[PATCH 0/7] Submodule improvements

This series is a reroll consisting of hv/submodule-config and sb/submodule-helper and it applies on top of origin/jk/git-path.

Our long term goal is to make submodule handling more scalable by parallelizing the submodule code. To write good parallelizable code I'd first want to port it to C, as there are no good portable solutions for shell scripts to run in parallel. This series is a first step on porting git-submodule.sh to C.

I did not alter the patches of Heiko, except for squashing $gmane/275799 (2 cleanup patches I proposed 5 days ago).

The module_{list, name, clone} functions are a direct translation of the shell counter parts. I took way longer than expected for module_clone, as I was fighting with absolute and relative paths for too long. (Whenever shell is translated to C, I estimate two times the number of lines of code which fits quite reasonably.)

Thanks, Stefan

Heiko Voigt (4):
  submodule: implement a config API for lookup of .gitmodules values
  submodule: extract functions for config set and lookup
  submodule: use new config API for worktree configurations
  submodule: Allow errornous values for the fetchrecursesubmodules
    option

Stefan Beller (3):
  submodule: implement `module_list` as a builtin helper
  submodule: implement `module_name` as a builtin helper
  submodule: implement `module_clone` as a builtin helper

 .gitignore                                       |   2 +
 Documentation/technical/api-submodule-config.txt |  62 +++
 Makefile                                         |   3 +
 builtin.h                                        |   1 +
 builtin/checkout.c                               |   1 +
 builtin/fetch.c                                  |   1 +
 builtin/submodule--helper.c                      | 299 ++++++++++++++
 diff.c                                           |   1 +
 git-submodule.sh                                 | 164 +-------
 git.c                                            |   1 +
 submodule-config.c                               | 482 +++++++++++++++++++++++
 submodule-config.h                               |  29 ++
 submodule.c                                      | 122 ++----
 submodule.h                                      |   4 +-
 t/t7411-submodule-config.sh                      | 153 +++++++
 test-submodule-config.c                          |  76 ++++
 16 files changed, 1154 insertions(+), 247 deletions(-)
 create mode 100644 Documentation/technical/api-submodule-config.txt
 create mode 100644 builtin/submodule--helper.c
 create mode 100644 submodule-config.c
 create mode 100644 submodule-config.h
 create mode 100755 t/t7411-submodule-config.sh
 create mode 100644 test-submodule-config.c