Function opt_set_hsm_secret

lightningd/options.c:1344–1426

}

static char *opt_set_hsm_secret(const char *arg, struct lightningd *ld)
{
	char *err;
	const struct hsm_secret *hsm_secret;

	err = hsm_secret_arg(tmpctx, arg, &hsm_secret);
	if (err)
		return err;

	/* Checks if hsm_secret exists */
	int fd = open("hsm_secret", O_CREAT|O_EXCL|O_WRONLY, 0400);
	if (fd < 0) {
		/* Don't do anything if the file already exists. */
		if (errno == EEXIST)
			return tal_fmt(tmpctx, "hsm_secret already exists!");

		return tal_fmt(tmpctx, "Creating hsm_secret: %s",
			       strerror(errno));
	}

	switch (hsm_secret->type) {
	case HSM_SECRET_PLAIN:
		/* Legacy 32-byte format */
		if (!write_all(fd, hsm_secret->secret_data, tal_count(hsm_secret->secret_data))) {
			unlink_noerr("hsm_secret");
			return tal_fmt(tmpctx, "Writing HSM: %s",
				       strerror(errno));
		}
		break;
	case HSM_SECRET_ENCRYPTED:
	case HSM_SECRET_MNEMONIC_WITH_PASS:
		return tal_fmt(tmpctx, "Recovery of encrypted/passworded secrets not supported");
	case HSM_SECRET_MNEMONIC_NO_PASS: {
		struct sha256 seed_hash;
		if (!derive_seed_hash(hsm_secret->mnemonic, NULL, &seed_hash)) {
			unlink_noerr("hsm_secret");
			return tal_fmt(tmpctx, "Deriving from mnemonic failed!");
		}
		/* Write seed hash (32 bytes) + mnemonic */
		if (!write_all(fd, &seed_hash, sizeof(seed_hash))
		    || !write_all(fd, hsm_secret->mnemonic, strlen(hsm_secret->mnemonic))) {
			unlink_noerr("hsm_secret");
			return tal_fmt(tmpctx, "Error writing to hsm_secret file: %s", strerror(errno));
		}
		break;
	}
	case HSM_SECRET_INVALID:
		/* Shouldn't happen? */
		unlink_noerr("hsm_secret");
		return tal_fmt(tmpctx, "invalid hsm secret?");
	}

	/*~ fsync (mostly!) ensures that the file has reached the disk. */
	if (fsync(fd) != 0) {
		unlink_noerr("hsm_secret");
		return tal_fmt(tmpctx, "fsync: %s", strerror(errno));
	}
	/*~ This should never fail if fsync succeeded.  But paranoia good, and