[newlib-cygwin] Fix return value on aio_read/write success

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=b1952c03a8d6970f0fb4bcfffb9cfb5b525884d6

commit b1952c03a8d6970f0fb4bcfffb9cfb5b525884d6
Author: Mark Geisert <***@maxrnd.com>
Date: Mon Aug 6 22:54:06 2018 -0700

Fix return value on aio_read/write success

Internally track resultant byte counts as ssize_t, but return 0 as int
for success indication, per POSIX.

Diff:
---
winsup/cygwin/aio.cc | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/winsup/cygwin/aio.cc b/winsup/cygwin/aio.cc
index fe63dec..7d5d982 100644
--- a/winsup/cygwin/aio.cc
+++ b/winsup/cygwin/aio.cc
@@ -265,7 +265,7 @@ aiowaiter (void *unused)
}
}

-static int
+static ssize_t
asyncread (struct aiocb *aio)
{ /* Try to initiate an asynchronous read, either from app or worker thread */
ssize_t res = 0;
@@ -296,7 +296,7 @@ asyncread (struct aiocb *aio)
return res;
}

-static int
+static ssize_t
asyncwrite (struct aiocb *aio)
{ /* Try to initiate an asynchronous write, either from app or worker thread */
ssize_t res = 0;
@@ -712,7 +712,7 @@ aio_read (struct aiocb *aio)
; /* I think this is not possible */
}

- return res;
+ return res < 0 ? (int) res : 0; /* return 0 on success */
}

ssize_t
@@ -902,7 +902,7 @@ aio_write (struct aiocb *aio)
; /* I think this is not possible */
}

- return res;
+ return res < 0 ? (int) res : 0; /* return 0 on success */
}

int