Re: [PATCH 2/2] fopencookie.3: Fix bugs in example

["Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>]

Hello Alex,

On 9/7/20 12:21 PM, Alejandro Colomar wrote:
> fread(3), unlike read(2) which returns a ssize_t, returns a size_t.
> It doesn't distinguish between error and enf-of-file.
> Instead, either ferror(3) or feof(3) need to be checked if
> fread() returned 0.

Well, gosh, the person who wrote that example really 
should have read the documentation more closely :-}.

Thanks. Patch applied.

Cheers,

Michael

> Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
> ---
>  man3/fopencookie.3 | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/man3/fopencookie.3 b/man3/fopencookie.3
> index 5394ce4a5..055ec64d7 100644
> --- a/man3/fopencookie.3
> +++ b/man3/fopencookie.3
> @@ -392,7 +392,7 @@ main(int argc, char *argv[])
>      };
>      FILE *stream;
>      struct memfile_cookie mycookie;
> -    ssize_t nread;
> +    size_t nread;
>      char buf[1000];
>  
>      /* Set up the cookie before calling fopencookie() */
> @@ -429,11 +429,11 @@ main(int argc, char *argv[])
>              exit(EXIT_FAILURE);
>          }
>          nread = fread(buf, 1, 2, stream);
> -        if (nread == \-1) {
> -            perror("fread");
> -            exit(EXIT_FAILURE);
> -        }
>          if (nread == 0) {
> +            if (ferror(stream) != 0) {
> +                fprintf(stderr, "fread failed\en");
> +                exit(EXIT_FAILURE);
> +            }
>              printf("Reached end of file\en");
>              break;
>          }
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/