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scattered.go
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scattered.go
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package scattered
import (
"crypto/md5"
"errors"
"fmt"
"io"
"os"
"path/filepath"
"regexp"
)
// HashReader reads the provided io.Reader and returns its MD5 hash as a string or an error.
func HashReader(r io.Reader) (string, error) {
h := md5.New()
_, err := io.Copy(h, r)
if err != nil {
return "", err
}
return fmt.Sprintf("%x", h.Sum(nil)), nil
}
// ErrIsDir is returned by HashPath when attempting to hash a directory
var ErrIsDir = errors.New("Tried to hash the path of a directory")
// HashPath opens the file at the provided filepath and returns a
// string containing the file's hash as part of its filename
func HashPath(path string) (string, error) {
f, err := os.Open(path)
if err != nil {
return "", err
}
defer f.Close()
if stat, err := f.Stat(); err != nil {
return "", err
} else if stat.IsDir() {
return "", ErrIsDir
}
hash, err := HashReader(f)
if err != nil {
return "", err
}
basename, ext := splitName(path)
return fmt.Sprintf("%s.%s%s", basename, hash, ext), nil
}
// IsHashedPath returns true if a filepath matches the
// pattern path/name.HASH.ext, where HASH is an MD5 hash.
func IsHashedPath(path string) bool {
basename, _ := splitName(path)
innerExt := filepath.Ext(basename)
return len(innerExt) == (md5.Size*2)+1
}
func splitName(path string) (basename, ext string) {
ext = filepath.Ext(path)
basename = path[:len(path)-len(ext)]
return
}
// HashFileGlobs returns a map from filepaths to their HashPath equivalent for
// all files whoses parents match the dirpat regex and themselves match one
// of the filepat globs.
func HashFileGlobs(basepath, dirpat string, filepats ...string) (map[string]string, error) {
paths, err := getPaths(basepath, dirpat, filepats...)
if err != nil {
return nil, err
}
var pathsMap = map[string]string{}
for _, src := range paths {
dst, err := HashPath(src)
if err == ErrIsDir {
continue
}
if err != nil {
return nil, err
}
src, _ = filepath.Rel(basepath, src)
dst, _ = filepath.Rel(basepath, dst)
pathsMap[src] = dst
}
return pathsMap, nil
}
func getPaths(basepath, recpat string, globs ...string) (paths []string, err error) {
regex, err := regexp.Compile(recpat)
if err != nil {
return nil, err
}
err = filepath.Walk(basepath, func(path string, info os.FileInfo, err error) error {
if err != nil {
return err
}
finaldir, err := filepath.Rel(basepath, path)
finaldir = filepath.Base(filepath.Dir(finaldir))
if err != nil {
return err
}
if !regex.MatchString(finaldir) && finaldir != "." {
return filepath.SkipDir
}
if info.IsDir() {
return nil
}
for _, glob := range globs {
if matched, err := filepath.Match(glob, filepath.Base(path)); err != nil {
return err
} else if matched && !IsHashedPath(path) {
paths = append(paths, path)
}
}
return nil
})
return paths, err
}
// Link creates hardlinks for the mapped resources.
func Link(srcBase, destBase string, paths map[string]string) (err error) {
for src, dst := range paths {
src = filepath.Join(srcBase, src)
dst = filepath.Join(destBase, dst)
// Make containing directory if it doesn't already exist
_ = os.MkdirAll(filepath.Dir(dst), 0777)
_, err := os.Stat(dst)
if !os.IsNotExist(err) {
return err
} else if err == nil {
if err = os.Remove(dst); err != nil {
return err
}
}
if err = os.Link(src, dst); err != nil {
return err
}
}
return nil
}
// Copy creates copies of the mapped resources.
func Copy(srcBase, dstBase string, paths map[string]string) (err error) {
for src, dst := range paths {
src = filepath.Join(srcBase, src)
dst = filepath.Join(dstBase, dst)
// Make containing directory if it doesn't already exist
_ = os.MkdirAll(filepath.Dir(dst), 0777)
if err := copy(src, dst); err != nil {
return err
}
}
return nil
}
func copy(src, dst string) error {
fsrc, err := os.Open(src)
if err != nil {
return err
}
fdst, err := os.Create(dst)
if err != nil {
return err
}
_, err = io.Copy(fdst, fsrc)
return err
}