common/io_debug: replacement for ccan/io's poll which does sanity checks.

For now we just check for outstanding take() or tal_tmpctx().

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

common/Makefile

@@ -15,6 +15,7 @@ COMMON_SRC :=					\
 	common/htlc_wire.c			\
 	common/initial_channel.c		\
 	common/initial_commit_tx.c		\
+	common/io_debug.c			\
 	common/json.c				\
 	common/key_derive.c			\
 	common/keyset.c				\

common/io_debug.c

@@ -0,0 +1,19 @@
+#include <ccan/err/err.h>
+#include <ccan/take/take.h>
+#include <common/io_debug.h>
+#include <common/utils.h>
+
+int debug_poll(struct pollfd *fds, nfds_t nfds, int timeout)
+{
+	const char *t;
+
+	t = taken_any();
+	if (t)
+		errx(1, "Outstanding taken pointers: %s", t);
+
+	t = tmpctx_any();
+	if (t)
+		errx(1, "Outstanding tmpctx: %s", t);
+
+	return poll(fds, nfds, timeout);
+}

common/io_debug.h

@@ -0,0 +1,9 @@
+#ifndef LIGHTNING_COMMON_IO_DEBUG_H
+#define LIGHTNING_COMMON_IO_DEBUG_H
+#include "config.h"
+#include <poll.h>
+
+/* Replacement poll which checks for memory leaks in middle of ccan/io loop. */
+int debug_poll(struct pollfd *fds, nfds_t nfds, int timeout);
+
+#endif /* LIGHTNING_COMMON_IO_DEBUG_H */

common/status.c

@@ -31,7 +31,9 @@ void status_setup_async(struct daemon_conn *master)
 	assert(status_fd == -1);
 	assert(!status_conn);
 	status_conn = master;
-	trc = tal_tmpctx(NULL);
+
+	/* Don't use tmpctx here, otherwise debug_poll gets upset. */
+	trc = tal(NULL, char);
 }
 
 static bool too_large(size_t len, int type)
@@ -85,8 +87,10 @@ void status_trace(const char *fmt, ...)
 	va_end(ap);
 
 	/* Free up any temporary children. */
+	if (tal_first(trc)) {
 		tal_free(trc);
-	trc = tal_tmpctx(NULL);
+		trc = tal(NULL, char);
+	}
 }
 
 void status_failed(enum status_fail code, const char *fmt, ...)

lightningd/log.c

@@ -113,7 +113,7 @@ struct log_book *new_log_book(const tal_t *ctx,
 
 	/* In case ltmp not initialized, do so now. */
 	if (!ltmp)
-		ltmp = tal_tmpctx(lr);
+		ltmp = tal(lr, char);
 
 	return lr;
 }
@@ -196,7 +196,7 @@ static void add_entry(struct log *log, struct log_entry *l)
 	/* Free up temporaries now if any */
 	if (tal_first(ltmp)) {
 		tal_free(ltmp);
-		ltmp = tal_tmpctx(log->lr);
+		ltmp = tal(log->lr, char);
 	}
 }