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folder.go
77 lines (62 loc) · 1.39 KB
/
folder.go
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package folder
import (
"bufio"
"bytes"
"io"
"github.com/bobg/uncompress/v2"
"github.com/bobg/folder/v3/maildir"
"github.com/bobg/folder/v3/mbox"
"github.com/bobg/folder/v3/tar"
)
// Folder allows reading messages one by one.
type Folder interface {
// Message returns an io.ReadCloser for the next message in the folder.
// After the last message,
// Message returns a nil ReadCloser.
// After calling Message,
// it is an error to call it again before first closing the ReadCloser.
Message() (io.ReadCloser, error)
// Close releases resources held by the folder.
Close() error
}
// Open opens the given pathname as a mail folder if possible,
// trying one type after another and uncompressing on the fly if needed.
func Open(name string) (Folder, error) {
m, err := maildir.New(name)
if err == nil {
return m, nil
}
r, err := uncompress.Open(name)
if err != nil {
return nil, err
}
defer func() {
if err != nil {
r.Close()
}
}()
b := bufio.NewReader(r)
from, err := b.Peek(5)
if err != nil {
return nil, err
}
rc := &readCloser{
b: b,
r: r,
}
if bytes.Equal(from, []byte("From ")) {
m, err := mbox.New(rc)
return m, err
}
return tar.New(rc), nil
}
type readCloser struct {
b *bufio.Reader
r io.ReadCloser
}
func (rc *readCloser) Read(buf []byte) (int, error) {
return rc.b.Read(buf)
}
func (rc *readCloser) Close() error {
return rc.r.Close()
}