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libctf: don't leak hash keys or values on value replacement

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When a ctf_dynhash_insert() finds a slot already existing, it should
call the key and value free functions on the existing key and value and
move the passed-in key into place, so that the lifetime rules for hash
keys are always the same no matter whether the key existed or not but
neither are the keys or values leaked.

New in v3.
v5: fix tabdamage.

libctf/
	* ctf-hash.c (ctf_hashtab_insert): Pass in the key and value
	freeing functions: if set, free the key and value if the slot
	already exists.  Always reassign the key.
	(ctf_dynhash_insert): Adjust call appropriately.
	(ctf_hash_insert_type): Likewise.
This commit is contained in:
Nick Alcock 2019-07-24 15:21:56 +01:00
parent 5de9eada3b
commit 1820745a0a
2 changed files with 22 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

18
libctf/ctf-hash.c
View file

@ -152,7 +152,9 @@ ctf_hashtab_lookup (struct htab *htab, const void *key, enum insert_option inser
}
static ctf_helem_t *
ctf_hashtab_insert (struct htab *htab, void *key, void *value)
ctf_hashtab_insert (struct htab *htab, void *key, void *value,
ctf_hash_free_fun key_free,
ctf_hash_free_fun value_free)
{
ctf_helem_t **slot;
@ -169,8 +171,15 @@ ctf_hashtab_insert (struct htab *htab, void *key, void *value)
*slot = malloc (sizeof (ctf_helem_t));
if (!*slot)
return NULL;
(*slot)->key = key;
}
else
{
if (key_free)
key_free ((*slot)->key);
if (value_free)
value_free ((*slot)->value);
}
(*slot)->key = key;
(*slot)->value = value;
return *slot;
}
@ -180,7 +189,8 @@ ctf_dynhash_insert (ctf_dynhash_t *hp, void *key, void *value)
{
ctf_helem_t *slot;
slot = ctf_hashtab_insert (hp->htab, key, value);
slot = ctf_hashtab_insert (hp->htab, key, value,
hp->key_free, hp->value_free);
if (!slot)
return errno;
@ -317,7 +327,7 @@ ctf_hash_insert_type (ctf_hash_t *hp, ctf_file_t *fp, uint32_t type,
return 0; /* Just ignore empty strings on behalf of caller. */
if (ctf_hashtab_insert ((struct htab *) hp, (char *) str,
(void *) (ptrdiff_t) type) != NULL)
(void *) (ptrdiff_t) type, NULL, NULL) != NULL)
return 0;
return errno;
}