On 21 October 2014 10:02, Yousong Zhou <yszhou4t...@gmail.com> wrote:
> Hi, Pär. I got a few comments inline.
>
> On 21 October 2014 05:47, Pär Karlsson <feino...@gmail.com> wrote:
>> Whoops, I realised I failed on the GNU coding standards, please disregard
>> the last one; the patch below should be better.
>>
>> My apologies :-/
>>
>> /Pär
>>
>> diff --git a/src/ChangeLog b/src/ChangeLog
>> index d5aeca0..87abd85 100644
>> --- a/src/ChangeLog
>> +++ b/src/ChangeLog
>> @@ -1,3 +1,8 @@
>> +2014-10-20 Pär Karlsson <feino...@gmail.com>
>> +
>> + * utils.c (concat_strings): got rid of double loop, cleaned up
>> potential
>> + memory corruption if concat_strings was called with more than five
>> args
>> +
>> 2014-10-16 Tim Ruehsen <tim.rueh...@gmx.de>
>>
>> * url.c (url_parse): little code cleanup
>> diff --git a/src/utils.c b/src/utils.c
>> index 78c282e..5f359e0 100644
>> --- a/src/utils.c
>> +++ b/src/utils.c
>> @@ -356,42 +356,36 @@ char *
>> concat_strings (const char *str0, ...)
>> {
>> va_list args;
>> - int saved_lengths[5]; /* inspired by Apache's apr_pstrcat */
>> char *ret, *p;
>>
>> const char *next_str;
>> - int total_length = 0;
>> - size_t argcount;
>> + size_t len;
>> + size_t total_length = 0;
>> + size_t charsize = sizeof (char);
>
> I am not sure here. Do we always assume sizeof(char) to be 1 for
> platforms supported by wget?
>
>> + size_t chunksize = 64;
>> + size_t bufsize = 64;
>> +
>> + p = ret = xmalloc (charsize * bufsize);
>>
>> /* Calculate the length of and allocate the resulting string. */
>>
>> - argcount = 0;
>> va_start (args, str0);
>> for (next_str = str0; next_str != NULL; next_str = va_arg (args, char *))
>> {
>> - int len = strlen (next_str);
>> - if (argcount < countof (saved_lengths))
>> - saved_lengths[argcount++] = len;
>> + len = strlen (next_str);
>> + if (len == 0)
>> + continue;
>> total_length += len;
>> - }
>> - va_end (args);
>> - p = ret = xmalloc (total_length + 1);
>> -
>> - /* Copy the strings into the allocated space. */
>> -
>> - argcount = 0;
>> - va_start (args, str0);
>> - for (next_str = str0; next_str != NULL; next_str = va_arg (args, char *))
>> - {
>> - int len;
>> - if (argcount < countof (saved_lengths))
>> - len = saved_lengths[argcount++];
>> - else
>> - len = strlen (next_str);
>> + if (total_length > bufsize)
>> + {
>> + bufsize += chunksize;
>
> Should be `bufsize = total_length` ?
>
>> + ret = xrealloc (ret, charsize * bufsize);
>> + }
>> memcpy (p, next_str, len);
>
> Xrealloc may return a new block different from p, so memcpy(p, ...)
> may not be what you want.
>
>> p += len;
>> }
>> va_end (args);
>> + ret = xrealloc (ret, charsize * total_length + 1);
>> *p = '\0';
>
> Malloc takes time. How about counting total_length in one loop and
> doing the copy in another?
I mean, we can skip the strlen part and just do strcpy in the second
loop as we already know we have enough space in the dest buffer for
all those null-terminated arguments.
yousong
