Commit signatures can be verified using "git show -s --show-signature" or the "%G?" pretty format and parsing the output, which is well suited for user inspection, but not for scripting.
Provide a command "verify-commit" which is analogous to "verify-tag": It returns 0 for good signatures and non-zero otherwise, has the gpg output on stderr and (optionally) the commit object on stdout, sans the signature, just like "verify-tag" does.
Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
---
Documentation/git-verify-commit.txt | 28 +++++++++++
Makefile | 1 +
builtin.h | 1 +
builtin/verify-commit.c | 98 +++++++++++++++++++++++++++++++++++++
command-list.txt | 1 +
git.c | 1 +
6 files changed, 130 insertions(+)
create mode 100644 Documentation/git-verify-commit.txt
create mode 100644 builtin/verify-commit.c
Show changes to 6 files +130 −0
Documentation/git-verify-commit.txt, Makefile, builtin.h, builtin/verify-commit.c, command-list.txt, git.c
diff --git a/Documentation/git-verify-commit.txt b/Documentation/git-verify-commit.txt
new file mode 100644
index 0000000..dcd7803
--- /dev/null
+++ b/Documentation/git-verify-commit.txt
@@ -0,0 +1,28 @@
+git-verify-commit(1)
+=================
+
+NAME
+----
+git-verify-commit - Check the GPG signature of commits
+
+SYNOPSIS
+--------
+[verse]
+'git verify-commit' <commit>...
+
+DESCRIPTION
+-----------
+Validates the gpg signature created by 'git commit -S'.
+
+OPTIONS
+-------
+-v::
+--verbose::
+ Print the contents of the commit object before validating it.
+
+<commit>...::
+ SHA-1 identifiers of Git commit objects.
+
+GIT
+---
+Part of the linkgit:git[1] suite
diff --git a/Makefile b/Makefile
index 07ea105..b92418d 100644
--- a/Makefile
+++ b/Makefile
@@ -999,6 +999,7 @@ BUILTIN_OBJS += builtin/update-ref.o
BUILTIN_OBJS += builtin/update-server-info.o
BUILTIN_OBJS += builtin/upload-archive.o
BUILTIN_OBJS += builtin/var.o
+BUILTIN_OBJS += builtin/verify-commit.o
BUILTIN_OBJS += builtin/verify-pack.o
BUILTIN_OBJS += builtin/verify-tag.o
BUILTIN_OBJS += builtin/write-tree.o
diff --git a/builtin.h b/builtin.h
index c47c110..5d91f31 100644
--- a/builtin.h
+++ b/builtin.h
@@ -128,6 +128,7 @@ extern int cmd_update_server_info(int argc, const char **argv, const char *prefi
extern int cmd_upload_archive(int argc, const char **argv, const char *prefix);
extern int cmd_upload_archive_writer(int argc, const char **argv, const char *prefix);
extern int cmd_var(int argc, const char **argv, const char *prefix);
+extern int cmd_verify_commit(int argc, const char **argv, const char *prefix);
extern int cmd_verify_tag(int argc, const char **argv, const char *prefix);
extern int cmd_version(int argc, const char **argv, const char *prefix);
extern int cmd_whatchanged(int argc, const char **argv, const char *prefix);
diff --git a/builtin/verify-commit.c b/builtin/verify-commit.c
new file mode 100644
index 0000000..69b7c6d
--- /dev/null
+++ b/builtin/verify-commit.c
@@ -0,0 +1,98 @@
+/*
+ * Builtin "git commit-commit"
+ *
+ * Copyright (c) 2014 Michael J Gruber <git@drmicha.warpmail.net>
+ *
+ * Based on git-verify-tag
+ */
+#include "cache.h"
+#include "builtin.h"
+#include "commit.h"
+#include "run-command.h"
+#include <signal.h>
+#include "parse-options.h"
+#include "gpg-interface.h"
+
+static const char * const verify_commit_usage[] = {
+ N_("git verify-commit [-v|--verbose] <commit>..."),
+ NULL
+};
+
+static int run_gpg_verify(const unsigned char *sha1, const char *buf, unsigned long size, int verbose)
+{
+ struct signature_check signature_check;
+
+ memset(&signature_check, 0, sizeof(signature_check));
+
+ check_commit_signature(lookup_commit(sha1), &signature_check);
+
+ if (verbose && signature_check.payload)
+ fputs(signature_check.payload, stdout);
+
+ if (signature_check.gpg_output)
+ fputs(signature_check.gpg_output, stderr);
+
+ free(signature_check.gpg_output);
+ free(signature_check.gpg_status);
+ free(signature_check.signer);
+ free(signature_check.key);
+ return signature_check.result != 'G';
+}
+
+static int verify_commit(const char *name, int verbose)
+{
+ enum object_type type;
+ unsigned char sha1[20];
+ char *buf;
+ unsigned long size;
+ int ret;
+
+ if (get_sha1(name, sha1))
+ return error("commit '%s' not found.", name);
+
+ type = sha1_object_info(sha1, NULL);
+ if (type != OBJ_COMMIT)
+ return error("%s: cannot verify a non-commit object of type %s.",
+ name, typename(type));
+
+ buf = read_sha1_file(sha1, &type, &size);
+ if (!buf)
+ return error("%s: unable to read file.", name);
+
+ ret = run_gpg_verify(sha1, buf, size, verbose);
+
+ free(buf);
+ return ret;
+}
+
+static int git_verify_commit_config(const char *var, const char *value, void *cb)
+{
+ int status = git_gpg_config(var, value, cb);
+ if (status)
+ return status;
+ return git_default_config(var, value, cb);
+}
+
+int cmd_verify_commit(int argc, const char **argv, const char *prefix)
+{
+ int i = 1, verbose = 0, had_error = 0;
+ const struct option verify_commit_options[] = {
+ OPT__VERBOSE(&verbose, N_("print commit contents")),
+ OPT_END()
+ };
+
+ git_config(git_verify_commit_config, NULL);
+
+ argc = parse_options(argc, argv, prefix, verify_commit_options,
+ verify_commit_usage, PARSE_OPT_KEEP_ARGV0);
+ if (argc <= i)
+ usage_with_options(verify_commit_usage, verify_commit_options);
+
+ /* sometimes the program was terminated because this signal
+ * was received in the process of writing the gpg input: */
+ signal(SIGPIPE, SIG_IGN);
+ while (i < argc)
+ if (verify_commit(argv[i++], verbose))
+ had_error = 1;
+ return had_error;
+}
diff --git a/command-list.txt b/command-list.txt
index cf36c3d..a3ff0c9 100644
--- a/command-list.txt
+++ b/command-list.txt
@@ -132,6 +132,7 @@ git-update-server-info synchingrepositories
git-upload-archive synchelpers
git-upload-pack synchelpers
git-var plumbinginterrogators
+git-verify-commit ancillaryinterrogators
git-verify-pack plumbinginterrogators
git-verify-tag ancillaryinterrogators
gitweb ancillaryinterrogators
diff --git a/git.c b/git.c
index 7780572..bbc3293 100644
--- a/git.c
+++ b/git.c
@@ -441,6 +441,7 @@ static struct cmd_struct commands[] = {
{ "upload-archive", cmd_upload_archive },
{ "upload-archive--writer", cmd_upload_archive_writer },
{ "var", cmd_var, RUN_SETUP_GENTLY },
+ { "verify-commit", cmd_verify_commit, RUN_SETUP },
{ "verify-pack", cmd_verify_pack },
{ "verify-tag", cmd_verify_tag, RUN_SETUP },
{ "version", cmd_version },
Michael J Gruber
