summaryrefslogtreecommitdiffstats
path: root/mysys/my_delete.c
blob: 6854033f84b2bf1ad927220c8529066376bc8bc9 (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
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
/* Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.

   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; version 2 of the License.

   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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335  USA */

#include "mysys_priv.h"
#include "mysys_err.h"
#include <my_sys.h>

#ifdef _WIN32
#include <direct.h> /* rmdir */
static int my_win_unlink(const char *name);
#endif

CREATE_NOSYMLINK_FUNCTION(
  unlink_nosymlinks(const char *pathname),
  unlinkat(dfd, filename, 0),
  unlink(pathname)
);

int my_delete(const char *name, myf MyFlags)
{
  int err;
  DBUG_ENTER("my_delete");
  DBUG_PRINT("my",("name %s MyFlags %lu", name, MyFlags));

#ifdef _WIN32
  err = my_win_unlink(name);
#else
  if (MyFlags & MY_NOSYMLINKS)
    err= unlink_nosymlinks(name);
  else
    err= unlink(name);
#endif

  if ((MyFlags & MY_IGNORE_ENOENT) && errno == ENOENT)
    DBUG_RETURN(0);

  if (err)
  {
    my_errno= errno;
    if (MyFlags & (MY_FAE+MY_WME))
      my_error(EE_DELETE, MYF(ME_BELL), name, errno);
  }
  else if ((MyFlags & MY_SYNC_DIR) && my_sync_dir_by_file(name, MyFlags))
    err= -1;
  DBUG_RETURN(err);
} /* my_delete */


#if defined (_WIN32)

/* 
  Delete file.

  The function also makes best effort to minimize number of errors, 
  where another program (or thread in the current program) has the the same file
  open.

  We're using several tricks to prevent the errors, such as

  - Windows 10 "posix semantics" delete

  - Avoid the error by using CreateFile() with FILE_FLAG_DELETE_ON_CLOSE, instead
  of DeleteFile()

  - If file which is deleted (delete on close) but has not entirely gone,
  because it is still opened by some app, an attempt to trcreate file with the 
  same name would  result in yet another error. The workaround here is renaming 
  a file to unique name.

  Symbolic link are deleted without renaming. Directories are not deleted.
*/
#include <my_rdtsc.h>

static int my_win_unlink(const char *name)
{
  HANDLE handle= INVALID_HANDLE_VALUE;
  DWORD attributes;
  uint last_error;
  char unique_filename[MAX_PATH + 35];
  unsigned long long tsc; /* time stamp counter, for unique filename*/
  int retries;
  DBUG_ENTER("my_win_unlink");

  DBUG_INJECT_FILE_SHARING_VIOLATION(name);

  for (retries= FILE_SHARING_VIOLATION_RETRIES; ; retries--)
  {
    attributes= GetFileAttributes(name);
    if (attributes == INVALID_FILE_ATTRIBUTES)
    {
      last_error= GetLastError();
      DBUG_PRINT("error",
                 ("GetFileAttributes(%s) failed with %u\n", name, last_error));
      goto error;
    }

    if (attributes & FILE_ATTRIBUTE_DIRECTORY)
    {
      DBUG_PRINT("error", ("can't remove %s - it is a directory\n", name));
      errno= EINVAL;
      DBUG_RETURN(-1);
    }

    if (attributes & FILE_ATTRIBUTE_REPARSE_POINT)
    {
      /* Symbolic link. Delete link, the not target */
      if (!DeleteFile(name))
      {
        last_error= GetLastError();
        DBUG_PRINT("error",
                   ("DeleteFile(%s) failed with %u\n", name, last_error));
        goto error;
      }
      DBUG_RETURN(0);
    }

    /*
      Try Windows 10 method, delete with "posix semantics" (file is not
      visible, and creating a file with the same name won't fail, even if it
      the file was open)
    */
    handle= CreateFile(name, DELETE,
                       FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
                       NULL, OPEN_EXISTING, 0, NULL);
    if (handle != INVALID_HANDLE_VALUE)
    {
      /* 0x3 = FILE_DISPOSITION_FLAG_DELETE | FILE_DISPOSITION_FLAG_POSIX_SEMANTICS */
      struct {DWORD _Flags;} disp= {0x3};
      BOOL ok= SetFileInformationByHandle(
          handle, (FILE_INFO_BY_HANDLE_CLASS) 21, &disp, sizeof(disp));
      CloseHandle(handle);
      if (ok)
        DBUG_RETURN(0);
    }

    handle= CreateFile(name, DELETE, 0, NULL, OPEN_EXISTING,
                       FILE_FLAG_DELETE_ON_CLOSE, NULL);
    if (handle != INVALID_HANDLE_VALUE)
    {
      /*
        We opened file without sharing flags (exclusive), no one else has this
        file opened, thus it is safe to close handle to remove it. No renaming
        is necessary.
      */
      CloseHandle(handle);
      DBUG_RETURN(0);
    }

    /*
       Can't open file exclusively, hence the file must be already opened by
       someone else. Open it for delete (with all FILE_SHARE flags set),
       rename to unique name, close.
    */
    handle= CreateFile(name, DELETE,
                       FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
                       NULL, OPEN_EXISTING, FILE_FLAG_DELETE_ON_CLOSE, NULL);
    if (handle == INVALID_HANDLE_VALUE)
    {
      last_error= GetLastError();
      DBUG_PRINT(
          "error",
          ("CreateFile(%s) with FILE_FLAG_DELETE_ON_CLOSE failed with %u\n",
           name, last_error));
      goto error;
    }

    tsc= my_timer_cycles();
    my_snprintf(unique_filename, sizeof(unique_filename), "%s.%llx.deleted",
                name, tsc);
    if (!MoveFile(name, unique_filename))
    {
      DBUG_PRINT("warning",
                 ("moving %s to unique filename failed, error %lu\n", name,
                  GetLastError()));
    }
    CloseHandle(handle);
    DBUG_RETURN(0);

error:
    if (last_error != ERROR_SHARING_VIOLATION || retries == 0)
    {
      my_osmaperr(last_error);
      DBUG_RETURN(-1);
    }
    DBUG_CLEAR_FILE_SHARING_VIOLATION();
    Sleep(FILE_SHARING_VIOLATION_DELAY_MS);
  }
}
#endif

/*
   Remove directory recursively.
*/
int my_rmtree(const char *dir, myf MyFlags)
{
  char path[FN_REFLEN];
  char sep[] = { FN_LIBCHAR, 0 };
  int err = 0;
  size_t i;

  MY_DIR *dir_info = my_dir(dir, MYF(MY_DONT_SORT | MY_WANT_STAT));
  if (!dir_info)
    return 1;

  for (i = 0; i < dir_info->number_of_files; i++)
  {
    FILEINFO *file = dir_info->dir_entry + i;
    /* Skip "." and ".." */
    if (!strcmp(file->name, ".") || !strcmp(file->name, ".."))
      continue;

    strxnmov(path, sizeof(path), dir, sep, file->name, NULL);

    if (!MY_S_ISDIR(file->mystat->st_mode))
    {
      err = my_delete(path, MyFlags);
#ifdef _WIN32
      /*
        On Windows, check and possible reset readonly attribute.
        my_delete(), or DeleteFile does not remove theses files.
      */
      if (err)
      {
        DWORD attr = GetFileAttributes(path);
        if (attr != INVALID_FILE_ATTRIBUTES &&
          (attr & FILE_ATTRIBUTE_READONLY))
        {
          SetFileAttributes(path, attr &~FILE_ATTRIBUTE_READONLY);
          err = my_delete(path, MyFlags);
        }
      }
#endif
    }
    else
      err = my_rmtree(path, MyFlags);

    if (err)
      break;
  }

  my_dirend(dir_info);

  if (!err)
    err = rmdir(dir);

  return err;
}