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[Michael Widenius <monty@xxxxxxxxxxxx>]

Hi!

>>>>> "Lixun" == Lixun Peng <penglixun@xxxxxxxxx> writes:

Lixun> Hi Guys,
Lixun> I want to copy the contents of the IO_CACHE into a string.
Lixun> But I'm not found a function can do it, but I found
Lixun> "my_b_copy_to_file" can do the similar thing, so I implement a
Lixun> function "my_b_copy_to_string" by imitating "my_b_copy_to_file", to do
Lixun> this thing.

Lixun> Could you please review my code?


Lixun> char *my_b_copy_to_string(IO_CACHE *cache, size_t *bytes_in_cache)
Lixun> {
Lixun>   char *buff;
Lixun>   char *tmp_buff;
Lixun>   size_t now_size;
Lixun>   size_t inc_size;

Lixun>   /* Reinit the cache to read from the beginning of the cache */
Lixun>   if (reinit_io_cache(cache, READ_CACHE, 0L, FALSE, FALSE))
Lixun>     return NULL;

Lixun>   now_size= my_b_bytes_in_cache(cache);
Lixun>   inc_size= 0;
Lixun>   buff= (char *) my_malloc(now_size + 1, MYF(0));
Lixun>   tmp_buff= buff;
Lixun>   do
Lixun>   {
Lixun>     now_size+= inc_size;
Lixun>     if(inc_size > 0)
Lixun>     {
Lixun>       buff= (char *) my_realloc(buff, now_size + 1, MYF(0));
Lixun>       tmp_buff= buff + (now_size - inc_size);
Lixun>       memcpy(tmp_buff, cache->read_pos, inc_size);
Lixun>     }
Lixun>     else
Lixun>     {
Lixun>       memcpy(tmp_buff, cache->read_pos, now_size);
Lixun>     }
Lixun>     cache->read_pos= cache->read_end;
Lixun>   } while ((inc_size= my_b_fill(cache)));
Lixun>   buff[now_size]= '\0';

Lixun>   reinit_io_cache(cache, WRITE_CACHE, 0, FALSE, TRUE);
Lixun>   *bytes_in_cache= now_size;
Lixun>   return buff;
Lixun> }

A simpler way would be to use a String object, as this will
automaticly do all allocations for you.

In all normal cases, info->end_of_file contains the length of the
file.  This allows you to calculate the buffer once and for all and
simplify the code to something like:

if (reinit_io_cache(cache, READ_CACHE, 0L, FALSE, FALSE))
  return NULL;
if (!(buff= my_malloc(cache->end_of_file+1, MYF(MY_WME))))
  return NULL;
if (my_b_read(cache, buff, cache->end_of_file))
{
  my_free(buff);
  return NULL;
}
reinit_io_cache(cache, WRITE_CACHE, 0, FALSE, TRUE);
*bytes_in_cache= cache->end_of_file+1;
return buff;

Regards,
Monty