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https://github.com/RGBCube/serenity
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Add a simple /bin/sysctl that wraps the files in /proc/sys.
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parent
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5 changed files with 151 additions and 4 deletions
138
Userland/sysctl.cpp
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138
Userland/sysctl.cpp
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#include <stdio.h>
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#include <unistd.h>
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#include <dirent.h>
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#include <errno.h>
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#include <string.h>
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#include <getopt.h>
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#include <fcntl.h>
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#include <AK/AKString.h>
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#include <AK/StringBuilder.h>
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#include <AK/Vector.h>
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static bool flag_show_all = false;
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static int show_all();
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static int handle_var(const char*);
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static void usage()
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{
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printf("usage: sysctl [-a] [variable[=value]]\n");
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}
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int main(int argc, char** argv)
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{
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int opt;
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while ((opt = getopt(argc, argv, "a")) != -1) {
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switch (opt) {
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case 'a':
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flag_show_all = true;
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break;
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default:
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usage();
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return 0;
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}
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}
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if (flag_show_all)
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return show_all();
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if (optind >= argc) {
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usage();
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return 0;
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}
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const char* var = argv[optind];
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return handle_var(var);
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}
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int show_all()
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{
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DIR* dirp = opendir("/proc/sys");
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if (!dirp) {
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perror("opendir");
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return 1;
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}
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char pathbuf[256];
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while (auto* de = readdir(dirp)) {
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if (de->d_name[0] == '.')
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continue;
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sprintf(pathbuf, "/proc/sys/%s", de->d_name);
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int fd = open(pathbuf, O_RDONLY);
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if (fd < 0) {
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perror("open");
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continue;
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}
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char buffer[1024];
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int nread = read(fd, buffer, sizeof(buffer));
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close(fd);
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if (nread < 0) {
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perror("read");
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continue;
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}
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buffer[nread] = '\0';
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printf("%s = %s", de->d_name, buffer);
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if (nread && buffer[nread - 1] != '\n')
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printf("\n");
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}
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closedir(dirp);
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return 0;
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}
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static String read_var(const String& name)
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{
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StringBuilder builder;
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builder.append("/proc/sys/");
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builder.append(name);
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auto path = builder.build();
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int fd = open(path.characters(), O_RDONLY);
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if (fd < 0) {
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perror("open");
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exit(1);
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}
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char buffer[1024];
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int nread = read(fd, buffer, sizeof(buffer));
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close(fd);
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if (nread < 0) {
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perror("read");
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exit(1);
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}
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return String(buffer, nread, Chomp);
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}
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static void write_var(const String& name, const String& value)
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{
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StringBuilder builder;
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builder.append("/proc/sys/");
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builder.append(name);
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auto path = builder.build();
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int fd = open(path.characters(), O_WRONLY);
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if (fd < 0) {
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perror("open");
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exit(1);
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}
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int nwritten = write(fd, value.characters(), value.length());
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if (nwritten < 0) {
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perror("read");
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exit(1);
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}
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close(fd);
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}
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int handle_var(const char* var)
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{
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String spec(var, Chomp);
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auto parts = spec.split('=');
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String variable_name = parts[0];
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bool is_write = parts.size() > 1;
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if (!is_write) {
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printf("%s = %s\n", variable_name.characters(), read_var(variable_name).characters());
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return 0;
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}
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printf("%s = %s", variable_name.characters(), read_var(variable_name).characters());
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write_var(variable_name, parts[1]);
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printf(" -> %s\n", read_var(variable_name).characters());
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return 0;
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}
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