test-cli/txid-of: simple helper to get txid.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

test-cli/txid-of.c

@@ -0,0 +1,43 @@
+#include <ccan/crypto/shachain/shachain.h>
+#include <ccan/read_write_all/read_write_all.h>
+#include <ccan/short_types/short_types.h>
+#include <ccan/tal/tal.h>
+#include <ccan/opt/opt.h>
+#include <ccan/str/hex/hex.h>
+#include <ccan/err/err.h>
+#include "bitcoin/tx.h"
+#include <unistd.h>
+
+int main(int argc, char *argv[])
+{
+	const tal_t *ctx = tal_arr(NULL, char, 0);
+	struct bitcoin_tx *tx;
+	struct sha256_double txid;
+	char str[hex_str_size(sizeof(txid))];
+
+	err_set_progname(argv[0]);
+
+	/* FIXME: Take update.pbs to adjust channel */
+	opt_register_noarg("--help|-h", opt_usage_and_exit,
+			   "<tx>\n"
+			   "Print txid of the transaction in the file",
+			   "Print this message.");
+
+ 	opt_parse(&argc, argv, opt_log_stderr_exit);
+
+	if (argc != 2)
+		opt_usage_exit_fail("Expected 1 argument");
+
+	tx = bitcoin_tx_from_file(ctx, argv[1]);
+	bitcoin_txid(tx, &txid);
+
+	if (!bitcoin_txid_to_hex(&txid, str, sizeof(str)))
+		abort();
+
+	/* Print it out. */
+	if (!write_all(STDOUT_FILENO, str, strlen(str)))
+		err(1, "Writing out txid");
+
+	tal_free(ctx);
+	return 0;
+}