curl: check for end of input in writeout backslash handling

Reported-by: Brian Carpenter

Added test 1442 to verify

src/tool_writeout.c

@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2016, Daniel Stenberg, <[email protected]>, et al.
+ * Copyright (C) 1998 - 2017, Daniel Stenberg, <[email protected]>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -341,7 +341,7 @@ void ourWriteOut(CURL *curl, struct OutStruct *outs, const char *writeinfo)
         }
       }
     }
-    else if('\\' == *ptr) {
+    else if('\\' == *ptr && ptr[1]) {
       switch(ptr[1]) {
       case 'r':
         fputc('\r', stream);

tests/data/Makefile.inc

@@ -153,7 +153,7 @@ test1408 test1409 test1410 test1411 test1412 test1413 test1414 test1415 \
 test1416 test1417 test1418 test1419 test1420 test1421 test1422 test1423 \
 test1424 \
 test1428 test1429 test1430 test1431 test1432 test1433 test1434 test1435 \
-test1436 test1437 test1438 test1439 test1440 test1441 \
+test1436 test1437 test1438 test1439 test1440 test1441 test1442 \
 \
 test1500 test1501 test1502 test1503 test1504 test1505 test1506 test1507 \
 test1508 test1509 test1510 test1511 test1512 test1513 test1514 test1515 \

tests/data/test1442

@@ -0,0 +1,35 @@
+<testcase>
+<info>
+<keywords>
+--write-out
+FILE
+</keywords>
+</info>
+# Server-side
+<reply>
+</reply>
+
+# Client-side
+<client>
+<server>
+file
+</server>
+
+<name>
+Check --write-out with trailing \
+</name>
+<command>
+file://localhost/%PWD/log/non-existent-file.txt --write-out '\'
+</command>
+</client>
+
+# Verify data
+<verify>
+<errorcode>
+37
+</errorcode>
+<stdout nonewline="yes">
+\
+</stdout>
+</verify>
+</testcase>