Build fix: missing initializer for member 'payload'
[lttng-tools.git] / src / common / readwrite.cpp
CommitLineData
33b14136 1/*
ab5be9fa 2 * Copyright (C) 2013 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
33b14136 3 *
ab5be9fa 4 * SPDX-License-Identifier: LGPL-2.1-only
33b14136 5 *
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6 */
7
6c1c0768 8#define _LGPL_SOURCE
636ae5db 9#include <limits.h>
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10#include <unistd.h>
11
c9e313bc 12#include <common/compat/errno.hpp>
edf4b93e 13
c9e313bc 14#include "readwrite.hpp"
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15
16/*
17 * lttng_read and lttng_write take care of EINTR and partial read/write.
18 * Upon success, they return the "count" received as parameter.
19 * They can return a negative value if an error occurs.
20 * If a value lower than the requested "count" is returned, it means an
83f4233d 21 * error occurred.
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22 * The error can be checked by querying errno.
23 */
24ssize_t lttng_read(int fd, void *buf, size_t count)
25{
26 size_t i = 0;
27 ssize_t ret;
28
a0377dfe 29 LTTNG_ASSERT(buf);
aeb16260 30
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31 /*
32 * Deny a read count that can be bigger then the returned value max size.
33 * This makes the function to never return an overflow value.
34 */
35 if (count > SSIZE_MAX) {
36 return -EINVAL;
37 }
38
33b14136 39 do {
a6bc4ca9 40 ret = read(fd, (char *) buf + i, count - i);
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41 if (ret < 0) {
42 if (errno == EINTR) {
43 continue; /* retry operation */
44 } else {
45 goto error;
46 }
47 }
48 i += ret;
a0377dfe 49 LTTNG_ASSERT(i <= count);
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50 } while (count - i > 0 && ret > 0);
51 return i;
52
53error:
54 if (i == 0) {
55 return -1;
56 } else {
57 return i;
58 }
59}
60
61ssize_t lttng_write(int fd, const void *buf, size_t count)
62{
63 size_t i = 0;
64 ssize_t ret;
65
a0377dfe 66 LTTNG_ASSERT(buf);
aeb16260 67
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68 /*
69 * Deny a write count that can be bigger then the returned value max size.
70 * This makes the function to never return an overflow value.
71 */
72 if (count > SSIZE_MAX) {
73 return -EINVAL;
74 }
75
33b14136 76 do {
a6bc4ca9 77 ret = write(fd, (char *) buf + i, count - i);
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78 if (ret < 0) {
79 if (errno == EINTR) {
80 continue; /* retry operation */
81 } else {
82 goto error;
83 }
84 }
85 i += ret;
a0377dfe 86 LTTNG_ASSERT(i <= count);
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87 } while (count - i > 0 && ret > 0);
88 return i;
89
90error:
91 if (i == 0) {
92 return -1;
93 } else {
94 return i;
95 }
96}
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