backends: Have HostMemoryBackendClass::alloc() handler return a boolean

Following the example documented since commit e3fe3988d7 ("error:
Document Error API usage rules"), have HostMemoryBackendClass::alloc
return a boolean indicating whether an error is set or not.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Message-Id: <20231120213301.24349-17-philmd@linaro.org>
diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c
index fe8c481..ac3e433 100644
--- a/backends/hostmem-file.c
+++ b/backends/hostmem-file.c
@@ -36,12 +36,13 @@
     OnOffAuto rom;
 };
 
-static void
+static bool
 file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
 {
 #ifndef CONFIG_POSIX
     error_setg(errp, "backend '%s' not supported on this host",
                object_get_typename(OBJECT(backend)));
+    return false;
 #else
     HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(backend);
     g_autofree gchar *name = NULL;
@@ -49,11 +50,11 @@
 
     if (!backend->size) {
         error_setg(errp, "can't create backend with size 0");
-        return;
+        return false;
     }
     if (!fb->mem_path) {
         error_setg(errp, "mem-path property not set");
-        return;
+        return false;
     }
 
     switch (fb->rom) {
@@ -65,18 +66,18 @@
         if (!fb->readonly) {
             error_setg(errp, "property 'rom' = 'on' is not supported with"
                        " 'readonly' = 'off'");
-            return;
+            return false;
         }
         break;
     case ON_OFF_AUTO_OFF:
         if (fb->readonly && backend->share) {
             error_setg(errp, "property 'rom' = 'off' is incompatible with"
                        " 'readonly' = 'on' and 'share' = 'on'");
-            return;
+            return false;
         }
         break;
     default:
-        assert(false);
+        g_assert_not_reached();
     }
 
     name = host_memory_backend_get_name(backend);
@@ -86,9 +87,9 @@
     ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
     ram_flags |= fb->is_pmem ? RAM_PMEM : 0;
     ram_flags |= RAM_NAMED_FILE;
-    memory_region_init_ram_from_file(&backend->mr, OBJECT(backend), name,
-                                     backend->size, fb->align, ram_flags,
-                                     fb->mem_path, fb->offset, errp);
+    return memory_region_init_ram_from_file(&backend->mr, OBJECT(backend), name,
+                                            backend->size, fb->align, ram_flags,
+                                            fb->mem_path, fb->offset, errp);
 #endif
 }