From bb54b940c0475da8e90531f14608de438d7b0f41 Mon Sep 17 00:00:00 2001
From: Calvin Rose <calsrose@gmail.com>
Date: Sat, 19 Oct 2019 10:51:11 -0500
Subject: [PATCH] Don't call fwrite with size = 0

---
 src/core/io.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/core/io.c b/src/core/io.c
index a4109b07..99198dca 100644
--- a/src/core/io.c
+++ b/src/core/io.c
@@ -425,8 +425,10 @@ static Janet cfun_io_print_impl(int32_t argc, Janet *argv,
             vstr = janet_to_string(argv[i]);
             len = janet_string_length(vstr);
         }
-        if (1 != fwrite(vstr, len, 1, f)) {
-            janet_panicf("could not print %d bytes to (dyn :%s)", len, name);
+        if (len) {
+            if (1 != fwrite(vstr, len, 1, f)) {
+                janet_panicf("could not print %d bytes to (dyn :%s)", len, name);
+            }
         }
     }
     if (newline)
@@ -480,8 +482,10 @@ static Janet cfun_io_printf_impl(int32_t argc, Janet *argv,
     }
     JanetBuffer *buf = janet_buffer(10);
     janet_buffer_format(buf, fmt, 0, argc, argv);
-    if (1 != fwrite(buf->data, buf->count, 1, f)) {
-        janet_panicf("could not print %d bytes to file", buf->count, name);
+    if (buf->count) {
+        if (1 != fwrite(buf->data, buf->count, 1, f)) {
+            janet_panicf("could not print %d bytes to file", buf->count, name);
+        }
     }
     /* Clear buffer to make things easier for GC */
     buf->count = 0;