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

4 files changed, 148 insertions, 47 deletions

diff --git a/mysys/Makefile.am b/mysys/Makefile.am
index 827367ac755..6dd9bb06fe9 100644
--- a/mysys/Makefile.am
+++ b/mysys/Makefile.am
@@ -33,7 +33,7 @@ libmysys_a_SOURCES =	my_init.c my_getwd.c mf_getdate.c\
 			my_alloc.c safemalloc.c my_fopen.c my_fstream.c \
 			my_error.c errors.c my_div.c my_messnc.c \
 			mf_format.c mf_same.c mf_dirname.c mf_fn_ext.c \
-			my_symlink.c \
+			my_symlink.c my_symlink2.c \
 			mf_pack.c mf_pack2.c mf_unixpath.c mf_stripp.c \
 			mf_casecnv.c mf_soundex.c mf_wcomp.c mf_wfile.c \
 			mf_qsort.c mf_qsort2.c mf_sort.c \
diff --git a/mysys/mf_same.c b/mysys/mf_same.c
index 5b8c5ecf970..c1a5cae11cb 100644
--- a/mysys/mf_same.c
+++ b/mysys/mf_same.c
@@ -20,19 +20,22 @@
 #include "mysys_priv.h"
 #include <m_string.h>
 
-	/* Formaterar ett filnamn i avsende p} ett annat namn */
-	/* Klarar {ven to = name */
-	/* Denna funktion r|r inte p} utg}ngsnamnet */
+        /*
+	  Copy directory and/or extension between filenames.
+	  (For the meaning of 'flag', check mf_format.c)
+	  'to' may be equal to 'name'.
+	  Returns 'to'.
+	*/
 
-my_string fn_same(my_string toname, const char *name, int flag)
+my_string fn_same(char *to, const char *name, int flag)
 {
   char dev[FN_REFLEN];
   const char *ext;
   DBUG_ENTER("fn_same");
-  DBUG_PRINT("mfunkt",("to: %s  name: %s  flag: %d",toname,name,flag));
+  DBUG_PRINT("enter",("to: %s  name: %s  flag: %d",to,name,flag));
 
   if ((ext=strrchr(name+dirname_part(dev,name),FN_EXTCHAR)) == 0)
     ext="";
 
-  DBUG_RETURN(fn_format(toname,toname,dev,ext,flag));
+  DBUG_RETURN(fn_format(to,to,dev,ext,flag));
 } /* fn_same */
diff --git a/mysys/my_symlink.c b/mysys/my_symlink.c
index e195adcd4c5..65d165fc026 100644
--- a/mysys/my_symlink.c
+++ b/mysys/my_symlink.c
@@ -18,6 +18,7 @@
 #include "mysys_priv.h"
 #include "mysys_err.h"
 #include <m_string.h>
+#include <errno.h>
 #ifdef HAVE_REALPATH
 #include <sys/param.h>
 #include <sys/stat.h>
@@ -26,13 +27,16 @@
 /*
   Reads the content of a symbolic link
   If the file is not a symbolic link, return the original file name in to.
+  Returns: 0 if table was a symlink,
+           1 if table was a normal file
+	   -1 on error.
 */
 
 int my_readlink(char *to, const char *filename, myf MyFlags)
 {
 #ifndef HAVE_READLINK
   strmov(to,filename);
-  return 0;
+  return 1;
 #else
   int result=0;
   int length;
@@ -43,6 +47,7 @@ int my_readlink(char *to, const char *filename, myf MyFlags)
     /* Don't give an error if this wasn't a symlink */
     if ((my_errno=errno) == EINVAL)
     {
+      result= 1;
       strmov(to,filename);
     }
     else
@@ -81,44 +86,6 @@ int my_symlink(const char *content, const char *linkname, myf MyFlags)
 #endif /* HAVE_READLINK */
 }
 
-
-/*
-  Create a file and a symbolic link that points to this file
-  If linkname is a null pointer or equal to filename, we don't
-  create a link.
- */
-
-
-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);
-}
-
-
 /*
   Resolve all symbolic links in path
   'to' may be equal to 'filename'
@@ -162,7 +129,7 @@ int my_realpath(char *to, const char *filename, myf MyFlags)
       result= -1;
     }
   }
-  return result;
+  DBUG_RETURN(result);
 #else
   if (to != filename)
     strmov(to,filename);
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 */
+}