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#include <stdio.h>
#include <unistd.h>
#include <dirent.h>
#include <errno.h>
#include <string.h>
#include <getopt.h>
#include <fcntl.h>
#include <AK/AKString.h>
#include <AK/StringBuilder.h>
#include <AK/Vector.h>
static bool flag_show_all = false;
static int show_all();
static int handle_var(const char*);
static void usage()
{
printf("usage: sysctl [-a] [variable[=value]]\n");
}
int main(int argc, char** argv)
{
int opt;
while ((opt = getopt(argc, argv, "a")) != -1) {
switch (opt) {
case 'a':
flag_show_all = true;
break;
default:
usage();
return 0;
}
}
if (flag_show_all)
return show_all();
if (optind >= argc) {
usage();
return 0;
}
const char* var = argv[optind];
return handle_var(var);
}
int show_all()
{
DIR* dirp = opendir("/proc/sys");
if (!dirp) {
perror("opendir");
return 1;
}
char pathbuf[PATH_MAX];
while (auto* de = readdir(dirp)) {
if (de->d_name[0] == '.')
continue;
sprintf(pathbuf, "/proc/sys/%s", de->d_name);
int fd = open(pathbuf, O_RDONLY);
if (fd < 0) {
perror("open");
continue;
}
char buffer[1024];
int nread = read(fd, buffer, sizeof(buffer));
close(fd);
if (nread < 0) {
perror("read");
continue;
}
buffer[nread] = '\0';
printf("%s = %s", de->d_name, buffer);
if (nread && buffer[nread - 1] != '\n')
printf("\n");
}
closedir(dirp);
return 0;
}
static String read_var(const String& name)
{
StringBuilder builder;
builder.append("/proc/sys/");
builder.append(name);
auto path = builder.to_string();
int fd = open(path.characters(), O_RDONLY);
if (fd < 0) {
perror("open");
exit(1);
}
char buffer[1024];
int nread = read(fd, buffer, sizeof(buffer));
close(fd);
if (nread < 0) {
perror("read");
exit(1);
}
return String(buffer, nread, Chomp);
}
static void write_var(const String& name, const String& value)
{
StringBuilder builder;
builder.append("/proc/sys/");
builder.append(name);
auto path = builder.to_string();
int fd = open(path.characters(), O_WRONLY);
if (fd < 0) {
perror("open");
exit(1);
}
int nwritten = write(fd, value.characters(), value.length());
if (nwritten < 0) {
perror("read");
exit(1);
}
close(fd);
}
int handle_var(const char* var)
{
String spec(var, Chomp);
auto parts = spec.split('=');
String variable_name = parts[0];
bool is_write = parts.size() > 1;
if (!is_write) {
printf("%s = %s\n", variable_name.characters(), read_var(variable_name).characters());
return 0;
}
printf("%s = %s", variable_name.characters(), read_var(variable_name).characters());
write_var(variable_name, parts[1]);
printf(" -> %s\n", read_var(variable_name).characters());
return 0;
}
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