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dll2: explicitly confim detached dll2 has no linkage

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This commit is contained in:
Andy Green 2020-12-29 11:58:48 +00:00
parent 5570692cab
commit 1422b23899
2 changed files with 27 additions and 2 deletions
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4
include/libwebsockets/lws-dll2.h
View file

@ -207,8 +207,8 @@ typedef struct lws_dll2_owner {
uint32_t count;
} lws_dll2_owner_t;
static LWS_INLINE int
lws_dll2_is_detached(const struct lws_dll2 *d) { return !d->owner; }
LWS_VISIBLE LWS_EXTERN int
lws_dll2_is_detached(const struct lws_dll2 *d);
static LWS_INLINE const struct lws_dll2_owner *
lws_dll2_owner(const struct lws_dll2 *d) { return d->owner; }

25
lib/core/lws_dll2.c
View file

@ -28,6 +28,31 @@
#include <sys/types.h>
#endif
int
lws_dll2_is_detached(const struct lws_dll2 *d)
{
if (d->owner)
return 0;
if (d->next || d->prev) {
lwsl_err("%s: dll2 %p: detached but next %p, prev %p\n",
__func__, d, d->next, d->prev);
/*
* New lws_dll2 objects and removed lws_dll2 objects
* have .owner, .next and .prev all set to NULL, so we
* can just check .owner to see if we are detached.
*
* We assert here if we encounter an lws_dll2 in the illegal
* state of NULL .owner, but non-NULL in .next or .prev,
* it's evidence of corruption, use-after-free, threads
* contending on accessing without locking etc.
*/
assert(0);
}
return 1;
}
int
lws_dll2_foreach_safe(struct lws_dll2_owner *owner, void *user,
int (*cb)(struct lws_dll2 *d, void *user))