Revert "os: add support for long path names on unix RemoveAll"

This reverts commit 85143d3.

Reason for revert: Breaking all Darwin and FreeBSD builds. Trybots did not pass for this.

Change-Id: I5494e14ad5ab9cf6e1e225a25b2e8b38f3359d13
Reviewed-on: https://go-review.googlesource.com/c/145897
Reviewed-by: Katie Hockman <[email protected]>
Run-TryBot: Katie Hockman <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>

Author: katiehockman

src/internal/syscall/unix/at.go

@@ -5,6 +5,7 @@
 package os
 
 import (
+	"io"
 	"syscall"
 )
 
@@ -57,3 +58,101 @@ func MkdirAll(path string, perm FileMode) error {
 	}
 	return nil
 }
+
+// RemoveAll removes path and any children it contains.
+// It removes everything it can but returns the first error
+// it encounters. If the path does not exist, RemoveAll
+// returns nil (no error).
+func RemoveAll(path string) error {
+	// Simple case: if Remove works, we're done.
+	err := Remove(path)
+	if err == nil || IsNotExist(err) {
+		return nil
+	}
+
+	// Otherwise, is this a directory we need to recurse into?
+	dir, serr := Lstat(path)
+	if serr != nil {
+		if serr, ok := serr.(*PathError); ok && (IsNotExist(serr.Err) || serr.Err == syscall.ENOTDIR) {
+			return nil
+		}
+		return serr
+	}
+	if !dir.IsDir() {
+		// Not a directory; return the error from Remove.
+		return err
+	}
+
+	// Remove contents & return first error.
+	err = nil
+	for {
+		fd, err := Open(path)
+		if err != nil {
+			if IsNotExist(err) {
+				// Already deleted by someone else.
+				return nil
+			}
+			return err
+		}
+
+		const request = 1024
+		names, err1 := fd.Readdirnames(request)
+
+		// Removing files from the directory may have caused
+		// the OS to reshuffle it. Simply calling Readdirnames
+		// again may skip some entries. The only reliable way
+		// to avoid this is to close and re-open the
+		// directory. See issue 20841.
+		fd.Close()
+
+		for _, name := range names {
+			err1 := RemoveAll(path + string(PathSeparator) + name)
+			if err == nil {
+				err = err1
+			}
+		}
+
+		if err1 == io.EOF {
+			break
+		}
+		// If Readdirnames returned an error, use it.
+		if err == nil {
+			err = err1
+		}
+		if len(names) == 0 {
+			break
+		}
+
+		// We don't want to re-open unnecessarily, so if we
+		// got fewer than request names from Readdirnames, try
+		// simply removing the directory now. If that
+		// succeeds, we are done.
+		if len(names) < request {
+			err1 := Remove(path)
+			if err1 == nil || IsNotExist(err1) {
+				return nil
+			}
+
+			if err != nil {
+				// We got some error removing the
+				// directory contents, and since we
+				// read fewer names than we requested
+				// there probably aren't more files to
+				// remove. Don't loop around to read
+				// the directory again. We'll probably
+				// just get the same error.
+				return err
+			}
+		}
+	}
+
+	// Remove directory.
+	err1 := Remove(path)
+	if err1 == nil || IsNotExist(err1) {
+		return nil
+	}
+	if err == nil {
+		err = err1
+	}
+	return err
+}