ping tech@, Any developer can comment on this patch? Thanks!
On 9/25/2018 10:10 PM, Nan Xiao wrote: > Hi tech@, > > I am reading write(2) manual, and come across the following example: > > for (off = 0; off < bsz; off += nw) > if ((nw = write(d, buf + off, bsz - off)) == 0 || nw == -1) > err(1, "write"); > > I am just wondering when the write(2) will return 0? If in some cases, > it will indeed return 0, according to the manual: > >> Upon successful completion the number of bytes which were written is > returned. Otherwise, a -1 is returned and the global variable errno is > set to indicate the error. > > Because the errno is only set when return value is -1, if write(2) > returns 0, the errno should be an undefined value, and "err(1, > "write");" also won't print correct information. > > If write(2) won't return 0, my following patch fixes the example code: > > diff --git write.2 write.2 > index c1686b1a910..db134959002 100644 > --- write.2 > +++ write.2 > @@ -164,7 +164,7 @@ ssize_t nw; > int d; > > for (off = 0; off < bsz; off += nw) > - if ((nw = write(d, buf + off, bsz - off)) == 0 || nw == -1) > + if ((nw = write(d, buf + off, bsz - off)) == -1) > err(1, "write"); > .Ed > .Sh ERRORS > > Thanks! > -- Best Regards Nan Xiao(肖楠)
