+static void determine_author_info(struct strbuf *sb)
+{
+ char *name, *email, *date;
+
+ name = getenv("GIT_AUTHOR_NAME");
+ email = getenv("GIT_AUTHOR_EMAIL");
+ date = getenv("GIT_AUTHOR_DATE");
+
+ if (use_message) {
+ const char *a, *lb, *rb, *eol;
+
+ a = strstr(use_message_buffer, "\nauthor ");
+ if (!a)
+ die("invalid commit: %s", use_message);
+
+ lb = strstr(a + 8, " <");
+ rb = strstr(a + 8, "> ");
+ eol = strchr(a + 8, '\n');
+ if (!lb || !rb || !eol)
+ die("invalid commit: %s", use_message);
+
+ name = xstrndup(a + 8, lb - (a + 8));
+ email = xstrndup(lb + 2, rb - (lb + 2));
+ date = xstrndup(rb + 2, eol - (rb + 2));
+ }
+
+ if (force_author) {
+ const char *lb = strstr(force_author, " <");
+ const char *rb = strchr(force_author, '>');
+
+ if (!lb || !rb)
+ die("malformed --author parameter");
+ name = xstrndup(force_author, lb - force_author);
+ email = xstrndup(lb + 2, rb - (lb + 2));
+ }
+
+ strbuf_addf(sb, "author %s\n", fmt_ident(name, email, date, IDENT_ERROR_ON_NO_NAME));
+}
+