From 354bb40e75d94466e91fe6960523612c9d17ccfb Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Thu, 2 Nov 2017 23:11:29 +0300
Subject: Add implementation

---
 mysql/mysys/my_seek.c | 111 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 111 insertions(+)
 create mode 100644 mysql/mysys/my_seek.c

(limited to 'mysql/mysys/my_seek.c')

diff --git a/mysql/mysys/my_seek.c b/mysql/mysys/my_seek.c
new file mode 100644
index 0000000..3a73e06
--- /dev/null
+++ b/mysql/mysys/my_seek.c
@@ -0,0 +1,111 @@
+/* Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
+
+#include "mysys_priv.h"
+#include "my_sys.h"
+#include "mysys_err.h"
+#include "my_thread_local.h"
+
+/* 
+  Seek to a position in a file.
+
+  ARGUMENTS
+  File fd          The file descriptor
+  my_off_t pos     The expected position (absolute or relative)
+  int whence       A direction parameter and one of 
+                   {SEEK_SET, SEEK_CUR, SEEK_END}
+  myf MyFlags      MY_THREADSAFE must be set in case my_seek may be mixed
+                   with my_pread/my_pwrite calls and fd is shared among
+                   threads.
+
+  DESCRIPTION
+    The my_seek  function  is a wrapper around the system call lseek and
+    repositions  the  offset of the file descriptor fd to the argument 
+    offset according to the directive whence as follows:
+      SEEK_SET    The offset is set to offset bytes.
+      SEEK_CUR    The offset is set to its current location plus offset bytes
+      SEEK_END    The offset is set to the size of the file plus offset bytes
+
+  RETURN VALUE
+    my_off_t newpos    The new position in the file.
+    MY_FILEPOS_ERROR   An error was encountered while performing 
+                       the seek. my_errno is set to indicate the
+                       actual error.
+*/
+
+my_off_t my_seek(File fd, my_off_t pos, int whence, myf MyFlags)
+{
+  os_off_t newpos= -1;
+  DBUG_ENTER("my_seek");
+  DBUG_PRINT("my",("fd: %d Pos: %llu  Whence: %d  MyFlags: %d",
+		   fd, (ulonglong) pos, whence, MyFlags));
+
+  /*
+      Make sure we are using a valid file descriptor!
+  */
+  DBUG_ASSERT(fd != -1);
+#if defined (_WIN32)
+  newpos= my_win_lseek(fd, pos, whence);
+#else
+  newpos= lseek(fd, pos, whence);
+#endif
+  if (newpos == (os_off_t) -1)
+  {
+    set_my_errno(errno);
+    if (MyFlags & MY_WME)
+    {
+      char errbuf[MYSYS_STRERROR_SIZE];
+      my_error(EE_CANT_SEEK, MYF(0), my_filename(fd),
+               my_errno(), my_strerror(errbuf, sizeof(errbuf), my_errno()));
+    }
+    DBUG_PRINT("error", ("lseek: %llu  errno: %d", (ulonglong) newpos, errno));
+    DBUG_RETURN(MY_FILEPOS_ERROR);
+  }
+  if ((my_off_t) newpos != pos)
+  {
+    DBUG_PRINT("exit",("pos: %llu", (ulonglong) newpos));
+  }
+  DBUG_RETURN((my_off_t) newpos);
+} /* my_seek */
+
+
+	/* Tell current position of file */
+	/* ARGSUSED */
+
+my_off_t my_tell(File fd, myf MyFlags)
+{
+  os_off_t pos;
+  DBUG_ENTER("my_tell");
+  DBUG_PRINT("my",("fd: %d  MyFlags: %d",fd, MyFlags));
+  DBUG_ASSERT(fd >= 0);
+#if defined (HAVE_TELL) && !defined (_WIN32)
+  pos= tell(fd);
+#else
+  pos= my_seek(fd, 0L, MY_SEEK_CUR,0);
+#endif
+  if (pos == (os_off_t) -1)
+  {
+    set_my_errno(errno);
+    if (MyFlags & MY_WME)
+    {
+      char errbuf[MYSYS_STRERROR_SIZE];
+      my_error(EE_CANT_SEEK, MYF(0), my_filename(fd),
+               my_errno(), my_strerror(errbuf, sizeof(errbuf), my_errno()));
+    }
+    DBUG_PRINT("error", ("tell: %llu  errno: %d", (ulonglong) pos, my_errno()));
+  }
+  DBUG_PRINT("exit",("pos: %llu", (ulonglong) pos));
+  DBUG_RETURN((my_off_t) pos);
+} /* my_tell */
-- 
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