Added symlink support to mysys library.

Docs/manual.texi:
  Link info change
include/my_sys.h:
  Added functions for symlink support
libmysql/Makefile.shared:
  Added mf_symlink.c to library.
mysys/Makefile.am:
  Added functions for symlink support
mysys/mf_same.c:
  cleanup
mysys/my_symlink.c:
  Added functions for symlink support

1 files changed, 131 insertions, 0 deletions

diff --git a/mysys/my_symlink2.c b/mysys/my_symlink2.c
new file mode 100644
index 00000000000..671531393f7
--- /dev/null
+++ b/mysys/my_symlink2.c
@@ -0,0 +1,131 @@
+/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
+   
+   This library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public
+   License as published by the Free Software Foundation; either
+   version 2 of the License, or (at your option) any later version.
+   
+   This library 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
+   Library General Public License for more details.
+   
+   You should have received a copy of the GNU Library General Public
+   License along with this library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+   MA 02111-1307, USA */
+
+/*
+  Advanced symlink handling.
+  This is used in MyISAM to let users symlinks tables to different disk.
+  The main idea with these functions is to automaticly create, delete and
+  rename files and symlinks like they would be one unit.
+*/
+
+#include "mysys_priv.h"
+#include <m_string.h>
+
+File my_create_with_symlink(const char *linkname, const char *filename,
+			    int createflags, int access_flags, myf MyFlags)
+{
+  File file;
+  int tmp_errno;
+  DBUG_ENTER("my_create_with_symlink");
+  if ((file=my_create(filename, createflags, access_flags, MyFlags)) >= 0)
+  {
+    /* Test if we should create a link */
+    if (linkname && strcmp(linkname,filename))
+    {
+      /* Delete old link/file */
+      if (MyFlags & MY_DELETE_OLD)
+	my_delete(linkname, MYF(0));
+      /* Create link */
+      if (my_symlink(filename, linkname, MyFlags))
+      {
+	/* Fail, remove everything we have done */
+	tmp_errno=my_errno;
+	my_close(file,MYF(0));
+	my_delete(filename, MYF(0));
+	file= -1;
+	my_errno=tmp_errno;
+      }
+    }
+  }
+  DBUG_RETURN(file);
+}
+
+/*
+  If the file was a symlink, delete both symlink and the file which the
+  symlink pointed to.
+*/
+
+int my_delete_with_symlink(const char *name, myf MyFlags)
+{
+  char link_name[FN_REFLEN];
+  int was_symlink= !my_readlink(link_name, name, MYF(0));
+  int result;
+  DBUG_ENTER("my_delete_with_symlink");
+
+  if (!(result=my_delete(name, MyFlags)))
+  {
+    if (was_symlink)
+      result=my_delete(link_name, MyFlags);
+  }
+  DBUG_RETURN(result);
+}
+
+/*
+  If the file is a normal file, just rename it.
+  If the file is a symlink:
+   - Create a new file with the name 'to' that points at
+     symlink_dir/basename(to)
+   - Rename the symlinked file to symlink_dir/basename(to)
+   - Delete 'from'
+   If something goes wrong, restore everything.
+*/
+
+int my_rename_with_symlink(const char *from, const char *to, myf MyFlags)
+{
+#ifdef HAVE_READLINK
+  return my_rename(from, to, MyFlags);
+#else
+  char link_name[FN_REFLEN], tmp_name[FN_REFLEN];
+  int was_symlink= !my_readlink(link_name, name, MYF(0));
+  int result;
+  DBUG_ENTER("my_rename_with_symlink");
+
+  if (!was_symlink)
+    DBUG_RETURN(my_rename(from, to, MyFlags));
+
+  /* Change filename that symlink pointed to */
+  strmov(tmp_name, to);
+  fn_same(tmp_name,link_name,1);		/* Copy dir */
+
+  /* Create new symlink */
+  if (my_symlink(tmp_name, to, MyFlags))
+    DBUG_RETURN(-1);
+
+  /*
+    Rename symlinked file if the base name didn't change.
+    This can happen if you use this function where 'from' and 'to' has
+    the same basename and different directories.
+   */
+
+  if (strcmp(link_name, tmp_name) && my_rename(link_name, tmp_name, MyFlags))
+  {
+    my_delete(to, MyFlags);			/* Remove created symlink */
+    DBUG_RETURN(-1);
+  }
+
+  /* Remove original symlink */
+  if (my_delete(from, MyFlags))
+  {
+    /* Remove created link */
+    my_delete(to, MyFlags);
+    /* Rename file back */
+    if (strcmp(link_name, tmp_name))
+      (void) my_rename(tmp_name, link_name, MyFlags);
+  }
+  DBUG_RETURN(result);
+#endif /* HAVE_READLINK */
+}