From 8c0be6fd9101746235b63ddfb84106d1e9ca286b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jakub=20Kul=C3=ADk?= <Kulikjak@gmail.com>
Date: Sat, 5 Sep 2020 21:10:01 +0200
Subject: [PATCH] bpo-41687: Fix sendfile implementation to work with Solaris
 (#22040)

---
 Lib/test/test_asyncio/test_sendfile.py        |  6 ++++++
 .../2020-09-01-15-57-51.bpo-41687.m1b1KA.rst  |  1 +
 Modules/posixmodule.c                         | 19 +++++++++++++++++++
 3 files changed, 26 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2020-09-01-15-57-51.bpo-41687.m1b1KA.rst

diff --git a/Lib/test/test_asyncio/test_sendfile.py b/Lib/test/test_asyncio/test_sendfile.py
index a30d9b9b4d9..01c698653ec 100644
--- a/Lib/test/test_asyncio/test_sendfile.py
+++ b/Lib/test/test_asyncio/test_sendfile.py
@@ -446,6 +446,12 @@ class SendfileMixin(SendfileBase):
         self.assertEqual(srv_proto.data, self.DATA)
         self.assertEqual(self.file.tell(), len(self.DATA))
 
+    # On Solaris, lowering SO_RCVBUF on a TCP connection after it has been
+    # established has no effect. Due to its age, this bug affects both Oracle
+    # Solaris as well as all other OpenSolaris forks (unless they fixed it
+    # themselves).
+    @unittest.skipIf(sys.platform.startswith('sunos'),
+                     "Doesn't work on Solaris")
     def test_sendfile_close_peer_in_the_middle_of_receiving(self):
         srv_proto, cli_proto = self.prepare_sendfile(close_after=1024)
         with self.assertRaises(ConnectionError):
diff --git a/Misc/NEWS.d/next/Library/2020-09-01-15-57-51.bpo-41687.m1b1KA.rst b/Misc/NEWS.d/next/Library/2020-09-01-15-57-51.bpo-41687.m1b1KA.rst
new file mode 100644
index 00000000000..284f5007357
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-09-01-15-57-51.bpo-41687.m1b1KA.rst
@@ -0,0 +1 @@
+Fix implementation of sendfile to be compatible with Solaris.
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index a6a4b9f012f..00ba7580302 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -9518,6 +9518,25 @@ done:
     if (!Py_off_t_converter(offobj, &offset))
         return NULL;
 
+#if defined(__sun) && defined(__SVR4)
+    // On Solaris, sendfile raises EINVAL rather than returning 0
+    // when the offset is equal or bigger than the in_fd size.
+    int res;
+    struct stat st;
+
+    do {
+        Py_BEGIN_ALLOW_THREADS
+        res = fstat(in_fd, &st);
+        Py_END_ALLOW_THREADS
+    } while (res != 0 && errno == EINTR && !(async_err = PyErr_CheckSignals()));
+    if (ret < 0)
+        return (!async_err) ? posix_error() : NULL;
+
+    if (offset >= st.st_size) {
+        return Py_BuildValue("i", 0);
+    }
+#endif
+
     do {
         Py_BEGIN_ALLOW_THREADS
         ret = sendfile(out_fd, in_fd, &offset, count);