commit 9082a6db3f31c768ba862ed22f0824e99b4e0e22 Author: Nick Mathewson nickm@torproject.org Date: Sun Dec 15 18:40:12 2019 -0500

Support a flag to indicate that a config var is disabled

Like "obsolete" variables, these variables produce a warning when you try to set them, but the warning says that the relevant module doesn't have support.

The confdecl macros now have a CONF_CONTEXT that you can define to make all the modules in a given table disabled. --- src/lib/conf/confdecl.h | 22 ++++++++++++++++++++++ src/lib/conf/conftypes.h | 12 ++++++++++++ src/lib/confmgt/confmgt.c | 3 +++ 3 files changed, 37 insertions(+)

diff --git a/src/lib/conf/confdecl.h b/src/lib/conf/confdecl.h index 064ab324f..723aea187 100644 --- a/src/lib/conf/confdecl.h +++ b/src/lib/conf/confdecl.h @@ -135,6 +135,28 @@ .initvalue = initval \ }, /**@}*/ + +/* @defgroup STUB_TABLE_MACROS Internal macros: stub table declarations, + * for use when a module is disabled. + * Implementation helpers: the regular confdecl macros expand to these + * when CONF_CONTEXT is defined to LL_TABLE. Don't use them directly. + * @{*/ +#define BEGIN_CONF_STRUCT__STUB_TABLE(structname) \ + static const config_var_t structname##_vars[] = { +#define END_CONF_STRUCT__STUB_TABLE(structname) \ + { .member = { .name = NULL } } \ + }; +#define CONF_VAR__STUB_TABLE(varname, vartype, varflags, initval) \ + { \ + .member = \ + { .name = #varname, \ + .type = CONFIG_TYPE_IGNORE, \ + .offset = -1, \ + }, \ + .flags = CFLG_GROUP_DISABLED, \ + }, +/**@}*/ + #endif /* !defined(COCCI) */

/** Type aliases for the "commonly used" configuration types. diff --git a/src/lib/conf/conftypes.h b/src/lib/conf/conftypes.h index 19ea99731..44171068a 100644 --- a/src/lib/conf/conftypes.h +++ b/src/lib/conf/conftypes.h @@ -199,6 +199,11 @@ typedef struct struct_magic_decl_t { * whenever the user tries to use it. **/ #define CFLG_WARN_OBSOLETE (1u<<7) +/** + * Flag to indicate that we should warn that an option applies only to + * a disabled module, whenever the user tries to use it. + **/ +#define CFLG_WARN_DISABLED (1u<<8)

/** * A group of flags that should be set on all obsolete options and types. @@ -207,6 +212,13 @@ typedef struct struct_magic_decl_t { (CFLG_NOCOPY|CFLG_NOCMP|CFLG_NODUMP|CFLG_NOSET|CFLG_NOLIST|\ CFLG_WARN_OBSOLETE)

+/** + * A group of fflags that should be set on all disabled options. + **/ +#define CFLG_GROUP_DISABLED \ + (CFLG_NOCOPY|CFLG_NOCMP|CFLG_NODUMP|CFLG_NOSET|CFLG_NOLIST|\ + CFLG_WARN_DISABLED) + /** A variable allowed in the configuration file or on the command line. */ typedef struct config_var_t { struct_member_t member; /** A struct member corresponding to this diff --git a/src/lib/confmgt/confmgt.c b/src/lib/confmgt/confmgt.c index c72efa847..eaa4468d5 100644 --- a/src/lib/confmgt/confmgt.c +++ b/src/lib/confmgt/confmgt.c @@ -660,6 +660,9 @@ config_assign_value(const config_mgr_t *mgr, void *options, if (config_var_has_flag(var->cvar, CFLG_WARN_OBSOLETE)) { log_warn(LD_GENERAL, "Skipping obsolete configuration option "%s".", var->cvar->member.name); + } else if (config_var_has_flag(var->cvar, CFLG_WARN_DISABLED)) { + log_warn(LD_GENERAL, "This copy of Tor was built without support for " + "the option "%s". Skipping.", var->cvar->member.name); }

return struct_var_kvassign(object, c, msg, &var->cvar->member);