tftp-hpa: fix the empty file writing error

make write_behind to return 0 if a empty file is written, to
distinguish a true writing failure[on which the write_behind
will return -1], then the annoying wrong log will disappear.
    ____
    |Error code 3: Disk full or allocation exceeded
    -----
Signed-off-by: Roy.Li <rongqing.li@windriver.com>
Signed-off-by: Joe MacDonald <joe_macdonald@mentor.com>

meta-networking/recipes-daemons/tftp-hpa/files/fix-writing-emtpy-file.patch

@@ -0,0 +1,39 @@
+[PATCH] fix the empty file writting
+
+Upstream-Status: pending
+
+With the feature that checking the disk filled up, the return
+value of function write_behind was checked and used to detect
+the disk status. While for empty file, without data being
+written, this function will return -1 thus the disk filled up
+error was miss-raised.
+
+make write_behind to return 0 if written file is empty, to fix
+the this bug.
+
+Signed-off-by: Roy.Li <rongqing.li@windriver.com>
+---
+ common/tftpsubs.c | 5 ++++-
+ 1 file changed, 4 insertions(+), 1 deletion(-)
+
+diff --git a/common/tftpsubs.c b/common/tftpsubs.c
+index b4ea3f2..9f6cafc 100644
+--- a/common/tftpsubs.c
++++ b/common/tftpsubs.c
+@@ -198,9 +198,12 @@ int write_behind(FILE * file, int convert)
+     nextone = !nextone;         /* incr for next time */
+     buf = dp->th_data;
+ 
+-    if (count <= 0)
++    if (count < 0)
+         return -1;              /* nak logic? */
+ 
++    if (count == 0)
++        return 0;
++
+     if (convert == 0)
+         return write(fileno(file), buf, count);
+ 
+-- 
+1.9.1
+

meta-networking/recipes-daemons/tftp-hpa/tftp-hpa_5.2.bb

@@ -25,6 +25,7 @@ SRC_URI = "http://kernel.org/pub/software/network/tftp/tftp-hpa/tftp-hpa-${PV}.t
            file://init \
            file://add-error-check-for-disk-filled-up.patch \
            file://tftp-hpa-bug-fix-on-separated-CR-and-LF.patch \
+           file://fix-writing-emtpy-file.patch \
 "
 
 SRC_URI[md5sum] = "46c9bd20bbffa62f79c958c7b99aac21"