[Libguestfs] [PATCH libguestfs] generator.ml: constify do_mkdtemp

[Jim Meyering]

Richard W.M. Jones wrote:

> On Tue, Aug 11, 2009 at 05:20:37PM +0200, Jim Meyering wrote:
>> Not useful from a testing standpoint (since this presumes
>> a metric ton of other changes), but mostly a heads-up where I'm going.
>> +  char *r = strdup (template);
>> +  if (r == NULL) {
>> +    reply_with_perror ("strdup");
>> +    return NULL;
>> +  }
>>
>>    CHROOT_IN;
>> -  r = mkdtemp (template);
>> +  r = mkdtemp (r);
>>    CHROOT_OUT;
>>
>> -  if (r == NULL) {
>> +  if (r == NULL)
>>      reply_with_perror ("mkdtemp: %s", template);
>> -    return NULL;
>> -  }
>>
>> -  /* The caller will free template AND try to free the return value,
>> -   * so we must make a copy here.
>> -   */
>> -  if (r == template) {
>> -    r = strdup (template);
>> -    if (r == NULL) {
>> -      reply_with_perror ("strdup");
>> -      return NULL;
>> -    }
>> -  }
>>    return r;
>
> I think 'r' gets leaked along the error path (when mkdtemp returns NULL).

Good catch!
Here's the new version:

char *
do_mkdtemp (const char *template)
{
  char *writable = strdup (template);
  if (writable == NULL) {
    reply_with_perror ("strdup");
    return NULL;
  }

  CHROOT_IN;
  char *r = mkdtemp (writable);
  CHROOT_OUT;

  if (r == NULL) {
    reply_with_perror ("mkdtemp: %s", template);
    free (writable);
  }

  return r;
}