On 19-Jul-2021, at 08:28, Kaartic Sivaraam <kaartic.sivaraam@xxxxxxxxx> wrote: > > Hi Atharva and all, > > On 19/07/21 12:49 am, Kaartic Sivaraam wrote: >> On 18/07/21 5:29 pm, Atharva Raykar wrote: >>> Passing the superprefix explicitly >> My gut instinct tells me we could get away without having to go this way but >> I haven't yet been able to figure out how. How 'prefix', 'super-prefix' and >> 'recursive-prefix' is still puzzling me. In case anyone has knowledge about >> this please chime in and enlighten us. It would be very helpful. >> > > I just noticed I was short and unhelpful here. To expand on what information would be > helpful on this respect, here's a snippet of a private e-mail I sent which I've > tweaked a little to make it relevant for the list audience: > > -- 8< -- >>> ... >>> > > I took a look at this. I'm not able to find the exact issue but my gut instinct tells me > it has something to do with how prefix, super-prefix and recursive-prefix > are handled before and after the conversion. To be more specific, I'm having doubts > about whether the following code snippet[4] in shell ... > > prefix=$(git submodule--helper relative-path "$prefix$sm_path/" "$wt_prefix") > wt_prefix= > sanitize_submodule_env > cd "$sm_path" && > eval cmd_update > > ... has been properly converted to C. Particularly, the fact that recursive calls to > 'cmd_update' is made in the existing shell implementation in case '--recusive' is > passed needs to be observed well. This would subsequently result in multiple calls to > 'cmd_init' with different 'prefix' and 'wt_prefix' values. So, that needs to be > observed well too. The whole deal with prefixes confused me initially a lot as well, so I'll try to explain what's going on there first, and then show why I had trouble with it. The terminology of 'recursive-prefix' was something I borrowed from the update-clone helper[5]. Just to give you a summary of which shell variable maps to which C variable, along with my understanding of what they represent: | shell | C | description | |------------+------------------+-------------------------------------------| | $prefix | recursive_prefix | this represents the superproject prefix, | | | | ie, the path of the superproject relative | | | | to the current subproject. | | | | | | $wt_prefix | prefix | this is the path into the working tree, | | | | ie, the path of the directory from the | | | | root of the git directory's worktree | The display paths that are generated for the error messages require one of these to be non-NULL, but not both[6]. I feel confident the values of the various prefixes are handled properly during the recursion because I setup a new worktree on based master as my "control", and a combination of running with GIT_TRACE2 and printing the values showed me that both of them handle the prefixes identically. The issue with the subprocess approach[7] seems to be not with the prefixes, but rather with the configuration not being properly read when it is set in the same command invocation. [5] https://github.com/git/git/blob/75ae10bc75336db031ee58d13c5037b929235912/git-submodule.sh#L536-L550 [6] https://github.com/git/git/blob/75ae10bc75336db031ee58d13c5037b929235912/builtin/submodule--helper.c#L258-L260 [7] https://github.com/tfidfwastaken/git/commits/submodule-helper-update-1a > I have not been able to get a complete picture of this myself. I'll try to take better > look later and see if I could get anything. > > Note that this could also be me just not being able to get a proper picture of it. > Just wanted to share it in case others are able to get any ideas or able to think of a > possible cause. > > [4]: https://github.com/git/git/blob/abb21c7263616f01c5e950861a29279ab21cb02f/git-submodule.sh#L654-L658 > -- >8 -- > > I hope that gives a better idea about what kind of information would be helpful. > Kindly let me know if it doesn't. > > Atharva, > > In the meanwhile, I think you could continue polishing your attempted solution > and preparing to send it to the list. I'll try to dig more on my gut instinct > and let you know if I get anything. If you have some free time left after > polishing your series, you could try digging into it too :) Sure. Thanks for the time and effort you are putting into this! > -- > Sivaraam
