Re: [PATCH 1/2] sequencer: factor out rewrite_file()

["René Scharfe" <l.s.r@web.de>]

Am 03.11.2017 um 20:13 schrieb Jeff King:
> On Fri, Nov 03, 2017 at 10:44:08PM +0900, Junio C Hamano wrote:
> 
>> Simon Ruderich <simon@ruderich.org> writes:
>>
>>> I tried looking into this by adding a new write_file_buf_gently()
>>> (or maybe renaming write_file_buf to write_file_buf_or_die) and
>>> using it from write_file_buf() but I don't know the proper way to
>>> handle the error-case in write_file_buf(). Just calling
>>> die("write_file_buf") feels ugly, as the real error was already
>>> printed on screen by error_errno() and I didn't find any function
>>> to just exit without writing a message (which still respects
>>> die_routine). Suggestions welcome.
>>
>> How about *not* printing the error at the place where you notice the
>> error, and instead return an error code to the caller to be noticed
>> which dies with an error message?
> 
> That ends up giving less-specific errors.

Not necessarily.  Function could return different codes for different
errors, e.g. -1 for an open(2) error and -2 for a write(2) error, and
the caller could use that to select the message to show.

Basically all of the messages in wrapper.c consist of some text mixed
with the affected path path and a strerror(3) string, so they're
compatible in that way.  A single function (get_path_error_format()?)
could thus be used and callers would be able to combine its result with
die(), error(), or warning().

René