Ops... :-(
Thank you very much!
On Mon, Apr 13, 2020 at 10:38 AM Christian Grothoff <[email protected]>
wrote:
> You're using strncpy(), which does NOT add the 0-terminator at the end
> that printf() expects.
>
> On 4/13/20 11:27 AM, Imóveis Nacionais wrote:
> > But I am just handling arrived data when *upload_data_size > 0. Here is
> > the code:
> >
> > else if(strcmp(method, "POST") == 0)
> > {
> > ST_PER_THREAD_DATA* pstThreadData = *ptr;
> > if( pstThreadData == NULL)
> > {
> > ST_PER_THREAD_DATA * cThreadData = (ST_PER_THREAD_DATA*)
> > malloc(sizeof(ST_PER_THREAD_DATA));
> > cThreadData->nThreadID = nThID;
> > cThreadData->strData[0]='\0';
> >
> > *ptr = cThreadData;
> > return MHD_YES;
> > }
> >
> > if(*upload_data_size > 0)
> > {
> > printf("Before strcpy (%s) (%s)
> > (%d)\n",pstThreadData->strData,upload_data,*upload_data_size);
> >
> strncpy(pstThreadData->strData,upload_data,*upload_data_size);
> > printf("After strcpy (%s) (%s)
> > (%d)\n",pstThreadData->strData,upload_data,*upload_data_size);
> >
> > *upload_data_size = 0;
> > return MHD_YES;
> >
> > //After strcpy ({"key98"}) ({"key98"}) (9)
> > }
> > else
> > {
> > //END OF POST DATA GATHERING
> > printf("In the end of post we have (%s) (%d)
> > \n",pstThreadData->strData, strlen(pstThreadData->strData));
> > HandleClientPost(pstThreadData->strData))
> > //In the end of post we have ({"key98"}) (10)
> > ...
> >
> > Please, is there anything wrong with the (testing) code?
> >
> > Thank you
> >
> >
> >
> > On Mon, Apr 13, 2020 at 10:00 AM Christian Grothoff <[email protected]
> > <mailto:[email protected]>> wrote:
> >
> > On 4/13/20 2:11 AM, Imóveis Nacionais wrote:
> > > Then when in the "*upload_data_size = 0" situation, using a printf
> > > sometimes I can see that the thread context data has the 0x7f char
> > appended
> > > and of course the strlen now is one char extra. This happens
> > between the
> > > last post call with *upload_data_size > 0 and *upload_data_size =
> 0.
> > >
> > > Does this char has any meaning in the libmicrohttpd context?
> > > Why is this char being added?
> >
> > You're seeing undefined behavior. When '*upload_data_size' is zero,
> you
> > are not allowed to look into '*upload_data'. It is NEVER warranted
> to be
> > a 0-terminated char* in the first place, and right now you're just
> > reading data out of bounds. Do not rely on getting 0x7f or anything
> > meaningful, in fact, expect reading more than '*upload_data_size'
> bytes
> > from '*upload_data' to be deadly.
> >
> > Happy hacking!
> >
> > Christian
> >
>
>
