patch 8.1.0889: MS-Windows: a channel write may hang
Problem: MS-Windows: a channel write may hang.
Solution: Check for WriteFile() not writing anything. (Yasuhiro Matsumoto,
closes #3920)
diff --git a/src/channel.c b/src/channel.c
index 34a1fc3..d728c77 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -91,9 +91,10 @@
size = MAX_NAMED_PIPE_SIZE;
else
size = (DWORD)todo;
- // If the pipe overflows while the job does not read the data, WriteFile
- // will block forever. This abandons the write.
+ // If the pipe overflows while the job does not read the data,
+ // WriteFile() will block forever. This abandons the write.
memset(&ov, 0, sizeof(ov));
+ nwrite = 0;
if (!WriteFile(h, buf + done, size, &nwrite, &ov))
{
DWORD err = GetLastError();
@@ -104,6 +105,10 @@
return -1;
FlushFileBuffers(h);
}
+ else if (nwrite == 0)
+ // WriteFile() returns TRUE but did not write anything. This causes
+ // a hang, so bail out.
+ break;
todo -= nwrite;
done += nwrite;
}