[PATCH v2 5/8] path.cc: Allow to skip filesystem checks

[Ben Wijen <ben@wijen.net>]

When file attributes are of no concern, there is no point to query them.
This can greatly speedup code which doesn't need it.

The idea is to have a shallow path conversion with only minimal information.

The upcoming unlink_nt for example, first tries a path without filesystem
checks, then - if necessary - retries with filesystem checks.
---
 winsup/cygwin/path.cc | 7 ++++---
 winsup/cygwin/path.h  | 2 ++
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/winsup/cygwin/path.cc b/winsup/cygwin/path.cc
index abd3687df..441fe113b 100644
--- a/winsup/cygwin/path.cc
+++ b/winsup/cygwin/path.cc
@@ -627,7 +627,7 @@ path_conv::check (const char *src, unsigned opt,
   char *pathbuf = tp.c_get ();
   char *tmp_buf = tp.t_get ();
   char *THIS_path = tp.c_get ();
-  symlink_info sym;
+  symlink_info sym = { 0 };
   bool need_directory = 0;
   bool add_ext = false;
   bool is_relpath;
@@ -931,7 +931,8 @@ path_conv::check (const char *src, unsigned opt,
 
     is_fs_via_procsys:
 
-	      symlen = sym.check (full_path, suff, fs, conv_handle);
+	      if (!(opt & PC_SKIP_SYM_CHECK))
+		symlen = sym.check (full_path, suff, fs, conv_handle);
 
     is_virtual_symlink:
 
@@ -1172,7 +1173,7 @@ path_conv::check (const char *src, unsigned opt,
 	  return;
 	}
 
-      if (dev.isfs ())
+      if (!(opt & PC_SKIP_FS_CHECK) && dev.isfs ())
 	{
 	  /* If FS hasn't been checked already in symlink_info::check,
 	     do so now. */
diff --git a/winsup/cygwin/path.h b/winsup/cygwin/path.h
index 62bd5ddd5..5821cdf57 100644
--- a/winsup/cygwin/path.h
+++ b/winsup/cygwin/path.h
@@ -59,6 +59,8 @@ enum pathconv_arg
   PC_KEEP_HANDLE	 = _BIT (12),	/* keep handle for later stat calls */
   PC_NO_ACCESS_CHECK	 = _BIT (13),	/* helper flag for error check */
   PC_SYM_NOFOLLOW_DIR	 = _BIT (14),	/* don't follow a trailing slash */
+  PC_SKIP_SYM_CHECK	 = _BIT (15),	/* skip symlink_info::check */
+  PC_SKIP_FS_CHECK	 = _BIT (16),	/* skip fs::update check */
   PC_DONT_USE		 = _BIT (31)	/* conversion to signed happens. */
 };
 
-- 
2.30.0