commit 419ba97df5bd168bf773478270c0043f20328e15 Author: Nick Mathewson nickm@torproject.org Date: Sun Dec 15 18:42:01 2019 -0500

Allow struct_magic to be disabled.

When a subsystem is disabled, there will be no corresponding object allocated, and no magic numbers on it. --- src/lib/conf/conftypes.h | 3 +++ src/lib/confmgt/structvar.c | 22 ++++++++++++++++++++-- 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/src/lib/conf/conftypes.h b/src/lib/conf/conftypes.h index 44171068a..52f9fceb2 100644 --- a/src/lib/conf/conftypes.h +++ b/src/lib/conf/conftypes.h @@ -131,6 +131,9 @@ typedef struct struct_member_t { * * These 'magic numbers' are 32-bit values used to tag objects to make sure * that they have the correct type. + * + * If all fields in this structure are zero or 0, the magic-number check is + * not performed. */ typedef struct struct_magic_decl_t { /** The name of the structure */ diff --git a/src/lib/confmgt/structvar.c b/src/lib/confmgt/structvar.c index de678d18c..a2411477d 100644 --- a/src/lib/confmgt/structvar.c +++ b/src/lib/confmgt/structvar.c @@ -30,13 +30,28 @@ #include <stddef.h>

/** + * Return true iff all fields on <b>decl</b> are NULL or 0, indicating that + * there is no object or no magic number to check. + **/ +static inline bool +magic_is_null(const struct_magic_decl_t *decl) +{ + return decl->typename == NULL && + decl->magic_offset == 0 && + decl->magic_val == 0; +} + +/** * Set the 'magic number' on <b>object</b> to correspond to decl. **/ void struct_set_magic(void *object, const struct_magic_decl_t *decl) { - tor_assert(object); tor_assert(decl); + if (magic_is_null(decl)) + return; + + tor_assert(object); uint32_t *ptr = STRUCT_VAR_P(object, decl->magic_offset); *ptr = decl->magic_val; } @@ -47,8 +62,11 @@ struct_set_magic(void *object, const struct_magic_decl_t *decl) void struct_check_magic(const void *object, const struct_magic_decl_t *decl) { - tor_assert(object); tor_assert(decl); + if (magic_is_null(decl)) + return; + + tor_assert(object);

const uint32_t *ptr = STRUCT_VAR_P(object, decl->magic_offset); tor_assertf(*ptr == decl->magic_val,