monitor: simplify functions for getting a dup'd fdset entry

Currently code has to call monitor_fdset_get_fd, then dup
the return fd, and then add the duplicate FD back into the
fdset. This dance is overly verbose for the caller and
introduces extra failure modes which can be avoided by
folding all the logic into monitor_fdset_dup_fd_add and
removing monitor_fdset_get_fd entirely.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

1 files changed, 25 insertions, 33 deletions

diff --git a/monitor/misc.c b/monitor/misc.c
index e847b58a8c..0b1b9b196c 100644
--- a/monitor/misc.c
+++ b/monitor/misc.c
@@ -1547,69 +1547,61 @@ AddfdInfo *monitor_fdset_add_fd(int fd, bool has_fdset_id, int64_t fdset_id,
     return fdinfo;
 }
 
-int monitor_fdset_get_fd(int64_t fdset_id, int flags)
+int monitor_fdset_dup_fd_add(int64_t fdset_id, int flags)
 {
 #ifdef _WIN32
     return -ENOENT;
 #else
     MonFdset *mon_fdset;
-    MonFdsetFd *mon_fdset_fd;
-    int mon_fd_flags;
-    int ret;
 
     qemu_mutex_lock(&mon_fdsets_lock);
     QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
+        MonFdsetFd *mon_fdset_fd;
+        MonFdsetFd *mon_fdset_fd_dup;
+        int fd = -1;
+        int dup_fd;
+        int mon_fd_flags;
+
         if (mon_fdset->id != fdset_id) {
             continue;
         }
+
         QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
             mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL);
             if (mon_fd_flags == -1) {
-                ret = -errno;
-                goto out;
+                qemu_mutex_unlock(&mon_fdsets_lock);
+                return -1;
             }
 
             if ((flags & O_ACCMODE) == (mon_fd_flags & O_ACCMODE)) {
-                ret = mon_fdset_fd->fd;
-                goto out;
+                fd = mon_fdset_fd->fd;
+                break;
             }
         }
-        ret = -EACCES;
-        goto out;
-    }
-    ret = -ENOENT;
-
-out:
-    qemu_mutex_unlock(&mon_fdsets_lock);
-    return ret;
-#endif
-}
-
-int monitor_fdset_dup_fd_add(int64_t fdset_id, int dup_fd)
-{
-    MonFdset *mon_fdset;
-    MonFdsetFd *mon_fdset_fd_dup;
 
-    qemu_mutex_lock(&mon_fdsets_lock);
-    QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
-        if (mon_fdset->id != fdset_id) {
-            continue;
+        if (fd == -1) {
+            qemu_mutex_unlock(&mon_fdsets_lock);
+            errno = EACCES;
+            return -1;
         }
-        QLIST_FOREACH(mon_fdset_fd_dup, &mon_fdset->dup_fds, next) {
-            if (mon_fdset_fd_dup->fd == dup_fd) {
-                goto err;
-            }
+
+        dup_fd = qemu_dup_flags(fd, flags);
+        if (dup_fd == -1) {
+            qemu_mutex_unlock(&mon_fdsets_lock);
+            return -1;
         }
+
         mon_fdset_fd_dup = g_malloc0(sizeof(*mon_fdset_fd_dup));
         mon_fdset_fd_dup->fd = dup_fd;
         QLIST_INSERT_HEAD(&mon_fdset->dup_fds, mon_fdset_fd_dup, next);
         qemu_mutex_unlock(&mon_fdsets_lock);
-        return 0;
+        return dup_fd;
     }
 
-err:
     qemu_mutex_unlock(&mon_fdsets_lock);
+    errno = ENOENT;
     return -1;
+#endif
 }
 
 static int64_t monitor_fdset_dup_fd_find_remove(int dup_fd, bool remove)