On Fri, Jan 17, 2020 at 03:32:36PM +0100, SZEDER Gábor wrote:

On Mon, Jan 13, 2020 at 06:04:17PM +0100, SZEDER Gábor wrote:

quoted

and 'GIT_TEST_ADD_I_USE_BUILTIN=1 ./t3701-add-interactive.sh -r 39,49'
fails with:

  + test_must_fail force_color git add -p
  about to run diffFilter
  attempting to xwrite() 224 bytes to a fd with revents flags 0x4
  test_must_fail: died by signal 13: force_color git add -p

I don't understand why we get SIGPIPE right away instead of some error
that we can act upon (ECONNRESET?).

Doh', because it's a pipe, not a socket, that's why.  pipe(7):

  "If all file descriptors referring to the read end of a pipe have
   been closed, then a write(2) will cause a SIGPIPE signal to be
   generated for the calling process."

So ECONNRESET is definitely not the right error to set on POLLERR,
though I'm still not sure what the right one would be (perhaps
EPIPE?).

Yes, if SIGPIPE is ignored, then that write() would produce EPIPE. So if
you're trying to emulate it via POLLERR, that would be accurate. Of
course it could fail for _other_ reasons, and I don't think we'd know
what those are without actually calling write(). Practically speaking,
though, if we know it's a pipe with a valid descriptor then any error is
basically equivalent to EPIPE (we don't care how, but for whatever
reason we couldn't write to the other end).

-Peff