param: hand arguments after -- straight to init

The kernel passes any args it doesn't need through to init, except it
assumes anything containing '.' belongs to the kernel (for a module).
This change means all users can clearly distinguish which arguments
are for init.

For example, the kernel uses debug ("dee-bug") to mean log everything to
the console, where systemd uses the debug from the Scandinavian "day-boog"
meaning "fail to boot".  If a future versions uses argv[] instead of
reading /proc/cmdline, this confusion will be avoided.

eg: test 'FOO="this is --foo"' -- 'systemd.debug="true true true"'

Gives:
argv[0] = '/debug-init'
argv[1] = 'test'
argv[2] = 'systemd.debug=true true true'
envp[0] = 'HOME=/'
envp[1] = 'TERM=linux'
envp[2] = 'FOO=this is --foo'

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 29 insertions, 4 deletions

diff --git a/init/main.c b/init/main.c
index 9c7fd4c9249f..e9d458b5d77b 100644
--- a/init/main.c
+++ b/init/main.c
@@ -252,6 +252,27 @@ static int __init repair_env_string(char *param, char *val, const char *unused)
         return 0;
 }
 
+/* Anything after -- gets handed straight to init. */
+static int __init set_init_arg(char *param, char *val, const char *unused)
+{
+        unsigned int i;
+
+        if (panic_later)
+                return 0;
+
+        repair_env_string(param, val, unused);
+
+        for (i = 0; argv_init[i]; i++) {
+                if (i == MAX_INIT_ARGS) {
+                        panic_later = "init";
+                        panic_param = param;
+                        return 0;
+                }
+        }
+        argv_init[i] = param;
+        return 0;
+}
+
 /*
  * Unknown boot options get handed to init, unless they look like
  * unused parameters (modprobe will find them in /proc/cmdline).
@@ -478,7 +499,7 @@ static void __init mm_init(void)
 
 asmlinkage void __init start_kernel(void)
 {
-        char * command_line;
+        char * command_line, *after_dashes;
         extern const struct kernel_param __start___param[], __stop___param[];
 
         /*
@@ -519,9 +540,13 @@ asmlinkage void __init start_kernel(void)
 
         pr_notice("Kernel command line: %s\n", boot_command_line);
         parse_early_param();
-        parse_args("Booting kernel", static_command_line, __start___param,
-                   __stop___param - __start___param,
-                   -1, -1, &unknown_bootoption);
+        after_dashes = parse_args("Booting kernel",
+                                  static_command_line, __start___param,
+                                  __stop___param - __start___param,
+                                  -1, -1, &unknown_bootoption);
+        if (after_dashes)
+                parse_args("Setting init args", after_dashes, NULL, 0, -1, -1,
+                           set_init_arg);
 
         jump_label_init();