[PATCH v3 6/7] gpg-interface: introduce new signature format "x509" using gpgsm

[Henning Schild]

This commit allows git to create and check x509 type signatures using
gpgsm.

Signed-off-by: Henning Schild <henning.sch...@siemens.com>
---
 Documentation/config.txt | 5 +++--
 gpg-interface.c          | 9 +++++++++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index c0bd80954..7cfce4dc8 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -1830,12 +1830,13 @@ gpg.program::
 
 gpg.format::
        Specifies which key format to use when signing with `--gpg-sign`.
-       Default is "openpgp", that is also the only supported value.
+       Default is "openpgp" and another possible value is "x509".
 
 gpg.<format>.program::
        Use this to customize the program used for the signing format you
        chose. (see gpg.program) gpg.openpgp.program is a synonym for the
-       legacy gpg.program.
+       legacy gpg.program, while the default gpg.x509.program is "gpgsm".
+
 
 gui.commitMsgWidth::
        Defines how wide the commit message window is in the
diff --git a/gpg-interface.c b/gpg-interface.c
index f3c22b551..62a9acf68 100644
--- a/gpg-interface.c
+++ b/gpg-interface.c
@@ -18,12 +18,18 @@ static const char *openpgp_verify_args[] = { 
"--keyid-format=long", NULL };
 static const char *openpgp_sigs[] = {
        "-----BEGIN PGP SIGNATURE-----",
        "-----BEGIN PGP MESSAGE-----", NULL };
+static const char *x509_verify_args[] = { NULL };
+static const char *x509_sigs[] = { "-----BEGIN SIGNED MESSAGE-----", NULL };
 
 static struct gpg_format gpg_formats[] = {
        { .name = "openpgp", .program = "gpg",
          .extra_args_verify = openpgp_verify_args,
          .sigs = openpgp_sigs
        },
+       { .name = "x509", .program = "gpgsm",
+         .extra_args_verify = x509_verify_args,
+         .sigs = x509_sigs
+       },
 };
 static struct gpg_format *current_format = &gpg_formats[0];
 
@@ -185,6 +191,9 @@ int git_gpg_config(const char *var, const char *value, void 
*cb)
        if (!strcmp(var, "gpg.program") || !strcmp(var, "gpg.openpgp.program"))
                fmtname = "openpgp";
 
+       if (!strcmp(var, "gpg.x509.program"))
+               fmtname = "x509";
+
        if (fmtname) {
                fmt = get_format_by_name(fmtname);
                return git_config_string(&fmt->program, var, value);
-- 
2.16.4