[PATCH v2 0/7] Raw gpg output support for verify-commit and verify-tag

Currently, verify-commit and verify-tag produce human-readable output. This is great for humans, and awful for machines. It also lacks a lot of the information that GnuPG's --status-fd output provides.

For example, if you wanted to know
* the hash algorithm;
* whether the signature was made with a subkey; or
* the OpenPGP signature version
none of that information is available in the human-readable output.

This series introduces a --raw option for verify-commit and verify-tag. If it's used, they provide the gpg --status-fd output on standard error instead of the human-readable output. The series also adds tests for verify-tag, since there were none; these are based off the ones for verify-commit.

v2 of the series corrects one of two incompatibilities between verify-commit and verify-tag. If a valid signature was made with an untrusted key, verify-commit would exit 1, but verify-tag would exit 0. This has been corrected (as Michael J Gruber suggested); both now return 0, as the signature is in fact good.

The other incompatibility is that verify-tag --verbose always prints the tag contents even if no signature is found, while verify-commit --verbose does not print the commit. I left this alone, as it seemed easy enough to accommodate at the expense of making the code slightly uglier.

Changes since v1:
* Unify some of the code between verify-commit and verify-tag.
* Pass the --verbose and --raw options as flags instead of individual
  boolean arguments.
* Reorder the patches to ensure that verify-tag tests came before
  refactors, to avoid regressing functionality.
* Changed verify-commit to succeed if a signature is good, regardless of
  whether it is trusted, at Michael J Gruber's suggestion.

brian m. carlson (7):
  verify-tag: add tests
  verify-tag: share code with verify-commit
  verify-commit: add test for exit status on untrusted signature
  gpg: centralize signature check
  gpg: centralize printing signature buffers
  verify-commit: add option to print raw gpg status information
  verify-tag: add option to print raw gpg status information

 Documentation/git-verify-commit.txt |   4 ++
 Documentation/git-verify-tag.txt    |   4 ++
 builtin/verify-commit.c             |  25 ++++----
 builtin/verify-tag.c                |  30 +++++++---
 commit.c                            |  21 ++-----
 commit.h                            |   2 +-
 gpg-interface.c                     |  37 ++++++++++++
 gpg-interface.h                     |   6 ++
 t/t7030-verify-tag.sh               | 115 ++++++++++++++++++++++++++++++++++++
 t/t7510-signed-commit.sh            |  38 ++++++++++++
 10 files changed, 246 insertions(+), 36 deletions(-)
 create mode 100755 t/t7030-verify-tag.sh