bpo-30228: FileIO seek() and tell() set seekable (#1384)

FileIO.seek() and FileIO.tell() method now set the internal seekable
attribute to avoid one syscall on open() (in buffered or text mode).

The seekable property is now also more reliable since its value is
set correctly on memory allocation failure.
This commit is contained in:
Victor Stinner 2017-05-02 15:10:39 +02:00 committed by GitHub
parent 1dae7450c6
commit 9997073736
2 changed files with 24 additions and 15 deletions

View File

@ -317,6 +317,9 @@ Extension Modules
Library Library
------- -------
- bpo-30228: The seek() and tell() methods of io.FileIO now set the internal
seekable attribute to avoid one syscall on open() (in buffered or text mode).
- bpo-30190: unittest's assertAlmostEqual and assertNotAlmostEqual provide a - bpo-30190: unittest's assertAlmostEqual and assertNotAlmostEqual provide a
better message in case of failure which includes the difference between better message in case of failure which includes the difference between
left and right arguments. (patch by Giampaolo Rodola') left and right arguments. (patch by Giampaolo Rodola')

View File

@ -73,6 +73,9 @@ _Py_IDENTIFIER(name);
#define PyFileIO_Check(op) (PyObject_TypeCheck((op), &PyFileIO_Type)) #define PyFileIO_Check(op) (PyObject_TypeCheck((op), &PyFileIO_Type))
/* Forward declarations */
static PyObject* portable_lseek(fileio *self, PyObject *posobj, int whence);
int int
_PyFileIO_closed(PyObject *self) _PyFileIO_closed(PyObject *self)
{ {
@ -98,11 +101,6 @@ fileio_dealloc_warn(fileio *self, PyObject *source)
Py_RETURN_NONE; Py_RETURN_NONE;
} }
static PyObject *
portable_lseek(int fd, PyObject *posobj, int whence);
static PyObject *portable_lseek(int fd, PyObject *posobj, int whence);
/* Returns 0 on success, -1 with exception set on failure. */ /* Returns 0 on success, -1 with exception set on failure. */
static int static int
internal_close(fileio *self) internal_close(fileio *self)
@ -478,7 +476,7 @@ _io_FileIO___init___impl(fileio *self, PyObject *nameobj, const char *mode,
/* For consistent behaviour, we explicitly seek to the /* For consistent behaviour, we explicitly seek to the
end of file (otherwise, it might be done only on the end of file (otherwise, it might be done only on the
first write()). */ first write()). */
PyObject *pos = portable_lseek(self->fd, NULL, 2); PyObject *pos = portable_lseek(self, NULL, 2);
if (pos == NULL) if (pos == NULL)
goto error; goto error;
Py_DECREF(pos); Py_DECREF(pos);
@ -600,13 +598,14 @@ _io_FileIO_seekable_impl(fileio *self)
if (self->fd < 0) if (self->fd < 0)
return err_closed(); return err_closed();
if (self->seekable < 0) { if (self->seekable < 0) {
PyObject *pos = portable_lseek(self->fd, NULL, SEEK_CUR); /* portable_lseek() sets the seekable attribute */
PyObject *pos = portable_lseek(self, NULL, SEEK_CUR);
assert(self->seekable >= 0);
if (pos == NULL) { if (pos == NULL) {
PyErr_Clear(); PyErr_Clear();
self->seekable = 0; }
} else { else {
Py_DECREF(pos); Py_DECREF(pos);
self->seekable = 1;
} }
} }
return PyBool_FromLong((long) self->seekable); return PyBool_FromLong((long) self->seekable);
@ -865,9 +864,10 @@ _io_FileIO_write_impl(fileio *self, Py_buffer *b)
/* Cribbed from posix_lseek() */ /* Cribbed from posix_lseek() */
static PyObject * static PyObject *
portable_lseek(int fd, PyObject *posobj, int whence) portable_lseek(fileio *self, PyObject *posobj, int whence)
{ {
Py_off_t pos, res; Py_off_t pos, res;
int fd = self->fd;
#ifdef SEEK_SET #ifdef SEEK_SET
/* Turn 0, 1, 2 into SEEK_{SET,CUR,END} */ /* Turn 0, 1, 2 into SEEK_{SET,CUR,END} */
@ -884,8 +884,9 @@ portable_lseek(int fd, PyObject *posobj, int whence)
} }
#endif /* SEEK_SET */ #endif /* SEEK_SET */
if (posobj == NULL) if (posobj == NULL) {
pos = 0; pos = 0;
}
else { else {
if(PyFloat_Check(posobj)) { if(PyFloat_Check(posobj)) {
PyErr_SetString(PyExc_TypeError, "an integer is required"); PyErr_SetString(PyExc_TypeError, "an integer is required");
@ -909,6 +910,11 @@ portable_lseek(int fd, PyObject *posobj, int whence)
#endif #endif
_Py_END_SUPPRESS_IPH _Py_END_SUPPRESS_IPH
Py_END_ALLOW_THREADS Py_END_ALLOW_THREADS
if (self->seekable < 0) {
self->seekable = (res >= 0);
}
if (res < 0) if (res < 0)
return PyErr_SetFromErrno(PyExc_OSError); return PyErr_SetFromErrno(PyExc_OSError);
@ -943,7 +949,7 @@ _io_FileIO_seek_impl(fileio *self, PyObject *pos, int whence)
if (self->fd < 0) if (self->fd < 0)
return err_closed(); return err_closed();
return portable_lseek(self->fd, pos, whence); return portable_lseek(self, pos, whence);
} }
/*[clinic input] /*[clinic input]
@ -961,7 +967,7 @@ _io_FileIO_tell_impl(fileio *self)
if (self->fd < 0) if (self->fd < 0)
return err_closed(); return err_closed();
return portable_lseek(self->fd, NULL, 1); return portable_lseek(self, NULL, 1);
} }
#ifdef HAVE_FTRUNCATE #ifdef HAVE_FTRUNCATE
@ -992,7 +998,7 @@ _io_FileIO_truncate_impl(fileio *self, PyObject *posobj)
if (posobj == Py_None || posobj == NULL) { if (posobj == Py_None || posobj == NULL) {
/* Get the current position. */ /* Get the current position. */
posobj = portable_lseek(fd, NULL, 1); posobj = portable_lseek(self, NULL, 1);
if (posobj == NULL) if (posobj == NULL)
return NULL; return NULL;
} }