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) 2000-2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdint.h>
#include <sys/fcntl.h>
#include <sys/stat.h>
#include <sys/statfs.h>
/* Reserve storage for the data of the file associated with FD. This
emulation is far from perfect, but the kernel cannot do not much
better for network file systems, either. */
int
__posix_fallocate64_l64 (int fd, __off64_t offset, __off64_t len)
{
struct __stat64_t64 st;
if (offset < 0 || len < 0)
return EINVAL;
/* Perform overflow check. The outer cast relies on a GCC
extension. */
if ((__off64_t) ((uint64_t) offset + (uint64_t) len) < 0)
return EFBIG;
/* pwrite64 below will not do the right thing in O_APPEND mode. */
{
int flags = __fcntl (fd, F_GETFL, 0);
if (flags < 0 || (flags & O_APPEND) != 0)
return EBADF;
}
/* We have to make sure that this is really a regular file. */
if (__fstat64_time64 (fd, &st) != 0)
return EBADF;
if (S_ISFIFO (st.st_mode))
return ESPIPE;
if (! S_ISREG (st.st_mode))
return ENODEV;
if (len == 0)
{
/* This is racy, but there is no good way to satisfy a
zero-length allocation request. */
if (st.st_size < offset)
{
int ret = __ftruncate64 (fd, offset);
if (ret != 0)
ret = errno;
return ret;
}
return 0;
}
/* Minimize data transfer for network file systems, by issuing
single-byte write requests spaced by the file system block size.
(Most local file systems have fallocate support, so this fallback
code is not used there.) */
unsigned increment;
{
struct statfs64 f;
if (__fstatfs64 (fd, &f) != 0)
return errno;
if (f.f_bsize == 0)
increment = 512;
else if (f.f_bsize < 4096)
increment = f.f_bsize;
else
/* NFS clients do not propagate the block size of the underlying
storage and may report a much larger value which would still
leave holes after the loop below, so we cap the increment at
4096. */
increment = 4096;
}
/* Write a null byte to every block. This is racy; we currently
lack a better option. Compare-and-swap against a file mapping
might address local races, but requires interposition of a signal
handler to catch SIGBUS. */
for (offset += (len - 1) % increment; len > 0; offset += increment)
{
len -= increment;
if (offset < st.st_size)
{
unsigned char c;
ssize_t rsize = __libc_pread64 (fd, &c, 1, offset);
if (rsize < 0)
return errno;
/* If there is a non-zero byte, the block must have been
allocated already. */
else if (rsize == 1 && c != 0)
continue;
}
if (__libc_pwrite64 (fd, "", 1, offset) != 1)
return errno;
}
return 0;
}
#undef __posix_fallocate64_l64
#include <shlib-compat.h>
#include <bits/wordsize.h>
#if __WORDSIZE == 32 && SHLIB_COMPAT(libc, GLIBC_2_2, GLIBC_2_3_3)
int
attribute_compat_text_section
__posix_fallocate64_l32 (int fd, off64_t offset, size_t len)
{
return __posix_fallocate64_l64 (fd, offset, len);
}
versioned_symbol (libc, __posix_fallocate64_l64, posix_fallocate64,
GLIBC_2_3_3);
compat_symbol (libc, __posix_fallocate64_l32, posix_fallocate64, GLIBC_2_2);
#else
strong_alias (__posix_fallocate64_l64, posix_fallocate64);
#endif
|
