msys2-runtime: restore blocking mode of read pipe on close()

The Cygwin runtime (and for that reason, the MSYS2 runtime, too), change
pipes from blocking to non-blocking, which is a problem when the pipe is
actually opened by something like Git when it asks a credential helper
for information. Git, not expecting the pipe mode to be changed behind
its back, will then error out with "fatal: read error: Invalid
argument".

To address this, this patch was proposed in the Cygwin project as
https://inbox.sourceware.org/cygwin-patches/20240830141553.12128-1-takashi.yano@nifty.ne.jp/

Ideally, Cygwin would not even _try_ to fiddle with the pipe mode,
therefore this patch was not applied as-is. At time of writing, there is
no consensus on any replacement patch, but I have to prepare _something_
for the already-late Git for Windows v2.46.1 (which is likely the last
Git for Windows version to support Windows 7 and Windows 8, hence the
urgency). And this patch at least improves the situation.

This patch will be dropped when Git for Windows will upgrade to MSYS2
runtime v3.5, and hopefully consensus will have been reached about a
better fix by that time.

This commit corresponds to
git-for-windows/msys2-runtime#72 which fixes
git-for-windows/git#5115.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

msys2-runtime/0083-Cygwin-pipe-Restore-blocking-mode-of-read-pipe-on-cl.patch

@@ -0,0 +1,75 @@
+From acc71340a481ff3ebe339b015f58ae7505fec585 Mon Sep 17 00:00:00 2001
+From: Takashi Yano <takashi.yano@nifty.ne.jp>
+Date: Fri, 30 Aug 2024 23:15:44 +0900
+Subject: [PATCH 83/N] Cygwin: pipe: Restore blocking mode of read pipe on
+ close()
+
+If a cygwin app is executed from a non-cygwin app and the cygwin
+app exits, read pipe remains on non-blocking mode because of the
+commit fc691d0246b9. Due to this behaviour, the non-cygwin app
+cannot read the pipe correctly after that. With this patch, the
+blocking mode of the read pipe is stored into was_blocking_read_pipe
+on set_pipe_non_blocking() when the cygwin app starts and restored
+on close().
+
+Addresses: https://github.com/git-for-windows/git/issues/5115
+Fixes: fc691d0246b9 ("Cygwin: pipe: Make sure to set read pipe non-blocking for cygwin apps.");
+Reported-by: isaacag, Johannes Schindelin <Johannes.Schindelin@gmx.de>
+Reported-at: https://github.com/git-for-windows/git/issues/5115
+Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
+Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
+---
+ winsup/cygwin/fhandler/pipe.cc          | 13 +++++++++++++
+ winsup/cygwin/local_includes/fhandler.h |  1 +
+ 2 files changed, 14 insertions(+)
+
+diff --git a/winsup/cygwin/fhandler/pipe.cc b/winsup/cygwin/fhandler/pipe.cc
+index 8daae8d..c47226b 100644
+--- a/winsup/cygwin/fhandler/pipe.cc
++++ b/winsup/cygwin/fhandler/pipe.cc
+@@ -54,6 +54,15 @@ fhandler_pipe::set_pipe_non_blocking (bool nonblocking)
+   IO_STATUS_BLOCK io;
+   FILE_PIPE_INFORMATION fpi;
+
++  if (get_device () == FH_PIPER && nonblocking && !was_blocking_read_pipe)
++    {
++      status = NtQueryInformationFile (get_handle (), &io, &fpi, sizeof fpi,
++				       FilePipeInformation);
++      if (NT_SUCCESS (status))
++	was_blocking_read_pipe =
++	  (fpi.CompletionMode == FILE_PIPE_QUEUE_OPERATION);
++    }
++
+   fpi.ReadMode = FILE_PIPE_BYTE_STREAM_MODE;
+   fpi.CompletionMode = nonblocking ? FILE_PIPE_COMPLETE_OPERATION
+     : FILE_PIPE_QUEUE_OPERATION;
+@@ -94,6 +103,8 @@ fhandler_pipe::init (HANDLE f, DWORD a, mode_t mode, int64_t uniq_id)
+        even with FILE_SYNCHRONOUS_IO_NONALERT. */
+     set_pipe_non_blocking (get_device () == FH_PIPER ?
+ 			   true : is_nonblocking ());
++  was_blocking_read_pipe = false;
++
+   return 1;
+ }
+
+@@ -675,6 +686,8 @@ fhandler_pipe::close ()
+     CloseHandle (query_hdl);
+   if (query_hdl_close_req_evt)
+     CloseHandle (query_hdl_close_req_evt);
++  if (was_blocking_read_pipe)
++    set_pipe_non_blocking (false);
+   int ret = fhandler_base::close ();
+   ReleaseMutex (hdl_cnt_mtx);
+   CloseHandle (hdl_cnt_mtx);
+diff --git a/winsup/cygwin/local_includes/fhandler.h b/winsup/cygwin/local_includes/fhandler.h
+index 15b19f7..f017a6d 100644
+--- a/winsup/cygwin/local_includes/fhandler.h
++++ b/winsup/cygwin/local_includes/fhandler.h
+@@ -1193,6 +1193,7 @@ private:
+   uint64_t pipename_key;
+   DWORD pipename_pid;
+   LONG pipename_id;
++  bool was_blocking_read_pipe;
+   void release_select_sem (const char *);
+   HANDLE get_query_hdl_per_process (WCHAR *, OBJECT_NAME_INFORMATION *);
+   HANDLE get_query_hdl_per_system (WCHAR *, OBJECT_NAME_INFORMATION *);

msys2-runtime/PKGBUILD

@@ -4,7 +4,7 @@
 pkgbase=msys2-runtime
 pkgname=('msys2-runtime' 'msys2-runtime-devel')
 pkgver=3.4.10
-pkgrel=6
+pkgrel=7
 pkgdesc="Cygwin POSIX emulation engine"
 arch=('x86_64')
 url="https://www.cygwin.com/"
@@ -108,9 +108,10 @@ source=('msys2-runtime'::git+https://github.com/cygwin/cygwin#tag=cygwin-${pkgve
         0079-Cygwin-pipe-Make-sure-to-set-read-pipe-non-blocking-.patch
         0080-Cygwin-try-to-avoid-recalling-offline-files.patch
         0081-Cygwin-get-set-security-descriptors-using-FILE_OPEN_.patch
-        0082-Cygwin-FILE_OPEN_NO_RECALL-is-incompatible-with-FILE.patch)
-sha256sums=('4fb94e9f3bab9666dcab50c8940de6e8801d0aae900f0b5a6f79406479e757f1'
-            '79be406cf3a35561e7873403cb24d84c5cd2c2af71c940319f969b061ac013f1'
+        0082-Cygwin-FILE_OPEN_NO_RECALL-is-incompatible-with-FILE.patch
+        0083-Cygwin-pipe-Restore-blocking-mode-of-read-pipe-on-cl.patch)
+sha256sums=('a40476d03803bfa6875cde92221db4326b3479147e873fbeca2e4236d48fe875'
+            '6f297ae4049c2a5b4ff085119284822d1b8045cd24c4b0328ab2808e68c18556'
             '351bb1efdbdafe80c981e92d6b425c6ab71c85ce4e990db184e2118158eb2ab6'
             'd3d3a01feeae9f7d5e6cb32f4662df74fc9476ff11a1aac3dad2df3e43fd88e4'
             '2e50ecd65f2fd413baaf39e5058a6b252245abc7d34f4ebf17dd4f7ffed60ced'
@@ -192,7 +193,8 @@ sha256sums=('4fb94e9f3bab9666dcab50c8940de6e8801d0aae900f0b5a6f79406479e757f1'
             '7b4e8e91b757d3597c85eb2d83a85ed5f57414b74967b0fa4c87a87332eb04c7'
             '7012f34047186556ae78b69bfe3eafccb2fe399ab122d5a21cadbf40533b4e0f'
             '7fd616f587212716ebdb21cad257c99ec5827638cf7c7819068c1d70020bd251'
-            '1b74ea7c955991440d61b6059386589e893ddd7513a86cb554833391cf172c41')
+            '1b74ea7c955991440d61b6059386589e893ddd7513a86cb554833391cf172c41'
+            'c8542adeb6324ee0edc96c1c9dfce3994cbbe3a42529e63db2b8b7213dbe393f')
 
 # Helper macros to help make tasks easier #
 apply_patch_with_msg() {
@@ -328,7 +330,8 @@ prepare() {
   0079-Cygwin-pipe-Make-sure-to-set-read-pipe-non-blocking-.patch \
   0080-Cygwin-try-to-avoid-recalling-offline-files.patch \
   0081-Cygwin-get-set-security-descriptors-using-FILE_OPEN_.patch \
-  0082-Cygwin-FILE_OPEN_NO_RECALL-is-incompatible-with-FILE.patch
+  0082-Cygwin-FILE_OPEN_NO_RECALL-is-incompatible-with-FILE.patch \
+  0083-Cygwin-pipe-Restore-blocking-mode-of-read-pipe-on-cl.patch
 }
 
 build() {

msys2-runtime/msys2-runtime.commit

@@ -1 +1 @@
-2e2ef940151485490aff0c7b00c00965ef7a71a4
+bc1f6498ab09182349c5d5daa2d81626990a2832