Cygwin: try to avoid recalling offline files

Chances are high that Cygwin recalls offline files from remote
storage, even if the file is only accessed during stat(2) or
readdir(3).

To avoid this
- make sure Cygwin is placeholder-aware,
- open files in path_conv handling, as well as in stat(2)/readdir(3)
  scenarios with FILE_OPEN_NO_RECALL, and
- during symlink checking or testing for executablility, don't even
  try to open the file if one of the OFFLINE attributes is set.

Reported-by: Marcin Wisnicki <mwisnicki@gmail.com>
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

diff --git a/winsup/cygwin/autoload.cc b/winsup/cygwin/autoload.cc
index 65e906e8b9d0a65bf6f1967b45821c3a0dcdbae7..cc9dafe1b62173c9d00117d84491633b2b10d63a 100644 (file)
--- a/winsup/cygwin/autoload.cc
+++ b/winsup/cygwin/autoload.cc
@@ -479,6 +479,7 @@ LoadDLLfuncEx (SetThreadDescription, KernelBase, 1)
 LoadDLLfunc (VirtualAlloc2, KernelBase)
 
 LoadDLLfunc (NtMapViewOfSectionEx, ntdll)
+LoadDLLfuncEx (RtlSetProcessPlaceholderCompatibilityMode, ntdll, 1)
 
 LoadDLLfunc (ldap_bind_s, wldap32)
 LoadDLLfunc (ldap_count_entries, wldap32)

diff --git a/winsup/cygwin/dcrt0.cc b/winsup/cygwin/dcrt0.cc
index a40129c222328568a909a22ff5fe26def12a0746..7229377eb3fe47f0b030a2489d61b0d6d9d00684 100644 (file)
--- a/winsup/cygwin/dcrt0.cc
+++ b/winsup/cygwin/dcrt0.cc
@@ -809,6 +809,9 @@ dll_crt0_1 (void *)
   if (dynamically_loaded)
     sigproc_init ();
 
+  /* Call this before accessing any files. */
+  RtlSetProcessPlaceholderCompatibilityMode (PHCM_EXPOSE_PLACEHOLDERS);
+
   check_sanity_and_sync (user_data);
 
   /* Initialize malloc and then call user_shared_initialize since it relies

diff --git a/winsup/cygwin/fhandler/disk_file.cc b/winsup/cygwin/fhandler/disk_file.cc
index d08fe9160d350a5412ef5a2da8e37a1cc77bebf7..f3592148fc5b953d796a3936e995bd81b9161206 100644 (file)
--- a/winsup/cygwin/fhandler/disk_file.cc
+++ b/winsup/cygwin/fhandler/disk_file.cc
@@ -176,7 +176,9 @@ readdir_check_reparse_point (POBJECT_ATTRIBUTES attr, bool remote)
   bool ret = false;
 
   status = NtOpenFile (&reph, READ_CONTROL, attr, &io, FILE_SHARE_VALID_FLAGS,
-                      FILE_OPEN_FOR_BACKUP_INTENT | FILE_OPEN_REPARSE_POINT);
+                      FILE_OPEN_NO_RECALL
+                      | FILE_OPEN_FOR_BACKUP_INTENT
+                      | FILE_OPEN_REPARSE_POINT);
   if (NT_SUCCESS (status))
     {
       PREPARSE_DATA_BUFFER rp = (PREPARSE_DATA_BUFFER) tp.c_get ();
@@ -328,6 +330,7 @@ fhandler_base::fstat_by_name (struct stat *buf)
       status = NtOpenFile (&dir, SYNCHRONIZE | FILE_LIST_DIRECTORY,
                           &attr, &io, FILE_SHARE_VALID_FLAGS,
                           FILE_SYNCHRONOUS_IO_NONALERT
+                          | FILE_OPEN_NO_RECALL
                           | FILE_OPEN_FOR_BACKUP_INTENT
                           | FILE_DIRECTORY_FILE);
       if (!NT_SUCCESS (status))
@@ -616,7 +619,8 @@ fhandler_disk_file::fstatvfs (struct statvfs *sfs)
       opened = NT_SUCCESS (NtOpenFile (&fh, READ_CONTROL,
                                       pc.get_object_attr (attr, sec_none_nih),
                                       &io, FILE_SHARE_VALID_FLAGS,
-                                      FILE_OPEN_FOR_BACKUP_INTENT));
+                                      FILE_OPEN_NO_RECALL
+                                      | FILE_OPEN_FOR_BACKUP_INTENT));
       if (!opened)
        {
          /* Can't open file.  Try again with parent dir. */
@@ -625,7 +629,8 @@ fhandler_disk_file::fstatvfs (struct statvfs *sfs)
          attr.ObjectName = &dirname;
          opened = NT_SUCCESS (NtOpenFile (&fh, READ_CONTROL, &attr, &io,
                                           FILE_SHARE_VALID_FLAGS,
-                                          FILE_OPEN_FOR_BACKUP_INTENT));
+                                          FILE_OPEN_NO_RECALL
+                                          | FILE_OPEN_FOR_BACKUP_INTENT));
          if (!opened)
            goto out;
        }
@@ -2323,7 +2328,8 @@ readdir_get_ino (const char *path, bool dot_dot)
           || NT_SUCCESS (NtOpenFile (&hdl, READ_CONTROL,
                                      pc.get_object_attr (attr, sec_none_nih),
                                      &io, FILE_SHARE_VALID_FLAGS,
-                                     FILE_OPEN_FOR_BACKUP_INTENT
+                                     FILE_OPEN_NO_RECALL
+                                     | FILE_OPEN_FOR_BACKUP_INTENT
                                      | (pc.is_known_reparse_point ()
                                      ? FILE_OPEN_REPARSE_POINT : 0)))
          )
@@ -2372,8 +2378,9 @@ fhandler_disk_file::readdir_helper (DIR *dir, dirent *de, DWORD w32_err,
      Mountpoints and unknown or unhandled reparse points will be treated
      as normal file/directory/unknown. In all cases, returning the INO of
      the reparse point (not of the target) matches behavior of posix systems.
+     Unless the file is OFFLINE. *.
      */
-  if (attr & FILE_ATTRIBUTE_REPARSE_POINT)
+  if ((attr & FILE_ATTRIBUTE_REPARSE_POINT) && !isoffline (attr))
     {
       OBJECT_ATTRIBUTES oattr;
 
@@ -2618,7 +2625,8 @@ go_ahead:
                                         &nfs_aol_ffei, sizeof nfs_aol_ffei)
                         : NtOpenFile (&hdl, READ_CONTROL, &attr, &io,
                                       FILE_SHARE_VALID_FLAGS,
-                                      FILE_OPEN_FOR_BACKUP_INTENT
+                                      FILE_OPEN_NO_RECALL
+                                      | FILE_OPEN_FOR_BACKUP_INTENT
                                       | FILE_OPEN_REPARSE_POINT);
              if (NT_SUCCESS (f_status))
                {

diff --git a/winsup/cygwin/local_includes/ntdll.h b/winsup/cygwin/local_includes/ntdll.h
index 9605784e32a8d7e91fc38abff8a8adf19f769d1f..7737ae503c1829db547f13351b13716bff60057c 100644 (file)
--- a/winsup/cygwin/local_includes/ntdll.h
+++ b/winsup/cygwin/local_includes/ntdll.h
@@ -169,6 +169,13 @@ extern GUID __cygwin_socket_guid;
 #define FILE_VC_QUOTAS_REBUILDING       0x00000200
 #define FILE_VC_VALID_MASK              0x000003ff
 
+#define PHCM_APPLICATION_DEFAULT        0
+#define PHCM_DISGUISE_PLACEHOLDER       1
+#define PHCM_EXPOSE_PLACEHOLDERS        2
+#define PHCM_MAX                        2
+#define PHCM_ERROR_INVALID_PARAMETER   -1
+#define PHCM_ERROR_NO_TEB              -2
+
 /* IOCTL code to impersonate client of named pipe. */
 
 #define FSCTL_PIPE_DISCONNECT  CTL_CODE(FILE_DEVICE_NAMED_PIPE, 1, \
@@ -1639,6 +1646,7 @@ extern "C"
                                         BOOLEAN);
   NTSTATUS RtlSetGroupSecurityDescriptor (PSECURITY_DESCRIPTOR, PSID, BOOLEAN);
   NTSTATUS RtlSetOwnerSecurityDescriptor (PSECURITY_DESCRIPTOR, PSID, BOOLEAN);
+  CHAR RtlSetProcessPlaceholderCompatibilityMode (CHAR);
   PUCHAR RtlSubAuthorityCountSid (PSID);
   PULONG RtlSubAuthoritySid (PSID, ULONG);
   ULONG RtlUnicodeStringToAnsiSize (PUNICODE_STRING);

diff --git a/winsup/cygwin/local_includes/path.h b/winsup/cygwin/local_includes/path.h
index 4e62287f6a6e38c5c64e938ac828e808643656c2..cb8c4ca9f4d6a449efcc86702f76e28a44055a26 100644 (file)
--- a/winsup/cygwin/local_includes/path.h
+++ b/winsup/cygwin/local_includes/path.h
@@ -23,6 +23,14 @@ has_attribute (DWORD attributes, DWORD attribs_to_test)
         && (attributes & attribs_to_test);
 }
 
+extern inline bool
+isoffline (DWORD attributes)
+{
+  return has_attribute (attributes, FILE_ATTRIBUTE_OFFLINE
+                                   | FILE_ATTRIBUTE_RECALL_ON_OPEN
+                                   | FILE_ATTRIBUTE_RECALL_ON_DATA_ACCESS);
+}
+
 enum executable_states
 {
   is_executable,
@@ -235,6 +243,12 @@ class path_conv
   bool exists () const {return fileattr != INVALID_FILE_ATTRIBUTES;}
   bool has_attribute (DWORD x) const {return exists () && (fileattr & x);}
   int isdir () const {return has_attribute (FILE_ATTRIBUTE_DIRECTORY);}
+  bool isoffline () const
+  {
+    return has_attribute (FILE_ATTRIBUTE_OFFLINE
+                         | FILE_ATTRIBUTE_RECALL_ON_OPEN
+                         | FILE_ATTRIBUTE_RECALL_ON_DATA_ACCESS);
+  }
   executable_states exec_state ()
   {
     extern int _check_for_executable;
@@ -242,7 +256,7 @@ class path_conv
       return is_executable;
     if (mount_flags & MOUNT_NOTEXEC)
       return not_executable;
-    if (!_check_for_executable)
+    if (isoffline () || !_check_for_executable)
       return dont_care_if_executable;
     return dont_know_if_executable;
   }

diff --git a/winsup/cygwin/local_includes/winlean.h b/winsup/cygwin/local_includes/winlean.h
index 113b2c6b0d3f31ace0a48665a59eb9403c2229d4..947109bdeee4fd2604bb52e54bdc2076d3700116 100644 (file)
--- a/winsup/cygwin/local_includes/winlean.h
+++ b/winsup/cygwin/local_includes/winlean.h
@@ -97,6 +97,13 @@ details. */
 #define FILE_SUPPORTS_GHOSTING                  0x40000000
 #endif
 
+#ifndef FILE_ATTRIBUTE_RECALL_ON_OPEN
+#define FILE_ATTRIBUTE_RECALL_ON_OPEN          0x00040000
+#endif
+#ifndef FILE_ATTRIBUTE_RECALL_ON_DATA_ACCESS
+#define FILE_ATTRIBUTE_RECALL_ON_DATA_ACCESS   0x00400000
+#endif
+
 /* So-called "Microsoft Account" SIDs (S-1-11-...) have a netbios domain name
    "MicrosoftAccounts".  The new "Application Container SIDs" (S-1-15-...)
    have a netbios domain name "APPLICATION PACKAGE AUTHORITY"

diff --git a/winsup/cygwin/path.cc b/winsup/cygwin/path.cc
index 68639f323972b857cda87f0966cb93ec3565553c..ddea4b3889eb673fe0a2b48303b6f696a9ddfb9a 100644 (file)
--- a/winsup/cygwin/path.cc
+++ b/winsup/cygwin/path.cc
@@ -608,6 +608,7 @@ getfileattr (const char *path, bool caseinsensitive) /* path has to be always ab
       status = NtOpenFile (&dir, SYNCHRONIZE | FILE_LIST_DIRECTORY,
                           &attr, &io, FILE_SHARE_VALID_FLAGS,
                           FILE_SYNCHRONOUS_IO_NONALERT
+                          | FILE_OPEN_NO_RECALL
                           | FILE_OPEN_FOR_BACKUP_INTENT
                           | FILE_DIRECTORY_FILE);
       if (NT_SUCCESS (status))
@@ -3208,7 +3209,8 @@ restart:
            }
          status = NtOpenFile (&h, READ_CONTROL | FILE_READ_ATTRIBUTES,
                               &attr, &io, FILE_SHARE_VALID_FLAGS,
-                              FILE_OPEN_REPARSE_POINT
+                              FILE_OPEN_NO_RECALL
+                              | FILE_OPEN_REPARSE_POINT
                               | FILE_OPEN_FOR_BACKUP_INTENT);
          debug_printf ("%y = NtOpenFile (no-EAs %S)", status, &upath);
        }
@@ -3336,6 +3338,7 @@ restart:
              status = NtOpenFile (&dir, SYNCHRONIZE | FILE_LIST_DIRECTORY,
                                   &dattr, &io, FILE_SHARE_VALID_FLAGS,
                                   FILE_SYNCHRONOUS_IO_NONALERT
+                                  | FILE_OPEN_NO_RECALL
                                   | FILE_OPEN_FOR_BACKUP_INTENT
                                   | FILE_DIRECTORY_FILE);
              if (!NT_SUCCESS (status))
@@ -3426,12 +3429,16 @@ restart:
         directory using a relative path, symlink evaluation goes totally
         awry.  We never want a virtual drive evaluated as symlink. */
       if (upath.Length <= 14)
-         goto file_not_symlink;
+       goto file_not_symlink;
+
+      /* Offline files, even if reparse points, are not symlinks. */
+      if (isoffline (fileattr ()))
+       goto file_not_symlink;
 
       /* Reparse points are potentially symlinks.  This check must be
         performed before checking the SYSTEM attribute for sysfile
         symlinks, since reparse points can have this flag set, too. */
-      if ((fileattr () & FILE_ATTRIBUTE_REPARSE_POINT))
+      if (fileattr () & FILE_ATTRIBUTE_REPARSE_POINT)
        {
          res = check_reparse_point (h, fs.is_remote_drive ());
          if (res > 0)
@@ -3474,7 +3481,8 @@ restart:
 
          status = NtOpenFile (&sym_h, SYNCHRONIZE | GENERIC_READ, &attr, &io,
                               FILE_SHARE_VALID_FLAGS,
-                              FILE_OPEN_FOR_BACKUP_INTENT
+                              FILE_OPEN_NO_RECALL
+                              | FILE_OPEN_FOR_BACKUP_INTENT
                               | FILE_SYNCHRONOUS_IO_NONALERT);
          if (!NT_SUCCESS (status))
            res = 0;
@@ -3529,7 +3537,8 @@ restart:
 
          status = NtOpenFile (&sym_h, SYNCHRONIZE | GENERIC_READ, &attr, &io,
                               FILE_SHARE_VALID_FLAGS,
-                              FILE_OPEN_FOR_BACKUP_INTENT
+                              FILE_OPEN_NO_RECALL
+                              | FILE_OPEN_FOR_BACKUP_INTENT
                               | FILE_SYNCHRONOUS_IO_NONALERT);
 
          if (!NT_SUCCESS (status))