sbase/sysctl.c

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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 int
getsysctl(char *variable, char **value)
{
char path[PATH_MAX];
char *p;
char *buf;
int fd;
ssize_t n;
for (p = variable; *p; p++)
if (*p == '.')
*p = '/';
strlcpy(path, "/proc/sys/", sizeof(path));
if (strlcat(path, variable, sizeof(path)) >= sizeof(path))
return -1;
fd = open(path, O_RDONLY);
if (fd < 0)
return -1;
buf = malloc(1024);
if (!buf) {
close(fd);
return -1;
}
n = read(fd, buf, 1023);
if (n <= 0) {
close(fd);
free(buf);
return -1;
}
buf[n] = '\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];
char *p;
int fd;
ssize_t n;
for (p = variable; *p; p++)
if (*p == '.')
*p = '/';
strlcpy(path, "/proc/sys/", sizeof(path));
if (strlcat(path, variable, sizeof(path)) >= sizeof(path))
return -1;
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;
argv0 = argv[0];
argv++;
argc--;
if (argc < 1)
usage();
for (i = 0; i < argc; i++) {
value = NULL;
variable = argv[i];
p = strchr(variable, '=');
if (p) {
if (p[1] == '\0') {
weprintf("malformed sysctl: %s\n", argv[i]);
continue;
}
*p = '\0';
value = &p[1];
}
if (variable) {
if (value) {
if (setsysctl(variable, value) < 0) {
weprintf("failed to set sysctl for %s\n", variable);
continue;
}
}
else {
if (getsysctl(variable, &value) < 0) {
weprintf("failed to get sysctl for %s\n", variable);
continue;
}
printf("%s = %s\n", variable, value);
free(value);
}
}
}
return EXIT_SUCCESS;
}