9p: darwin: Handle struct dirent differences

On darwin d_seekoff exists, but is optional and does not seem to
be commonly used by file systems. Use `telldir` instead to obtain
the seek offset and inject it into d_seekoff, and create a
qemu_dirent_off helper to call it appropriately when appropriate.

Signed-off-by: Keno Fischer <keno@juliacomputing.com>
[Michael Roitzsch: - Rebase for NixOS]
Signed-off-by: Michael Roitzsch <reactorcontrol@icloud.com>
[Will Cohen: - Adjust to pass testing
             - Ensure that d_seekoff is filled using telldir
               on darwin, and create qemu_dirent_off helper
               to decide which to access]
[Fabian Franz: - Add telldir error handling for darwin]
Signed-off-by: Fabian Franz <fabianfranz.oss@gmail.com>
[Will Cohen: - Ensure that telldir error handling uses
               signed int
             - Cleanup of telldir error handling
             - Remove superfluous error handling for
               qemu_dirent_off
             - Adjust formatting
             - Use qemu_dirent_off in codir.c
             - Declare qemu_dirent_off as static to prevent
               linker error
             - Move qemu_dirent_off above the end-of-file
               endif to fix compilation]
Signed-off-by: Will Cohen <wwcohen@gmail.com>
Message-Id: <20220227223522.91937-5-wwcohen@gmail.com>
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Christian Schoenebeck <qemu_oss@crudebyte.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
index 1a5e3eed73..f3272f0b43 100644
--- a/hw/9pfs/9p-local.c
+++ b/hw/9pfs/9p-local.c
@@ -562,6 +562,15 @@ again:
     if (!entry) {
         return NULL;
     }
+#ifdef CONFIG_DARWIN
+    int off;
+    off = telldir(fs->dir.stream);
+    /* If telldir fails, fail the entire readdir call */
+    if (off < 0) {
+        return NULL;
+    }
+    entry->d_seekoff = off;
+#endif
 
     if (ctx->export_flags & V9FS_SM_MAPPED) {
         entry->d_type = DT_UNKNOWN;