Make author and committer available to pre-commit hook

[Gisle Aas <gisle@aas.no>]

I would like to implement a pre-commit hook that validates the
--author set for the commit.  Our use case is a shared repository of
configuration info where different persons all commit as root; but we
want to make sure they override the --author to something sensible.

What would be the preferred mechanism to pass on this information?  It
could for instance be arguments to the hook script or via environment
variables.

I created the following patch to explore what it would take to pass on
this information as command line arguments.  It seems to do the trick
for me.  Any drawback with this approach?

Regards,
Gisle


diff --git a/builtin/commit.c b/builtin/commit.c
index c101f00..acb8dc2 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -557,8 +557,20 @@ static int prepare_to_commit(const char
*index_file, const char *prefix,
        const char *hook_arg2 = NULL;
        int ident_shown = 0;

-       if (!no_verify && run_hook(index_file, "pre-commit", NULL))
+       determine_author_info();
+       if (!no_verify) {
+           int rc;
+           hook_arg1 = xstrdup(fmt_name(author_name, author_email));
+           hook_arg2 = xstrdup(fmt_name(getenv("GIT_COMMITTER_NAME"),
+                                        getenv("GIT_COMMITTER_EMAIL")));
+           rc = run_hook(index_file, "pre-commit", hook_arg1, hook_arg2, NULL);
+           free((char*)hook_arg1);
+           free((char*)hook_arg2);
+           if (rc)
                return 0;
+           hook_arg1 = NULL;
+           hook_arg2 = NULL;
+       }

        if (message.len) {
                strbuf_addbuf(&sb, &message);
@@ -632,8 +644,6 @@ static int prepare_to_commit(const char
*index_file, const char *prefix,

        strbuf_release(&sb);

-       determine_author_info();
-
        /* This checks if committer ident is explicitly given */
        git_committer_info(0);
        if (use_editor && include_status) {