1/*
2 Copyright (c) 2001, 2011, Oracle and/or its affiliates
3 Copyright (c) 2010, 2017, MariaDB
4
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; version 2 of the License.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
17
18#include "mysys_priv.h"
19#include "mysys_err.h"
20#include <m_string.h>
21#include <errno.h>
22#ifdef HAVE_REALPATH
23#include <sys/param.h>
24#include <sys/stat.h>
25#endif
26
27static int always_valid(const char *filename __attribute__((unused)))
28{
29 return 0;
30}
31
32int (*mysys_test_invalid_symlink)(const char *filename)= always_valid;
33
34
35/*
36 Reads the content of a symbolic link
37 If the file is not a symbolic link, return the original file name in to.
38
39 RETURN
40 0 If filename was a symlink, (to will be set to value of symlink)
41 1 If filename was a normal file (to will be set to filename)
42 -1 on error.
43*/
44
45int my_readlink(char *to, const char *filename, myf MyFlags)
46{
47#ifndef HAVE_READLINK
48 strmov(to,filename);
49 return 1;
50#else
51 int result=0;
52 int length;
53 DBUG_ENTER("my_readlink");
54
55 if ((length=readlink(filename, to, FN_REFLEN-1)) < 0)
56 {
57 /* Don't give an error if this wasn't a symlink */
58 if ((my_errno=errno) == EINVAL)
59 {
60 result= 1;
61 strmov(to,filename);
62 }
63 else
64 {
65 if (MyFlags & MY_WME)
66 my_error(EE_CANT_READLINK, MYF(0), filename, errno);
67 result= -1;
68 }
69 }
70 else
71 to[length]=0;
72 DBUG_PRINT("exit" ,("result: %d", result));
73 DBUG_RETURN(result);
74#endif /* HAVE_READLINK */
75}
76
77
78/* Create a symbolic link */
79
80int my_symlink(const char *content, const char *linkname, myf MyFlags)
81{
82#ifndef HAVE_READLINK
83 return 0;
84#else
85 int result;
86 DBUG_ENTER("my_symlink");
87 DBUG_PRINT("enter",("content: %s linkname: %s", content, linkname));
88
89 result= 0;
90 if (symlink(content, linkname))
91 {
92 result= -1;
93 my_errno=errno;
94 if (MyFlags & MY_WME)
95 my_error(EE_CANT_SYMLINK, MYF(0), linkname, content, errno);
96 }
97 else if ((MyFlags & MY_SYNC_DIR) && my_sync_dir_by_file(linkname, MyFlags))
98 result= -1;
99 DBUG_RETURN(result);
100#endif /* HAVE_READLINK */
101}
102
103#if defined(SCO)
104#define BUFF_LEN 4097
105#elif defined(MAXPATHLEN)
106#define BUFF_LEN MAXPATHLEN
107#else
108#define BUFF_LEN FN_LEN
109#endif
110
111
112int my_is_symlink(const char *filename __attribute__((unused)))
113{
114#if defined (HAVE_LSTAT) && defined (S_ISLNK)
115 struct stat stat_buff;
116 return !lstat(filename, &stat_buff) && S_ISLNK(stat_buff.st_mode);
117#elif defined (_WIN32)
118 DWORD dwAttr = GetFileAttributes(filename);
119 return (dwAttr != INVALID_FILE_ATTRIBUTES) &&
120 (dwAttr & FILE_ATTRIBUTE_REPARSE_POINT);
121#else /* No symlinks */
122 return 0;
123#endif
124}
125
126/*
127 Resolve all symbolic links in path
128 'to' may be equal to 'filename'
129
130 to is guaranteed to never set to a string longer than FN_REFLEN
131 (including the end \0)
132
133 On error returns -1, unless error is file not found, in which case it
134 is 1.
135
136 Sets my_errno to specific error number.
137*/
138
139int my_realpath(char *to, const char *filename, myf MyFlags)
140{
141#if defined(HAVE_REALPATH) && !defined(HAVE_BROKEN_REALPATH)
142 int result=0;
143 char buff[BUFF_LEN];
144 char *ptr;
145 DBUG_ENTER("my_realpath");
146
147 DBUG_PRINT("info",("executing realpath"));
148 if ((ptr=realpath(filename,buff)))
149 strmake(to, ptr, FN_REFLEN-1);
150 else
151 {
152 /*
153 Realpath didn't work; Use my_load_path() which is a poor substitute
154 original name but will at least be able to resolve paths that starts
155 with '.'.
156 */
157 DBUG_PRINT("error",("realpath failed with errno: %d", errno));
158 my_errno=errno;
159 if (MyFlags & MY_WME)
160 my_error(EE_REALPATH, MYF(0), filename, my_errno);
161 my_load_path(to, filename, NullS);
162 if (my_errno == ENOENT)
163 result= 1;
164 else
165 result= -1;
166 }
167 DBUG_RETURN(result);
168#elif defined(_WIN32)
169 int ret= GetFullPathName(filename,FN_REFLEN, to, NULL);
170 if (ret == 0 || ret > FN_REFLEN)
171 {
172 my_errno= (ret > FN_REFLEN) ? ENAMETOOLONG : GetLastError();
173 if (MyFlags & MY_WME)
174 my_error(EE_REALPATH, MYF(0), filename, my_errno);
175 /*
176 GetFullPathName didn't work : use my_load_path() which is a poor
177 substitute original name but will at least be able to resolve
178 paths that starts with '.'.
179 */
180 my_load_path(to, filename, NullS);
181 return -1;
182 }
183#else
184 my_load_path(to, filename, NullS);
185#endif
186 return 0;
187}
188
189#ifdef HAVE_OPEN_PARENT_DIR_NOSYMLINKS
190/** opens the parent dir. walks the path, and does not resolve symlinks
191
192 returns the pointer to the file name (basename) within the pathname
193 or NULL in case of an error
194
195 stores the parent dir (dirname) file descriptor in pdfd.
196 It can be -1 even if there was no error!
197
198 This is used for symlinked tables for DATA/INDEX DIRECTORY.
199 The paths there have been realpath()-ed. So, we can assume here that
200
201 * `pathname` is an absolute path
202 * no '.', '..', and '//' in the path
203 * file exists
204*/
205
206const char *my_open_parent_dir_nosymlinks(const char *pathname, int *pdfd)
207{
208 char buf[FN_REFLEN + 1];
209 char *s= buf, *e= buf+1, *end= strnmov(buf, pathname, sizeof(buf));
210 int fd, dfd= -1;
211
212 if (*end)
213 {
214 errno= ENAMETOOLONG;
215 return NULL;
216 }
217
218 if (*s != '/') /* not an absolute path */
219 {
220 errno= ENOENT;
221 return NULL;
222 }
223
224 for (;;)
225 {
226 if (*e == '/') /* '//' in the path */
227 {
228 errno= ENOENT;
229 goto err;
230 }
231 while (*e && *e != '/')
232 e++;
233 *e= 0;
234
235 if (!memcmp(s, ".", 2) || !memcmp(s, "..", 3))
236 {
237 errno= ENOENT;
238 goto err;
239 }
240
241 if (++e >= end)
242 {
243 *pdfd= dfd;
244 return pathname + (s - buf);
245 }
246
247 fd = openat(dfd, s, O_NOFOLLOW | O_PATH);
248 if (fd < 0)
249 goto err;
250
251 if (dfd >= 0)
252 close(dfd);
253
254 dfd= fd;
255 s= e;
256 }
257err:
258 if (dfd >= 0)
259 close(dfd);
260 return NULL;
261}
262#endif
263