elif pos < 0:
raise ValueError("negative truncate position %r" % (pos,))
del self._buffer[pos:]
- return self.seek(pos)
+ return pos
def readable(self):
return True
if pos is None:
pos = self.tell()
# Use seek to flush the read buffer.
- self.seek(pos)
- return BufferedWriter.truncate(self)
+ return BufferedWriter.truncate(self, pos)
def read(self, n=None):
if n is None:
self.flush()
if pos is None:
pos = self.tell()
- self.seek(pos)
- return self.buffer.truncate()
+ return self.buffer.truncate(pos)
def detach(self):
if self.buffer is None:
return result
def truncate(self, size=None):
- StringIO.truncate(self, size)
+ self.seek(size)
+ StringIO.truncate(self)
# Worst-case linear-time ellipsis matching.
def _ellipsis_match(want, got):
f.close()
self.fail("no error for invalid mode: %s" % bad_mode)
+ def testTruncate(self):
+ f = _FileIO(TESTFN, 'w')
+ f.write(bytes(bytearray(range(10))))
+ self.assertEqual(f.tell(), 10)
+ f.truncate(5)
+ self.assertEqual(f.tell(), 10)
+ self.assertEqual(f.seek(0, os.SEEK_END), 5)
+ f.truncate(15)
+ self.assertEqual(f.tell(), 5)
+ self.assertEqual(f.seek(0, os.SEEK_END), 15)
+
def testTruncateOnWindows(self):
def bug801631():
# SF bug <http://www.python.org/sf/801631>
support.unlink(support.TESTFN)
def write_ops(self, f):
+ self.assertEqual(f.write(b"blah."), 5)
+ f.truncate(0)
+ self.assertEqual(f.tell(), 5)
+ f.seek(0)
+
self.assertEqual(f.write(b"blah."), 5)
self.assertEqual(f.seek(0), 0)
self.assertEqual(f.write(b"Hello."), 6)
self.assertEqual(f.write(b"h"), 1)
self.assertEqual(f.seek(-1, 2), 13)
self.assertEqual(f.tell(), 13)
+
self.assertEqual(f.truncate(12), 12)
- self.assertEqual(f.tell(), 12)
+ self.assertEqual(f.tell(), 13)
self.assertRaises(TypeError, f.seek, 0.0)
def read_ops(self, f, buffered=False):
self.assertEqual(f.tell(), self.LARGE + 2)
self.assertEqual(f.seek(0, 2), self.LARGE + 2)
self.assertEqual(f.truncate(self.LARGE + 1), self.LARGE + 1)
- self.assertEqual(f.tell(), self.LARGE + 1)
+ self.assertEqual(f.tell(), self.LARGE + 2)
self.assertEqual(f.seek(0, 2), self.LARGE + 1)
self.assertEqual(f.seek(-1, 2), self.LARGE)
self.assertEqual(f.read(2), b"x")
bufio = self.tp(raw, 8)
bufio.write(b"abcdef")
self.assertEqual(bufio.truncate(3), 3)
- self.assertEqual(bufio.tell(), 3)
+ self.assertEqual(bufio.tell(), 6)
with self.open(support.TESTFN, "rb", buffering=0) as f:
self.assertEqual(f.read(), b"abc")
self.assertEqual(s,
b"A" + b"B" * overwrite_size + b"A" * (9 - overwrite_size))
+ def test_truncate_after_read_or_write(self):
+ raw = self.BytesIO(b"A" * 10)
+ bufio = self.tp(raw, 100)
+ self.assertEqual(bufio.read(2), b"AA") # the read buffer gets filled
+ self.assertEqual(bufio.truncate(), 2)
+ self.assertEqual(bufio.write(b"BB"), 2) # the write buffer increases
+ self.assertEqual(bufio.truncate(), 4)
+
def test_misbehaved_io(self):
BufferedReaderTest.test_misbehaved_io(self)
BufferedWriterTest.test_misbehaved_io(self)
newsize -= 1
f.seek(42)
f.truncate(newsize)
- self.assertEqual(f.tell(), newsize) # else wasn't truncated
+ self.assertEqual(f.tell(), 42)
f.seek(0, 2)
self.assertEqual(f.tell(), newsize)
# XXX truncate(larger than true size) is ill-defined
# across platform; cut it waaaaay back
f.seek(0)
f.truncate(1)
- self.assertEqual(f.tell(), 1) # else pointer moved
+ self.assertEqual(f.tell(), 0) # else pointer moved
f.seek(0)
self.assertEqual(len(f.read()), 1) # else wasn't truncated
self.assertEqual(f.seek(0), 0)
self.assertEqual(f.write(t("h")), 1)
self.assertEqual(f.truncate(12), 12)
- self.assertEqual(f.tell(), 12)
+ self.assertEqual(f.tell(), 1)
def test_write(self):
buf = self.buftype("hello world\n")
self.assertEqual(memio.getvalue(), buf[:6])
self.assertEqual(memio.truncate(4), 4)
self.assertEqual(memio.getvalue(), buf[:4])
- self.assertEqual(memio.tell(), 4)
+ self.assertEqual(memio.tell(), 6)
+ memio.seek(0, 2)
memio.write(buf)
self.assertEqual(memio.getvalue(), buf[:4] + buf)
pos = memio.tell()
Donn Cave
Per Cederqvist
Octavian Cerna
+Pascal Chambon
Hye-Shik Chang
Jeffrey Chang
Mitch Chapman
Library
-------
+- Issue #6939: Fix file I/O objects in the `io` module to keep the original
+ file position when calling `truncate()`. It would previously change the
+ file position to the given argument, which goes against the tradition of
+ ftruncate() and other truncation APIs. Patch by Pascal Chambon.
+
- Issue #7792: Registering non-classes to ABCs raised an obscure error.
- Issue #7785: Don't accept bytes in FileIO.write().
"truncate([size]) -> int. Truncate the file to at most size bytes.\n"
"\n"
"Size defaults to the current file position, as returned by tell().\n"
-"Returns the new size. Imply an absolute seek to the position size.");
+"The current file position is unchanged. Returns the new size.\n");
static PyObject *
bytesio_truncate(bytesio *self, PyObject *args)
if (resize_buffer(self, size) < 0)
return NULL;
}
- self->pos = size;
return PyLong_FromSsize_t(size);
}
static PyObject *
fileio_truncate(fileio *self, PyObject *args)
{
- PyObject *posobj = NULL;
+ PyObject *posobj = NULL; /* the new size wanted by the user */
+#ifndef MS_WINDOWS
Py_off_t pos;
+#endif
int ret;
int fd;
if (posobj == Py_None || posobj == NULL) {
/* Get the current position. */
- posobj = portable_lseek(fd, NULL, 1);
- if (posobj == NULL)
+ posobj = portable_lseek(fd, NULL, 1);
+ if (posobj == NULL)
return NULL;
- }
- else {
- /* Move to the position to be truncated. */
- posobj = portable_lseek(fd, posobj, 0);
- }
- if (posobj == NULL)
- return NULL;
-
-#if defined(HAVE_LARGEFILE_SUPPORT)
- pos = PyLong_AsLongLong(posobj);
-#else
- pos = PyLong_AsLong(posobj);
-#endif
- if (pos == -1 && PyErr_Occurred())
- return NULL;
+ }
+ else {
+ Py_INCREF(posobj);
+ }
#ifdef MS_WINDOWS
/* MS _chsize doesn't work if newsize doesn't fit in 32 bits,
so don't even try using it. */
{
+ PyObject *oldposobj, *tempposobj;
HANDLE hFile;
+
+ /* we save the file pointer position */
+ oldposobj = portable_lseek(fd, NULL, 1);
+ if (oldposobj == NULL) {
+ Py_DECREF(posobj);
+ return NULL;
+ }
+
+ /* we then move to the truncation position */
+ tempposobj = portable_lseek(fd, posobj, 0);
+ if (tempposobj == NULL) {
+ Py_DECREF(oldposobj);
+ Py_DECREF(posobj);
+ return NULL;
+ }
+ Py_DECREF(tempposobj);
/* Truncate. Note that this may grow the file! */
Py_BEGIN_ALLOW_THREADS
errno = 0;
hFile = (HANDLE)_get_osfhandle(fd);
- ret = hFile == (HANDLE)-1;
+ ret = hFile == (HANDLE)-1; /* testing for INVALID_HANDLE value */
if (ret == 0) {
ret = SetEndOfFile(hFile) == 0;
if (ret)
errno = EACCES;
}
Py_END_ALLOW_THREADS
+
+ /* we restore the file pointer position in any case */
+ tempposobj = portable_lseek(fd, oldposobj, 0);
+ Py_DECREF(oldposobj);
+ if (tempposobj == NULL) {
+ Py_DECREF(posobj);
+ return NULL;
+ }
+ Py_DECREF(tempposobj);
}
#else
+
+#if defined(HAVE_LARGEFILE_SUPPORT)
+ pos = PyLong_AsLongLong(posobj);
+#else
+ pos = PyLong_AsLong(posobj);
+#endif
+ if (PyErr_Occurred()){
+ Py_DECREF(posobj);
+ return NULL;
+ }
+
Py_BEGIN_ALLOW_THREADS
errno = 0;
ret = ftruncate(fd, pos);
Py_END_ALLOW_THREADS
+
#endif /* !MS_WINDOWS */
if (ret != 0) {
+ Py_DECREF(posobj);
PyErr_SetFromErrno(PyExc_IOError);
return NULL;
}
return posobj;
}
-#endif
+#endif /* HAVE_FTRUNCATE */
static char *
mode_string(fileio *self)
PyDoc_STRVAR(iobase_truncate_doc,
"Truncate file to size bytes.\n"
"\n"
- "Size defaults to the current IO position as reported by tell(). Return\n"
- "the new size.");
+ "File pointer is left unchanged. Size defaults to the current IO\n"
+ "position as reported by tell(). Returns the new size.");
static PyObject *
iobase_truncate(PyObject *self, PyObject *args)
"Truncate size to pos.\n"
"\n"
"The pos argument defaults to the current file position, as\n"
- "returned by tell(). Imply an absolute seek to pos.\n"
+ "returned by tell(). The current file position is unchanged.\n"
"Returns the new absolute position.\n");
static PyObject *
return NULL;
self->string_size = size;
}
- self->pos = size;
return PyLong_FromSsize_t(size);
}
return NULL;
Py_DECREF(res);
- if (pos != Py_None) {
- res = PyObject_CallMethodObjArgs((PyObject *) self,
- _PyIO_str_seek, pos, NULL);
- if (res == NULL)
- return NULL;
- Py_DECREF(res);
- }
-
- return PyObject_CallMethodObjArgs(self->buffer, _PyIO_str_truncate, NULL);
+ return PyObject_CallMethodObjArgs(self->buffer, _PyIO_str_truncate, pos, NULL);
}
static PyObject *
projects / python / commitdiff