add --module flag

Support a new concept in containers.conf called "modules".  A "module"
is a containers.conf file located at a specific directory.  More than
one module can be loaded in the specified order, following existing
override semantics.

There are three directories to load modules from:
 - $CONFIG_HOME/containers/containers.conf.modules
 - /etc/containers/containers.conf.modules
 - /usr/share/containers/containers.conf.modules

With CONFIG_HOME pointing to $HOME/.config or, if set, $XDG_CONFIG_HOME.
Absolute paths will be loaded as is, relative paths will be resolved
relative to the three directories above allowing for admin configs
(/etc/) to override system configs (/usr/share/) and user configs
($CONFIG_HOME) to override admin configs.

Pulls in containers/common/pull/1599.

Signed-off-by: Valentin Rothberg <vrothberg@redhat.com>

vendor/github.com/pkg/sftp/client.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"encoding/binary"
 	"errors"
+	"fmt"
 	"io"
 	"math"
 	"os"
@@ -226,15 +227,22 @@ func NewClientPipe(rd io.Reader, wr io.WriteCloser, opts ...ClientOption) (*Clie
 
 	if err := sftp.sendInit(); err != nil {
 		wr.Close()
-		return nil, err
+		return nil, fmt.Errorf("error sending init packet to server: %w", err)
 	}
+
 	if err := sftp.recvVersion(); err != nil {
 		wr.Close()
-		return nil, err
+		return nil, fmt.Errorf("error receiving version packet from server: %w", err)
 	}
 
 	sftp.clientConn.wg.Add(1)
-	go sftp.loop()
+	go func() {
+		defer sftp.clientConn.wg.Done()
+
+		if err := sftp.clientConn.recv(); err != nil {
+			sftp.clientConn.broadcastErr(err)
+		}
+	}()
 
 	return sftp, nil
 }
@@ -251,11 +259,11 @@ func (c *Client) Create(path string) (*File, error) {
 	return c.open(path, flags(os.O_RDWR|os.O_CREATE|os.O_TRUNC))
 }
 
-const sftpProtocolVersion = 3 // http://tools.ietf.org/html/draft-ietf-secsh-filexfer-02
+const sftpProtocolVersion = 3 // https://filezilla-project.org/specs/draft-ietf-secsh-filexfer-02.txt
 
 func (c *Client) sendInit() error {
 	return c.clientConn.conn.sendPacket(&sshFxInitPacket{
-		Version: sftpProtocolVersion, // http://tools.ietf.org/html/draft-ietf-secsh-filexfer-02
+		Version: sftpProtocolVersion, // https://filezilla-project.org/specs/draft-ietf-secsh-filexfer-02.txt
 	})
 }
 
@@ -267,8 +275,13 @@ func (c *Client) nextID() uint32 {
 func (c *Client) recvVersion() error {
 	typ, data, err := c.recvPacket(0)
 	if err != nil {
+		if err == io.EOF {
+			return fmt.Errorf("server unexpectedly closed connection: %w", io.ErrUnexpectedEOF)
+		}
+
 		return err
 	}
+
 	if typ != sshFxpVersion {
 		return &unexpectedPacketErr{sshFxpVersion, typ}
 	}
@@ -277,6 +290,7 @@ func (c *Client) recvVersion() error {
 	if err != nil {
 		return err
 	}
+
 	if version != sftpProtocolVersion {
 		return &unexpectedVersionErr{sftpProtocolVersion, version}
 	}
@@ -910,6 +924,45 @@ func (c *Client) MkdirAll(path string) error {
 	return nil
 }
 
+// RemoveAll delete files recursively in the directory and Recursively delete subdirectories.
+// An error will be returned if no file or directory with the specified path exists
+func (c *Client) RemoveAll(path string) error {
+
+	// Get the file/directory information
+	fi, err := c.Stat(path)
+	if err != nil {
+		return err
+	}
+
+	if fi.IsDir() {
+		// Delete files recursively in the directory
+		files, err := c.ReadDir(path)
+		if err != nil {
+			return err
+		}
+
+		for _, file := range files {
+			if file.IsDir() {
+				// Recursively delete subdirectories
+				err = c.RemoveAll(path + "/" + file.Name())
+				if err != nil {
+					return err
+				}
+			} else {
+				// Delete individual files
+				err = c.Remove(path + "/" + file.Name())
+				if err != nil {
+					return err
+				}
+			}
+		}
+
+	}
+
+	return c.Remove(path)
+
+}
+
 // File represents a remote file.
 type File struct {
 	c      *Client
@@ -1660,7 +1713,7 @@ func (f *File) ReadFromWithConcurrency(r io.Reader, concurrency int) (read int64
 					Handle: f.handle,
 					Offset: uint64(off),
 					Length: uint32(n),
-					Data:   b,
+					Data:   b[:n],
 				})
 
 				select {