struct dir *dir_openat(struct dir *top_dir, const char *dirname)
{
struct dir *dir = _dir_new(top_dir->db, top_dir->pathname, dirname);
dir->dir = opendirat(top_dir->dir, dirname);
int r = (dir->dir != NULL) ? 0 : -1;
DIRTRACE(dir, r, "opendirat(\"%s\")", dir->pathname);
if (r == -1) {
r = mkdirat(dirfd(top_dir->dir), dirname, 0700);
DIRTRACE(dir, r, "mkdirat(\"%s\")", dir->pathname);
if (r == 0) {
dir->dir = opendirat(top_dir->dir, dirname);
r = (dir->dir != NULL) ? 0 : -1;
DIRTRACE(dir, r, "opendirat(\"%s\")", dir->pathname);
}
if (r == -1) {
dir_free(dir);
return NULL;
}
}
return dir;
}
bool FindProcessHoldingSocket(pid_t* pid_out, ino_t socket_inode) {
bool already_found = false;
DIR* proc = opendir("/proc");
if (!proc)
return false;
const uid_t uid = getuid();
struct dirent* dent;
while ((dent = readdir(proc))) {
char* endptr = NULL;
errno = 0;
const unsigned long int pid_ul = strtoul(dent->d_name, &endptr, 10);
if (pid_ul == ULONG_MAX || !endptr || *endptr || errno != 0)
continue;
// We have this setuid code here because the zygote and its children have
// /proc/$pid/fd owned by root. While scanning through /proc, we add this
// extra check so users cannot accidentally gain information about other
// users' processes. To determine process ownership, we use the property
// that if user foo owns process N, then /proc/N is owned by foo.
int proc_pid_fd = -1;
{
char buf[256];
struct stat statbuf;
snprintf(buf, sizeof(buf), "/proc/%lu", pid_ul);
proc_pid_fd = open(buf, O_RDONLY | O_DIRECTORY);
if (proc_pid_fd < 0)
continue;
if (fstat(proc_pid_fd, &statbuf) < 0 || uid != statbuf.st_uid) {
close(proc_pid_fd);
continue;
}
}
DIR* fd = opendirat(proc_pid_fd, "fd");
if (!fd) {
close(proc_pid_fd);
continue;
}
while ((dent = readdir(fd))) {
char buf[256];
int printed = snprintf(buf, sizeof(buf), "fd/%s", dent->d_name);
if (printed < 0 || printed >= (int)(sizeof(buf) - 1)) {
continue;
}
ino_t fd_inode;
if (ProcPathGetInodeAt(&fd_inode, proc_pid_fd, buf)) {
if (fd_inode == socket_inode) {
if (already_found) {
closedir(fd);
close(proc_pid_fd);
closedir(proc);
return false;
}
already_found = true;
*pid_out = pid_ul;
break;
}
}
}
closedir(fd);
close(proc_pid_fd);
}
closedir(proc);
return already_found;
}
