handle O_NONBLOCK'ed pipes specific error on write()

according to the write(2) docs:

When write requests greater than {PIPE_BUF} bytes to a pipe that
has available space at least 1 byte, if O_NONBLOCK is set,
write transfers what it can and returns the number of bytes written.

When write requests of {PIPE_BUF} or less  bytes to a pipe that has no
enough space, or write requests for greater than {PIPE_BUF} bytes
to a pipe that has no space, if O_NONBLOCK  is  set,
write returns -1 and sets errno to EAGAIN.

Merge-request: 997
Reviewed-by: Olivier Goffart <olivier.goffart@nokia.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/src/corelib/io/qprocess_unix.cpp b/src/corelib/io/qprocess_unix.cpp
index 0d5464ea7c..299280e109 100644
--- a/src/corelib/io/qprocess_unix.cpp
+++ b/src/corelib/io/qprocess_unix.cpp
@@ -869,6 +869,11 @@ qint64 QProcessPrivate::writeToStdin(const char *data, qint64 maxlen)
     if (written == -1)
         qDebug("QProcessPrivate::writeToStdin(), failed to write (%s)", qt_error_string(errno));
 #endif
+    // If the O_NONBLOCK flag is set and If some data can be written without blocking
+    // the process, write() will transfer what it can and return the number of bytes written.
+    // Otherwise, it will return -1 and set errno to EAGAIN
+    if (written == -1 && errno == EAGAIN)
+        written = 0;
     return written;
 }