os-posix.c: create and export os_set_chroot()

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-ID: <20230901101302.3618955-4-mjt@tls.msk.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

include/sysemu/os-posix.h

@@ -51,6 +51,7 @@ int os_set_daemonize(bool d);
 bool is_daemonized(void);
 void os_daemonize(void);
 bool os_set_runas(const char *optarg);
+void os_set_chroot(const char *optarg);
 void os_setup_post(void);
 int os_mlock(void);
 

os-posix.c

@@ -159,7 +159,7 @@ int os_parse_cmd_args(int index, const char *optarg)
         break;
     case QEMU_OPTION_chroot:
         warn_report("option is deprecated, use '-run-with chroot=...' instead");
-        chroot_dir = optarg;
+        os_set_chroot(optarg);
         break;
     case QEMU_OPTION_daemonize:
         daemonize = 1;
@@ -184,7 +184,7 @@ int os_parse_cmd_args(int index, const char *optarg)
 #endif
         str = qemu_opt_get(opts, "chroot");
         if (str) {
-            chroot_dir = str;
+            os_set_chroot(str);
         }
         break;
     }
@@ -232,6 +232,11 @@ static void change_process_uid(void)
     }
 }
 
+void os_set_chroot(const char *optarg)
+{
+    chroot_dir = optarg;
+}
+
 static void change_root(void)
 {
     if (chroot_dir) {