[Python-checkins] cpython: Close #10142: Support for SEEK_HOLE/SEEK_DATA
jesus.cea
python-checkins at python.org
Thu Apr 26 16:39:46 CEST 2012
http://hg.python.org/cpython/rev/86dc014cdd74
changeset: 76570:86dc014cdd74
user: Jesus Cea <jcea at jcea.es>
date: Thu Apr 26 16:39:35 2012 +0200
summary:
Close #10142: Support for SEEK_HOLE/SEEK_DATA
files:
Doc/library/io.rst | 5 +++++
Doc/library/os.rst | 4 ++++
Lib/_pyio.py | 12 +++---------
Lib/os.py | 1 +
Lib/test/test_posix.py | 20 ++++++++++++++++++++
Misc/NEWS | 2 ++
Modules/_io/bufferedio.c | 21 ++++++++++++++++++---
Modules/posixmodule.c | 7 +++++++
8 files changed, 60 insertions(+), 12 deletions(-)
diff --git a/Doc/library/io.rst b/Doc/library/io.rst
--- a/Doc/library/io.rst
+++ b/Doc/library/io.rst
@@ -291,6 +291,11 @@
.. versionadded:: 3.1
The ``SEEK_*`` constants.
+ .. versionadded:: 3.3
+ Some operating systems could support additional values, like
+ :data:`os.SEEK_HOLE` or :data:`os.SEEK_DATA`. The valid values
+ for a file could depend on it being open in text or binary mode.
+
.. method:: seekable()
Return ``True`` if the stream supports random access. If ``False``,
diff --git a/Doc/library/os.rst b/Doc/library/os.rst
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -992,6 +992,10 @@
Parameters to the :func:`lseek` function. Their values are 0, 1, and 2,
respectively. Availability: Windows, Unix.
+ .. versionadded:: 3.3
+ Some operating systems could support additional values, like
+ :data:`os.SEEK_HOLE` or :data:`os.SEEK_DATA`.
+
.. function:: mkdirat(dirfd, path, mode=0o777)
diff --git a/Lib/_pyio.py b/Lib/_pyio.py
--- a/Lib/_pyio.py
+++ b/Lib/_pyio.py
@@ -306,6 +306,7 @@
* 0 -- start of stream (the default); offset should be zero or positive
* 1 -- current stream position; offset may be negative
* 2 -- end of stream; offset is usually negative
+ Some operating systems / file systems could provide additional values.
Return an int indicating the new absolute position.
"""
@@ -866,7 +867,7 @@
elif whence == 2:
self._pos = max(0, len(self._buffer) + pos)
else:
- raise ValueError("invalid whence value")
+ raise ValueError("unsupported whence value")
return self._pos
def tell(self):
@@ -1041,8 +1042,6 @@
return _BufferedIOMixin.tell(self) - len(self._read_buf) + self._read_pos
def seek(self, pos, whence=0):
- if not (0 <= whence <= 2):
- raise ValueError("invalid whence value")
with self._read_lock:
if whence == 1:
pos -= len(self._read_buf) - self._read_pos
@@ -1138,8 +1137,6 @@
return _BufferedIOMixin.tell(self) + len(self._write_buf)
def seek(self, pos, whence=0):
- if not (0 <= whence <= 2):
- raise ValueError("invalid whence")
with self._write_lock:
self._flush_unlocked()
return _BufferedIOMixin.seek(self, pos, whence)
@@ -1235,8 +1232,6 @@
BufferedWriter.__init__(self, raw, buffer_size, max_buffer_size)
def seek(self, pos, whence=0):
- if not (0 <= whence <= 2):
- raise ValueError("invalid whence")
self.flush()
if self._read_buf:
# Undo read ahead.
@@ -1852,8 +1847,7 @@
self._decoder.reset()
return position
if whence != 0:
- raise ValueError("invalid whence (%r, should be 0, 1 or 2)" %
- (whence,))
+ raise ValueError("unsupported whence (%r)" % (whence,))
if cookie < 0:
raise ValueError("negative seek position %r" % (cookie,))
self.flush()
diff --git a/Lib/os.py b/Lib/os.py
--- a/Lib/os.py
+++ b/Lib/os.py
@@ -116,6 +116,7 @@
# Python uses fixed values for the SEEK_ constants; they are mapped
# to native constants if necessary in posixmodule.c
+# Other possible SEEK values are directly imported from posixmodule.c
SEEK_SET = 0
SEEK_CUR = 1
SEEK_END = 2
diff --git a/Lib/test/test_posix.py b/Lib/test/test_posix.py
--- a/Lib/test/test_posix.py
+++ b/Lib/test/test_posix.py
@@ -1009,6 +1009,26 @@
posix.RTLD_GLOBAL
posix.RTLD_LOCAL
+ @unittest.skipUnless('PC_MIN_HOLE_SIZE' in os.pathconf_names,
+ "test needs an OS that reports file holes")
+ def test_fs_holes(self) :
+ # Even if the filesystem doesn't report holes,
+ # if the OS supports it the SEEK_* constants
+ # will be defined and will have a consistent
+ # behaviour:
+ # os.SEEK_DATA = current position
+ # os.SEEK_HOLE = end of file position
+ with open(support.TESTFN, 'r+b') as fp :
+ fp.write(b"hello")
+ fp.flush()
+ size = fp.tell()
+ fno = fp.fileno()
+ for i in range(size) :
+ self.assertEqual(i, os.lseek(fno, i, os.SEEK_DATA))
+ self.assertLessEqual(size, os.lseek(fno, i, os.SEEK_HOLE))
+ self.assertRaises(OSError, os.lseek, fno, size, os.SEEK_DATA)
+ self.assertRaises(OSError, os.lseek, fno, size, os.SEEK_HOLE)
+
class PosixGroupsTester(unittest.TestCase):
def setUp(self):
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -423,6 +423,8 @@
- Issue #14259: The finditer() method of re objects did not take any
keyword arguments, contrary to the documentation.
+- Issue #10142: Support for SEEK_HOLE/SEEK_DATA (for example, under ZFS).
+
Tests
-----
diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -1157,9 +1157,20 @@
if (!PyArg_ParseTuple(args, "O|i:seek", &targetobj, &whence)) {
return NULL;
}
- if (whence < 0 || whence > 2) {
+
+ /* Do some error checking instead of trusting OS 'seek()'
+ ** error detection, just in case.
+ */
+ if ((whence < 0 || whence >2)
+#ifdef SEEK_HOLE
+ && (whence != SEEK_HOLE)
+#endif
+#ifdef SEEK_DATA
+ && (whence != SEEK_DATA)
+#endif
+ ) {
PyErr_Format(PyExc_ValueError,
- "whence must be between 0 and 2, not %d", whence);
+ "whence value %d unsupported", whence);
return NULL;
}
@@ -1172,7 +1183,11 @@
if (target == -1 && PyErr_Occurred())
return NULL;
- if (whence != 2 && self->readable) {
+ /* SEEK_SET and SEEK_CUR are special because we could seek inside the
+ buffer. Other whence values must be managed without this optimization.
+ Some Operating Systems can provide additional values, like
+ SEEK_HOLE/SEEK_DATA. */
+ if (((whence == 0) || (whence == 1)) && self->readable) {
Py_off_t current, avail;
/* Check if seeking leaves us inside the current buffer,
so as to return quickly if possible. Also, we needn't take the
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -11227,6 +11227,13 @@
#endif
+#ifdef SEEK_HOLE
+ if (ins(d, "SEEK_HOLE", (long)SEEK_HOLE)) return -1;
+#endif
+#ifdef SEEK_DATA
+ if (ins(d, "SEEK_DATA", (long)SEEK_DATA)) return -1;
+#endif
+
/* MS Windows */
#ifdef O_NOINHERIT
/* Don't inherit in child processes. */
--
Repository URL: http://hg.python.org/cpython
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