[BUG?] trailer command with multiple keys

The command

printf "body\n\ntest: foo\ntest: froz\n" | git -c trailer.test.key=tested -c trailer.test.command="echo by \$ARG" interpret-trailers

gives:

body

tested: foo tested: froz tested: by froz

I expected the command to be run on each "test" key, resulting in the output:

body:

tested: by foo tested: by froz

(In a real life scenario, I would use ifexists replace.)[*]

Maybe my expectation is wrong? The code breaks out of the loop after the first matching in_tok, apparently intentionally so. But I'm not sure - the key is replaced for both instances.

Simply replacing that "return 1" by a "ret = 1" etc. runs into problems with the way the freeing of in_tok and arg_tok is arranged there :|

Basically, I expected the trailer command to work "grep/sed-like" on all key value pairs that have matching keys, passing the value to the command, and using the (each) command's output as the new value for each of these pairs.

Michael

[*] My prime use case: fill in reported-by etc. with short author names, completed the same way we complete --author=jun using a trailer command (interpret-trailers in the commit-msg hook):

$ git help author `git author' is aliased to `!f() { a=$(git log -1 --all -i --format="%aN <%aE>" --author "$1"); echo ${a:-$1}; }; f'

$ cat .git/hooks/commit-msg #!/bin/sh git interpret-trailers --in-place "$1"

$ git config --get-regexp trailer trailer.report.key Reported-by trailer.report.command git author '$ARG' trailer.report.ifexists replace trailer.report.ifmissing doNothing

On Mon, Jun 6, 2016 at 2:27 PM, Michael J Gruber <git@drmicha.warpmail.net> wrote:

I wouldn't say that it is wrong, but for now trailer configuration applies mostly to trailer passed as argument to `git interpret-trailers`.

So you could perhaps get something close to what you want with:

-------- $ printf "body\n\n" | git -c trailer.test.key=tested -c trailer.test.command="/home/christian/git/test/interpret-trailers/trailer-script.sh \$ARG" interpret-trailers --trim-empty --trailer='test: foo' --trailer='test: frotz' body

tested: by foo tested: by frotz --------

and:

-------- $ cat /home/christian/git/test/interpret-trailers/trailer-script.sh #!/bin/sh test -n "$1" && echo "by $1" : --------

Yeah, it could have been designed like that.

The problem is that something like:

               $ git config trailer.sign.key "Signed-off-by: "
               $ git config trailer.sign.ifmissing add
               $ git config trailer.sign.ifexists doNothing
               $ git config trailer.sign.command 'echo "$(git config
user.name) <$(git config user.email)>"'

and piping any commit message into "git interpret-trailers" should work too.

In short it's not very natural to have both of the following by default:

- a configured command should run once to get a chance to add a new
trailer, even it doesn't exist in the input file
- a configured command should run once per trailer in the input file

(especially because as I said above for now configuration applies mostly to trailers on the command line).

One solution could be to add support for a new trailer.<token>.commandMode config option that could take values like "onceAnyway", "oncePerMatchingTrailerInInputFile", "oncePerMatchingTrailerOnCommandLine" and it should be possible to use one or more of those modes, like for example:

trailer.stuff.commandMode=onceAnyway,oncePerMatchingTrailerInInputFile

Yeah, it would be nice to be able to have things like that.