bug#80583: "dd" fails to account for short final write

On 2026-03-11 11:54, Collin Funk wrote:
> Minor style thing, but I thought it looked a bit nicer to write:
> 
>    w_partial += nwritten != 0;

Hah! I had the following instead, which I thought was even clearer. 
Pádraig's change to src/dd.c is fine of course. First to fix and all that.

> diff --git a/src/dd.c b/src/dd.c                                                                                                                            
> index 07b1c6445..585d02bb6 100644                                                                                                                           
> --- a/src/dd.c                                                                                                                                              
> +++ b/src/dd.c                                                                                                                                              
> @@ -2261,15 +2261,13 @@ dd_copy (void)                                                                                                                      
>          {                                                                                                                                                  
>            idx_t nwritten = iwrite (STDOUT_FILENO, obuf, n_bytes_read);                                                                                     
>            w_bytes += nwritten;                                                                                                                             
> +          w_partial += 0 < nwritten && nwritten < input_blocksize;                                                                                         
> +          w_full += nwritten == input_blocksize;                                                                                                           
>            if (nwritten != n_bytes_read)                                                                                                                    
>              {                                                                                                                                              
>                diagnose (errno, _("error writing %s"), quoteaf (output_file));                                                                              
>                return EXIT_FAILURE;                                                                                                                         
>              }                                                                                                                                              
> -          else if (n_bytes_read == input_blocksize)                                                                                                        
> -            w_full++;                                                                                                                                      
> -          else                                                                                                                                             
> -            w_partial++;                                                                                                                                   
>            continue;                                                                                                                                        
>          }