[PATCH qemu-server v2 3/5] remote migration: pull in checks from qm

[Erik Fastermann <e.fastermann@proxmox.com>]

Pull in the checks that previously lived only in the qm CLI into the
endpoint. Direct API callers such as the web UI now run them too, so
fewer migrations start only to fail partway.

The logic is mostly identical. Error messages are reworded slightly and
errors are collected instead of dying on the first one.

Signed-off-by: Erik Fastermann <e.fastermann@proxmox.com>
---
 src/PVE/API2/Qemu.pm | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/src/PVE/API2/Qemu.pm b/src/PVE/API2/Qemu.pm
index b16a1365..1d94babd 100644
--- a/src/PVE/API2/Qemu.pm
+++ b/src/PVE/API2/Qemu.pm
@@ -1136,6 +1136,47 @@ my sub validate_remote_migrate_preconditions {
         return;
     }
 
+    my $resources = eval { $api_client->get("/cluster/resources", { type => 'vm' }) };
+    if (my $err = $@) {
+        $add_error->('remote-query', $err);
+    } elsif (grep { defined($_->{vmid}) && $_->{vmid} eq $target_vmid } @$resources) {
+        $add_error->('target-vmid-exists', "remote: guest with ID '$target_vmid' already exists");
+    }
+
+    my $storages = eval { $api_client->get("/nodes/localhost/storage", { enabled => 1 }) };
+    if (my $err = $@) {
+        $add_error->('remote-query', $err);
+    } else {
+        my $check_remote_storage = sub {
+            my ($storage) = @_;
+            my $found = [grep { $_->{storage} eq $storage } @$storages];
+
+            if (!@$found) {
+                $add_error->(
+                    'storage-missing',
+                    "remote: storage '$storage' does not exist (or missing permission)",
+                    storage => $storage,
+                );
+                return;
+            }
+
+            $found = $found->[0];
+            my $content_types = [PVE::Tools::split_list($found->{content})];
+            $add_error->(
+                'storage-no-images',
+                "remote: storage '$storage' cannot store images",
+                storage => $storage,
+            ) if !grep { $_ eq 'images' } @$content_types;
+        };
+
+        for my $target_sid (values $storagemap->{entries}->%*) {
+            $check_remote_storage->($target_sid);
+        }
+
+        $check_remote_storage->($storagemap->{default})
+            if $storagemap->{default};
+    }
+
     my $repl_conf = PVE::ReplicationConfig->new();
     my $is_replicated = $repl_conf->check_for_existing_jobs($source_vmid, 1);
     $add_error->('vm-replicated', "cannot remote-migrate replicated VM")
-- 
2.47.3