From a592104acdc56fa6511311ecfe6d4de63415d5ab Mon Sep 17 00:00:00 2001
From: Paul Sokolovsky <pfalcon@users.sourceforge.net>
Date: Wed, 7 May 2014 01:39:38 +0300
Subject: [PATCH] stream: Add compliant handling of non-blocking
read()/write().
In case of empty non-blocking read()/write(), both return None. read()
cannot return 0, as that means EOF, so returns another value, and then
write() just follows. This is still pretty unexpected, and typical
"if not len:" check would treat this as EOF. Well, non-blocking files
require special handling!
This also kind of makes it depending on POSIX, but well, anything else
should emulate POSIX anyway ;-).
---
py/stream.c | 24 +++++++++++++++++++++---
1 file changed, 21 insertions(+), 3 deletions(-)
diff --git a/py/stream.c b/py/stream.c
index 596139d4a..486ad4bb1 100644
--- a/py/stream.c
+++ b/py/stream.c
@@ -25,6 +25,7 @@
*/
#include <string.h>
+#include <errno.h>
#include "mpconfig.h"
#include "nlr.h"
@@ -38,6 +39,10 @@
STATIC mp_obj_t stream_readall(mp_obj_t self_in);
+// TODO: This is POSIX-specific (but then POSIX is the only real thing,
+// and anything else just emulates it, right?)
+#define is_nonblocking_error(errno) ((errno) == EAGAIN || (errno) == EWOULDBLOCK)
+
STATIC mp_obj_t stream_read(uint n_args, const mp_obj_t *args) {
struct _mp_obj_base_t *o = (struct _mp_obj_base_t *)args[0];
if (o->type->stream_p == NULL || o->type->stream_p->read == NULL) {
@@ -53,6 +58,14 @@ STATIC mp_obj_t stream_read(uint n_args, const mp_obj_t *args) {
int error;
machine_int_t out_sz = o->type->stream_p->read(o, buf, sz, &error);
if (out_sz == -1) {
+ if (is_nonblocking_error(error)) {
+ // https://docs.python.org/3.4/library/io.html#io.RawIOBase.read
+ // "If the object is in non-blocking mode and no bytes are available,
+ // None is returned."
+ // This is actually very weird, as naive truth check will treat
+ // this as EOF.
+ return mp_const_none;
+ }
nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError, "[Errno %d]", error));
} else {
mp_obj_t s = mp_obj_new_str(buf, out_sz, false); // will reallocate to use exact size
@@ -74,11 +87,16 @@ STATIC mp_obj_t stream_write(mp_obj_t self_in, mp_obj_t arg) {
int error;
machine_int_t out_sz = o->type->stream_p->write(self_in, bufinfo.buf, bufinfo.len, &error);
if (out_sz == -1) {
+ if (is_nonblocking_error(error)) {
+ // http://docs.python.org/3/library/io.html#io.RawIOBase.write
+ // "None is returned if the raw stream is set not to block and
+ // no single byte could be readily written to it."
+ // This is for consistency with read() behavior, still weird,
+ // see abobe.
+ return mp_const_none;
+ }
nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError, "[Errno %d]", error));
} else {
- // http://docs.python.org/3/library/io.html#io.RawIOBase.write
- // "None is returned if the raw stream is set not to block and no single byte could be readily written to it."
- // Do they mean that instead of 0 they return None?
return MP_OBJ_NEW_SMALL_INT(out_sz);
}
}
--
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