1/* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
2
3 This program is free software; you can redistribute it and/or modify
4 it under the terms of the GNU General Public License as published by
5 the Free Software Foundation; version 2 of the License.
6
7 This program is distributed in the hope that it will be useful,
8 but WITHOUT ANY WARRANTY; without even the implied warranty of
9 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10 GNU General Public License for more details.
11
12 You should have received a copy of the GNU General Public License
13 along with this program; if not, write to the Free Software
14 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
15
16#include "mysys_priv.h"
17#include "mysys_err.h"
18#include <my_base.h>
19#include <errno.h>
20
21/*
22 Read a chunk of bytes from a file with retry's if needed
23
24 The parameters are:
25 File descriptor
26 Buffer to hold at least Count bytes
27 Bytes to read
28 Flags on what to do on error
29
30 Return:
31 -1 on error
32 0 if flag has bits MY_NABP or MY_FNABP set
33 N number of bytes read.
34*/
35
36size_t my_read(File Filedes, uchar *Buffer, size_t Count, myf MyFlags)
37{
38 size_t readbytes, save_count= 0;
39 DBUG_ENTER("my_read");
40 DBUG_PRINT("my",("fd: %d Buffer: %p Count: %lu MyFlags: %lu",
41 Filedes, Buffer, (ulong) Count, MyFlags));
42 if (!(MyFlags & (MY_WME | MY_FAE | MY_FNABP)))
43 MyFlags|= my_global_flags;
44
45 for (;;)
46 {
47 errno= 0; /* Linux, Windows don't reset this on EOF/success */
48#ifdef _WIN32
49 readbytes= my_win_read(Filedes, Buffer, Count);
50#else
51 readbytes= read(Filedes, Buffer, Count);
52#endif
53 DBUG_EXECUTE_IF ("simulate_file_read_error",
54 {
55 errno= ENOSPC;
56 readbytes= (size_t) -1;
57 DBUG_SET("-d,simulate_file_read_error");
58 DBUG_SET("-d,simulate_my_b_fill_error");
59 });
60
61 if (readbytes != Count)
62 {
63 int got_errno= my_errno= errno;
64 DBUG_PRINT("warning",("Read only %d bytes off %lu from %d, errno: %d",
65 (int) readbytes, (ulong) Count, Filedes,
66 got_errno));
67
68 if (got_errno == 0 || (readbytes != (size_t) -1 &&
69 (MyFlags & (MY_NABP | MY_FNABP))))
70 my_errno= HA_ERR_FILE_TOO_SHORT;
71
72 if ((readbytes == 0 || (int) readbytes == -1) && got_errno == EINTR)
73 {
74 DBUG_PRINT("debug", ("my_read() was interrupted and returned %ld",
75 (long) readbytes));
76 continue; /* Interrupted */
77 }
78
79 /* Do a read retry if we didn't get enough data on first read */
80 if (readbytes != (size_t) -1 && readbytes != 0 &&
81 (MyFlags & MY_FULL_IO))
82 {
83 Buffer+= readbytes;
84 Count-= readbytes;
85 save_count+= readbytes;
86 continue;
87 }
88
89 if (MyFlags & (MY_WME | MY_FAE | MY_FNABP))
90 {
91 if (readbytes == (size_t) -1)
92 my_error(EE_READ,
93 MYF(ME_BELL | ME_WAITTANG | (MyFlags & (ME_JUST_INFO | ME_NOREFRESH))),
94 my_filename(Filedes), got_errno);
95 else if (MyFlags & (MY_NABP | MY_FNABP))
96 my_error(EE_EOFERR,
97 MYF(ME_BELL | ME_WAITTANG | (MyFlags & (ME_JUST_INFO | ME_NOREFRESH))),
98 my_filename(Filedes), got_errno);
99 }
100 if (readbytes == (size_t) -1 ||
101 ((MyFlags & (MY_FNABP | MY_NABP)) && !(MyFlags & MY_FULL_IO)))
102 DBUG_RETURN(MY_FILE_ERROR); /* Return with error */
103 }
104
105 if (MyFlags & (MY_NABP | MY_FNABP))
106 readbytes= 0; /* Ok on read */
107 else
108 readbytes+= save_count;
109 break;
110 }
111 DBUG_RETURN(readbytes);
112} /* my_read */
113