[PATCH v2 0/5] fast-import: extend signed object handling modes

[Justin Tobler <jltobler@gmail.com>]

Greetings,

The '--signed-{commits,tags}=<mode>' options for git-fast-import(1)
allow users to configure how signed objects should be handled at time of
import. With c20f112e51 (fast-import: add 'strip-if-invalid' mode to
--signed-commits=<mode>, 2025-11-17) and ee66c793f8 (fast-import: add
mode to sign commits with invalid signatures, 2026-03-12), the
'strip-if-invalid' and 'sign-if-invalid' modes were added for the
'--signed-commits' option only.

This series extends '--signed-commits' by adding an 'abort-if-invalid'
mode which aborts the entire import operation when a commit signature
fails verification. Additionally, the '--signed-tags' option is brought
into parity with '--signed-commits' by supporting equivalent,
'strip-if-invalid', 'sign-if-invalid', and 'abort-if-invalid' modes.

This series is built on top of 1080981ddb (The 19th batch, 2026-03-23)
with ee66c793f8 (fast-import: add mode to sign commits with invalid
signatures, 2026-03-12) merged into it.

Changes since V1:
- Added a prepatory patch which unifies how unsupported signing modes
  are handled for git-fast-export(1). Now they are treated like any
  other unknown signing mode. Unsupported signing modes for
  '--signed-tags' in git-fast-import(1) are left alone because this
  series progressively adds support for all these currently unsupported
  modes.

Thanks,
-Justin

Justin Tobler (5):
  fast-export: check for unsupported signing modes earlier
  fast-import: add 'abort-if-invalid' mode to '--signed-commits=<mode>'
  fast-import: add 'strip-if-invalid' mode to '--signed-tags=<mode>'
  fast-import: add 'sign-if-invalid' mode to '--signed-tags=<mode>'
  fast-import: add 'abort-if-invalid' mode to '--signed-tags=<mode>'

 Documentation/git-fast-import.adoc |   9 ++-
 builtin/fast-export.c              |  15 +---
 builtin/fast-import.c              |  71 ++++++++++++++---
 gpg-interface.c                    |   2 +
 gpg-interface.h                    |   1 +
 t/t9305-fast-import-signatures.sh  |  10 ++-
 t/t9306-fast-import-signed-tags.sh | 118 +++++++++++++++++++++++++++++
 7 files changed, 197 insertions(+), 29 deletions(-)

Range-diff against v1:
-:  ---------- > 1:  1dd316e66c fast-export: check for unsupported signing modes earlier
1:  0e9721fa57 ! 2:  7f34a4ccd5 fast-import: add 'abort-if-invalid' mode to '--signed-commits=<mode>'
    @@ Documentation/git-fast-import.adoc: already trusted to run their own code.
      ~~~~~~~~~~~~~~~~~~~~~
     
      ## builtin/fast-export.c ##
    -@@ builtin/fast-export.c: static void handle_commit(struct commit *commit, struct rev_info *rev,
    - 			die(_("encountered signed commit %s; use "
    - 			      "--signed-commits=<mode> to handle it"),
    - 			    oid_to_hex(&commit->object.oid));
    -+		case SIGN_ABORT_IF_INVALID:
    -+			die(_("'abort-if-invalid' is not a valid mode for "
    -+			      "git fast-export with --signed-commits=<mode>"));
    - 		case SIGN_STRIP_IF_INVALID:
    - 			die(_("'strip-if-invalid' is not a valid mode for "
    - 			      "git fast-export with --signed-commits=<mode>"));
    -@@ builtin/fast-export.c: static void handle_tag(const char *name, struct tag *tag)
    - 				die(_("encountered signed tag %s; use "
    - 				      "--signed-tags=<mode> to handle it"),
    - 				    oid_to_hex(&tag->object.oid));
    -+			case SIGN_ABORT_IF_INVALID:
    -+				die(_("'abort-if-invalid' is not a valid mode for "
    -+				      "git fast-export with --signed-tags=<mode>"));
    - 			case SIGN_STRIP_IF_INVALID:
    - 				die(_("'strip-if-invalid' is not a valid mode for "
    - 				      "git fast-export with --signed-tags=<mode>"));
    +@@ builtin/fast-export.c: static int parse_opt_sign_mode(const struct option *opt,
    + 		return 0;
    + 
    + 	if (parse_sign_mode(arg, val, NULL) || (*val == SIGN_STRIP_IF_INVALID) ||
    +-	    (*val == SIGN_SIGN_IF_INVALID))
    ++	    (*val == SIGN_SIGN_IF_INVALID) || (*val == SIGN_ABORT_IF_INVALID))
    + 		return error(_("unknown %s mode: %s"), opt->long_name, arg);
    + 
    + 	return 0;
     
      ## builtin/fast-import.c ##
     @@ builtin/fast-import.c: static void handle_signature_if_invalid(struct strbuf *new_data,
2:  18c145c630 = 3:  adc7289213 fast-import: add 'strip-if-invalid' mode to '--signed-tags=<mode>'
3:  58a8216447 = 4:  47ff0060a8 fast-import: add 'sign-if-invalid' mode to '--signed-tags=<mode>'
4:  83476b8971 = 5:  552fea76ca fast-import: add 'abort-if-invalid' mode to '--signed-tags=<mode>'
-- 
2.53.0.381.g628a66ccf6