msys2-runtime: fix creating native symlinks pointing to ..

This commit corresponds to
https://github.com/msys2/msys2-runtime/pull/292.

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

msys2-runtime/0041-symlink_native-allow-linking-to.patch

@@ -0,0 +1,62 @@
+From bc3e285ac0a2c91080ac68279f0c9fd697a2d9b6 Mon Sep 17 00:00:00 2001
+From: Johannes Schindelin <johannes.schindelin@gmx.de>
+Date: Thu, 19 Jun 2025 20:46:03 +0200
+Subject: [PATCH 41/N] symlink_native: allow linking to `..`
+
+When running
+
+	CYGWIN=winsymlinks:nativestrict ln -s .. abc
+
+the counter-intuitive result is _not_ a symbolic link to `..`, but
+instead to `../../$(basename "$PWD")`.
+
+The reason for this is that the search for the longest common prefix
+assumes that the link target is not a strict prefix of the parent
+directory of the link itself.
+
+Let's fix that.
+
+Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
+---
+ winsup/cygwin/path.cc | 21 ++++++++++++++++-----
+ 1 file changed, 16 insertions(+), 5 deletions(-)
+
+diff --git a/winsup/cygwin/path.cc b/winsup/cygwin/path.cc
+index 6f04658..ead7d16 100644
+--- a/winsup/cygwin/path.cc
++++ b/winsup/cygwin/path.cc
+@@ -2030,9 +2030,18 @@ symlink_native (const char *oldpath, path_conv &win32_newpath)
+       while (towupper (*++c_old) == towupper (*++c_new))
+ 	;
+       /* The last component could share a common prefix, so make sure we end
+-         up on the first char after the last common backslash. */
+-      while (c_old[-1] != L'\\')
+-	--c_old, --c_new;
++         up on the first char after the last common backslash.
++
++	 However, if c_old is a strict prefix of c_new (at a component
++	 boundary), or vice versa, then do not try to find the last common
++	 backslash. */
++      if ((!*c_old || *c_old == L'\\') && (!*c_new || *c_new == L'\\'))
++	c_old += !!*c_old, c_new += !!*c_new;
++      else
++	{
++	  while (c_old[-1] != L'\\')
++	    --c_old, --c_new;
++	}
+ 
+       /* 2. Check if prefix is long enough.  The prefix must at least points to
+             a complete device:  \\?\X:\ or \\?\UNC\server\share\ are the minimum
+@@ -2057,8 +2066,10 @@ symlink_native (const char *oldpath, path_conv &win32_newpath)
+ 	  final_oldpath = &final_oldpath_buf;
+ 	  final_oldpath->Buffer = tp.w_get ();
+ 	  PWCHAR e_old = final_oldpath->Buffer;
+-	  while (num-- > 0)
+-	    e_old = wcpcpy (e_old, L"..\\");
++	  while (num > 1 || (num == 1 && *c_old))
++	    e_old = wcpcpy (e_old, L"..\\"), num--;
++	  if (num > 0)
++	    e_old = wcpcpy (e_old, L"..");
+ 	  wcpcpy (e_old, c_old);
+ 	}
+     }

msys2-runtime/PKGBUILD

@@ -4,7 +4,7 @@
 pkgbase=msys2-runtime
 pkgname=('msys2-runtime' 'msys2-runtime-devel')
 pkgver=3.6.3
-pkgrel=3
+pkgrel=4
 pkgdesc="Cygwin POSIX emulation engine"
 arch=('x86_64')
 url="https://www.cygwin.com/"
@@ -69,9 +69,10 @@ source=('msys2-runtime'::git://sourceware.org/git/newlib-cygwin.git#tag=cygwin-$
         0037-Avoid-sharing-cygheaps-across-Cygwin-versions.patch
         0038-uname-report-msys2-runtime-commit-hash-too.patch
         0039-Cygwin-Adjust-CWD-magic-to-accommodate-for-the-lates.patch
-        0040-Cygwin-Fix-compatibility-with-w32api-headers-v13.patch)
+        0040-Cygwin-Fix-compatibility-with-w32api-headers-v13.patch
+        0041-symlink_native-allow-linking-to.patch)
 sha256sums=('dd3cb54af2f8828d6857a3a595b02b09b23209570e0cc44342f4c9826845fb63'
-            'ff4f032ec1fdee986071bc20bb1480189b7bb4efdd5693b327ca664ee0bef3a1'
+            'eea82d3aac8b57ab34acf1e7dbb6e916f1bdc5106199379517adf2cf5edfd2ab'
             '5538db757661949423563bab5e4f383dfa4ef0cf3301cf43f23b482392554b3b'
             '2fb9b2b297797d20cd901eaee2de735e8cdda1c1e5836e9ff77856c0d1216860'
             '780977d71e35bbe4c0dcda5272895267d68d635f311e224f7981858f7192a85e'
@@ -111,7 +112,8 @@ sha256sums=('dd3cb54af2f8828d6857a3a595b02b09b23209570e0cc44342f4c9826845fb63'
             'e2f58cba187f16b21df69dc3b7372f41bf2edfc543d136c62f85c83e0f22f3ad'
             'd8baf6e0e9c44a60d133f506fc91fa79043543266c6142918fad2c234cf4d0b5'
             'c5a5dd5645ce86f83824a2fe50ab3cc9df1211d2983bc18bbd11c608249e31b1'
-            '519323947b0f80d9416fff31eb981ce2cd9c74a3b42c3cd2f74bca3c8a703aa5')
+            '519323947b0f80d9416fff31eb981ce2cd9c74a3b42c3cd2f74bca3c8a703aa5'
+            '2d477d5ebb89c5674686306454356a093765e69719102224c7ab59ac50a7a99e')
 
 # Helper macros to help make tasks easier #
 apply_patch_with_msg() {
@@ -189,7 +191,8 @@ prepare() {
   0037-Avoid-sharing-cygheaps-across-Cygwin-versions.patch \
   0038-uname-report-msys2-runtime-commit-hash-too.patch \
   0039-Cygwin-Adjust-CWD-magic-to-accommodate-for-the-lates.patch \
-  0040-Cygwin-Fix-compatibility-with-w32api-headers-v13.patch
+  0040-Cygwin-Fix-compatibility-with-w32api-headers-v13.patch \
+  0041-symlink_native-allow-linking-to.patch
 }
 
 build() {

msys2-runtime/msys2-runtime.commit

@@ -1 +1 @@
-1f8def9f776a7dd0d0381f4bf25e84f805393cc1
+bc3e285ac0a2c91080ac68279f0c9fd697a2d9b6