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Re: [PATCH] gethostid (Linux variant): Switch to struct scratch_buffer [BZ #18023]
- From: Andreas Schwab <schwab at suse dot de>
- To: Florian Weimer <fweimer at redhat dot com>
- Cc: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>, libc-alpha at sourceware dot org
- Date: Tue, 18 Sep 2018 12:51:27 +0200
- Subject: Re: [PATCH] gethostid (Linux variant): Switch to struct scratch_buffer [BZ #18023]
- References: <20180626154633.BC8B943994575@oldenburg.str.redhat.com> <aa50fb15-99d8-28c3-d3ea-a883a8563634@linaro.org> <df00e77d-528d-e410-ecb2-7699d45ebd5d@redhat.com>
On Jun 26 2018, Florian Weimer <fweimer@redhat.com> wrote:
> @@ -88,29 +88,43 @@ gethostid (void)
> return id;
> }
>
> - /* Getting from the file was not successful. An intelligent guess for
> - a unique number of a host is its IP address. Return this. */
> + /* Getting from the file was not successful. An intelligent guess
> + for a unique number of a host is its IP address. To get the IP
> + address we need to know the host name. */
> if (__gethostname (hostname, MAXHOSTNAMELEN) < 0 || hostname[0] == '\0')
> /* This also fails. Return and arbitrary value. */
> return 0;
>
> - buflen = 1024;
> - buffer = __alloca (buflen);
> -
> - /* To get the IP address we need to know the host name. */
> - while (__gethostbyname_r (hostname, &hostbuf, buffer, buflen, &hp, &herr)
> - != 0
> - || hp == NULL)
> - if (herr != NETDB_INTERNAL || errno != ERANGE)
> - return 0;
> - else
> - /* Enlarge buffer. */
> - buffer = extend_alloca (buffer, buflen, 2 * buflen);
> + /* Determine the IP address of the host name. */
> + struct scratch_buffer tmpbuf;
> + scratch_buffer_init (&tmpbuf);
> + while (true)
> + {
> + int ret = __gethostbyname_r (hostname, &hostbuf,
> + tmpbuf.data, tmpbuf.length, &hp, &herr);
> + if (ret == 0)
> + break;
That fails to handle hp == NULL any more, see bug 23679.
Andreas.
--
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."