From e514a5d43c2c3477941e2548d8a01be0e1294b0e Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Sun, 9 Apr 2023 12:55:09 +0930
Subject: [PATCH] common: lookup function for symnames.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 common/daemon.c | 34 ++++++++++++++++++++++++++++++++++
 common/daemon.h |  4 ++++
 2 files changed, 38 insertions(+)

diff --git a/common/daemon.c b/common/daemon.c
index 83b0ff12a..e8f40f534 100644
--- a/common/daemon.c
+++ b/common/daemon.c
@@ -38,6 +38,35 @@ void send_backtrace(const char *why)
 		backtrace_full(backtrace_state, 0, backtrace_status, NULL, NULL);
 }
 
+static void extract_symname(void *data, uintptr_t pc,
+			    const char *symname,
+			    uintptr_t symval,
+			    uintptr_t symsize)
+{
+	const char **ret = data;
+
+	/* ret is context to alloc off, and value to set */
+	if (symname)
+		*ret = tal_strdup(*ret, symname);
+	else
+		*ret = NULL;
+}
+
+const char *backtrace_symname(const tal_t *ctx, const void *addr)
+{
+	const char *ret = ctx;
+	if (!backtrace_state)
+		return tal_fmt(ctx, "%p (backtrace disabled)", addr);
+
+	if (!backtrace_syminfo(backtrace_state, (uintptr_t)addr,
+			       extract_symname, NULL, &ret))
+		ret = NULL;
+
+	if (ret)
+		return ret;
+	return tal_fmt(ctx, "%p", addr);
+}
+
 static void crashdump(int sig)
 {
 	char why[100];
@@ -71,6 +100,11 @@ static void crashlog_activate(void)
 void send_backtrace(const char *why)
 {
 }
+
+const char *backtrace_symname(const tal_t *ctx, const void *addr)
+{
+	return "unknown (backtrace unsupported)";
+}
 #endif
 
 int daemon_poll(struct pollfd *fds, nfds_t nfds, int timeout)
diff --git a/common/daemon.h b/common/daemon.h
index b1703685d..2db8cf437 100644
--- a/common/daemon.h
+++ b/common/daemon.h
@@ -1,6 +1,7 @@
 #ifndef LIGHTNING_COMMON_DAEMON_H
 #define LIGHTNING_COMMON_DAEMON_H
 #include "config.h"
+#include <ccan/tal/tal.h>
 #include <poll.h>
 
 /* Common setup for all daemons */
@@ -14,6 +15,9 @@ int daemon_poll(struct pollfd *fds, nfds_t nfds, int timeout);
 /* Print a backtrace to stderr, and via backtrace_print */
 void send_backtrace(const char *why);
 
+/* Try to extract a name for this function/var/etc */
+const char *backtrace_symname(const tal_t *ctx, const void *addr);
+
 /* Shutdown for a valgrind-clean exit (frees everything) */
 void daemon_shutdown(void);