Re: Use a self-defined memory acquirement function instead of realloc(3) in the l_alloc function
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- Subject: Re: Use a self-defined memory acquirement function instead of realloc(3) in the l_alloc function
- From: Roberto Ierusalimschy <roberto@...>
- Date: 2020年8月10日 11:51:45 -0300
> I want to use a self-defined memory acquirement function instead of
> using realloc(3) in the l_alloc function.
> Since I am a newbie, I don't know if there are some potential problems.
> Could somebody shed some light on this problem?
All you need to know is documented here:
https://www.lua.org/manual/5.3/manual.html#lua_Alloc
As long as you meet those requirements, everything should be fine.
As already pointed out and documented in the above link, Lua assumes
that its l_alloc function cannot fail when shrinking a block. If your
collector does not assure it, it is trivial to change l_alloc so that it
returns the original block when a shrinking would fail:
static void *l_alloc (void *ud, void *ptr, size_t osize, size_t nsize) {
(void)ud; (void)osize; /* not used */
if (nsize == 0) {
free(ptr);
return NULL;
}
else {
void *newptr = realloc(ptr, nsize);
if (newptr == NULL && ptr != NULL && nsize <= osize)
return ptr; /* keep the original block */
else
return newptr;
}
}
-- Roberto