Re: [PATCH 02/11] repository: introduce repo_read_index_or_die

[Brandon Williams <bmwill@google.com>]

On 05/21, Stefan Beller wrote:
> On Fri, May 18, 2018 at 11:37 PM, Duy Nguyen <pclouds@gmail.com> wrote:
> > On Wed, May 16, 2018 at 03:21:09PM -0700, Stefan Beller wrote:
> >> A common pattern with the repo_read_index function is to die if the return
> >> of repo_read_index is negative.  Move this pattern into a function.
> >>
> >> This patch replaces the calls of repo_read_index with its _or_die version,
> >> if the error message is exactly the same.
> >>
> >> Signed-off-by: Stefan Beller <sbeller@google.com>
> >> ---
> >>  builtin/add.c               | 3 +--
> >>  builtin/check-ignore.c      | 7 ++++---
> >>  builtin/clean.c             | 4 ++--
> >>  builtin/mv.c                | 3 +--
> >>  builtin/reset.c             | 3 +--
> >>  builtin/rm.c                | 3 +--
> >>  builtin/submodule--helper.c | 3 +--
> >
> > 'git grep -w -A3 read_cache' tells me you're missing (*)
> 
> > (*) yes yes you did mention "if the error message is exactly the
> > same". But these look like good candicates to convert anyway
> >
> > builtin/diff-tree.c:    if (read_cache() < 0)
> > builtin/diff-tree.c-            die(_("index file corrupt"));
> >
> 
> I would expect this to be covered in a follow up patch as I did look
> for (read_cache() < 0) specifically.
> 
> > builtin/merge-ours.c:   if (read_cache() < 0)
> > builtin/merge-ours.c:           die_errno("read_cache failed");
> >
> > builtin/update-index.c: entries = read_cache();
> > builtin/update-index.c- if (entries < 0)
> > builtin/update-index.c-         die("cache corrupted");
> >
> > merge-ours.c is interesting because it uses die_errno() version
> > instead. I think that might give inaccurate diagnostics because we do
> > not only fail when a libc/system call fails in read_cache(), so it
> > should be safe to just use die() here.
> >
> > update-index.c is also interesting because it actually saves the
> > return value. I don't think it's used anywhere, so you can just drop
> > that 'entries' variable. But perhaps it's good to make
> > repo_read_index_or_die() return the number of entries too.
> 
> Yeah this series left out all the interesting cases, as I just sent it out
> without much thought.
> 
> Returning the number of entries makes sense.
> 
> One of the reviewers of the series questioned the overall goal of the
> series as we want to move away from _die() in top level code but this
> series moves more towards it.

I've heard every once in a while that we want to move toward this but I
don't believe there is an actual effort along those lines just yet.  For
that to be the case we would need a clearly defined error handling
methodology (aside from the existing "die"ing behavior), which we don't
currently have.

> 
> I don't know.
> 
> Stefan

-- 
Brandon Williams