[Qemu-devel] [PATCH v2] blockdev: clean up error handling in do_open_tray

[Colin Lord <clord@redhat.com>]

Returns negative error codes and accompanying error messages in cases where
the device has no tray or the tray is locked and isn't forced open. This
extra information should result in better flexibility in functions that
call do_open_tray.

Signed-off-by: Colin Lord <clord@redhat.com>
---
v2: fix function documentation, improve commit wording, and remove
unnecessary null check
 blockdev.c | 36 +++++++++++++++++++++---------------
 1 file changed, 21 insertions(+), 15 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index 717785e..d50a2a5 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2286,17 +2286,14 @@ void qmp_eject(const char *device, bool has_force, bool force, Error **errp)
     }
 
     rc = do_open_tray(device, force, &local_err);
-    if (local_err) {
+    if (rc == -ENOSYS) {
+        error_free(local_err);
+        local_err = NULL;
+    } else if (local_err) {
         error_propagate(errp, local_err);
         return;
     }
 
-    if (rc == EINPROGRESS) {
-        error_setg(errp, "Device '%s' is locked and force was not specified, "
-                   "wait for tray to open and try again", device);
-        return;
-    }
-
     qmp_x_blockdev_remove_medium(device, errp);
 }
 
@@ -2325,10 +2322,9 @@ void qmp_block_passwd(bool has_device, const char *device,
 }
 
 /**
- * returns -errno on fatal error, +errno for non-fatal situations.
- * errp will always be set when the return code is negative.
- * May return +ENOSYS if the device has no tray,
- * or +EINPROGRESS if the tray is locked and the guest has been notified.
+ * returns -errno on all errors, and errp will be set on error
+ * May return the non-fatal error codes -ENOSYS if the device has no tray,
+ * or -EINPROGRESS if the tray is locked and the guest has been notified.
  */
 static int do_open_tray(const char *device, bool force, Error **errp)
 {
@@ -2348,8 +2344,8 @@ static int do_open_tray(const char *device, bool force, Error **errp)
     }
 
     if (!blk_dev_has_tray(blk)) {
-        /* Ignore this command on tray-less devices */
-        return ENOSYS;
+        error_setg(errp, "Device '%s' does not have a tray", device);
+        return -ENOSYS;
     }
 
     if (blk_dev_is_tray_open(blk)) {
@@ -2366,7 +2362,9 @@ static int do_open_tray(const char *device, bool force, Error **errp)
     }
 
     if (locked && !force) {
-        return EINPROGRESS;
+        error_setg(errp, "Device '%s' is locked and force was not specified, "
+                   "wait for tray to open and try again", device);
+        return -EINPROGRESS;
     }
 
     return 0;
@@ -2375,10 +2373,18 @@ static int do_open_tray(const char *device, bool force, Error **errp)
 void qmp_blockdev_open_tray(const char *device, bool has_force, bool force,
                             Error **errp)
 {
+    Error *local_err = NULL;
+    int rc;
+
     if (!has_force) {
         force = false;
     }
-    do_open_tray(device, force, errp);
+    rc = do_open_tray(device, force, &local_err);
+    if (rc == -EINPROGRESS || rc == -ENOSYS) {
+        error_free(local_err);
+    } else {
+        error_propagate(errp, local_err);
+    }
 }
 
 void qmp_blockdev_close_tray(const char *device, Error **errp)
-- 
2.5.5