From 6b0902de6c7fdd9f9f207d5d1675d07e23059639 Mon Sep 17 00:00:00 2001
From: Emil Fresk <emil.fresk@gmail.com>
Date: Tue, 23 Apr 2019 11:14:44 +0200
Subject: [PATCH] Fix for JLink debuggers

When sending 1 character it returns -1 from syscall. This fix mitigates
the issue, but it not correct.
---
 src/hio.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/hio.rs b/src/hio.rs
index 7eac6eb..d202f60 100644
--- a/src/hio.rs
+++ b/src/hio.rs
@@ -68,12 +68,14 @@ fn write_all(fd: usize, mut buffer: &[u8]) -> Result<(), ()> {
             // Done
             0 => return Ok(()),
             // `n` bytes were not written
-            n if n <= buffer.len() => {
+            n if n <= buffer.len() && n > 0 => {
                 let offset = (buffer.len() - n) as isize;
                 buffer = unsafe {
                     slice::from_raw_parts(buffer.as_ptr().offset(offset), n)
                 }
             }
+            // Error (-1) - should be an error but JLink can return -1
+            0xffffffff => return Ok(()),
             // Error
             _ => return Err(()),
         }