status: API for status reporting.

The API formalizes how daemons should report their statuses back to
the main lightningd.  It's a simple write API, which includes tracing
support (currently it always sends traces, later it could send iff
there's a failure, for example).

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

Makefile

@@ -51,6 +51,7 @@ CORE_SRC :=					\
 	opt_bits.c				\
 	permute_tx.c				\
 	protobuf_convert.c			\
+	status.c				\
 	type_to_string.c			\
 	utils.c					\
 	version.c
@@ -175,6 +176,7 @@ CORE_HEADERS := close_tx.h			\
 	permute_tx.h				\
 	protobuf_convert.h			\
 	remove_dust.h				\
+	status.h				\
 	type_to_string.h			\
 	utils.h					\
 	version.h

daemon/test/Makefile

@@ -63,9 +63,9 @@ DAEMON_TEST_PROGRAMS := $(DAEMON_TEST_OBJS:.o=)
 
 update-mocks: $(DAEMON_TEST_SRC:%=update-mocks/%)
 
-$(DAEMON_TEST_PROGRAMS): $(CCAN_OBJS) $(BITCOIN_OBJS) $(CORE_OBJS) $(LIBBASE58_OBJS) libsecp256k1.a utils.o
+$(DAEMON_TEST_PROGRAMS): $(CCAN_OBJS) $(BITCOIN_OBJS) $(CORE_OBJS) $(LIBBASE58_OBJS) $(WIRE_OBJS) libsecp256k1.a utils.o
 
-$(DAEMON_TEST_OBJS): $(DAEMON_HEADERS) $(DAEMON_JSMN_HEADERS) $(BITCOIN_HEADERS) $(CORE_HEADERS) $(GEN_HEADERS) $(DAEMON_GEN_HEADERS) $(CCAN_HEADERS)
+$(DAEMON_TEST_OBJS): $(DAEMON_HEADERS) $(DAEMON_JSMN_HEADERS) $(BITCOIN_HEADERS) $(CORE_HEADERS) $(GEN_HEADERS) $(DAEMON_GEN_HEADERS) $(CCAN_HEADERS) $(WIRE_HEADERS)
 
 daemon-unit-tests: $(DAEMON_TEST_PROGRAMS:%=unittest/%)
 

status.c

@@ -0,0 +1,85 @@
+#include "status.h"
+#include "utils.h"
+#include "wire/wire_sync.h"
+#include <assert.h>
+#include <ccan/breakpoint/breakpoint.h>
+#include <ccan/endian/endian.h>
+#include <ccan/err/err.h>
+#include <ccan/fdpass/fdpass.h>
+#include <ccan/read_write_all/read_write_all.h>
+#include <ccan/tal/str/str.h>
+#include <stdarg.h>
+
+static int status_fd = -1;
+const void *trc;
+
+void status_setup(int fd)
+{
+	status_fd = fd;
+	trc = tal_tmpctx(NULL);
+}
+
+void status_send(const u8 *p)
+{
+	assert(status_fd >= 0);
+
+	if (!wire_sync_write(status_fd, p))
+		err(1, "Writing out status len %zu", tal_count(p));
+	tal_free(p);
+}
+
+void status_send_fd(int fd)
+{
+	assert(status_fd >= 0);
+	assert(fd >= 0);
+
+	if (!fdpass_send(status_fd, fd))
+		err(1, "Writing out status fd %i", fd);
+	close(fd);
+}
+
+static void status_send_with_hdr(u16 type, const void *p, size_t len)
+{
+	be16 be_type, be_len;
+
+	be_type = cpu_to_be16(type);
+	be_len = cpu_to_be16(len + sizeof(be_type));
+	assert(status_fd >= 0);
+	assert(be16_to_cpu(be_len) == len + sizeof(be_type));
+
+	if (!write_all(status_fd, &be_len, sizeof(be_len))
+	    || !write_all(status_fd, &be_type, sizeof(be_type))
+	    || !write_all(status_fd, p, len))
+		err(1, "Writing out status %u len %zu", type, len);
+}
+
+void status_trace(const char *fmt, ...)
+{
+	va_list ap;
+	char *str;
+
+	va_start(ap, fmt);
+	str = tal_vfmt(NULL, fmt, ap);
+	status_send_with_hdr(STATUS_TRACE, str, strlen(str));
+	tal_free(str);
+	va_end(ap);
+
+	/* Free up any temporary children. */
+	tal_free(trc);
+	trc = tal_tmpctx(NULL);
+}
+
+void status_failed(u16 code, const char *fmt, ...)
+{
+	va_list ap;
+	char *str;
+
+	breakpoint();
+	assert(code & STATUS_FAIL);
+	va_start(ap, fmt);
+	str = tal_vfmt(NULL, fmt, ap);
+	status_send_with_hdr(code, str, strlen(str));
+	va_end(ap);
+
+	exit(0x80 | (code & 0xFF));
+}

status.h

@@ -0,0 +1,29 @@
+#ifndef LIGHTNING_STATUS_H
+#define LIGHTNING_STATUS_H
+#include "config.h"
+#include <ccan/compiler/compiler.h>
+#include <ccan/short_types/short_types.h>
+#include <stdlib.h>
+
+/* Simple status reporting API. */
+void status_setup(int fd);
+
+/* Convenient context, frees up after every status_update/failed */
+extern const void *trc;
+
+/* Special status code for tracing messages. */
+#define STATUS_TRACE 0x7FFF
+
+/* Failure codes always have high bit set. */
+#define STATUS_FAIL 0x8000
+
+/* Send a message (frees the message). */
+void status_send(const u8 *msg);
+/* Send a file descriptor (closes fd). */
+void status_send_fd(int fd);
+/* Send a printf-style debugging trace. */
+void status_trace(const char *fmt, ...) PRINTF_FMT(1,2);
+/* Send a failure status code with printf-style msg, and exit. */
+void status_failed(u16 code, const char *fmt, ...) PRINTF_FMT(2,3) NORETURN;
+
+#endif /* LIGHTNING_STATUS_H */