syscallcompat: build emulated syscalls under linux, too
This will allow to test them under linux as well.
This commit is contained in:
Jakob Unterwurzacher
parent
614745ee57
commit
bd79a8cd0d
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@ -0,0 +1,193 @@
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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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"golang.org/x/sys/unix"
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)
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var chdirMutex sync.Mutex
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// emulateOpenat emulates the syscall for platforms that don't have it
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// in the kernel (darwin).
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func emulateOpenat(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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// emulateRenameat emulates the syscall for platforms that don't have it
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// in the kernel (darwin).
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func emulateRenameat(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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// emulateUnlinkat emulates the syscall for platforms that don't have it
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// in the kernel (darwin).
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func emulateUnlinkat(dirfd int, path string, flags int) (err error) {
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chdirMutex.Lock()
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defer chdirMutex.Unlock()
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cwd, err := syscall.Open(".", syscall.O_RDONLY, 0)
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if err != nil {
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return err
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}
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defer syscall.Close(cwd)
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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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defer syscall.Fchdir(cwd)
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if (flags & unix.AT_REMOVEDIR) != 0 {
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return syscall.Rmdir(path)
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} else {
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return syscall.Unlink(path)
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}
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}
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// emulateMknodat emulates the syscall for platforms that don't have it
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// in the kernel (darwin).
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func emulateMknodat(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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// emulateFchmodat emulates the syscall for platforms that don't have it
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// in the kernel (darwin).
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func emulateFchmodat(dirfd int, path string, mode uint32, flags int) (err error) {
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chdirMutex.Lock()
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defer chdirMutex.Unlock()
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cwd, err := syscall.Open(".", syscall.O_RDONLY, 0)
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if err != nil {
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return err
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}
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defer syscall.Close(cwd)
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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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defer syscall.Fchdir(cwd)
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return syscall.Chmod(path, mode)
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}
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// emulateFchownat emulates the syscall for platforms that don't have it
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// in the kernel (darwin).
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func emulateFchownat(dirfd int, path string, uid int, gid int, flags int) (err error) {
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chdirMutex.Lock()
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defer chdirMutex.Unlock()
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cwd, err := syscall.Open(".", syscall.O_RDONLY, 0)
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if err != nil {
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return err
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}
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defer syscall.Close(cwd)
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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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defer syscall.Fchdir(cwd)
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return syscall.Lchown(path, uid, gid)
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}
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// emulateSymlinkat emulates the syscall for platforms that don't have it
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// in the kernel (darwin).
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func emulateSymlinkat(oldpath string, newdirfd int, newpath string) (err error) {
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chdirMutex.Lock()
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defer chdirMutex.Unlock()
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cwd, err := syscall.Open(".", syscall.O_RDONLY, 0)
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if err != nil {
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return err
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}
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defer syscall.Close(cwd)
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err = syscall.Fchdir(newdirfd)
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if err != nil {
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return err
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}
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defer syscall.Fchdir(cwd)
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return syscall.Symlink(oldpath, newpath)
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}
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// emulateMkdirat emulates the syscall for platforms that don't have it
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// in the kernel (darwin).
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func emulateMkdirat(dirfd int, path string, mode uint32) (err error) {
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chdirMutex.Lock()
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defer chdirMutex.Unlock()
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cwd, err := syscall.Open(".", syscall.O_RDONLY, 0)
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if err != nil {
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return err
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}
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defer syscall.Close(cwd)
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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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defer syscall.Fchdir(cwd)
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return syscall.Mkdir(path, mode)
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}
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@ -2,12 +2,7 @@ package syscallcompat
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import (
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"log"
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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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"golang.org/x/sys/unix"
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)
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// Sorry, fallocate is not available on OSX at all and
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@ -22,113 +17,6 @@ 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, flags int) (err error) {
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chdirMutex.Lock()
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defer chdirMutex.Unlock()
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cwd, err := syscall.Open(".", syscall.O_RDONLY, 0)
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if err != nil {
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return err
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}
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defer syscall.Close(cwd)
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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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defer syscall.Fchdir(cwd)
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if (flags & unix.AT_REMOVEDIR) != 0 {
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return syscall.Rmdir(path)
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} else {
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return syscall.Unlink(path)
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}
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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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// Dup3 is not available on Darwin, so we use Dup2 instead.
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func Dup3(oldfd int, newfd int, flags int) (err error) {
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if flags != 0 {
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@ -137,70 +25,38 @@ func Dup3(oldfd int, newfd int, flags int) (err error) {
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return syscall.Dup2(oldfd, newfd)
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}
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// Poor man's Fchmodat.
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////////////////////////////////////////////////////////
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//// Emulated Syscalls (see emulate.go) ////////////////
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////////////////////////////////////////////////////////
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func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error) {
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return emulateOpenat(dirfd, path, flags, mode)
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}
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func Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) (err error) {
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return emulateRenameat(olddirfd, oldpath, newdirfd, newpath)
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}
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func Unlinkat(dirfd int, path string, flags int) (err error) {
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return emulateUnlinkat(dirfd, path, flags)
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}
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func Mknodat(dirfd int, path string, mode uint32, dev int) (err error) {
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return emulateMknodat(dirfd, path, mode, dev)
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}
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func Fchmodat(dirfd int, path string, mode uint32, flags int) (err error) {
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chdirMutex.Lock()
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defer chdirMutex.Unlock()
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cwd, err := syscall.Open(".", syscall.O_RDONLY, 0)
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if err != nil {
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return err
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}
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defer syscall.Close(cwd)
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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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defer syscall.Fchdir(cwd)
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return syscall.Chmod(path, mode)
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return emulateFchmodat(dirfd, path, mode, flags)
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}
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// Poor man's Fchownat.
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func Fchownat(dirfd int, path string, uid int, gid int, flags int) (err error) {
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chdirMutex.Lock()
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defer chdirMutex.Unlock()
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cwd, err := syscall.Open(".", syscall.O_RDONLY, 0)
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if err != nil {
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return err
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}
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defer syscall.Close(cwd)
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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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defer syscall.Fchdir(cwd)
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return syscall.Lchown(path, uid, gid)
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return emulateFchownat(dirfd, path, uid, gid, flags)
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}
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// Poor man's Symlinkat.
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func Symlinkat(oldpath string, newdirfd int, newpath string) (err error) {
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chdirMutex.Lock()
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defer chdirMutex.Unlock()
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cwd, err := syscall.Open(".", syscall.O_RDONLY, 0)
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if err != nil {
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return err
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}
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defer syscall.Close(cwd)
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err = syscall.Fchdir(newdirfd)
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if err != nil {
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return err
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}
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defer syscall.Fchdir(cwd)
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return syscall.Symlink(oldpath, newpath)
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return emulateSymlinkat(oldpath, newdirfd, newpath)
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}
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// Poor man's Mkdirat.
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func Mkdirat(dirfd int, path string, mode uint32) (err error) {
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chdirMutex.Lock()
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defer chdirMutex.Unlock()
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cwd, err := syscall.Open(".", syscall.O_RDONLY, 0)
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if err != nil {
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return err
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}
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defer syscall.Close(cwd)
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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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defer syscall.Fchdir(cwd)
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return syscall.Mkdir(path, mode)
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return emulateMkdirat(dirfd, path, mode)
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}
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