Issue #17976: Fixed potential problem with file.write() not detecting IO error
by inspecting the return value of fwrite(). Based on patches by Jaakko Moisio
and test by Victor Stinner.
diff --git a/Lib/test/test_file2k.py b/Lib/test/test_file2k.py
index 0c633b4..5b90852 100644
--- a/Lib/test/test_file2k.py
+++ b/Lib/test/test_file2k.py
@@ -415,6 +415,14 @@
finally:
os.unlink(TESTFN)
+ @unittest.skipUnless(os.name == 'posix', 'test requires a posix system.')
+ def test_write_full(self):
+ # Issue #17976
+ with open('/dev/full', 'w', 1) as f:
+ with self.assertRaises(IOError):
+ f.write('hello')
+ f.write('\n')
+
class FileSubclassTests(unittest.TestCase):
def testExit(self):
diff --git a/Misc/ACKS b/Misc/ACKS
index cb2af18..35c9cf0 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -710,6 +710,7 @@
Dom Mitchell
Florian Mladitsch
Doug Moen
+Jaakko Moisio
The Dragon De Monsyne
Skip Montanaro
Paul Moore
diff --git a/Misc/NEWS b/Misc/NEWS
index 5a921c9..5f74858 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -9,6 +9,10 @@
Core and Builtins
-----------------
+- Issue #17976: Fixed potential problem with file.write() not detecting IO error
+ by inspecting the return value of fwrite(). Based on patches by Jaakko Moisio
+ and Victor Stinner.
+
- Issue #14432: Generator now clears the borrowed reference to the thread
state. Fix a crash when a generator is created in a C thread that is
destroyed while the generator is still used. The issue was that a generator
diff --git a/Objects/fileobject.c b/Objects/fileobject.c
index 76cdf74..d3b1cf6 100644
--- a/Objects/fileobject.c
+++ b/Objects/fileobject.c
@@ -1804,6 +1804,7 @@
const char *s;
Py_ssize_t n, n2;
PyObject *encoded = NULL;
+ int err = 0;
if (f->f_fp == NULL)
return err_closed();
@@ -1849,11 +1850,14 @@
FILE_BEGIN_ALLOW_THREADS(f)
errno = 0;
n2 = fwrite(s, 1, n, f->f_fp);
+ if (n2 != n || ferror(f->f_fp))
+ err = errno;
FILE_END_ALLOW_THREADS(f)
Py_XDECREF(encoded);
if (f->f_binary)
PyBuffer_Release(&pbuf);
- if (n2 != n) {
+ if (err) {
+ errno = err;
PyErr_SetFromErrno(PyExc_IOError);
clearerr(f->f_fp);
return NULL;