[PATCH] gethostid (Linux variant): Switch to struct scratch_buffer [BZ #18023]

[Florian Weimer]

* Andreas Schwab:

> 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.

Oops.  Do you want me to write a patch?