From: Torbjorn SVENSSON <torbjorn.svensson@foss.st.com>
To: Nick Alcock <nick.alcock@oracle.com>
Cc: <binutils@sourceware.org>, <amodra@gmail.com>,
Yvan ROUX <yvan.roux@foss.st.com>
Subject: Re: [PATCH v3] libctf: ctf_member_next needs to return (ssize_t)-1 on error
Date: Wed, 13 Sep 2023 22:20:44 +0200 [thread overview]
Message-ID: <657dadf8-4b7b-67e6-9de2-9a1cdb79f081@foss.st.com> (raw)
In-Reply-To: <87a5tp2a3n.fsf@esperi.org.uk>
On 2023-09-13 20:37, Nick Alcock wrote:
> On 13 Sep 2023, Torbjörn SVENSSON verbalised:
>
>> v1 -> v2:
>> Changed all functions with signed interger return type to return -1 based on
>> comment from Alan.
>>
>> v2 -> v3:
>> Added ctf_set_errno_signed function to return a signed -1 value based on
>> comment from Nick.
>>
>> Ok for trunk?
>
> If this touches exactly those functions that return int, and fixes the
> reported bug, it's good as far as I'm concerned, except for a couple of
> possible comment improvements:
I've verified the calls by building binutils (with the configure flags
mentioned in my last mail) with CFLAGS="-Wsign-conversion -Wconversion"
and looking for any warnings related to ctf_set_errno. After applying
this patch, there were no warnings left.
>> +/* Store the specified error code into the CTF dict, and then return -1
>> + (CTF_ERR) for the benefit of the caller. */
>
> It's not CTF_ERR in this case, it's just -1. Perhaps:
True, but why is then ctf_set_errno returning CTF_ERR?
I somehow want to make it obvious that it's not wrong and that it should
*never* be CTF_ERR in the signed function or the problem would reappear.
The other possibility is to do the inverse, meaning that the
ctf_set_errno function is returning an integer (-1) and that there is a
function ctf_set_errno_unsigned that is calling the ctf_set_errno
function but casting the returned value to unsigned long (or ctf_id_t).
I personally think this solution is a bit more clean as -1 is the error
value from all functions, just a matter if it's signed or unsigned.
I.e:
int
ctf_set_errno (ctf_dict_t *fp, int err)
{
fp->ctf_errno = err;
return -1;
}
unsigned long
ctf_set_errno_unsigned (ctf_dict_t *fp, int err)
{
return (unsigned long)ctf_set_errno (fp, err);
}
I suppose the ctf_set_errno_unsigned could even be a macro in the
ctf-impl.h header file.
> /* Store the specified error code into the CTF dict, and then return -1
> for the benefit of the caller, which is expected to return int,
> as opposed to ctf_id_t. */
>
Ok!
>> +int
>> +ctf_set_errno_signed (ctf_dict_t *fp, int err)
>> +{
>> + fp->ctf_errno = err;
>> + /* Don't rely on CTF_ERR here as it will not properly sign extend on 64-bit
>> + Windows ABI. */
>> + return -1;
>> +}
>
> ... that Windows is not really the problem here. It's more
>
> /* Don't rely on CTF_ERR here; it is a ctf_id_t (unsigned long), and
> it will be truncated to a non--1 value on platforms on which int
> and unsigned long are different sizes. */
>
> perhaps? (At least, I think that's what's going on.)
The problem happens when the signed integral type is wider than unsigned
long.
/* Don't rely on CTF_ERR here; it is a ctf_id_t (unsigned long), and
it will be extended to a non--1 value on platforms on which int
is larger than unsigned long are different sizes. */
>
> This probably needs testing on a wide variety of platforms with
> different type sizes. I'll add throwing this through my entire test
> matrix to my todo list, and fix any bugs observed: but the basic idea
> looks sound to me.
Do you want to run this full matrix before or after submitting the patch?
If it's before; when do you think you will have time to do that?
Let me know how you want to proceed.
next prev parent reply other threads:[~2023-09-13 21:23 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-24 11:32 [PATCH] " Torbjörn SVENSSON
2023-08-25 2:22 ` Alan Modra
2023-08-25 16:53 ` [PATCH v2] " Torbjörn SVENSSON
2023-08-30 8:34 ` Torbjorn SVENSSON
2023-08-30 9:39 ` Alan Modra
2023-09-07 12:10 ` Nick Alcock
2023-09-08 12:58 ` Torbjorn SVENSSON
2023-09-12 14:23 ` Nick Alcock
2023-09-12 18:44 ` Torbjorn SVENSSON
2023-09-13 9:57 ` [PATCH v3] " Torbjörn SVENSSON
2023-09-13 18:37 ` Nick Alcock
2023-09-13 20:20 ` Torbjorn SVENSSON [this message]
2023-09-20 17:44 ` Torbjorn SVENSSON
2023-09-26 14:51 ` Nick Alcock
2023-09-26 17:28 ` [PATCH v4] " Torbjörn SVENSSON
2023-09-26 17:49 ` [PATCH v3] " Torbjorn SVENSSON
2023-09-28 16:41 ` Nick Alcock
2023-09-29 12:11 ` Torbjorn SVENSSON
2023-10-02 10:57 ` Nick Alcock
2023-10-03 12:59 ` Torbjorn SVENSSON
2023-10-03 20:53 ` Nick Alcock
2023-10-05 8:39 ` [PATCH v5] libctf: Sanitize error types for PR 30836 Torbjörn SVENSSON
2023-10-09 10:27 ` Nick Alcock
2023-10-09 14:44 ` [PATCH v6] " Torbjörn SVENSSON
2023-10-09 15:11 ` [PATCH v7] " Torbjörn SVENSSON
2023-10-11 11:14 ` Nick Alcock
2023-10-13 14:01 ` [PATCH] libctf: check for problems with error returns Nick Alcock
2023-10-13 18:31 ` Torbjorn SVENSSON
2023-10-15 19:18 ` Nick Alcock
2023-10-16 12:51 ` [PATCH v8] libctf: Sanitize error types for PR 30836 Torbjörn SVENSSON
2023-10-17 15:15 ` Nick Alcock
2023-10-17 15:35 ` Torbjorn SVENSSON
2023-10-17 18:54 ` [PATCH] libctf: Return CTF_ERR in ctf_type_resolve_unsliced " Torbjörn SVENSSON
2023-10-17 19:40 ` Nick Alcock
2023-10-18 7:40 ` Torbjorn SVENSSON
2023-10-20 17:01 ` Nick Alcock
2023-10-16 13:02 ` [PATCH] libctf: check for problems with error returns Torbjorn SVENSSON
2023-10-17 14:45 ` Nick Alcock
2024-01-30 12:46 ` Andreas Schwab
2024-01-30 14:22 ` Nick Alcock
2024-01-30 14:27 ` Andreas Schwab
2024-03-09 2:44 ` Sam James
2024-03-11 15:14 ` Nick Alcock
2024-03-12 6:52 ` Sam James
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