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
|
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Lightweight buffered reading library.
*
* Copyright 2019 Google LLC.
*/
#ifndef __API_IO__
#define __API_IO__
#include <errno.h>
#include <poll.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <linux/types.h>
struct io {
/* File descriptor being read/ */
int fd;
/* Size of the read buffer. */
unsigned int buf_len;
/* Pointer to storage for buffering read. */
char *buf;
/* End of the storage. */
char *end;
/* Currently accessed data pointer. */
char *data;
/* Read timeout, 0 implies no timeout. */
int timeout_ms;
/* Set true on when the end of file on read error. */
bool eof;
};
static inline void io__init(struct io *io, int fd,
char *buf, unsigned int buf_len)
{
io->fd = fd;
io->buf_len = buf_len;
io->buf = buf;
io->end = buf;
io->data = buf;
io->timeout_ms = 0;
io->eof = false;
}
/* Read from fd filling the buffer. Called when io->data == io->end. */
static inline int io__fill_buffer(struct io *io)
{
ssize_t n;
if (io->eof)
return -1;
if (io->timeout_ms != 0) {
struct pollfd pfds[] = {
{
.fd = io->fd,
.events = POLLIN,
},
};
n = poll(pfds, 1, io->timeout_ms);
if (n == 0)
errno = ETIMEDOUT;
if (n > 0 && !(pfds[0].revents & POLLIN)) {
errno = EIO;
n = -1;
}
if (n <= 0) {
io->eof = true;
return -1;
}
}
n = read(io->fd, io->buf, io->buf_len);
if (n <= 0) {
io->eof = true;
return -1;
}
io->data = &io->buf[0];
io->end = &io->buf[n];
return 0;
}
/* Reads one character from the "io" file with similar semantics to fgetc. */
static inline int io__get_char(struct io *io)
{
if (io->data == io->end) {
int ret = io__fill_buffer(io);
if (ret)
return ret;
}
return *io->data++;
}
/* Read a hexadecimal value with no 0x prefix into the out argument hex. If the
* first character isn't hexadecimal returns -2, io->eof returns -1, otherwise
* returns the character after the hexadecimal value which may be -1 for eof.
* If the read value is larger than a u64 the high-order bits will be dropped.
*/
static inline int io__get_hex(struct io *io, __u64 *hex)
{
bool first_read = true;
*hex = 0;
while (true) {
int ch = io__get_char(io);
if (ch < 0)
return ch;
if (ch >= '0' && ch <= '9')
*hex = (*hex << 4) | (ch - '0');
else if (ch >= 'a' && ch <= 'f')
*hex = (*hex << 4) | (ch - 'a' + 10);
else if (ch >= 'A' && ch <= 'F')
*hex = (*hex << 4) | (ch - 'A' + 10);
else if (first_read)
return -2;
else
return ch;
first_read = false;
}
}
/* Read a positive decimal value with out argument dec. If the first character
* isn't a decimal returns -2, io->eof returns -1, otherwise returns the
* character after the decimal value which may be -1 for eof. If the read value
* is larger than a u64 the high-order bits will be dropped.
*/
static inline int io__get_dec(struct io *io, __u64 *dec)
{
bool first_read = true;
*dec = 0;
while (true) {
int ch = io__get_char(io);
if (ch < 0)
return ch;
if (ch >= '0' && ch <= '9')
*dec = (*dec * 10) + ch - '0';
else if (first_read)
return -2;
else
return ch;
first_read = false;
}
}
/* Read up to and including the first delim. */
static inline ssize_t io__getdelim(struct io *io, char **line_out, size_t *line_len_out, int delim)
{
char buf[128];
int buf_pos = 0;
char *line = NULL, *temp;
size_t line_len = 0;
int ch = 0;
/* TODO: reuse previously allocated memory. */
free(*line_out);
while (ch != delim) {
ch = io__get_char(io);
if (ch < 0)
break;
if (buf_pos == sizeof(buf)) {
temp = realloc(line, line_len + sizeof(buf));
if (!temp)
goto err_out;
line = temp;
memcpy(&line[line_len], buf, sizeof(buf));
line_len += sizeof(buf);
buf_pos = 0;
}
buf[buf_pos++] = (char)ch;
}
temp = realloc(line, line_len + buf_pos + 1);
if (!temp)
goto err_out;
line = temp;
memcpy(&line[line_len], buf, buf_pos);
line[line_len + buf_pos] = '\0';
line_len += buf_pos;
*line_out = line;
*line_len_out = line_len;
return line_len;
err_out:
free(line);
*line_out = NULL;
return -ENOMEM;
}
static inline ssize_t io__getline(struct io *io, char **line_out, size_t *line_len_out)
{
return io__getdelim(io, line_out, line_len_out, /*delim=*/'\n');
}
#endif /* __API_IO__ */
|
