Closes #15676: mmap: add empty file check prior to offset check
diff --git a/Lib/test/test_mmap.py b/Lib/test/test_mmap.py
index 2c2863e..31b3695 100644
--- a/Lib/test/test_mmap.py
+++ b/Lib/test/test_mmap.py
@@ -466,6 +466,22 @@
f.flush ()
return mmap.mmap (f.fileno(), 0)
+ def test_empty_file (self):
+ f = open (TESTFN, 'w+b')
+ f.close()
+ f = open(TESTFN, "rb")
+ try:
+ m = mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ)
+ m.close()
+ f.close()
+ self.fail("should not have been able to mmap empty file")
+ except ValueError as e:
+ f.close()
+ self.assertEqual(e.message, "cannot mmap an empty file")
+ except:
+ f.close()
+ self.fail("unexpected exception: " + str(e))
+
def test_offset (self):
f = open (TESTFN, 'w+b')
diff --git a/Misc/NEWS b/Misc/NEWS
index c073619..680cb18 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -103,6 +103,9 @@
Library
-------
+- Issue #15676: Now "mmap" check for empty files before doing the
+ offset check. Patch by Steven Willis.
+
- Issue #15340: Fix importing the random module when /dev/urandom cannot
be opened. This was a regression caused by the hash randomization patch.
diff --git a/Modules/mmapmodule.c b/Modules/mmapmodule.c
index a5027f5..8cf0e87 100644
--- a/Modules/mmapmodule.c
+++ b/Modules/mmapmodule.c
@@ -1189,6 +1189,11 @@
if (fd != -1 && fstat(fd, &st) == 0 && S_ISREG(st.st_mode)) {
if (map_size == 0) {
off_t calc_size;
+ if (st.st_size == 0) {
+ PyErr_SetString(PyExc_ValueError,
+ "cannot mmap an empty file");
+ return NULL;
+ }
if (offset >= st.st_size) {
PyErr_SetString(PyExc_ValueError,
"mmap offset is greater than file size");