From: Antoine Pitrou <solipsis@pitrou.net>
Date: Wed, 21 Jan 2009 01:05:40 +0000 (+0000)
Subject: Merged revisions 68836 via svnmerge from
X-Git-Tag: v3.0.1~110
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=25f4347a9ad97babfb74d6aedbec00013300f246;p=thirdparty%2FPython%2Fcpython.git

Merged revisions 68836 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/branches/py3k

................
  r68836 | antoine.pitrou | 2009-01-21 01:55:13 +0100 (mer., 21 janv. 2009) | 12 lines

  Merged revisions 68835 via svnmerge from
  svn+ssh://pythondev@svn.python.org/python/trunk

  ........
    r68835 | antoine.pitrou | 2009-01-21 01:45:36 +0100 (mer., 21 janv. 2009) | 6 lines

    Issue #5008: When a file is opened in append mode with the new IO library,
    do an explicit seek to the end of file (so that e.g. tell() returns the
    file size rather than 0). This is consistent with the behaviour of the
    traditional 2.x file object.
  ........
................
---

diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index e8bba86ae080..987fca4ea74d 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -233,6 +233,17 @@ class IOTest(unittest.TestCase):
             else:
                 self.fail("1/0 didn't raise an exception")
 
+    # issue 5008
+    def test_append_mode_tell(self):
+        with io.open(support.TESTFN, "wb") as f:
+            f.write(b"xxx")
+        with io.open(support.TESTFN, "ab", buffering=0) as f:
+            self.assertEqual(f.tell(), 3)
+        with io.open(support.TESTFN, "ab") as f:
+            self.assertEqual(f.tell(), 3)
+        with io.open(support.TESTFN, "a") as f:
+            self.assert_(f.tell() > 0)
+
     def test_destructor(self):
         record = []
         class MyFileIO(io.FileIO):
diff --git a/Misc/NEWS b/Misc/NEWS
index 443cffb16dff..234c200f91aa 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -98,6 +98,11 @@ Core and Builtins
 Library
 -------
 
+- Issue #5008: When a file is opened in append mode with the new IO library,
+  do an explicit seek to the end of file (so that e.g. tell() returns the
+  file size rather than 0). This is consistent with the behaviour of the
+  traditional 2.x file object.
+
 - Issue #5013: Fixed a bug in FileHandler which occurred when the delay
   parameter was set.
 
diff --git a/Modules/_fileio.c b/Modules/_fileio.c
index 22b473c51390..300449349b95 100644
--- a/Modules/_fileio.c
+++ b/Modules/_fileio.c
@@ -55,6 +55,9 @@ PyTypeObject PyFileIO_Type;
 
 #define PyFileIO_Check(op) (PyObject_TypeCheck((op), &PyFileIO_Type))
 
+static PyObject *
+portable_lseek(int fd, PyObject *posobj, int whence);
+
 /* Returns 0 on success, -1 with exception set on failure. */
 static int
 internal_close(PyFileIOObject *self)
@@ -315,6 +318,16 @@ fileio_init(PyObject *oself, PyObject *args, PyObject *kwds)
 			goto error;
 	}
 
+	if (append) {
+		/* For consistent behaviour, we explicitly seek to the
+		   end of file (otherwise, it might be done only on the
+		   first write()). */
+		PyObject *pos = portable_lseek(self->fd, NULL, 2);
+		if (pos == NULL)
+			goto error;
+		Py_DECREF(pos);
+	}
+
 	goto done;
 
  error: