Issue #23708: Add _Py_read() and _Py_write() functions to factorize code handle

EINTR error and special cases for Windows.

These functions now truncate the length to PY_SSIZE_T_MAX to have a portable
and reliable behaviour. For example, read() result is undefined if counter is
greater than PY_SSIZE_T_MAX on Linux.

1 files changed, 31 insertions, 111 deletions

diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
index 0f226eafbf..6152cde464 100644
--- a/Modules/_io/fileio.c
+++ b/Modules/_io/fileio.c
@@ -570,8 +570,8 @@ static PyObject *
 fileio_readinto(fileio *self, PyObject *args)
 {
     Py_buffer pbuf;
-    Py_ssize_t n, len;
-    int err, async_err = 0;
+    Py_ssize_t n;
+    int err;
 
     if (self->fd < 0)
         return err_closed();
@@ -581,36 +581,16 @@ fileio_readinto(fileio *self, PyObject *args)
     if (!PyArg_ParseTuple(args, "w*", &pbuf))
         return NULL;
 
-    if (_PyVerify_fd(self->fd)) {
-        len = pbuf.len;
-#ifdef MS_WINDOWS
-        if (len > INT_MAX)
-            len = INT_MAX;
-#endif
-
-        do {
-            Py_BEGIN_ALLOW_THREADS
-            errno = 0;
-#ifdef MS_WINDOWS
-            n = read(self->fd, pbuf.buf, (int)len);
-#else
-            n = read(self->fd, pbuf.buf, len);
-#endif
-            Py_END_ALLOW_THREADS
-        } while (n < 0 && errno == EINTR &&
-                 !(async_err = PyErr_CheckSignals()));
-
-        if (async_err)
-            return NULL;
-    } else
-        n = -1;
+    n = _Py_read(self->fd, pbuf.buf, pbuf.len);
+    /* copy errno because PyBuffer_Release() can indirectly modify it */
     err = errno;
     PyBuffer_Release(&pbuf);
-    if (n < 0) {
-        if (err == EAGAIN)
+
+    if (n == -1) {
+        if (err == EAGAIN) {
+            PyErr_Clear();
             Py_RETURN_NONE;
-        errno = err;
-        PyErr_SetFromErrno(PyExc_IOError);
+        }
         return NULL;
     }
 
@@ -645,9 +625,8 @@ fileio_readall(fileio *self)
     Py_off_t pos, end;
     PyObject *result;
     Py_ssize_t bytes_read = 0;
-    Py_ssize_t len, n;
+    Py_ssize_t n;
     size_t bufsize;
-    int async_err = 0;
 
     if (self->fd < 0)
         return err_closed();
@@ -695,36 +674,21 @@ fileio_readall(fileio *self)
             }
         }
 
-        len = bufsize - bytes_read;
-#ifdef MS_WINDOWS
-        if (len > INT_MAX)
-            len = INT_MAX;
-#endif
-        do {
-            Py_BEGIN_ALLOW_THREADS
-            errno = 0;
-#ifdef MS_WINDOWS
-            n = read(self->fd, PyBytes_AS_STRING(result) + bytes_read, (int)len);
-#else
-            n = read(self->fd, PyBytes_AS_STRING(result) + bytes_read, len);
-#endif
-            Py_END_ALLOW_THREADS
-        } while (n < 0 && errno == EINTR &&
-                 !(async_err = PyErr_CheckSignals()));
+        n = _Py_read(self->fd,
+                     PyBytes_AS_STRING(result) + bytes_read,
+                     bufsize - bytes_read);
 
-        if (async_err)
-            return NULL;
         if (n == 0)
             break;
-        if (n < 0) {
+        if (n == -1) {
             if (errno == EAGAIN) {
+                PyErr_Clear();
                 if (bytes_read > 0)
                     break;
                 Py_DECREF(result);
                 Py_RETURN_NONE;
             }
             Py_DECREF(result);
-            PyErr_SetFromErrno(PyExc_IOError);
             return NULL;
         }
         bytes_read += n;
@@ -756,7 +720,6 @@ fileio_read(fileio *self, PyObject *args)
     char *ptr;
     Py_ssize_t n;
     Py_ssize_t size = -1;
-    int async_err = 0;
     PyObject *bytes;
 
     if (self->fd < 0)
@@ -767,44 +730,29 @@ fileio_read(fileio *self, PyObject *args)
     if (!PyArg_ParseTuple(args, "|O&", &_PyIO_ConvertSsize_t, &size))
         return NULL;
 
-    if (size < 0) {
+    if (size < 0)
         return fileio_readall(self);
-    }
 
 #ifdef MS_WINDOWS
+    /* On Windows, the count parameter of read() is an int */
     if (size > INT_MAX)
         size = INT_MAX;
 #endif
+
     bytes = PyBytes_FromStringAndSize(NULL, size);
     if (bytes == NULL)
         return NULL;
     ptr = PyBytes_AS_STRING(bytes);
 
-    if (_PyVerify_fd(self->fd)) {
-        do {
-            Py_BEGIN_ALLOW_THREADS
-            errno = 0;
-#ifdef MS_WINDOWS
-            n = read(self->fd, ptr, (int)size);
-#else
-            n = read(self->fd, ptr, size);
-#endif
-            Py_END_ALLOW_THREADS
-        } while (n < 0 && errno == EINTR &&
-                 !(async_err = PyErr_CheckSignals()));
-
-        if (async_err)
-            return NULL;
-    } else
-        n = -1;
-
-    if (n < 0) {
+    n = _Py_read(self->fd, ptr, size);
+    if (n == -1) {
+        /* copy errno because Py_DECREF() can indirectly modify it */
         int err = errno;
         Py_DECREF(bytes);
-        if (err == EAGAIN)
+        if (err == EAGAIN) {
+            PyErr_Clear();
             Py_RETURN_NONE;
-        errno = err;
-        PyErr_SetFromErrno(PyExc_IOError);
+        }
         return NULL;
     }
 
@@ -822,8 +770,8 @@ static PyObject *
 fileio_write(fileio *self, PyObject *args)
 {
     Py_buffer pbuf;
-    Py_ssize_t n, len;
-    int err, async_err = 0;
+    Py_ssize_t n;
+    int err;
 
     if (self->fd < 0)
         return err_closed();
@@ -833,44 +781,16 @@ fileio_write(fileio *self, PyObject *args)
     if (!PyArg_ParseTuple(args, "y*", &pbuf))
         return NULL;
 
-    if (_PyVerify_fd(self->fd)) {
-        len = pbuf.len;
-#ifdef MS_WINDOWS
-        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;
-#endif
-
-        do {
-            Py_BEGIN_ALLOW_THREADS
-            errno = 0;
-#ifdef MS_WINDOWS
-            n = write(self->fd, pbuf.buf, (int)len);
-#else
-            n = write(self->fd, pbuf.buf, len);
-#endif
-            Py_END_ALLOW_THREADS
-        } while (n < 0 && errno == EINTR &&
-                 !(async_err = PyErr_CheckSignals()));
-
-        if (async_err)
-            return NULL;
-    } else
-        n = -1;
+    n = _Py_write(self->fd, pbuf.buf, pbuf.len);
+    /* copy errno because PyBuffer_Release() can indirectly modify it */
     err = errno;
-
     PyBuffer_Release(&pbuf);
 
     if (n < 0) {
-        if (err == EAGAIN)
+        if (err == EAGAIN) {
+            PyErr_Clear();
             Py_RETURN_NONE;
-        errno = err;
-        PyErr_SetFromErrno(PyExc_IOError);
+        }
         return NULL;
     }