Fix compatibility issue around fuse_custom_io->clone_fd (#953)

Fixes: 73cd124d0408 ("Add clone_fd to custom IO (#927)")

Signed-off-by: Xiaoguang Wang <lege.wang@jaguarmicro.com>

1 files changed, 20 insertions, 4 deletions

diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index 1f3a5fa..dc1b7a6 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -3190,9 +3190,15 @@ struct fuse_session *fuse_session_new_30(struct fuse_args *args,
 	return _fuse_session_new_317(args, op, op_size, &version, userdata);
 }
 
-int fuse_session_custom_io(struct fuse_session *se, const struct fuse_custom_io *io,
-			   int fd)
+FUSE_SYMVER("fuse_session_custom_io_317", "fuse_session_custom_io@@FUSE_3.17")
+int fuse_session_custom_io_317(struct fuse_session *se,
+				const struct fuse_custom_io *io, size_t op_size, int fd)
 {
+	if (sizeof(struct fuse_custom_io) < op_size) {
+		fuse_log(FUSE_LOG_ERR, "fuse: warning: library too old, some operations may not work\n");
+		op_size = sizeof(struct fuse_custom_io);
+	}
+
 	if (fd < 0) {
 		fuse_log(FUSE_LOG_ERR, "Invalid file descriptor value %d passed to "
 			"fuse_session_custom_io()\n", fd);
@@ -3212,7 +3218,7 @@ int fuse_session_custom_io(struct fuse_session *se, const struct fuse_custom_io
 		return -EINVAL;
 	}
 
-	se->io = malloc(sizeof(struct fuse_custom_io));
+	se->io = calloc(1, sizeof(struct fuse_custom_io));
 	if (se->io == NULL) {
 		fuse_log(FUSE_LOG_ERR, "Failed to allocate memory for custom io. "
 			"Error: %s\n", strerror(errno));
@@ -3220,10 +3226,20 @@ int fuse_session_custom_io(struct fuse_session *se, const struct fuse_custom_io
 	}
 
 	se->fd = fd;
-	*se->io = *io;
+	memcpy(se->io, io, op_size);
 	return 0;
 }
 
+int fuse_session_custom_io_30(struct fuse_session *se,
+			const struct fuse_custom_io *io, int fd);
+FUSE_SYMVER("fuse_session_custom_io_30", "fuse_session_custom_io@FUSE_3.0")
+int fuse_session_custom_io_30(struct fuse_session *se,
+			const struct fuse_custom_io *io, int fd)
+{
+	return fuse_session_custom_io_317(se, io,
+			offsetof(struct fuse_custom_io, clone_fd), fd);
+}
+
 int fuse_session_mount(struct fuse_session *se, const char *mountpoint)
 {
 	int fd;