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
|
/*
* libdpkg - Debian packaging suite library routines
* meminfo.c - system memory information functions
*
* Copyright © 2021 Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
* Copyright © 2021-2022 Guillem Jover <guillem@debian.org>
*
* This 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 2 of the License, or
* (at your option) any later version.
*
* This 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 <https://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <compat.h>
#include <sys/stat.h>
#include <errno.h>
#include <inttypes.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <dpkg/dpkg.h>
#include <dpkg/fdio.h>
#include <dpkg/meminfo.h>
/*
* An estimate of how much memory is available. Swap will not be used, the
* page cache may be purged, not everything will be reclaimed that might be
* reclaimed, watermarks are considered.
*/
struct meminfo_field {
const char *name;
ssize_t len;
int tag;
uint64_t value;
};
#define MEMINFO_FIELD(name, tag) name, sizeof(name) - 1, tag, 0
static struct meminfo_field *
meminfo_find_field(struct meminfo_field *fields, const size_t nfields,
const char *fieldname, const ssize_t fieldlen)
{
size_t f;
for (f = 0; f < nfields; f++) {
if (fieldlen != fields[f].len)
continue;
if (strncmp(fieldname, fields[f].name, fields[f].len) != 0)
continue;
return &fields[f];
}
return NULL;
}
static uint64_t
meminfo_sum_fields(const struct meminfo_field *fields, const size_t nfields)
{
uint64_t sum = 0;
size_t f;
for (f = 0; f < nfields; f++)
sum += fields[f].value;
return sum;
}
enum meminfo_error_code
meminfo_get_available_from_file(const char *filename, uint64_t *val)
{
char buf[4096];
char *str;
ssize_t bytes;
int fd;
struct meminfo_field fields[] = {
{ MEMINFO_FIELD("MemFree", DPKG_BIT(0)) },
{ MEMINFO_FIELD("Buffers", DPKG_BIT(1)) },
{ MEMINFO_FIELD("Cached", DPKG_BIT(2)) },
};
const int want_tags = DPKG_BIT(array_count(fields)) - 1;
int seen_tags = 0;
*val = 0;
fd = open(filename, O_RDONLY);
if (fd < 0)
return MEMINFO_NO_FILE;
bytes = fd_read(fd, buf, sizeof(buf));
close(fd);
if (bytes <= 0)
return MEMINFO_NO_DATA;
buf[bytes] = '\0';
str = buf;
while (1) {
struct meminfo_field *field;
char *end;
end = strchr(str, ':');
if (end == 0)
break;
field = meminfo_find_field(fields, array_count(fields),
str, end - str);
if (field) {
intmax_t num;
str = end + 1;
errno = 0;
num = strtoimax(str, &end, 10);
if (num <= 0)
return MEMINFO_INT_NEG;
if ((num == INTMAX_MAX) && errno == ERANGE)
return MEMINFO_INT_MAX;
/* It should end with ' kB\n'. */
if (*end != ' ' || *(end + 1) != 'k' ||
*(end + 2) != 'B')
return MEMINFO_NO_UNIT;
/* This should not overflow, but just in case. */
if (num < (INTMAX_MAX / 1024))
num *= 1024;
field->value = num;
seen_tags |= field->tag;
}
if (seen_tags == want_tags)
break;
end = strchr(end + 1, '\n');
if (end == 0)
break;
str = end + 1;
}
if (seen_tags != want_tags)
return MEMINFO_NO_INFO;
*val = meminfo_sum_fields(fields, array_count(fields));
return MEMINFO_OK;
}
enum meminfo_error_code
meminfo_get_available(uint64_t *val)
{
#ifdef __linux__
return meminfo_get_available_from_file("/proc/meminfo", val);
#else
return MEMINFO_NO_FILE;
#endif
}
|
