sascha-andres/go-template

/* MIT License
 *
 * Copyright (c) 2017 Roland Singer [roland.singer@desertbit.com]
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package engine

import (
    "fmt"
    "io"
    "io/ioutil"
    "os"
    "path/filepath"
)

// CopyFile copies the contents of the file named src to the file named
// by dst. The file will be created if it does not already exist. If the
// destination file exists, all it's contents will be replaced by the contents
// of the source file. The file mode will be copied from the source and
// the copied data is synced/flushed to stable storage.
func copyFile(src, dst string) (err error) {
    in, err := os.Open(src)
    if err != nil {
        return
    }
    defer in.Close()

    out, err := os.Create(dst)
    if err != nil {
        return
    }
    defer func() {
        if e := out.Close(); e != nil {
            err = e
        }
    }()

    _, err = io.Copy(out, in)
    if err != nil {
        return
    }

    err = out.Sync()
    if err != nil {
        return
    }

    si, err := os.Stat(src)
    if err != nil {
        return
    }
    err = os.Chmod(dst, si.Mode())
    if err != nil {
        return
    }

    return
}

// CopyDir recursively copies a directory tree, attempting to preserve permissions.
// Source directory must exist, destination directory must *not* exist.
// Symlinks are ignored and skipped.
func copyDir(src string, dst string) (err error) {
    src = filepath.Clean(src)
    dst = filepath.Clean(dst)

    si, err := os.Stat(src)
    if err != nil {
        return err
    }
    if !si.IsDir() {
        return fmt.Errorf("source is not a directory")
    }

    _, err = os.Stat(dst)
    if err != nil && !os.IsNotExist(err) {
        return
    }
    if err == nil {
        return fmt.Errorf("destination already exists")
    }

    err = os.MkdirAll(dst, si.Mode())
    if err != nil {
        return
    }

    entries, err := ioutil.ReadDir(src)
    if err != nil {
        return
    }

    for _, entry := range entries {
        srcPath := filepath.Join(src, entry.Name())
        dstPath := filepath.Join(dst, entry.Name())

        if entry.IsDir() {
            err = copyDir(srcPath, dstPath)
            if err != nil {
                return
            }
        } else {
            // Skip symlinks.
            if entry.Mode()&os.ModeSymlink != 0 {
                continue
            }

            err = copyFile(srcPath, dstPath)
            if err != nil {
                return
            }
        }
    }

    return
}