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
|
/**
* slack — Spawn processes with customised timer slack
* Copyright © 2014 Mattias Andrée (maandree@member.fsf.org)
*
* 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 <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/prctl.h>
#define NS (1L)
#define US (1000L)
#define MS (1000L * 1000L)
#define S (1000L * 1000L * 1000L)
static void usage(void)
{
printf("USAGE: slack (get | GET | (reset | <interval> <options..> [--fatal] [--] <command..>))\n");
printf("\n");
printf("The <interval> must be a positive number optionally with a suffix:\n");
printf(" ns n nanoseconds (default)\n");
printf(" µs µ ns n microseconds\n");
printf(" ms m milliseconds\n");
printf(" s seconds\n");
printf("\n");
printf("If `GET' is used rather than `get', the timer slack value will be printed in\n");
printf("nanoseconds without suffix. `GET' and `get' prints the current timer slack\n");
printf("value and exits.\n");
printf("\n");
printf("`reset` reset the timer slack value to the default (the time slack value for\n");
printf("the init process (PID 1) has.)\n");
printf("\n");
printf("Unless `--fatal` is used, the program will run <command> even if the timer\n");
printf("slack could not be set.\n");
printf("\n");
}
int main(int argc, char** argv)
{
long slackvalue, r;
int i, j, fatal = 0;
char** exec_argv;
if ((argc < 2) || !strcmp(argv[1], "--help") || !strcmp(argv[1], "help"))
return usage(), argc < 2 ? 1 : 0;
if (!strcmp(argv[1], "get") || !strcmp(argv[1], "GET"))
{
const char* suffix;
if (r = prctl(PR_GET_TIMERSLACK), r < 0)
perror(*argv);
else
{
if (!strcmp(argv[1], "GET"))
suffix = "";
else if (r % S == 0) suffix = "s", r /= S;
else if (r % MS == 0) suffix = "ms", r /= MS;
else if (r % US == 0) suffix = "µs", r /= US;
else suffix = "ns";
printf("%li%s\n", r, suffix);
}
return r > 0 ? 0 : 1;
}
for (i = 2; i < argc; i++)
if (!strcmp(argv[i], "--fatal"))
fatal = 1;
else if (!strcmp(argv[i], "--"))
{
i++;
break;
}
else if (strstr(argv[i], "-") == argv[i])
return usage(), 1;
else
break;
if (i == argc)
return usage(), 1;
exec_argv = malloc((argc - i + 1) * sizeof(char*));
if (exec_argv == NULL)
return perror(*argv), 2;
exec_argv[argc - i] = NULL;
for (j = 0; i < argc; j++, i++)
exec_argv[j] = argv[i];
if (!strcmp(argv[1], "reset"))
slackvalue = 0;
else
{
char* end;
slackvalue = strtol(argv[1], &end, 10);
if (end == argv[1])
return fprintf(stderr, "No slack value specified."), free(exec_argv), 1;
if (!strcmp(end, "n") || !strcmp(end, "ns") || !strcmp(end, "")) slackvalue *= NS;
else if (!strcmp(end, "µ") || !strcmp(end, "µs")) slackvalue *= US;
else if (!strcmp(end, "u") || !strcmp(end, "us")) slackvalue *= US;
else if (!strcmp(end, "m") || !strcmp(end, "ms")) slackvalue *= MS;
else if (!strcmp(end, "s")) slackvalue *= S;
else
return fprintf(stderr, "Unrecognised suffix for slack value."), free(exec_argv), 1;
if (slackvalue <= 0)
return fprintf(stderr, "Invalid slack value: %lins", slackvalue), free(exec_argv), 1;
}
if (r = prctl(PR_SET_TIMERSLACK, slackvalue), r < 0)
if (perror(*argv), fatal)
return free(exec_argv), 2;
execvp(*exec_argv, exec_argv);
perror(*argv);
free(exec_argv);
return 2;
}
|
