syscallcompat: Introduce unlinkat syscall with flags argument

2 files changed, 27 insertions, 12 deletions

diff --git a/internal/syscallcompat/sys_darwin.go b/internal/syscallcompat/sys_darwin.go
index 4068e1a..527598b 100644
--- a/internal/syscallcompat/sys_darwin.go
+++ b/internal/syscallcompat/sys_darwin.go
@@ -6,6 +6,8 @@ import (
 	"path/filepath"
 	"sync"
 	"syscall"
+
+	"golang.org/x/sys/unix"
 )
 
 // Sorry, fallocate is not available on OSX at all and
@@ -71,21 +73,24 @@ func Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) error
 }
 
 // Poor man's Unlinkat
-func Unlinkat(dirfd int, path string) error {
+func Unlinkat(dirfd int, path string, flags int) (err error) {
 	chdirMutex.Lock()
 	defer chdirMutex.Unlock()
-	if !filepath.IsAbs(path) {
-		oldWd, err := os.Getwd()
-		if err != nil {
-			return err
-		}
-		defer os.Chdir(oldWd)
+	cwd, err := syscall.Open(".", syscall.O_RDONLY, 0)
+	if err != nil {
+		return err
 	}
-	path, err := dirfdAbs(dirfd, path)
+	defer syscall.Close(cwd)
+	err = syscall.Fchdir(dirfd)
 	if err != nil {
 		return err
 	}
-	return syscall.Unlink(path)
+	defer syscall.Fchdir(cwd)
+	if (flags & unix.AT_REMOVEDIR) != 0 {
+		return syscall.Rmdir(path)
+	} else {
+		return syscall.Unlink(path)
+	}
 }
 
 // Poor man's Mknodat
diff --git a/internal/syscallcompat/sys_linux.go b/internal/syscallcompat/sys_linux.go
index 277015e..0e9d6ac 100644
--- a/internal/syscallcompat/sys_linux.go
+++ b/internal/syscallcompat/sys_linux.go
@@ -54,9 +54,19 @@ func Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) (err e
 	return syscall.Renameat(olddirfd, oldpath, newdirfd, newpath)
 }
 
-// Unlinkat wraps the Unlinkat syscall.
-func Unlinkat(dirfd int, path string) error {
-	return syscall.Unlinkat(dirfd, path)
+// Unlinkat syscall. In old versions the 'flags' argument was missing, so
+// manually call it by using the corresponding syscall number.
+func Unlinkat(dirfd int, path string, flags int) (err error) {
+	var _p0 *byte
+	_p0, err = syscall.BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	_, _, e1 := syscall.Syscall(syscall.SYS_UNLINKAT, uintptr(dirfd), uintptr(unsafe.Pointer(_p0)), uintptr(flags))
+	if e1 != 0 {
+		err = e1
+	}
+	return
 }
 
 // Mknodat wraps the Mknodat syscall.