[PATCH v3 0/4] RUNTIME_PREFIX relocatable Git

Previous threads: v1: https://public-inbox.org/git/20171116170523.28696-1-dnj@google.com/ v2: https://public-inbox.org/git/20171119173141.4896-1-dnj@google.com/

After working with avarab@, I isolated the Perl changes into a separate set of patches and adapted the code to be more correct and readable. I opted to prescribe a relative Perl library path instead of letting MakeMaker or the Config module choose one, since the latter both incorporate build system parameters and a major purpose of this is to be portable between ABI-compatible systems.

I've tested this via Travis and run full test suite with and without RUNTIME_PREFIX/RUNTIME_PREFIX_PERL, and tested locally on Mac, Linux, and FreeBSD systems. Please take a look!

Built using this "config.mak":

=== BEGIN config.mak ===

RUNTIME_PREFIX = YesPlease RUNTIME_PREFIX_PERL = YesPlease gitexecdir = libexec/git-core template_dir = share/git-core/templates sysconfdir = etc

=== END config.mak ===

Changes in v3 from v2:

- Broken into multiple patches now that Perl is isolated in its own
  RUNTIME_PREFIX_PERL flag.

- Working with avarab@, several changes to Perl script runtime prefix
  support:

  - Moved Perl header body content from Makefile into external template
    file(s).

  - Added generic "perllibdir" variable to override Perl installation
    path.

  - RUNTIME_PREFIX_PERL generated script header is more descriptive and
    consistent with how the C version operates.

  - Fixed Generated Perl header Makefile dependency, should rebuild
    when dependent files and flags change.

- Changed some of the new RUNTIME_PREFIX trace strings to use consistent
  formatting and terminology.

Changes in v2 from v1:

- Added comments and formatting to improve readability of
  platform-sepecific executable path resolution sleds in
  `git_get_exec_path`.

- Consolidated "cached_exec_path" and "argv_exec_path" globals
  into "exec_path_value".

- Use `strbuf_realpath` instead of `realpath` for procfs resolution.

- Removed new environment variable exports. Git with RUNTIME_PREFIX no
  longer exports or consumes any additional environment information.

- Updated Perl script resolution strategy: rather than having Git export
  the relative executable path to the Perl scripts, they now resolve
  it independently when RUNTIME_PREFIX_PERL is enabled.

- Updated resolution strategy for "gettext()": use system_path() instead
  of special environment variable.

- Added `sysctl` executable resolution support for BSDs that don't
  mount "procfs" by default (most of them).

Dan Jacques (4):
  Makefile: generate Perl header from template file
  Makefile: add support for "perllibdir"
  Makefile: add Perl runtime prefix support
  exec_cmd: RUNTIME_PREFIX on some POSIX systems

 .gitignore                             |   1 +
 Makefile                               | 110 +++++++++++++--
 cache.h                                |   1 +
 common-main.c                          |   4 +-
 config.mak.uname                       |   7 +
 exec_cmd.c                             | 239 ++++++++++++++++++++++++++++-----
 exec_cmd.h                             |   4 +-
 gettext.c                              |   8 +-
 git.c                                  |   2 +-
 perl/Makefile                          |  52 ++++++-
 perl/header_fixed_prefix.pl.template   |   1 +
 perl/header_runtime_prefix.pl.template |  24 ++++
 12 files changed, 395 insertions(+), 58 deletions(-)
 create mode 100644 perl/header_fixed_prefix.pl.template
 create mode 100644 perl/header_runtime_prefix.pl.template