Re: [committed] openmp: Fix up strtoul and strtoull uses in libgomp

[Thomas Schwinge <thomas@codesourcery.com>]

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Hi!

On 2021-10-15T16:46:33+0200, Jakub Jelinek via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
> also discovered that the hang was a result of making wrong assumptions
> about strtoul/strtoull.

(Also 'strtol'.)  ;-)

> All the uses were for portability setting
> errno = 0 before the calls and treating non-zero errno after the call
> as invalid input, but for the case where there are no valid digits at
> all strtoul may set errno to EINVAL, but doesn't have to and with
> glibc doesn't do that.  So, this patch goes through all the strtoul calls
> and next to errno != 0 checks adds also endptr == startptr check.
> Haven't done it in places where we immediately reject strtoul returning 0
> the same as we reject errno != 0, because strtoul must return 0 in the
> case where it sets endptr to the start pointer.  In some spots the code
> was using errno = 0; x = strtoul (p, &p, 10); if (errno) { /*invalid*/ }
> and those spots had to be changed to
> errno = 0; x = strtoul (p, &end, 10); if (errno || end == p) { /*invalid*/ }
> p = end;

ACK.

> Regtested on x86_64-linux and i686-linux, committed to trunk.

Thanks for addressing that one, too -- but evidently not properly tested
the one OpenACC change:

>       (parse_gomp_openacc_dim): Likewise.  Avoid strict aliasing violation.
>       Make code valid C89.

(Why the C89 "re-formatting", by the way?  Surely we're "violating" that
in a lot of other places?)

> --- libgomp/env.c.jj  2021-10-14 22:04:30.594333475 +0200
> +++ libgomp/env.c     2021-10-15 14:07:07.464919497 +0200

> @@ -1202,27 +1207,30 @@ parse_gomp_openacc_dim (void)
>    /* The syntax is the same as for the -fopenacc-dim compilation option.  */
>    const char *var_name = "GOMP_OPENACC_DIM";
>    const char *env_var = getenv (var_name);
> +  const char *pos = env_var;
> +  int i;
> +
>    if (!env_var)
>      return;
>
> -  const char *pos = env_var;
> -  int i;
>    for (i = 0; *pos && i != GOMP_DIM_MAX; i++)
>      {
> +      char *eptr;
> +      long val;
> +
>        if (i && *pos++ != ':')
>       break;
>
>        if (*pos == ':')
>       continue;
>
> -      const char *eptr;
>        errno = 0;
> -      long val = strtol (pos, (char **)&eptr, 10);
> -      if (errno || val < 0 || (unsigned)val != val)
> +      val = strtol (pos, &eptr, 10);
> +      if (errno || eptr != pos || val < 0 || (unsigned)val != val)
>       break;

Instead of 'eptr != pos', this needs to be 'eptr == pos', like everywhere
else.

(That there are no diagnostics for malformed 'GOMP_OPENACC_DIM', is a
different topic, of course.)

>
>        goacc_default_dims[i] = (int)val;
> -      pos = eptr;
> +      pos = (const char *) eptr;
>      }
>  }

Pushed to master branch commit 00c9ce13a64e324dabd8dfd236882919a3119479
"Restore 'GOMP_OPENACC_DIM' environment variable parsing", see attached.


Grüße
 Thomas


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From 00c9ce13a64e324dabd8dfd236882919a3119479 Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <thomas@codesourcery.com>
Date: Fri, 5 Nov 2021 14:42:21 +0100
Subject: [PATCH] Restore 'GOMP_OPENACC_DIM' environment variable parsing

... that got broken by recent commit c057ed9c52c6a63a1a692268f916b1a9131cd4b7
"openmp: Fix up strtoul and strtoull uses in libgomp", resulting in spurious
FAILs for tests specifying 'dg-set-target-env-var "GOMP_OPENACC_DIM" "[...]"'.

	libgomp/
	* env.c (parse_gomp_openacc_dim): Restore parsing.
---
 libgomp/env.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libgomp/env.c b/libgomp/env.c
index df10ff656b6..75018e8c252 100644
--- a/libgomp/env.c
+++ b/libgomp/env.c
@@ -1243,7 +1243,7 @@ parse_gomp_openacc_dim (void)
 
       errno = 0;
       val = strtol (pos, &eptr, 10);
-      if (errno || eptr != pos || val < 0 || (unsigned)val != val)
+      if (errno || eptr == pos || val < 0 || (unsigned)val != val)
 	break;
 
       goacc_default_dims[i] = (int)val;
-- 
2.33.0