Issue #11395: io.FileIO().write() clamps the data length to 32,767 bytes on
Windows if the file is a TTY to workaround a Windows bug. The Windows console
returns an error (12: not enough space error) on writing into stdout if
stdout mode is binary and the length is greater than 66,000 bytes (or less,
depending on heap usage).
diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
index f96f2e2..1aa5ee9 100644
--- a/Modules/_io/fileio.c
+++ b/Modules/_io/fileio.c
@@ -712,7 +712,14 @@
errno = 0;
len = pbuf.len;
#if defined(MS_WIN64) || defined(MS_WINDOWS)
- if (len > INT_MAX)
+ if (len > 32767 && isatty(self->fd)) {
+ /* Issue #11395: the Windows console returns an error (12: not
+ enough space error) on writing into stdout if stdout mode is
+ binary and the length is greater than 66,000 bytes (or less,
+ depending on heap usage). */
+ len = 32767;
+ }
+ else if (len > INT_MAX)
len = INT_MAX;
n = write(self->fd, pbuf.buf, (int)len);
#else