summaryrefslogtreecommitdiff
path: root/mysys/my_symlink.c
blob: abef0096e2822e021eb757fe026c6240ca1bfb12 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
/* 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 */

#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>
#endif

/*
  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 1;
#else
  int result=0;
  int length;
  DBUG_ENTER("my_readlink");

  if ((length=readlink(filename, to, FN_REFLEN-1)) < 0)
  {
    /* Don't give an error if this wasn't a symlink */
    if ((my_errno=errno) == EINVAL)
    {
      result= 1;
      strmov(to,filename);
    }
    else
    {
      if (MyFlags & MY_WME)
	my_error(EE_CANT_READLINK, MYF(0), filename, errno);
      result= -1;
    }
  }
  else
    to[length]=0;
  DBUG_RETURN(result);
#endif /* HAVE_READLINK */
}


/* Create a symbolic link */

int my_symlink(const char *content, const char *linkname, myf MyFlags)
{
#ifndef HAVE_READLINK
  return 0;
#else
  int result;
  DBUG_ENTER("my_symlink");

  result= 0;
  if (symlink(content, linkname))
  {
    result= -1;
    my_errno=errno;
    if (MyFlags & MY_WME)
      my_error(EE_CANT_SYMLINK, MYF(0), linkname, content, errno);
  }
  DBUG_RETURN(result);
#endif /* HAVE_READLINK */
}

/*
  Resolve all symbolic links in path
  'to' may be equal to 'filename'

  Because purify gives a lot of UMR errors when using realpath(),
  this code is disabled when using purify.

  If MY_RESOLVE_LINK is given, only do realpath if the file is a link.
*/

#if defined(SCO)
#define BUFF_LEN 4097
#elif defined(MAXPATHLEN)
#define BUFF_LEN MAXPATHLEN
#else
#define BUFF_LEN FN_LEN
#endif

int my_realpath(char *to, const char *filename,
		myf MyFlags __attribute__((unused)))
{
#if defined(HAVE_REALPATH) && !defined(HAVE_purify) && !defined(HAVE_BROKEN_REALPATH)
  int result=0;
  char buff[BUFF_LEN];
  struct stat stat_buff;
  DBUG_ENTER("my_realpath");

  if (!(MyFlags & MY_RESOLVE_LINK) ||
      (!lstat(filename,&stat_buff) && S_ISLNK(stat_buff.st_mode)))
  {
    char *ptr;
    DBUG_PRINT("info",("executing realpath"));
    if ((ptr=realpath(filename,buff)))
    {
      strmake(to,ptr,FN_REFLEN-1);
    }
    else
    {
      /* Realpath didn't work;  Use original name */
      DBUG_PRINT("error",("realpath failed with errno: %d", errno));
      my_errno=errno;
      if (MyFlags & MY_WME)
	my_error(EE_REALPATH, MYF(0), filename, my_errno);
      if (to != filename)
	strmov(to,filename);
      result= -1;
    }
  }
  DBUG_RETURN(result);
#else
  if (to != filename)
    strmov(to,filename);
  return 0;
#endif
}