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
|
/* Copyright (c) 2000, 2025, Oracle and/or its affiliates.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License, version 2.0,
as published by the Free Software Foundation.
This program is designed to work with certain software (including
but not limited to OpenSSL) that is licensed under separate terms,
as designated in a particular file or component or in included license
documentation. The authors of MySQL hereby grant you an additional
permission to link the program and your derivative works with the
separately licensed software that they have either included with
the program or referenced in the documentation.
Without limiting anything contained in the foregoing, this file,
which is part of C Driver for MySQL (Connector/C), is also subject to the
Universal FOSS Exception, version 1.0, a copy of which can be found at
http://oss.oracle.com/licenses/universal-foss-exception.
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, version 2.0, 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 02110-1301 USA */
/**
@file mysys/my_pread.cc
*/
#include "my_config.h"
#include <errno.h>
#include <fcntl.h>
#include <stddef.h>
#include <stdio.h>
#include <sys/types.h>
#include <limits>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include "my_base.h"
#include "my_dbug.h"
#include "my_inttypes.h"
#include "my_io.h"
#include "my_sys.h"
#include "my_thread_local.h"
#include "mysys_err.h"
#if defined(_WIN32)
#include "mysys/mysys_priv.h"
#endif
#ifndef _WIN32
// Mock away pwrite() for unit testing.
ssize_t (*mock_pwrite)(int fd, const void *buf, size_t count,
off_t offset) = nullptr;
#endif
/**
Read a chunk of bytes from a file from a given position.
@note This differs from the normal pread() call in that we don't care
to set the position in the file back to the original position
if the system doesn't support pread().
@param Filedes File descriptor
@param Buffer Buffer to read data into
@param Count Number of bytes to read
@param offset Position to read from
@param MyFlags Flags
@retval MY_FILE_ERROR in case of error
@retval Number of bytes read, otherwise
*/
size_t my_pread(File Filedes, uchar *Buffer, size_t Count, my_off_t offset,
myf MyFlags) {
DBUG_TRACE;
for (;;) {
errno = 0; /* Linux, Windows don't reset this on EOF/success */
const int64_t readbytes =
#if defined(_WIN32)
my_win_pread(Filedes, Buffer, Count, offset);
#else
pread(Filedes, Buffer, Count, offset);
#endif
const bool error = (readbytes != static_cast<int64_t>(Count));
if (error) {
set_my_errno(errno ? errno : -1);
if (errno == 0 || (readbytes != -1 && (MyFlags & (MY_NABP | MY_FNABP))))
set_my_errno(HA_ERR_FILE_TOO_SHORT);
if ((readbytes == 0 || readbytes == -1) && errno == EINTR) {
continue; /* Interrupted */
}
if (MyFlags & (MY_WME | MY_FAE | MY_FNABP)) {
if (readbytes == -1)
MyOsError(my_errno(), EE_READ, MYF(0), my_filename(Filedes));
else if (MyFlags & (MY_NABP | MY_FNABP))
MyOsError(my_errno(), EE_EOFERR, MYF(0), my_filename(Filedes));
}
if (readbytes == -1 || (MyFlags & (MY_FNABP | MY_NABP)))
return MY_FILE_ERROR;
} // if (error)
if (MyFlags & (MY_NABP | MY_FNABP)) return 0; /* Read went ok; Return 0 */
assert(readbytes >= 0);
return readbytes; /* purecov: inspected */
} // for (;;)
}
/**
Write a chunk of bytes to a file at a given position
@note
This differs from the normal pwrite() call in that we don't care
to set the position in the file back to the original position
if the system doesn't support pwrite()
@param Filedes File descriptor
@param Buffer Buffer to write data from
@param Count Number of bytes to write
@param offset Position to write to
@param MyFlags Flags
@return
If Count == 0, returns 0. If failure, (size_t)-1 == MY_FILE_ERROR.
Behavior otherwise depends on MyFlags:
if (MyFlags & (MY_NABP | MY_FNABP))
On success, 0
otherwise
On success or partial success, the number of bytes actually written
(which can be less than Count).
*/
size_t my_pwrite(File Filedes, const uchar *Buffer, size_t Count,
my_off_t offset, myf MyFlags) {
int64_t sum_written = 0;
uint errors = 0;
const size_t initial_count = Count;
DBUG_TRACE;
for (;;) {
errno = 0;
int64_t writtenbytes;
#if defined(_WIN32)
writtenbytes = my_win_pwrite(Filedes, Buffer, Count, offset);
#else
if (mock_pwrite)
writtenbytes = mock_pwrite(Filedes, Buffer, Count, offset);
else
writtenbytes = pwrite(Filedes, Buffer, Count, offset);
#endif
if (writtenbytes == static_cast<int64_t>(Count)) {
sum_written += writtenbytes;
break;
}
set_my_errno(errno);
if (writtenbytes != -1) {
sum_written += writtenbytes;
Buffer += writtenbytes;
Count -= writtenbytes;
offset += writtenbytes;
}
if (is_killed_hook(nullptr))
MyFlags &= ~MY_WAIT_IF_FULL; /* End if aborted by user */
if ((my_errno() == ENOSPC || my_errno() == EDQUOT) &&
(MyFlags & MY_WAIT_IF_FULL)) {
wait_for_free_space(my_filename(Filedes), errors);
errors++;
continue;
}
if (writtenbytes != 0 && writtenbytes != -1) continue;
if (my_errno() == EINTR) {
continue; /* Retry */
}
if (writtenbytes == 0 && !errors++) /* Retry once */
{
/* We may come here if the file quota is exeeded */
continue;
}
break; /* Return bytes written */
}
if (MyFlags & (MY_NABP | MY_FNABP)) {
if (sum_written == static_cast<int64_t>(initial_count))
return 0; /* Want only errors, not bytes written */
if (MyFlags & (MY_WME | MY_FAE | MY_FNABP)) {
MyOsError(my_errno(), EE_WRITE, MYF(0), my_filename(Filedes));
}
return MY_FILE_ERROR;
}
DBUG_EXECUTE_IF("check", my_seek(Filedes, -1, SEEK_SET, MYF(0)););
if (sum_written == 0) return MY_FILE_ERROR;
return sum_written;
}
|
