Author: antoine.pitrou Date: Sun Jan 31 23:26:04 2010 New Revision: 77890 Log: - 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. Modified: python/trunk/Lib/_pyio.py python/trunk/Lib/test/test_fileio.py python/trunk/Lib/test/test_io.py python/trunk/Lib/test/test_largefile.py python/trunk/Lib/test/test_memoryio.py python/trunk/Misc/ACKS python/trunk/Misc/NEWS python/trunk/Modules/_io/bytesio.c python/trunk/Modules/_io/fileio.c python/trunk/Modules/_io/iobase.c python/trunk/Modules/_io/stringio.c python/trunk/Modules/_io/textio.c Modified: python/trunk/Lib/_pyio.py ============================================================================== --- python/trunk/Lib/_pyio.py (original) +++ python/trunk/Lib/_pyio.py Sun Jan 31 23:26:04 2010 @@ -867,7 +867,7 @@ 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 @@ -1226,8 +1226,7 @@ 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: @@ -1727,8 +1726,7 @@ 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: Modified: python/trunk/Lib/test/test_fileio.py ============================================================================== --- python/trunk/Lib/test/test_fileio.py (original) +++ python/trunk/Lib/test/test_fileio.py Sun Jan 31 23:26:04 2010 @@ -329,6 +329,17 @@ 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> Modified: python/trunk/Lib/test/test_io.py ============================================================================== --- python/trunk/Lib/test/test_io.py (original) +++ python/trunk/Lib/test/test_io.py Sun Jan 31 23:26:04 2010 @@ -234,6 +234,11 @@ 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.tell(), 6) @@ -244,8 +249,9 @@ 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): @@ -290,7 +296,7 @@ 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") @@ -988,7 +994,7 @@ 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") @@ -1374,6 +1380,14 @@ 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) Modified: python/trunk/Lib/test/test_largefile.py ============================================================================== --- python/trunk/Lib/test/test_largefile.py (original) +++ python/trunk/Lib/test/test_largefile.py Sun Jan 31 23:26:04 2010 @@ -125,7 +125,7 @@ f.seek(42) f.truncate(newsize) if self.new_io: - 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 @@ -133,7 +133,7 @@ f.seek(0) f.truncate(1) if self.new_io: - 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 Modified: python/trunk/Lib/test/test_memoryio.py ============================================================================== --- python/trunk/Lib/test/test_memoryio.py (original) +++ python/trunk/Lib/test/test_memoryio.py Sun Jan 31 23:26:04 2010 @@ -76,7 +76,7 @@ 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") @@ -127,7 +127,8 @@ # truncate() accepts long objects self.assertEqual(memio.truncate(4L), 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() Modified: python/trunk/Misc/ACKS ============================================================================== --- python/trunk/Misc/ACKS (original) +++ python/trunk/Misc/ACKS Sun Jan 31 23:26:04 2010 @@ -124,6 +124,7 @@ Charles Cazabon Per Cederqvist Octavian Cerna +Pascal Chambon Hye-Shik Chang Jeffrey Chang Mitch Chapman Modified: python/trunk/Misc/NEWS ============================================================================== --- python/trunk/Misc/NEWS (original) +++ python/trunk/Misc/NEWS Sun Jan 31 23:26:04 2010 @@ -50,6 +50,11 @@ 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. + - UserDict is now a new-style class. - Issue #7610: Reworked implementation of the internal Modified: python/trunk/Modules/_io/bytesio.c ============================================================================== --- python/trunk/Modules/_io/bytesio.c (original) +++ python/trunk/Modules/_io/bytesio.c Sun Jan 31 23:26:04 2010 @@ -414,7 +414,7 @@ "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) @@ -453,7 +453,6 @@ if (resize_buffer(self, size) < 0) return NULL; } - self->pos = size; return PyLong_FromSsize_t(size); } Modified: python/trunk/Modules/_io/fileio.c ============================================================================== --- python/trunk/Modules/_io/fileio.c (original) +++ python/trunk/Modules/_io/fileio.c Sun Jan 31 23:26:04 2010 @@ -758,8 +758,10 @@ 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; @@ -774,58 +776,86 @@ 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) Modified: python/trunk/Modules/_io/iobase.c ============================================================================== --- python/trunk/Modules/_io/iobase.c (original) +++ python/trunk/Modules/_io/iobase.c Sun Jan 31 23:26:04 2010 @@ -102,8 +102,8 @@ 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) Modified: python/trunk/Modules/_io/stringio.c ============================================================================== --- python/trunk/Modules/_io/stringio.c (original) +++ python/trunk/Modules/_io/stringio.c Sun Jan 31 23:26:04 2010 @@ -350,7 +350,7 @@ "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 * @@ -390,7 +390,6 @@ return NULL; self->string_size = size; } - self->pos = size; return PyLong_FromSsize_t(size); } Modified: python/trunk/Modules/_io/textio.c ============================================================================== --- python/trunk/Modules/_io/textio.c (original) +++ python/trunk/Modules/_io/textio.c Sun Jan 31 23:26:04 2010 @@ -2313,15 +2313,7 @@ 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 *