my_symlink2.c
上传用户:romrleung
上传日期:2022-05-23
资源大小:18897k
文件大小:5k
- /* Copyright (C) 2000 MySQL AB
- 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; either version 2 of the License, or
- (at your option) any later version.
- 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., 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 "mysys_err.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;
- /* Test if we should create a link */
- int create_link;
- char abs_linkname[FN_REFLEN];
- DBUG_ENTER("my_create_with_symlink");
- if (my_disable_symlinks)
- {
- /* Create only the file, not the link and file */
- create_link= 0;
- if (linkname)
- filename= linkname;
- }
- else
- {
- if (linkname)
- my_realpath(abs_linkname, linkname, MYF(0));
- create_link= (linkname && strcmp(abs_linkname,filename));
- }
- if (!(MyFlags & MY_DELETE_OLD))
- {
- if (!access(filename,F_OK))
- {
- my_error(EE_CANTCREATEFILE, MYF(0), filename, EEXIST);
- DBUG_RETURN(-1);
- }
- if (create_link && !access(linkname,F_OK))
- {
- my_error(EE_CANTCREATEFILE, MYF(0), linkname, EEXIST);
- DBUG_RETURN(-1);
- }
- }
- if ((file=my_create(filename, createflags, access_flags, MyFlags)) >= 0)
- {
- if (create_link)
- {
- /* 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_disable_symlinks &&
- !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)
- {
- #ifndef HAVE_READLINK
- return my_rename(from, to, MyFlags);
- #else
- char link_name[FN_REFLEN], tmp_name[FN_REFLEN];
- int was_symlink= (!my_disable_symlinks &&
- !my_readlink(link_name, from, MYF(0)));
- int result=0;
- 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))
- {
- int save_errno=my_errno;
- my_delete(to, MyFlags); /* Remove created symlink */
- my_errno=save_errno;
- DBUG_RETURN(1);
- }
- /* Remove original symlink */
- if (my_delete(from, MyFlags))
- {
- int save_errno=my_errno;
- /* Remove created link */
- my_delete(to, MyFlags);
- /* Rename file back */
- if (strcmp(link_name, tmp_name))
- (void) my_rename(tmp_name, link_name, MyFlags);
- my_errno=save_errno;
- result= 1;
- }
- DBUG_RETURN(result);
- #endif /* HAVE_READLINK */
- }