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WIP: [2.7] bpo-24658: Fix read/write greater than 2 GiB on macOS (GH-1705) #9938

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WIP: [2.7] bpo-24658: Fix read/write greater than 2 GiB on macOS (GH-1705) #9938

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5e6aa97
[2.7] bpo-24658: Fix read/write greater than 2 GiB on macOS (GH-1705)
matrixise Oct 18, 2018
9ae079d
patch posixmodule.c and fileio.c, move the #define to pyport.h
matrixise Oct 18, 2018
c6a483e
add test_large_read in the tests discovery
matrixise Oct 18, 2018
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13 changes: 13 additions & 0 deletions Include/pyport.h
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Original file line number Diff line number Diff line change
Expand Up @@ -947,4 +947,17 @@ typedef struct fd_set {
#define Py_ULL(x) Py_LL(x##U)
#endif

#if defined (MS_WINDOWS) || defined(__APPLE__)
/* On Windows, the count parameter of read() is an int (bpo-9015, bpo-9611).
On macOS 10.13, read() and write() with more than INT_MAX bytes
fail with EINVAL (bpo-24658). */
# define _PY_READ_MAX INT_MAX
# define _PY_WRITE_MAX INT_MAX
#else
/* write() should truncate the input to PY_SSIZE_T_MAX bytes,
but it's safer to do it ourself to have a portable behaviour */
# define _PY_READ_MAX PY_SSIZE_T_MAX
# define _PY_WRITE_MAX PY_SSIZE_T_MAX
#endif

#endif /* Py_PYPORT_H */
12 changes: 11 additions & 1 deletion Lib/test/test_largefile.py
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@
import sys
import unittest
from test.test_support import run_unittest, TESTFN, verbose, requires, \
unlink
unlink, bigmemtest
import io # C implementation of io
import _pyio as pyio # Python implementation of io

Expand Down Expand Up @@ -48,6 +48,15 @@ def test_seek(self):
print('check file size with os.fstat')
self.assertEqual(os.fstat(f.fileno())[stat.ST_SIZE], size+1)

# _pyio.FileIO.readall() uses a temporary bytearry then casted to bytes,
# so memuse=2 is needed
@bigmemtest(minsize=size, memuse=2)
def test_large_read(self, _size):
# bpo-24658: Test that a read greater than 2GB does not fail.
with self.open(TESTFN, "rb") as f:
self.assertEqual(len(f.read()), size + 1)
self.assertEqual(f.tell(), size + 1)

def test_osstat(self):
if verbose:
print('check file size with os.stat')
Expand Down Expand Up @@ -186,6 +195,7 @@ class TestCase(LargeFileTest):
suite.addTest(TestCase('test_osstat'))
suite.addTest(TestCase('test_seek_read'))
suite.addTest(TestCase('test_lseek'))
suite.addTest(TestCase('test_large_read'))
with _open(TESTFN, 'wb') as f:
if hasattr(f, 'truncate'):
suite.addTest(TestCase('test_truncate'))
Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/macOS/2018-10-18-02-20-38.bpo-24658.c7F8Pu.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
On macOS, fix reading from and writing into a file with a size larger than 2
GiB.
23 changes: 13 additions & 10 deletions Modules/_io/fileio.c
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Expand Up @@ -515,9 +515,10 @@ fileio_readinto(fileio *self, PyObject *args)
len = pbuf.len;
Py_BEGIN_ALLOW_THREADS
errno = 0;
if (len > _PY_READ_MAX) {
len = _PY_READ_MAX;
}
#if defined(MS_WIN64) || defined(MS_WINDOWS)
if (len > INT_MAX)
len = INT_MAX;
n = read(self->fd, pbuf.buf, (int)len);
#else
n = read(self->fd, pbuf.buf, len);
Expand Down Expand Up @@ -604,9 +605,10 @@ fileio_readall(fileio *self)
Py_BEGIN_ALLOW_THREADS
errno = 0;
n = newsize - total;
if (n > _PY_READ_MAX) {
n = _PY_READ_MAX;
}
#if defined(MS_WIN64) || defined(MS_WINDOWS)
if (n > INT_MAX)
n = INT_MAX;
n = read(self->fd,
PyBytes_AS_STRING(result) + total,
(int)n);
Expand Down Expand Up @@ -668,10 +670,10 @@ fileio_read(fileio *self, PyObject *args)
return fileio_readall(self);
}

#if defined(MS_WIN64) || defined(MS_WINDOWS)
if (size > INT_MAX)
size = INT_MAX;
#endif
if (size > _PY_READ_MAX) {
size = _PY_READ_MAX;
}

bytes = PyBytes_FromStringAndSize(NULL, size);
if (bytes == NULL)
return NULL;
Expand Down Expand Up @@ -723,9 +725,10 @@ fileio_write(fileio *self, PyObject *args)
Py_BEGIN_ALLOW_THREADS
errno = 0;
len = pbuf.len;
if (len > _PY_WRITE_MAX) {
len = _PY_WRITE_MAX;
}
#if defined(MS_WIN64) || defined(MS_WINDOWS)
if (len > INT_MAX)
len = INT_MAX;
n = write(self->fd, pbuf.buf, (int)len);
#else
n = write(self->fd, pbuf.buf, len);
Expand Down
8 changes: 6 additions & 2 deletions Modules/posixmodule.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6805,6 +6805,9 @@ posix_read(PyObject *self, PyObject *args)
return posix_error();
}
Py_BEGIN_ALLOW_THREADS
if (size > _PY_READ_MAX) {
size = _PY_READ_MAX;
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Hum. It seems inefficient to allocate size bytes and only later pass _PY_READ_MAX. This truncation should be done before PyString_FromStringAndSize().

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ping @matrixise

}
n = read(fd, PyString_AsString(buffer), size);
Py_END_ALLOW_THREADS
if (n < 0) {
Expand Down Expand Up @@ -6836,9 +6839,10 @@ posix_write(PyObject *self, PyObject *args)
}
len = pbuf.len;
Py_BEGIN_ALLOW_THREADS
if (len > _PY_WRITE_MAX) {
len = _PY_WRITE_MAX;
}
#if defined(MS_WIN64) || defined(MS_WINDOWS)
if (len > INT_MAX)
len = INT_MAX;
size = write(fd, pbuf.buf, (int)len);
#else
size = write(fd, pbuf.buf, len);
Expand Down