ubase/sysctl.c

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2.7 KiB
C
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/* See LICENSE file for copyright and license details. */
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "util.h"
static void
streplace(char *s, int a, int b)
{
for (; *s; s++)
if (*s == a)
*s = b;
}
static int
getsysctl(char *variable, char **value)
{
char path[PATH_MAX];
char *p;
char *buf, *tmp, c;
int fd;
ssize_t n;
size_t sz, i;
streplace(variable, '.', '/');
strlcpy(path, "/proc/sys/", sizeof(path));
if (strlcat(path, variable, sizeof(path)) >= sizeof(path)) {
streplace(variable, '/', '.');
return -1;
}
streplace(variable, '/', '.');
fd = open(path, O_RDONLY);
if (fd < 0)
return -1;
i = 0;
sz = 1;
buf = NULL;
while (1) {
n = read(fd, &c, 1);
if (n < 0) {
close(fd);
free(buf);
return -1;
}
if (n == 0)
break;
if (i == sz - 1) {
sz *= 2;
tmp = realloc(buf, sz);
if (!tmp) {
close(fd);
free(buf);
return -1;
}
buf = tmp;
}
buf[i++] = c;
}
buf[i] = '\0';
p = strrchr(buf, '\n');
if (p)
*p = '\0';
*value = buf;
close(fd);
return 0;
}
static int
setsysctl(char *variable, char *value)
{
char path[PATH_MAX];
int fd;
ssize_t n;
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streplace(variable, '.', '/');
strlcpy(path, "/proc/sys/", sizeof(path));
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if (strlcat(path, variable, sizeof(path)) >= sizeof(path)) {
streplace(variable, '/', '.');
return -1;
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}
streplace(variable, '/', '.');
fd = open(path, O_WRONLY);
if (fd < 0)
return -1;
n = write(fd, value, strlen(value));
if (n != (ssize_t)strlen(value)) {
close(fd);
return -1;
}
close(fd);
return 0;
}
static void
usage(void)
{
eprintf("usage: %s variable[=value]...\n", argv0);
}
int
main(int argc, char *argv[])
{
char *variable;
char *value;
char *p;
int i;
int r = EXIT_SUCCESS;
argv0 = argv[0];
argv++;
argc--;
if (argc < 1)
usage();
for (i = 0; i < argc; i++) {
for (p = argv[i]; *p; p++) {
if (p[0] == '.' && p[1] == '.') {
r = EXIT_FAILURE;
weprintf("malformed input: %s\n", argv[i]);
break;
}
}
if (*p != '\0')
continue;
p = strchr(argv[i], '=');
if (p) {
if (p[1] == '\0') {
r = EXIT_FAILURE;
weprintf("malformed input: %s\n", argv[i]);
continue;
}
*p = '\0';
value = &p[1];
} else {
value = NULL;
}
variable = argv[i];
if (variable) {
if (value) {
if (setsysctl(variable, value) < 0) {
r = EXIT_FAILURE;
weprintf("failed to set sysctl for %s\n", variable);
continue;
}
}
else {
if (getsysctl(variable, &value) < 0) {
r = EXIT_FAILURE;
weprintf("failed to get sysctl for %s\n", variable);
continue;
}
printf("%s = %s\n", variable, value);
free(value);
}
}
}
return r;
}