MDEV-4576 : Aria storage engine's temporary files might not be deleted (Errcode : 13)

See also MySQL Bug #39750  and similar ones.

Fix my_delete() on Windows, to safely remvoe files on Windows, including files  that are opened by another threads in the same process, antiviruses and  backup applications. If file to be deleted is  also  opened by another thread, the file is renamed to unique name prior to deletion - this makes it possible to create file with the same name right after deletion.
With this patch my_delete_allow_opened() becomes obsolete and is replaced with my_delete().

This patch is rework of the patch  http://lists.mysql.com/commits/59327  for MySQL bug#39750.

2 files changed, 98 insertions, 70 deletions

diff --git a/mysys/my_delete.c b/mysys/my_delete.c
index cf9573f592b..f5737ea66e0 100644
--- a/mysys/my_delete.c
+++ b/mysys/my_delete.c
@@ -17,13 +17,23 @@
 #include "mysys_err.h"
 #include <my_sys.h>
 
+#ifdef _WIN32
+static int my_win_unlink(const char *name);
+#endif
+
 int my_delete(const char *name, myf MyFlags)
 {
   int err;
   DBUG_ENTER("my_delete");
   DBUG_PRINT("my",("name %s MyFlags %d", name, MyFlags));
 
-  if ((err = unlink(name)) == -1)
+#ifdef _WIN32
+  err = my_win_unlink(name);
+#else
+  err = unlink(name);
+#endif
+
+  if(err)
   {
     my_errno=errno;
     if (MyFlags & (MY_FAE+MY_WME))
@@ -36,90 +46,108 @@ int my_delete(const char *name, myf MyFlags)
   DBUG_RETURN(err);
 } /* my_delete */
 
-#if defined(__WIN__)
-/**
-  Delete file which is possibly not closed.
 
-  This function is intended to be used exclusively as a temporal solution
-  for Win NT in case when it is needed to delete a not closed file (note
-  that the file must be opened everywhere with FILE_SHARE_DELETE mode).
-  Deleting not-closed files can not be supported on Win 98|ME (and because
-  of that is considered harmful).
-  
-  The function deletes the file with its preliminary renaming. This is
-  because when not-closed share-delete file is deleted it still lives on
-  a disk until it will not be closed everwhere. This may conflict with an
-  attempt to create a new file with the same name. The deleted file is
-  renamed to <name>.<num>.deleted where <name> - the initial name of the
-  file, <num> - a hexadecimal number chosen to make the temporal name to
-  be unique.
+#if defined (_WIN32)
+/* 
+  Delete file.
 
-  @param the name of the being deleted file
-  @param the flags instructing how to react on an error internally in
-         the function
+  The function also makes best effort to minimize number of errors, 
+  where another program (or thread in the current program) has the the same file
+  open.
 
-  @note The per-thread @c my_errno holds additional info for a caller to
-        decide how critical the error can be.
+  We're using 2 tricks to prevent the errors.
 
-  @retval
-    0	ok
-  @retval
-    1   error
+  1. A usual Win32's DeleteFile() can with ERROR_SHARED_VIOLATION,
+  because the file is opened in another application (often, antivirus or backup)
+  
+  We avoid the error by using CreateFile() with FILE_FLAG_DELETE_ON_CLOSE, instead
+  of DeleteFile()
 
+  2. If file which is deleted (delete on close) but has not entirely gone,
+  because it is still opened by some app, an attempt to trcreate file with the 
+  same name would  result in yet another error. The workaround here is renaming 
+  a file to unique name.
 
-*/
-int nt_share_delete(const char *name, myf MyFlags)
+  Symbolic link are deleted without renaming. Directories are not deleted.
+ */
+static int my_win_unlink(const char *name)
 {
-  char buf[MAX_PATH + 20];
-  ulong cnt;
-  DBUG_ENTER("nt_share_delete");
-  DBUG_PRINT("my",("name %s MyFlags %d", name, MyFlags));
-
-  for (cnt= GetTickCount(); cnt; cnt--)
+  HANDLE handle= INVALID_HANDLE_VALUE;
+  DWORD attributes;
+  DWORD last_error;
+  char unique_filename[MAX_PATH + 35];
+  unsigned long long tsc; /* time stamp counter, for unique filename*/
+
+  DBUG_ENTER("my_win_unlink");
+  attributes= GetFileAttributes(name);
+  if (attributes == INVALID_FILE_ATTRIBUTES)
   {
-    errno= 0;
-    sprintf(buf, "%s.%08X.deleted", name, cnt);
-    if (MoveFile(name, buf))
-      break;
-
-    if ((errno= GetLastError()) == ERROR_ALREADY_EXISTS)
-      continue;
-
-    /* This happened during tests with MERGE tables. */
-    if (errno == ERROR_ACCESS_DENIED)
-      continue;
-
-    DBUG_PRINT("warning", ("Failed to rename %s to %s, errno: %d",
-                           name, buf, errno));
-    break;
+    last_error= GetLastError();
+    DBUG_PRINT("error",("GetFileAttributes(%s) failed with %u\n", name, last_error));
+    goto error;
   }
 
-  if (errno == ERROR_FILE_NOT_FOUND)
+  if (attributes & FILE_ATTRIBUTE_DIRECTORY)
   {
-    my_errno= ENOENT;    // marking, that `name' doesn't exist 
+    DBUG_PRINT("error",("can't remove %s - it is a directory\n", name));
+    errno= EINVAL;
+    DBUG_RETURN(-1);
   }
-  else if (errno == 0)
+ 
+  if (attributes & FILE_ATTRIBUTE_REPARSE_POINT)
+  {
+    /* Symbolic link. Delete link, the not target */
+    if (!DeleteFile(name))
+    {
+       last_error= GetLastError();
+       DBUG_PRINT("error",("DeleteFile(%s) failed with %u\n", name,last_error));
+       goto error;
+    }
+    DBUG_RETURN(0);
+  }
+
+  handle= CreateFile(name, DELETE, 0,  NULL, OPEN_EXISTING, FILE_FLAG_DELETE_ON_CLOSE, NULL);
+  if (handle != INVALID_HANDLE_VALUE)
   {
-    if (DeleteFile(buf))
-      DBUG_RETURN(0);
     /*
-      The below is more complicated than necessary. For some reason, the
-      assignment to my_errno clears the error number, which is retrieved
-      by GetLastError() (VC2005EE). Assigning to errno first, allows to
-      retrieve the correct value.
+      We opened file without sharing flags (exclusive), noone else has this file
+      opened, thus it is save to close handle to remove it. No renaming is 
+      necessary.
     */
-    errno= GetLastError();
-    if (errno == 0)
-      my_errno= ENOENT; // marking, that `buf' doesn't exist
-    else
-      my_errno= errno;
+    CloseHandle(handle);
+    DBUG_RETURN(0);
+  }
+
+  /*
+     Can't open file exclusively, hence the file must be already opened by 
+     someone else. Open it for delete (with all FILE_SHARE flags set), 
+     rename to unique name, close.
+  */
+  handle= CreateFile(name, DELETE, FILE_SHARE_READ|FILE_SHARE_WRITE|FILE_SHARE_DELETE,
+    NULL, OPEN_EXISTING, FILE_FLAG_DELETE_ON_CLOSE, NULL);
+  if (handle == INVALID_HANDLE_VALUE)
+  {
+     last_error= GetLastError();
+     DBUG_PRINT("error",
+       ("CreateFile(%s) with FILE_FLAG_DELETE_ON_CLOSE failed with %u\n",
+        name,last_error));
+     goto error;
   }
-  else
-    my_errno= errno;
 
-  if (MyFlags & (MY_FAE+MY_WME))
-    my_error(EE_DELETE, MYF(ME_BELL + ME_WAITTANG + (MyFlags & ME_NOINPUT)),
-             name, my_errno);
+  tsc= __rdtsc();
+  my_snprintf(unique_filename,sizeof(unique_filename),"%s.%llx.deleted", 
+    name, tsc);
+  if (!MoveFile(name, unique_filename)) 
+  {
+    DBUG_PRINT("warning",  ("moving %s to unique filename failed, error %u\n",
+    name,GetLastError()));
+  }
+
+  CloseHandle(handle);
+  DBUG_RETURN(0);
+ 
+error:
+  my_osmaperr(last_error);
   DBUG_RETURN(-1);
 }
-#endif
+#endif
\ No newline at end of file
diff --git a/mysys/my_redel.c b/mysys/my_redel.c
index d096a5c071c..b285bb25e2e 100644
--- a/mysys/my_redel.c
+++ b/mysys/my_redel.c
@@ -58,7 +58,7 @@ int my_redel(const char *org_name, const char *tmp_name,
     if (my_rename(org_name, name_buff, MyFlags))
       goto end;
   }
-  else if (my_delete_allow_opened(org_name, MyFlags))
+  else if (my_delete(org_name, MyFlags))
       goto end;
   if (my_rename(tmp_name,org_name,MyFlags))
     goto end;