From: "Richard W.M. Jones" <rich@annexia.org>
To: immanuel litzroth <ilitzroth@gmail.com>
Cc: OCaML List Mailing <caml-list@inria.fr>
Subject: Re: [Caml-list] Raising invalid_argument with a constructed string.
Date: Sat, 3 Dec 2016 13:20:28 +0000 [thread overview]
Message-ID: <20161203132028.GA28111@annexia.org> (raw)
In-Reply-To: <CAJjmLU4n0NVWzzCQ6-P+R1Neg0Er7gUQFJYNeHfLja7VbzEhAA@mail.gmail.com>
On Mon, Nov 28, 2016 at 03:39:05PM +0100, immanuel litzroth wrote:
> caml_invalid_argument(str) is no return and does not free it's
> argument.
> So calling it with a string constructed dynamically will mean it'll never
> get freed.
> I could construct an ocaml string and pass that to caml_raise_with_arg,
> but I don't seem to be able to get to the caml_exn_Invalid_argument from
> c. Am I missing something?
We have the same problem in libguestfs in a few places. The solution
is to use an allocation on the C stack, either a fixed size buffer or
[although we don't currently use this] a variable sized one using
alloca. The string is freed when the stack is unwound. Examples:
https://github.com/libguestfs/libguestfs/blob/master/builder/yajl-c.c#L108-L114
https://github.com/libguestfs/libguestfs/blob/master/v2v/domainxml-c.c#L120
Be nice to have a "freeing" version of caml_raise* I suppose.
Rich.
next prev parent reply other threads:[~2016-12-03 13:20 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-28 14:39 immanuel litzroth
2016-11-28 15:43 ` David Allsopp
2016-11-28 15:50 ` Gabriel Scherer
2016-11-29 10:21 ` immanuel litzroth
2016-12-03 13:20 ` Richard W.M. Jones [this message]
2016-12-03 14:00 ` immanuel litzroth
2016-12-03 19:36 ` Richard W.M. Jones
2016-12-03 19:44 ` Gabriel Scherer
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