[sr-dev] git:master: core: use offsetof() extension to finding the memory offset of a member of a structure

Module: sip-router Branch: master Commit: b23832622f9211a04b1718741fd46eabb41937d5 URL: http://git.sip-router.org/cgi-bin/gitweb.cgi/sip-router/?a=commit;h=b238326… Author: Marius Zbihlei &lt;marius.zbihlei(a)1and1.ro&gt; Committer: Marius Zbihlei &lt;marius.zbihlei(a)1and1.ro&gt; Date: Tue Aug 17 11:12:38 2010 +0300 core: use offsetof() extension to finding the memory offset of a member of a structure This replaces some undefined behavior code in the form of null pointer dereferences Offsetof is present in stddef.h and it is fairly portable across platforms/compilers. --- sr_module.c | 7 ++++--- 1 files changed, 4 insertions(+), 3 deletions(-) diff --git a/sr_module.c b/sr_module.c index 9c7a2a9..e4f94a3 100644 --- a/sr_module.c +++ b/sr_module.c @@ -69,6 +69,7 @@ #include <strings.h> #include <stdlib.h> #include <string.h> +#include <stddef.h> /* for offsetof */ struct sr_module* modules=0; @@ -922,9 +923,9 @@ int init_modules(void) action_u_t *fixup_get_param(void **cur_param, int cur_param_no, int required_param_no) { - action_u_t *a, a2; + action_u_t *a; /* cur_param points to a->u.string, get pointer to a */ - a = (void*) ((char *)cur_param - ((char *)&a2.u.string-(char *)&a2)); + a = (void*) ((char *)cur_param - offsetof(action_u_t, u.string)); return a + required_param_no - cur_param_no; } @@ -947,7 +948,7 @@ int fixup_get_param_count(void **cur_param, int cur_param_no) action_param_type* fixup_get_param_ptype(void** param) { action_u_t* a; - a = (void*)((char*)param - (char*)&(((action_u_t*)(0))->u.string)); + a = (void*)((char*)param - offsetof(action_u_t, u.string)); return &a->type; }