qemu-config: add error propagation to qemu_config_parse

This enables some simplification of vl.c via error_fatal, and improves
error messages.  Before:

  $ ./qemu-system-x86_64 -readconfig .
  qemu-system-x86_64: error reading file
  qemu-system-x86_64: -readconfig .: read config .: Invalid argument
  $ /usr/libexec/qemu-kvm -readconfig foo
  qemu-kvm: -readconfig foo: read config foo: No such file or directory

After:

  $ ./qemu-system-x86_64 -readconfig .
  qemu-system-x86_64: -readconfig .: Cannot read config file: Is a directory
  $ ./qemu-system-x86_64 -readconfig foo
  qemu-system-x86_64: -readconfig foo: Could not open 'foo': No such file or directory

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20210226170816.231173-1-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 11 insertions, 18 deletions

diff --git a/softmmu/vl.c b/softmmu/vl.c
index 7e8110bd6e..2f4958db2a 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -2062,17 +2062,19 @@ static int global_init_func(void *opaque, QemuOpts *opts, Error **errp)
     return 0;
 }
 
-static int qemu_read_default_config_file(void)
+static void qemu_read_default_config_file(Error **errp)
 {
+    ERRP_GUARD();
     int ret;
     g_autofree char *file = get_relocated_path(CONFIG_QEMU_CONFDIR "/qemu.conf");
 
-    ret = qemu_read_config_file(file);
-    if (ret < 0 && ret != -ENOENT) {
-        return ret;
+    ret = qemu_read_config_file(file, errp);
+    if (ret < 0) {
+        if (ret == -ENOENT) {
+            error_free(*errp);
+            *errp = NULL;
+        }
     }
-
-    return 0;
 }
 
 static int qemu_set_option(const char *str)
@@ -2633,9 +2635,7 @@ void qemu_init(int argc, char **argv, char **envp)
     }
 
     if (userconfig) {
-        if (qemu_read_default_config_file() < 0) {
-            exit(1);
-        }
+        qemu_read_default_config_file(&error_fatal);
     }
 
     /* second pass of option parsing */
@@ -3323,15 +3323,8 @@ void qemu_init(int argc, char **argv, char **envp)
                 qemu_plugin_opt_parse(optarg, &plugin_list);
                 break;
             case QEMU_OPTION_readconfig:
-                {
-                    int ret = qemu_read_config_file(optarg);
-                    if (ret < 0) {
-                        error_report("read config %s: %s", optarg,
-                                     strerror(-ret));
-                        exit(1);
-                    }
-                    break;
-                }
+                qemu_read_config_file(optarg, &error_fatal);
+                break;
             case QEMU_OPTION_spice:
                 olist = qemu_find_opts_err("spice", NULL);
                 if (!olist) {