Re: [PATCH 2/5] 9pfs: fix qemu_mknodat(S_IFSOCK) on macOS

[Will Cohen]

On Tue, Apr 19, 2022 at 8:18 AM Christian Schoenebeck <qemu_oss@crudebyte.com> wrote:

mknod() on macOS does not support creating sockets, so divert to
call sequence socket(), bind() and chmod() respectively if S_IFSOCK
was passed with mode argument.

Link: https://lore.kernel.org/qemu-devel/17933734.zYzKuhC07K@silver/
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
---
 hw/9pfs/9p-util-darwin.c | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/hw/9pfs/9p-util-darwin.c b/hw/9pfs/9p-util-darwin.c
index 53e0625501..252a6fc5dd 100644
--- a/hw/9pfs/9p-util-darwin.c
+++ b/hw/9pfs/9p-util-darwin.c
@@ -74,6 +74,24 @@ int fsetxattrat_nofollow(int dirfd, const char *filename, const char *name,
  */
 #if defined CONFIG_PTHREAD_FCHDIR_NP

+static int create_socket_file_at_cwd(const char *filename, mode_t mode) {
+    int fd, err;
+    struct sockaddr_un addr = {
+        .sun_family = AF_UNIX
+    };
+
+    fd = socket(PF_UNIX, SOCK_DGRAM, 0);
+    if (fd < 0) {
+        return fd;
+    }
+    snprintf(addr.sun_path, sizeof(addr.sun_path), "./%s", filename);
+    err = bind(fd, (struct sockaddr *) &addr, sizeof(addr));
+    if (err < 0) {
+        return err;
+    }
+    return chmod(addr.sun_path, mode);
+}
+
 int qemu_mknodat(int dirfd, const char *filename, mode_t mode, dev_t dev)
 {
     int preserved_errno, err;
@@ -88,7 +106,11 @@ int qemu_mknodat(int dirfd, const char *filename, mode_t mode, dev_t dev)
     if (pthread_fchdir_np(dirfd) < 0) {
         return -1;
     }
-    err = mknod(filename, mode, dev);
+    if (S_ISSOCK(mode)) {
+        err = create_socket_file_at_cwd(filename, mode);
+    } else {
+        err = mknod(filename, mode, dev);
+    }
     preserved_errno = errno;
     /* Stop using the thread-local cwd */
     pthread_fchdir_np(-1);
--
2.32.0 (Apple Git-132)

Reviewed-by: Will Cohen <wwcohen@gmail.com>