What are cherry-pick's exit codes?
Hi folks,
We're developing some internal tooling wrapping git-cherry-pick and need to be able to distinguish its different error codes. Problem is: these exit codes don't seem to be documented in git-cherry-pick.txt.
Looking at the source, I found myself down the rabbit-hole very quickly. I'm not too familiar with the coding patterns quite yet -- but I'm pretty sure I eventually found myself redirected to git-commit in one case. At that point, I thought it better to ask here.
I'd like to document these exit codes in the manpage and I'm more than happy to submit the patch, but I thought I'd confirm my understanding first since it's based purely on reading the cherry-pick tests:
Exit code:
- 0: success, sequencer complete -- no conflicts
- 1: 'success', sequencer incomplete -- conflicts encountered
- 127: fatal -- lots of reasons -- I'm guessing this is value for the 'return -1' and 'return error(...)' statements speckled throughout the code, but it's been a long time since I cared about two's complement so I may be wrong here.
- 128: fatal -- sequence is interrupted, possibly due to some other fatal error, e.g., 'commit doesn't exist' or 'mainline parent number doesn't exist'
- 129: fatal -- there was nothing to cherry-pick at all (e.g. empty range)
I'm reasonably confident about 0/1 just anecdotally -- I'm less sure about everything else.
Obviously the actual text put in the manpage should be friendlier and possibly vaguer for clarity (paradoxical, perhaps, but it seems more direct to say '0 for success, 1 for conflicts, and anything else is a fatal error'), but I wanted to make sure that I have an actually- accurate understanding rather than something only surface-level.
Two questions:
1. Are the exit codes actually documented somewhere already that should simply be linked from git-cherry-pick.txt?
2. If not, is the above listing the exit codes accurate and complete?
Thanks!
--
Sean Allred
Quoted 10 lines · Sean Allred
Hi folks,
We're developing some internal tooling wrapping git-cherry-pick and need to be able to distinguish its different error codes. Problem is: these exit codes don't seem to be documented in git-cherry-pick.txt.
Looking at the source, I found myself down the rabbit-hole very quickly. I'm not too familiar with the coding patterns quite yet -- but I'm pretty sure I eventually found myself redirected to git-commit in one case. At that point, I thought it better to ask here.
This is definitely worth doing, and there's a bit of a rabbit hole here, so it'l also good you asked.
Quoted 9 lines
I'd like to document these exit codes in the manpage and I'm more than happy to submit the patch, but I thought I'd confirm my understanding first since it's based purely on reading the cherry-pick tests:
Exit code:
- 0: success, sequencer complete -- no conflicts
- 1: 'success', sequencer incomplete -- conflicts encountered
In general I think you'd do well to follow the template of what I did in 9144ba4cf52 (remote: add meaningful exit code on missing/existing, 2020-10-27).
In particular, I don't think we should exhaustively document exit codes for a given command, as we really have a hard time controlling all the possible values.
Rather, we should define specific non-zero values as having specific meanings, as I did with "git remote" in that commit.
We'd also ideally leave "exit(1)" alone, and if we need to disambiguate it start with "exit(2)", but maybe it's easy to make it unambiguous in this case, or it's already unambiguous...
Quoted 4 lines
- 127: fatal -- lots of reasons -- I'm guessing this is value for the 'return -1' and 'return error(...)' statements speckled throughout the code, but it's been a long time since I cared about two's complement so I may be wrong here.
If it's "return -1" you generally end up with 255 in your shell, although that's unportable both for the C language, and for POSIX.
See 19d75948ef7 (common-main.c: move non-trace2 exit() behavior out of trace2.c, 2022-06-02) for some code dealing with that (where we fake up the -1 to 255, for logging).
But from looking at cmd_cherry_pick() we catch any <0 return values and die() on them, but maybe we exit() elsewhere? Do you have an example of these.
Quoted 6 lines
- 128: fatal -- sequence is interrupted, possibly due to some other fatal error, e.g., 'commit doesn't exist' or 'mainline parent number doesn't exist'
- 129: fatal -- there was nothing to cherry-pick at all (e.g. empty range)
I think as in 9144ba4cf52 (remote: add meaningful exit code on missing/existing, 2020-10-27) it's good to just leave these undocumented.
We typically return these when we invoke die() or usage_with_options() (or similar).
So, if we are documenting them (which would be a good change, as an aside) that probably belongs in gitcli(7), we could then reference that from other man pages.
Quoted 9 lines
I'm reasonably confident about 0/1 just anecdotally -- I'm less sure about everything else.
Obviously the actual text put in the manpage should be friendlier and possibly vaguer for clarity (paradoxical, perhaps, but it seems more direct to say '0 for success, 1 for conflicts, and anything else is a fatal error'), but I wanted to make sure that I have an actually- accurate understanding rather than something only surface-level.
Quoted 4 lines
Two questions:
1. Are the exit codes actually documented somewhere already that should simply be linked from git-cherry-pick.txt?
No, just when we promise specific codes for specific commands. E.g. git-remote, git-config etc. come to mind.
Quoted 1 line
2. If not, is the above listing the exit codes accurate and complete?
I don't know, but skimming the code I don't see the "return 1", unless by the above " - 1" you mean "minus one", i.e. 255.
I.e. cmd_cherry_pick() calls run_sequencer(), which on error seems to return -1 for most things, which we then coerce to that die().
But I haven't looked in much detail, so...
Quoted 10 lines · Ævar Arnfjörð Bjarmason
In general I think you'd do well to follow the template of what I did in
9144ba4cf52(remote: add meaningful exit code on missing/existing, 2020-10-27).In particular, I don't think we should exhaustively document exit codes for a given command, as we really have a hard time controlling all the possible values.
Rather, we should define specific non-zero values as having specific meanings, as I did with "git remote" in that commit.
Definitely agree (this is roughly what I've had in my WIP patch), and I'm glad to see precedent for an explicit 'exit status' section.
Quoted 3 lines
We'd also ideally leave "exit(1)" alone, and if we need to disambiguate it start with "exit(2)", but maybe it's easy to make it unambiguous in this case, or it's already unambiguous...
I'm not 100% sure what you mean here, though. Do you mean that if something returns an exit code of '1', we shouldn't touch it without more specific review since it's more likely someone will be depending on that value?
I think in my case, at least for what I see right now, the more urgent need is getting exit codes documented -- but I can see where doing so might create a situation where we can't improve the exit codes in the future -- thus implying that the 'improving' and the 'documenting' may need to be done in one go.
Quoted 8 lines
Quoted 4 lines
- 127: fatal -- lots of reasons -- I'm guessing this is value for the 'return -1' and 'return error(...)' statements speckled throughout the code, but it's been a long time since I cared about two's complement so I may be wrong here.
If it's "return -1" you generally end up with 255 in your shell, although that's unportable both for the C language, and for POSIX.
Quoted 7 lines
See
19d75948ef7(common-main.c: move non-trace2exit()behavior out oftrace2.c, 2022-06-02) for some code dealing with that (where we fake up the -1 to 255, for logging).But from looking at
cmd_cherry_pick()we catch any <0 return values anddie()on them, but maybe weexit()elsewhere? Do you have an example of these.
No, I don't think so -- at least not by the point we hit 'run_git_command()'.
Quoted 11 lines
Quoted 6 lines
- 128: fatal -- sequence is interrupted, possibly due to some other fatal error, e.g., 'commit doesn't exist' or 'mainline parent number doesn't exist'
- 129: fatal -- there was nothing to cherry-pick at all (e.g. empty range)
I think as in
9144ba4cf52(remote: add meaningful exit code on missing/existing, 2020-10-27) it's good to just leave these undocumented.
Quoted 6 lines
We typically return these when we invoke
die()orusage_with_options()(or similar).So, if we are documenting them (which would be a good change, as an aside) that probably belongs in gitcli(7), we could then reference that from other man pages.
Ah, gitcli(7) makes sense for these statuses. I'll see about submitting a patch for review later tonight / this week; I'm cautiously optimistic that it will be straightforward.
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Quoted 1 line
2. If not, is the above listing the exit codes accurate and complete?
I don't know, but skimming the code I don't see the "return 1", unless by the above " - 1" you mean "minus one", i.e. 255.
I do indeed mean 'negative one'.
Quoted 4 lines
I.e.
cmd_cherry_pick()callsrun_sequencer(), which on error seems to return -1 for most things, which we then coerce to thatdie().But I haven't looked in much detail, so...
Seems like I (or someone) has some pretty 'fun' code tracing in my future...
What's the next step here? Submit a patch with my best effort and suss out the problems during review?
--
Sean Allred
Hi Sean
Quoted 11 lines · Sean Allred
Hi folks,
We're developing some internal tooling wrapping git-cherry-pick and need to be able to distinguish its different error codes. Problem is: these exit codes don't seem to be documented in git-cherry-pick.txt.
Looking at the source, I found myself down the rabbit-hole very quickly. I'm not too familiar with the coding patterns quite yet -- but I'm pretty sure I eventually found myself redirected to git-commit in one case. At that point, I thought it better to ask here.
Quoted 7 lines
I'd like to document these exit codes in the manpage and I'm more than happy to submit the patch, but I thought I'd confirm my understanding first since it's based purely on reading the cherry-pick tests:
Exit code:
- 0: success, sequencer complete -- no conflicts
I believe this is correct.
Quoted 1 line
- 1: 'success', sequencer incomplete -- conflicts encountered
One can get exit code 1 without conflicts. One example is when it cannot cherry-pick a commit because it would overwrite an untracked file. Another example is when a picked commit would be empty because the changes are already in HEAD.
Quoted 11 lines
- 127: fatal -- lots of reasons -- I'm guessing this is value for the 'return -1' and 'return error(...)' statements speckled throughout the code, but it's been a long time since I cared about two's complement so I may be wrong here.
- 128: fatal -- sequence is interrupted, possibly due to some other fatal error, e.g., 'commit doesn't exist' or 'mainline parent number doesn't exist'
- 129: fatal -- there was nothing to cherry-pick at all (e.g. empty range)
A high exit code from die() indicates something bad happened but I'm not sure one can rely on the exact value to tell you what happened.
Best Wishes
Phillip
Quoted 20 lines
I'm reasonably confident about 0/1 just anecdotally -- I'm less sure about everything else.
Obviously the actual text put in the manpage should be friendlier and possibly vaguer for clarity (paradoxical, perhaps, but it seems more direct to say '0 for success, 1 for conflicts, and anything else is a fatal error'), but I wanted to make sure that I have an actually- accurate understanding rather than something only surface-level.
Two questions:
1. Are the exit codes actually documented somewhere already that should simply be linked from git-cherry-pick.txt?
2. If not, is the above listing the exit codes accurate and complete?
Thanks!
--
Sean Allred
Quoted 4 lines · Phillip Wood
One can get exit code 1 without conflicts. One example is when it cannot cherry-pick a commit because it would overwrite an untracked file. Another example is when a picked commit would be empty because the changes are already in HEAD.
These are good cases to know/test, thank you!
--
Sean Allred