smbd: Refactor reopen_from_fsp(), factor out automounter mountpoint check

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15805

Signed-off-by: Samuel Cabrero <scabrero@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>

diff --git a/source3/smbd/open.c b/source3/smbd/open.c
index 9751aba0c527515b6e6cc2ba4e5bcd3295c21ec1..081b85c80ec75b7bf79258a295506ca23f658df1 100644 (file)
--- a/source3/smbd/open.c
+++ b/source3/smbd/open.c
@@ -872,6 +872,30 @@ static NTSTATUS reopen_from_fsp_namebased(struct files_struct *dirfsp,
        return status;
 }
 
+static bool fsp_is_automount_mountpoint(struct files_struct *fsp, int old_fd)
+{
+#if defined(HAVE_FSTATFS) && defined(HAVE_LINUX_MAGIC_H)
+       struct statfs sbuf = {};
+       int ret;
+
+       if (!S_ISDIR(fsp->fsp_name->st.st_ex_mode)) {
+               return false;
+       }
+
+       ret = fstatfs(old_fd, &sbuf);
+       if (ret == -1) {
+               DBG_ERR("fstatfs failed: %s\n", strerror(errno));
+               return false;
+       }
+       if (sbuf.f_type == AUTOFS_SUPER_MAGIC) {
+               return true;
+       }
+       return false;
+#else
+       return false;
+#endif
+}
+
 NTSTATUS reopen_from_fsp(struct files_struct *dirfsp,
                         struct smb_filename *smb_fname,
                         struct files_struct *fsp,
@@ -906,33 +930,23 @@ NTSTATUS reopen_from_fsp(struct files_struct *dirfsp,
                                        fsp,
                                        how);
                if (new_fd == -1) {
-#if defined(HAVE_FSTATFS) && defined(HAVE_LINUX_MAGIC_H)
-                       if (S_ISDIR(fsp->fsp_name->st.st_ex_mode) &&
-                           (errno == ENOENT)) {
-                               struct statfs sbuf = {};
-                               int ret = fstatfs(old_fd, &sbuf);
-                               if (ret == -1) {
-                                       DBG_ERR("fstatfs failed: %s\n",
-                                               strerror(errno));
-                               } else if (sbuf.f_type == AUTOFS_SUPER_MAGIC) {
-                                       /*
-                                        * When reopening an as-yet
-                                        * unmounted autofs mount
-                                        * point we get ENOENT. We
-                                        * have to retry pathbased.
-                                        */
-                                       return reopen_from_fsp_namebased(dirfsp,
-                                                                        smb_fname,
-                                                                        fsp,
-                                                                        how,
-                                                                        p_file_created);
-
-                               }
-                               /* restore ENOENT if changed in the meantime */
-                               errno = ENOENT;
+                       int saved_errno = errno;
+                       if (saved_errno == ENOENT &&
+                           fsp_is_automount_mountpoint(fsp, old_fd))
+                       {
+                               /*
+                                * When reopening an as-yet unmounted autofs
+                                * mount point we get ENOENT. We have to retry
+                                * pathbased.
+                                */
+                               return reopen_from_fsp_namebased(dirfsp,
+                                                                smb_fname,
+                                                                fsp,
+                                                                how,
+                                                                p_file_created);
                        }
-#endif
-                       status = map_nt_error_from_unix(errno);
+
+                       status = map_nt_error_from_unix(saved_errno);
                        fd_close(fsp);
                        return status;
                }