io/Open: add OpenDirectoryPath()

Author: MaxKellermann

src/io/Open.cxx

@@ -101,6 +101,16 @@ OpenDirectory(FileAt file, int flags)
 	return fd;
 }
 
+UniqueFileDescriptor
+OpenDirectoryPath(FileAt file, int flags)
+{
+	UniqueFileDescriptor fd;
+	if (!fd.Open(file, O_PATH|O_DIRECTORY|flags))
+		throw FmtErrno("Failed to open {:?}", file.name);
+
+	return fd;
+}
+
 #ifdef HAVE_OPENAT2
 
 UniqueFileDescriptor

src/io/Open.hxx

@@ -37,6 +37,14 @@ OpenWriteOnly(FileAt file, int flags=0);
 UniqueFileDescriptor
 OpenDirectory(FileAt file, int flags=0);
 
+/**
+ * Combination of OpenDirectory() and OpenPath() - open a directory as
+ * an O_PATH file descriptor.  Like OpenDirectory(), it will fail with
+ * ENOTDIR if the specified path exists but is not a directory
+ */
+UniqueFileDescriptor
+OpenDirectoryPath(FileAt file, int flags=0);
+
 struct opwn_how;
 
 /**