From ac2433cb8daa1279d14f8b2cd4c7e1f3405787d4 Mon Sep 17 00:00:00 2001
From: Matt Johnston <matt@ucc.asn.au>
Date: Fri, 1 Apr 2022 12:10:48 +0800
Subject: [PATCH] Add m_snprintf() that won't return negative

---
 dbutil.c | 13 +++++++++++++
 dbutil.h |  2 ++
 2 files changed, 15 insertions(+)

diff --git a/dbutil.c b/dbutil.c
index 588c8d0..bd66454 100644
--- a/dbutil.c
+++ b/dbutil.c
@@ -771,3 +771,16 @@ int fd_read_pending(int fd) {
 		return FD_ISSET(fd, &fds);
 	}
 }
+
+int m_snprintf(char *str, size_t size, const char *format, ...) {
+	va_list param;
+	int ret;
+
+	va_start(param, format);
+	ret = vsnprintf(str, size, format, param);
+	va_end(param);
+	if (ret < 0) {
+		dropbear_exit("snprintf failed");
+	}
+	return ret;
+}
diff --git a/dbutil.h b/dbutil.h
index c2d384a..64af170 100644
--- a/dbutil.h
+++ b/dbutil.h
@@ -73,6 +73,8 @@ void m_close(int fd);
 void setnonblocking(int fd);
 void disallow_core(void);
 int m_str_to_uint(const char* str, unsigned int *val);
+/* The same as snprintf() but exits rather than returning negative */
+int m_snprintf(char *str, size_t size, const char *format, ...);
 
 /* Used to force mp_ints to be initialised */
 #define DEF_MP_INT(X) mp_int X = {0, 0, 0, NULL}