monitor: Enable adding an inherited fd to an fd set

qmp_add_fd() gets an fd that was received over a socket with
SCM_RIGHTS and adds it to an fd set.  This patch adds support
that will enable adding an fd that was inherited on the
command line to an fd set.

Note: All of the code added to monitor_fdset_add_fd(), with the
exception of the error path for non-valid fdset-id, is code motion
from qmp_add_fd().
Signed-off-by: NCorey Bryant <coreyb@linux.vnet.ibm.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

monitor.c

@@ -2135,8 +2135,6 @@ AddfdInfo *qmp_add_fd(bool has_fdset_id, int64_t fdset_id, bool has_opaque,
 {
     int fd;
     Monitor *mon = cur_mon;
-    MonFdset *mon_fdset = NULL;
-    MonFdsetFd *mon_fdset_fd;
     AddfdInfo *fdinfo;
 
     fd = qemu_chr_fe_get_msgfd(mon->chr);
@@ -2145,78 +2143,12 @@ AddfdInfo *qmp_add_fd(bool has_fdset_id, int64_t fdset_id, bool has_opaque,
         goto error;
     }
 
-    if (has_fdset_id) {
-        QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
-            /* Break if match found or match impossible due to ordering by ID */
-            if (fdset_id <= mon_fdset->id) {
-                if (fdset_id < mon_fdset->id) {
-                    mon_fdset = NULL;
-                }
-                break;
-            }
-        }
+    fdinfo = monitor_fdset_add_fd(fd, has_fdset_id, fdset_id,
+                                  has_opaque, opaque, errp);
+    if (fdinfo) {
+        return fdinfo;
     }
 
-    if (mon_fdset == NULL) {
-        int64_t fdset_id_prev = -1;
-        MonFdset *mon_fdset_cur = QLIST_FIRST(&mon_fdsets);
-
-        if (has_fdset_id) {
-            if (fdset_id < 0) {
-                error_set(errp, QERR_INVALID_PARAMETER_VALUE, "fdset-id",
-                          "a non-negative value");
-                goto error;
-            }
-            /* Use specified fdset ID */
-            QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
-                mon_fdset_cur = mon_fdset;
-                if (fdset_id < mon_fdset_cur->id) {
-                    break;
-                }
-            }
-        } else {
-            /* Use first available fdset ID */
-            QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
-                mon_fdset_cur = mon_fdset;
-                if (fdset_id_prev == mon_fdset_cur->id - 1) {
-                    fdset_id_prev = mon_fdset_cur->id;
-                    continue;
-                }
-                break;
-            }
-        }
-
-        mon_fdset = g_malloc0(sizeof(*mon_fdset));
-        if (has_fdset_id) {
-            mon_fdset->id = fdset_id;
-        } else {
-            mon_fdset->id = fdset_id_prev + 1;
-        }
-
-        /* The fdset list is ordered by fdset ID */
-        if (!mon_fdset_cur) {
-            QLIST_INSERT_HEAD(&mon_fdsets, mon_fdset, next);
-        } else if (mon_fdset->id < mon_fdset_cur->id) {
-            QLIST_INSERT_BEFORE(mon_fdset_cur, mon_fdset, next);
-        } else {
-            QLIST_INSERT_AFTER(mon_fdset_cur, mon_fdset, next);
-        }
-    }
-
-    mon_fdset_fd = g_malloc0(sizeof(*mon_fdset_fd));
-    mon_fdset_fd->fd = fd;
-    mon_fdset_fd->removed = false;
-    if (has_opaque) {
-        mon_fdset_fd->opaque = g_strdup(opaque);
-    }
-    QLIST_INSERT_HEAD(&mon_fdset->fds, mon_fdset_fd, next);
-
-    fdinfo = g_malloc0(sizeof(*fdinfo));
-    fdinfo->fdset_id = mon_fdset->id;
-    fdinfo->fd = mon_fdset_fd->fd;
-
-    return fdinfo;
-
 error:
     if (fd != -1) {
         close(fd);
@@ -2301,6 +2233,87 @@ FdsetInfoList *qmp_query_fdsets(Error **errp)
     return fdset_list;
 }
 
+AddfdInfo *monitor_fdset_add_fd(int fd, bool has_fdset_id, int64_t fdset_id,
+                                bool has_opaque, const char *opaque,
+                                Error **errp)
+{
+    MonFdset *mon_fdset = NULL;
+    MonFdsetFd *mon_fdset_fd;
+    AddfdInfo *fdinfo;
+
+    if (has_fdset_id) {
+        QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
+            /* Break if match found or match impossible due to ordering by ID */
+            if (fdset_id <= mon_fdset->id) {
+                if (fdset_id < mon_fdset->id) {
+                    mon_fdset = NULL;
+                }
+                break;
+            }
+        }
+    }
+
+    if (mon_fdset == NULL) {
+        int64_t fdset_id_prev = -1;
+        MonFdset *mon_fdset_cur = QLIST_FIRST(&mon_fdsets);
+
+        if (has_fdset_id) {
+            if (fdset_id < 0) {
+                error_set(errp, QERR_INVALID_PARAMETER_VALUE, "fdset-id",
+                          "a non-negative value");
+                return NULL;
+            }
+            /* Use specified fdset ID */
+            QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
+                mon_fdset_cur = mon_fdset;
+                if (fdset_id < mon_fdset_cur->id) {
+                    break;
+                }
+            }
+        } else {
+            /* Use first available fdset ID */
+            QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
+                mon_fdset_cur = mon_fdset;
+                if (fdset_id_prev == mon_fdset_cur->id - 1) {
+                    fdset_id_prev = mon_fdset_cur->id;
+                    continue;
+                }
+                break;
+            }
+        }
+
+        mon_fdset = g_malloc0(sizeof(*mon_fdset));
+        if (has_fdset_id) {
+            mon_fdset->id = fdset_id;
+        } else {
+            mon_fdset->id = fdset_id_prev + 1;
+        }
+
+        /* The fdset list is ordered by fdset ID */
+        if (!mon_fdset_cur) {
+            QLIST_INSERT_HEAD(&mon_fdsets, mon_fdset, next);
+        } else if (mon_fdset->id < mon_fdset_cur->id) {
+            QLIST_INSERT_BEFORE(mon_fdset_cur, mon_fdset, next);
+        } else {
+            QLIST_INSERT_AFTER(mon_fdset_cur, mon_fdset, next);
+        }
+    }
+
+    mon_fdset_fd = g_malloc0(sizeof(*mon_fdset_fd));
+    mon_fdset_fd->fd = fd;
+    mon_fdset_fd->removed = false;
+    if (has_opaque) {
+        mon_fdset_fd->opaque = g_strdup(opaque);
+    }
+    QLIST_INSERT_HEAD(&mon_fdset->fds, mon_fdset_fd, next);
+
+    fdinfo = g_malloc0(sizeof(*fdinfo));
+    fdinfo->fdset_id = mon_fdset->id;
+    fdinfo->fd = mon_fdset_fd->fd;
+
+    return fdinfo;
+}
+
 int monitor_fdset_get_fd(int64_t fdset_id, int flags)
 {
 #ifndef _WIN32

monitor.h

@@ -90,6 +90,9 @@ int qmp_qom_set(Monitor *mon, const QDict *qdict, QObject **ret);
 
 int qmp_qom_get(Monitor *mon, const QDict *qdict, QObject **ret);
 
+AddfdInfo *monitor_fdset_add_fd(int fd, bool has_fdset_id, int64_t fdset_id,
+                                bool has_opaque, const char *opaque,
+                                Error **errp);
 int monitor_fdset_get_fd(int64_t fdset_id, int flags);
 int monitor_fdset_dup_fd_add(int64_t fdset_id, int dup_fd);
 int monitor_fdset_dup_fd_remove(int dup_fd);