On Thu, Jun 18, 2020 at 08:37:02AM +0000, Walter Harms wrote: > Isn't it already covered by this fragment: > > "If an error occurs, or the end of the file is reached, the return > value is a short item count (or zero)." > > IMHO no, > what does a "short item count" mean ? "items of data" refers to nmemb: "The function fread() reads nmemb items of data" so "item count" means number of size-long sequences of bytes and "short" means fewer than requested. But I think you know that well and you just think that "short item count" is not clear enough, right? (And of course I hope that I get it right.) > E.g. my size is 4 bytes and there are 3 bytes left to read. what is > the return value? If the requested size is 4 but there are only 3 bytes left then fread() will return 0, no matter what's the value of nmemb because it's not able to read even a single item and feof() will return non-zero. I think that this is explained clearly enough in the manpage. > and will the last few bytes ever read ? That is interesting. POSIX https://pubs.opengroup.org/onlinepubs/9699919799.2008edition/ says that "If a partial element is read, its value is unspecified.". But as fread() returns number of items it has successfully read the returned value should always be checked and it's different than requested nmemb it means an error and I guess there is no way to tell how many bytes have been partially read - for example if size == 4 and nmemb == 1 and returned value is 0 you don't know if fread() read 1, 2 or 3 bytes. Anyway, the patch that I sent explains that file pointer is moved after fread()/fwrite(). The discussion about return value should be started in a separate thread. -- Arkadiusz Drabczyk <arkadiusz@xxxxxxxxxxxx>
