125 lines
2.8 KiB
Go
125 lines
2.8 KiB
Go
package syscallcompat
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import (
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"os"
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"path/filepath"
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"sync"
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"syscall"
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)
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// Sorry, fallocate is not available on OSX at all and
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// fcntl F_PREALLOCATE is not accessible from Go.
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// See https://github.com/rfjakob/gocryptfs/issues/18 if you want to help.
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func EnospcPrealloc(fd int, off int64, len int64) error {
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return nil
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}
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// See above.
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func Fallocate(fd int, mode uint32, off int64, len int64) error {
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return syscall.EOPNOTSUPP
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}
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var chdirMutex sync.Mutex
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// Poor man's Openat
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func Openat(dirfd int, path string, flags int, mode uint32) (int, error) {
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chdirMutex.Lock()
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defer chdirMutex.Unlock()
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if !filepath.IsAbs(path) {
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// Save the old working directory
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oldWd, err := os.Getwd()
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if err != nil {
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return -1, err
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}
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// Chdir to target directory
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err = syscall.Fchdir(dirfd)
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if err != nil {
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return -1, err
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}
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// Chdir back at the end
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defer os.Chdir(oldWd)
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}
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return syscall.Open(path, flags, mode)
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}
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// Poor man's Renameat
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func Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) error {
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chdirMutex.Lock()
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defer chdirMutex.Unlock()
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// Unless both paths are absolute we have to save the old working dir and
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// Chdir(oldWd) back to it in the end. If we error out before the first
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// chdir, Chdir(oldWd) is unneccassary but does no harm.
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if !filepath.IsAbs(oldpath) || !filepath.IsAbs(newpath) {
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oldWd, err := os.Getwd()
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if err != nil {
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return err
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}
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defer os.Chdir(oldWd)
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}
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// Make oldpath absolute
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oldpath, err := dirfdAbs(olddirfd, oldpath)
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if err != nil {
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return err
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}
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// Make newpath absolute
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newpath, err = dirfdAbs(newdirfd, newpath)
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if err != nil {
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return err
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}
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return syscall.Rename(oldpath, newpath)
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}
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// Poor man's Unlinkat
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func Unlinkat(dirfd int, path string) error {
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chdirMutex.Lock()
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defer chdirMutex.Unlock()
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if !filepath.IsAbs(path) {
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oldWd, err := os.Getwd()
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if err != nil {
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return err
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}
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defer os.Chdir(oldWd)
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}
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path, err := dirfdAbs(dirfd, path)
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if err != nil {
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return err
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}
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return syscall.Unlink(path)
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}
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// Poor man's Mknodat
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func Mknodat(dirfd int, path string, mode uint32, dev int) error {
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chdirMutex.Lock()
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defer chdirMutex.Unlock()
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if !filepath.IsAbs(path) {
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oldWd, err := os.Getwd()
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if err != nil {
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return err
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}
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defer os.Chdir(oldWd)
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}
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path, err := dirfdAbs(dirfd, path)
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if err != nil {
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return err
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}
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return syscall.Mknod(path, mode, dev)
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}
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// dirfdAbs transforms the dirfd-relative "path" to an absolute one. If the
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// path is not already absolute, this function will change the working
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// directory. The caller has to chdir back.
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func dirfdAbs(dirfd int, path string) (string, error) {
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if filepath.IsAbs(path) {
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return path, nil
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}
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err := syscall.Fchdir(dirfd)
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if err != nil {
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return "", err
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}
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wd, err := os.Getwd()
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if err != nil {
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return "", err
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}
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return filepath.Join(wd, path), nil
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}
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