Merge 'fix-ssh-hangs-reloaded'

This commit merges the backport of the fix for freezes during Git clones
of large repositories via SSH.

That should fix git-for-windows/git#5682,
git-for-windows/git#5688 and potentially also
git-for-windows/git#5663.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

winsup/cygwin/fhandler/pipe.cc

@@ -561,7 +561,7 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len)
       ULONG len1;
       DWORD waitret = WAIT_OBJECT_0;
 
-      if (left > chunk && !is_nonblocking ())
+      if (left > chunk && !real_non_blocking_mode)
 	len1 = chunk;
       else
 	len1 = (ULONG) left;

winsup/cygwin/fhandler/socket_inet.cc

@@ -20,7 +20,12 @@
 #undef u_long
 #define u_long __ms_u_long
 #include <w32api/ws2tcpip.h>
+/* 2025-06-09: win32api headers v13 now define a cmsghdr type which clashes with
+   our socket.h. Arrange not to see it here. */
+#undef cmsghdr
+#define cmsghdr __ms_cmsghdr
 #include <w32api/mswsock.h>
+#undef cmsghdr
 #include <w32api/mstcpip.h>
 #include <netinet/tcp.h>
 #include <netinet/udp.h>

winsup/cygwin/fhandler/socket_local.cc

@@ -21,7 +21,12 @@
 #define u_long __ms_u_long
 #include "ntsecapi.h"
 #include <w32api/ws2tcpip.h>
+/* 2025-06-09: win32api headers v13 now define a cmsghdr type which clashes with
+   our socket.h. Arrange not to see it here. */
+#undef cmsghdr
+#define cmsghdr __ms_cmsghdr
 #include <w32api/mswsock.h>
+#undef cmsghdr
 #include <unistd.h>
 #include <asm/byteorder.h>
 #include <sys/socket.h>

winsup/cygwin/local_includes/ntdll.h

@@ -489,6 +489,8 @@ typedef struct _FILE_DISPOSITION_INFORMATION_EX	// 64
   ULONG Flags;
 } FILE_DISPOSITION_INFORMATION_EX, *PFILE_DISPOSITION_INFORMATION_EX;
 
+#if __MINGW64_VERSION_MAJOR < 13
+
 typedef struct _FILE_STAT_INFORMATION		// 68
 {
   LARGE_INTEGER FileId;
@@ -509,6 +511,8 @@ typedef struct _FILE_CASE_SENSITIVE_INFORMATION	// 71
   ULONG Flags;
 } FILE_CASE_SENSITIVE_INFORMATION, *PFILE_CASE_SENSITIVE_INFORMATION;
 
+#endif
+
 enum {
   FILE_LINK_REPLACE_IF_EXISTS				= 0x01,
   FILE_LINK_POSIX_SEMANTICS				= 0x02,

winsup/cygwin/net.cc

@@ -18,7 +18,12 @@ details. */
 #undef u_long
 #define u_long __ms_u_long
 #include <w32api/ws2tcpip.h>
+/* 2025-06-09: win32api headers v13 now define a cmsghdr type which clashes with
+   our socket.h. Arrange not to see it here. */
+#undef cmsghdr
+#define cmsghdr __ms_cmsghdr
 #include <w32api/mswsock.h>
+#undef cmsghdr
 #include <w32api/iphlpapi.h>
 #define gethostname cygwin_gethostname
 #include <unistd.h>

winsup/cygwin/path.cc

@@ -2031,9 +2031,18 @@ 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
@@ -2058,8 +2067,10 @@ 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);
 	}
     }