summaryrefslogtreecommitdiffstats
path: root/lib/util/sys_rw.c
blob: d25a42b7082c555b808685eac5393bc1511119c6 (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
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
/*
 * Unix SMB/CIFS implementation.
 * Samba system utilities
 * Copyright (C) Andrew Tridgell 1992-1998
 * Copyright (C) Jeremy Allison  1998-2005
 * Copyright (C) Timur Bakeyev        2005
 * Copyright (C) Bjoern Jacke    2006-2007
 *
 * 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; either version 3 of the License, or
 * (at your option) any later version.
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include "replace.h"
#include "system/filesys.h"
#include "lib/util/sys_rw.h"
#include <assert.h>

bool sys_valid_io_range(off_t offset, size_t length)
{
	uint64_t last_byte_ofs;

	if (offset < 0) {
		return false;
	}

	if (offset > INT64_MAX) {
		return false;
	}

	if (length > UINT32_MAX) {
		return false;
	}

	last_byte_ofs = (uint64_t)offset + (uint64_t)length;
	if (last_byte_ofs > INT64_MAX) {
		return false;
	}

	return true;
}

bool sys_io_ranges_overlap(size_t c1, off_t o1,
			   size_t c2, off_t o2)
{
	if (c1 == 0 || c2 == 0) {
		return false;
	}
	if (o2 < o1) {
		/*
		 *          o1
		 *          |····c1····|
		 *  o2
		 *  |····c2···| ?
		 */
		return (o2 + c2 > o1);
	} else {
		/*
		 *  o1
		 *  |····c1···|
		 *          o2
		 *          |····c2····| ?
		 */
		return (o1 + c1 > o2);
	}
}

off_t sys_block_align_truncate(off_t len, off_t align)
{
	assert(align > 1);
	assert(((align - 1) & align) == 0);
	return len & (~align + 1);
}

off_t sys_block_align(off_t len, off_t align)
{
	assert(align > 1);
	assert(((align - 1) & align) == 0);
	return (len + (align - 1)) & ~(align - 1);
}

/*******************************************************************
A read wrapper that will deal with EINTR/EWOULDBLOCK
********************************************************************/

ssize_t sys_read(int fd, void *buf, size_t count)
{
	ssize_t ret;

	do {
		ret = read(fd, buf, count);
	} while (ret == -1 && (errno == EINTR || errno == EAGAIN ||
			       errno == EWOULDBLOCK));

	return ret;
}

/**
 * read wrapper, void variant:
 * This is intended to be used as a void variant of
 * read in situations where the caller wants to ignore
 * the result. Hence not checking for EAGAIN|EWOULDBLOCK.
 */
void sys_read_v(int fd, void *buf, size_t count)
{
	ssize_t ret;

	do {
		ret = read(fd, buf, count);
	} while (ret == -1 && errno == EINTR);
}


/*******************************************************************
A write wrapper that will deal with EINTR/EWOULDBLOCK.
********************************************************************/

ssize_t sys_write(int fd, const void *buf, size_t count)
{
	ssize_t ret;

	do {
		ret = write(fd, buf, count);
	} while (ret == -1 && (errno == EINTR || errno == EAGAIN ||
			       errno == EWOULDBLOCK));

	return ret;
}

/**
 * write wrapper to deal with EINTR and friends.
 * void-variant that ignores the number of bytes written.
 * This is intended to be used as a void variant of
 * write in situations where the caller wants to ignore
 * the result. Hence not checking for EAGAIN|EWOULDBLOCK.
 */
void sys_write_v(int fd, const void *buf, size_t count)
{
	ssize_t ret;

	do {
		ret = write(fd, buf, count);
	} while (ret == -1 && errno == EINTR);
}


/*******************************************************************
A writev wrapper that will deal with EINTR.
********************************************************************/

ssize_t sys_writev(int fd, const struct iovec *iov, int iovcnt)
{
	ssize_t ret;

	do {
		ret = writev(fd, iov, iovcnt);
	} while (ret == -1 && (errno == EINTR || errno == EAGAIN ||
			       errno == EWOULDBLOCK));

	return ret;
}

/*******************************************************************
A pread wrapper that will deal with EINTR
********************************************************************/

ssize_t sys_pread(int fd, void *buf, size_t count, off_t off)
{
	ssize_t ret;

	do {
		ret = pread(fd, buf, count, off);
	} while (ret == -1 && errno == EINTR);
	return ret;
}

/*******************************************************************
 A pread wrapper that will deal with EINTR and never return a short
 read unless pread returns zero meaning EOF.
********************************************************************/

ssize_t sys_pread_full(int fd, void *buf, size_t count, off_t off)
{
	ssize_t total_read = 0;
	uint8_t *curr_buf = (uint8_t *)buf;
	size_t curr_count = count;
	off_t curr_off = off;
	bool ok;

	ok = sys_valid_io_range(off, count);
	if (!ok) {
		errno = EINVAL;
		return -1;
	}

	while (curr_count != 0) {
		ssize_t ret = sys_pread(fd,
					curr_buf,
					curr_count,
					curr_off);

		if (ret == -1) {
			return -1;
		}
		if (ret == 0) {
			/* EOF */
			break;
		}

		if (ret > curr_count) {
			errno = EIO;
			return -1;
		}

		curr_buf += ret;
		curr_count -= ret;
		curr_off += ret;

		total_read += ret;
	}

	return total_read;
}

/*******************************************************************
A write wrapper that will deal with EINTR
********************************************************************/

ssize_t sys_pwrite(int fd, const void *buf, size_t count, off_t off)
{
	ssize_t ret;

	do {
		ret = pwrite(fd, buf, count, off);
	} while (ret == -1 && errno == EINTR);
	return ret;
}

/*******************************************************************
 A pwrite wrapper that will deal with EINTR and never allow a short
 write unless the file system returns an error.
********************************************************************/

ssize_t sys_pwrite_full(int fd, const void *buf, size_t count, off_t off)
{
	ssize_t total_written = 0;
	const uint8_t *curr_buf = (const uint8_t *)buf;
	size_t curr_count = count;
	off_t curr_off = off;
	bool ok;

	ok = sys_valid_io_range(off, count);
	if (!ok) {
		errno = EINVAL;
		return -1;
	}

	while (curr_count != 0) {
		ssize_t ret = sys_pwrite(fd,
					 curr_buf,
					 curr_count,
					 curr_off);

		if (ret == -1) {
			return -1;
		}
		if (ret == 0) {
			/* Ensure we can never spin. */
			errno = ENOSPC;
			return -1;
		}

		if (ret > curr_count) {
			errno = EIO;
			return -1;
		}

		curr_buf += ret;
		curr_count -= ret;
		curr_off += ret;

		total_written += ret;
	}

	return total_written;
}