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Return-Path: <adhemerval.zanella@linaro.org>
Subject: Re: [PATCH 3/5] resolv: Fix file handle leak in __resolv_conf_load
 [BZ #25429]
To: libc-alpha@sourceware.org
References: <cover.1579631655.git.fweimer@redhat.com>
 <4d8628bf1d8630c16de30d47732058ec82293429.1579631655.git.fweimer@redhat.com>
From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Message-ID: <dd59f273-a62f-114a-b718-57a0ac74567f@linaro.org>
Date: Thu, 13 Feb 2020 21:01:00 -0000
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On 21/01/2020 15:41, Florian Weimer wrote:
> res_vinit_1 did not close the stream on errors, only on success.
> This change moves closing the stream to __resolv_conf_load, for both
> the success and error cases.
> 
> Fixes commit 89f187a40fc0ad4e22838526bfe34d73f758b776 ("resolv: Use
> getline for configuration file reading in res_vinit_1") and commit
> 3f853f22c87f0b671c0366eb290919719fa56c0e ("resolv: Lift domain search
> list limits [BZ #19569] [BZ #21475]"), where memory allocation was
> introduced into res_vinit_1.
> ---
>  resolv/res_init.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/resolv/res_init.c b/resolv/res_init.c
> index 95dce098aa..09345718cd 100644
> --- a/resolv/res_init.c
> +++ b/resolv/res_init.c
> @@ -508,7 +508,6 @@ res_vinit_1 (FILE *fp, struct resolv_conf_parser *parser)
>                continue;
>              }
>          }
> -      fclose (fp);
>      }
>    if (__glibc_unlikely (nameserver_list_size (&parser->nameserver_list) == 0))
>      {
> @@ -593,6 +592,13 @@ __resolv_conf_load (struct __res_state *preinit)
>      }
>    resolv_conf_parser_free (&parser);
>  
> +  if (fp != NULL)
> +    {
> +      int saved_errno = errno;
> +      fclose (fp);
> +      __set_errno (saved_errno);
> +    }
> +
>    return conf;
>  }

Why not close the FILE on __resolv_conf_load? It make the FILE object 
cleanup as close as its creation, which usually improves readability.