first commit

LICENSE

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+MIT License
+
+Copyright (c) 2023 Leonid Emar-Kar
+
+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.

README.md

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+# copy
+Simple copy module for go applications, which allows to create copies of files and folders
+
+### Install:
+
+```bash
+go get github.com/emar-kar/copy@latest
+```

copy.go

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+package copy
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"io/fs"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+)
+
+// options allows to configure Copy behavior.
+type options struct {
+	force       bool
+	contentOnly bool
+}
+
+type optFunc func(*options)
+
+// Force re-write destination if it is already exists.
+func Force(o *options) { o.force = true }
+
+// ContentOnly if copy folder and set this flag to true,
+// will copy only source content without creating root folder.
+func ContentOnly(o *options) { o.contentOnly = true }
+
+// Copy copies src to dst with given options.
+func Copy(ctx context.Context, src, dst string, opts ...optFunc) error {
+	opt := &options{}
+	for _, fn := range opts {
+		fn(opt)
+	}
+
+	src, err := evalSymlink(src)
+	if err != nil {
+		return err
+	}
+
+	srcInfo, err := os.Stat(src)
+	if err != nil {
+		return fmt.Errorf("cannot get source information: %w", err)
+	}
+
+	if srcInfo.IsDir() {
+		if !opt.contentOnly {
+			dst = path.Join(dst, path.Base(src))
+		}
+
+		return copyFolder(ctx, src, dst, opt.force)
+	}
+
+	if _, f := path.Split(src); f != path.Base(dst) {
+		if err := os.MkdirAll(dst, srcInfo.Mode()); err != nil {
+			return err
+		}
+
+		dst = path.Join(dst, f)
+	}
+
+	if _, err := os.Stat(dst); !os.IsNotExist(err) || opt.force {
+		return copyFile(ctx, src, dst)
+	}
+
+	return nil
+}
+
+// copyFolder is a support function to copy whole folder.
+func copyFolder(ctx context.Context, src, dst string, force bool) error {
+	return filepath.Walk(
+		src, func(root string, info fs.FileInfo, err error,
+		) error {
+			select {
+			case <-ctx.Done():
+				return ctx.Err()
+			default:
+				if err != nil {
+					return err
+				}
+
+				subDst := strings.ReplaceAll(root, src, dst)
+				if info.IsDir() {
+					if err := os.MkdirAll(subDst, info.Mode()); err != nil {
+						return fmt.Errorf("cannot create sub-folder: %w", err)
+					}
+
+					return nil
+				}
+
+				if _, err := os.Stat(subDst); !os.IsNotExist(err) || force {
+					return copyFile(ctx, root, subDst)
+				}
+
+				return nil
+			}
+		})
+}
+
+// copyFile is a support function to copy file content. Copies with buffer.
+// If context canceled during the copy, dst file will be removed before return.
+func copyFile(ctx context.Context, src, dst string) error {
+	srcF, err := os.Open(src)
+	if err != nil {
+		return err
+	}
+	defer srcF.Close()
+
+	stat, err := os.Stat(src)
+	if err != nil {
+		return err
+	}
+
+	dstF, err := os.OpenFile(
+		dst,
+		os.O_RDWR|os.O_CREATE|os.O_TRUNC,
+		stat.Mode().Perm(),
+	)
+	if err != nil {
+		return err
+	}
+	defer dstF.Close()
+
+	buf := make([]byte, 4096)
+
+	for {
+		select {
+		case <-ctx.Done():
+			if err := os.RemoveAll(dst); err != nil {
+				return fmt.Errorf(
+					"%w: cannot remove dst file: %w", ctx.Err(), err,
+				)
+			}
+
+			return ctx.Err()
+		default:
+			b, err := srcF.Read(buf)
+			if err != nil && err != io.EOF {
+				return err
+			}
+
+			if b == 0 {
+				return nil
+			}
+
+			if _, err := dstF.Write(buf[:b]); err != nil {
+				return err
+			}
+		}
+	}
+}
+
+// evalSymlink returns the path name after the evaluation of any symbolic links.
+// Check [filepath.EvalSymlinks] for details.
+func evalSymlink(p string) (string, error) {
+	info, err := os.Lstat(p)
+	if err != nil {
+		return "", fmt.Errorf("cannot get %s info: %w", p, err)
+	}
+
+	if info.Mode()&os.ModeSymlink == os.ModeSymlink {
+		return filepath.EvalSymlinks(p)
+	}
+
+	return p, nil
+}

go.mod

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+module github.com/emar-kar/copy
+
+go 1.20