal/renameio # extracted from Go code
+    - internal/robustio # extracted from Go code

internal/cache/cache.go

@@ -51,7 +51,6 @@ type Cache struct {
 // to share a cache directory (for example, if the directory were stored
 // in a network file system). File locking is notoriously unreliable in
 // network file systems and may not suffice to protect the cache.
-//
 func Open(dir string) (*Cache, error) {
 	info, err := os.Stat(dir)
 	if err != nil {
@@ -159,7 +158,7 @@ func (c *Cache) get(id ActionID) (Entry, error) {
 	defer f.Close()
 	entry := make([]byte, entrySize+1) // +1 to detect whether f is too long
 	if n, readErr := io.ReadFull(f, entry); n != entrySize || readErr != io.ErrUnexpectedEOF {
-		return failed(fmt.Errorf("read %d/%d bytes from %s with error %s", n, entrySize, fileName, readErr))
+		return failed(fmt.Errorf("read %d/%d bytes from %s with error %w", n, entrySize, fileName, readErr))
 	}
 	if entry[0] != 'v' || entry[1] != '1' || entry[2] != ' ' || entry[3+hexSize] != ' ' || entry[3+hexSize+1+hexSize] != ' ' || entry[3+hexSize+1+hexSize+1+20] != ' ' || entry[entrySize-1] != '\n' {
 		return failed(fmt.Errorf("bad data in %s", fileName))
@@ -181,15 +180,15 @@ func (c *Cache) get(id ActionID) (Entry, error) {
 	}
 	size, err := strconv.ParseInt(string(esize[i:]), 10, 64)
 	if err != nil || size < 0 {
-		return failed(fmt.Errorf("failed to parse esize int from %s with error %s", fileName, err))
+		return failed(fmt.Errorf("failed to parse esize int from %s with error %w", fileName, err))
 	}
 	i = 0
 	for i < len(etime) && etime[i] == ' ' {
 		i++
 	}
 	tm, err := strconv.ParseInt(string(etime[i:]), 10, 64)
 	if err != nil || tm < 0 {
-		return failed(fmt.Errorf("failed to parse etime int from %s with error %s", fileName, err))
+		return failed(fmt.Errorf("failed to parse etime int from %s with error %w", fileName, err))
 	}
 
 	if err = c.used(fileName); err != nil {
@@ -498,7 +497,7 @@ func (c *Cache) copyFile(file io.ReadSeeker, out OutputID, size int64) error {
 		return err
 	}
 	if n, wErr := h.Write(buf); n != len(buf) {
-		return fmt.Errorf("wrote to hash %d/%d bytes with error %s", n, len(buf), wErr)
+		return fmt.Errorf("wrote to hash %d/%d bytes with error %w", n, len(buf), wErr)
 	}
 
 	sum := h.Sum(nil)

internal/cache/readme.md

@@ -0,0 +1,18 @@
+# cache
+
+Extracted from go/src/cmd/go/internal/cache/
+I don't know what version of Go this package was pulled from.
+
+Adapted for golangci-lint:
+- https://github.com/golangci/golangci-lint/pull/699
+- https://github.com/golangci/golangci-lint/pull/779
+- https://github.com/golangci/golangci-lint/pull/788
+- https://github.com/golangci/golangci-lint/pull/808
+- https://github.com/golangci/golangci-lint/pull/1063
+- https://github.com/golangci/golangci-lint/pull/1070
+- https://github.com/golangci/golangci-lint/pull/1162
+- https://github.com/golangci/golangci-lint/pull/2318
+- https://github.com/golangci/golangci-lint/pull/2352
+- https://github.com/golangci/golangci-lint/pull/3012
+- https://github.com/golangci/golangci-lint/pull/3096
+- https://github.com/golangci/golangci-lint/pull/3204

internal/renameio/readme.md

@@ -0,0 +1,10 @@
+# renameio
+
+Extracted from go/src/cmd/go/internal/renameio/
+I don't know what version of Go this package was pulled from.
+
+Adapted for golangci-lint:
+- https://github.com/golangci/golangci-lint/pull/699
+- https://github.com/golangci/golangci-lint/pull/808
+- https://github.com/golangci/golangci-lint/pull/1063
+- https://github.com/golangci/golangci-lint/pull/3204

internal/renameio/umask_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !plan9,!windows,!js
+//go:build !plan9 && !windows && !js
 
 package renameio
 

internal/robustio/readme.md

@@ -0,0 +1,6 @@
+# robustio
+
+Extracted from go1.19.1/src/cmd/go/internal/robustio
+
+There is only one modification:
+- ERROR_SHARING_VIOLATION extracted from go1.19.1/src/internal/syscall/windows/syscall_windows.go to remove the dependencies to `internal/syscall/windows`

internal/robustio/robustio.go

@@ -42,9 +42,9 @@ func RemoveAll(path string) error {
 // in this package attempt to mitigate.
 //
 // Errors considered ephemeral include:
-// 	- syscall.ERROR_ACCESS_DENIED
-// 	- syscall.ERROR_FILE_NOT_FOUND
-// 	- internal/syscall/windows.ERROR_SHARING_VIOLATION
+//   - syscall.ERROR_ACCESS_DENIED
+//   - syscall.ERROR_FILE_NOT_FOUND
+//   - internal/syscall/windows.ERROR_SHARING_VIOLATION
 //
 // This set may be expanded in the future; programs must not rely on the
 // non-ephemerality of any given error.

internal/robustio/robustio_darwin.go

@@ -5,24 +5,16 @@
 package robustio
 
 import (
-	"os"
+	"errors"
 	"syscall"
 )
 
 const errFileNotFound = syscall.ENOENT
 
 // isEphemeralError returns true if err may be resolved by waiting.
 func isEphemeralError(err error) bool {
-	switch werr := err.(type) {
-	case *os.PathError:
-		err = werr.Err
-	case *os.LinkError:
-		err = werr.Err
-	case *os.SyscallError:
-		err = werr.Err
-
-	}
-	if errno, ok := err.(syscall.Errno); ok {
+	var errno syscall.Errno
+	if errors.As(err, &errno) {
 		return errno == errFileNotFound
 	}
 	return false

internal/robustio/robustio_flaky.go

@@ -2,20 +2,19 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build windows darwin
+//go:build windows || darwin
 
 package robustio
 
 import (
+	"errors"
 	"math/rand"
 	"os"
 	"syscall"
 	"time"
 )
 
-const arbitraryTimeout = 500 * time.Millisecond
-
-const ERROR_SHARING_VIOLATION = 32
+const arbitraryTimeout = 2000 * time.Millisecond
 
 // retry retries ephemeral errors from f up to an arbitrary timeout
 // to work around filesystem flakiness on Windows and Darwin.
@@ -32,7 +31,8 @@ func retry(f func() (err error, mayRetry bool)) error {
 			return err
 		}
 
-		if errno, ok := err.(syscall.Errno); ok && (lowestErrno == 0 || errno < lowestErrno) {
+		var errno syscall.Errno
+		if errors.As(err, &errno) && (lowestErrno == 0 || errno < lowestErrno) {
 			bestErr = err
 			lowestErrno = errno
 		} else if bestErr == nil {
@@ -78,8 +78,7 @@ func readFile(filename string) ([]byte, error) {
 		// Unlike in rename, we do not retry errFileNotFound here: it can occur
 		// as a spurious error, but the file may also genuinely not exist, so the
 		// increase in robustness is probably not worth the extra latency.
-
-		return err, isEphemeralError(err) && err != errFileNotFound
+		return err, isEphemeralError(err) && !errors.Is(err, errFileNotFound)
 	})
 	return b, err
 }

internal/robustio/robustio_other.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//+build !windows,!darwin
+//go:build !windows && !darwin
 
 package robustio