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// Copyright 2024 Huawei Cloud Computing Technology Co., Ltd.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <cstring>
#include <iostream>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
void print_buffer(char *start, char *end) {
++end;
while (start != end) {
std::cout << *start++;
}
}
bool ends_with(char *end, std::string const &token) {
auto it = token.rbegin();
while (it != token.rend()) {
if (*it++ != *end--) {
return false;
}
}
return true;
}
int main(int argc, char **argv) {
int pipefd_a[2]; // pipefd_a[0] reads from pipe
// pipefd_a[1] writes to pipe
int pipefd_b[2];
if (pipe(pipefd_a) == -1) {
perror("pipe error");
exit(EXIT_FAILURE);
}
if (pipe(pipefd_b) == -1) {
perror("pipe error");
exit(EXIT_FAILURE);
}
auto pid = fork();
if (pid == -1) {
perror("fork error");
exit(EXIT_FAILURE);
}
if (pid == 0) {
std::string const s{argv[1]};
std::string const token = s.substr(s.rfind('/') + 1);
std::cout << "playing: " << s << std::endl;
// child reads from pipefd_a[0];
// writes to pipefd_b[1];
dup2(pipefd_b[1], STDOUT_FILENO);
dup2(pipefd_a[0], STDIN_FILENO);
close(pipefd_a[1]); // close unused write end
close(pipefd_b[0]); // close unused read end
close(pipefd_b[1]);
close(pipefd_a[0]);
execl(s.c_str(), token.c_str());
_exit(0);
} else {
// master reads from pipefd_b[0]
// writes to pipefd_a[1];
close(pipefd_a[0]);
close(pipefd_b[1]);
bool run = true;
int a = 1;
int b = 101;
int trial = 50;
char buffer[1024];
char *p = buffer;
std::string s;
while (run) {
while (read(pipefd_b[0], p, 1)) {
if (*p == '\n') {
print_buffer(buffer, p);
p = buffer;
continue;
}
if (*p == '!') {
if (ends_with(p, "win!")) {
run = false;
print_buffer(buffer, p);
std::cout << std::endl;
break;
}
if (ends_with(p, "small!")) {
a = trial;
trial = (a + b) / 2;
}
if (ends_with(p, "big!")) {
b = trial;
trial = (a + b) / 2;
}
char trial_buf[80];
int len = sprintf(trial_buf, "%d\n", trial);
write(pipefd_a[1], trial_buf, len);
}
if (!run) {
break;
}
++p;
}
}
close(pipefd_b[0]);
close(pipefd_a[1]);
int status;
waitpid(0, &status, 0);
}
}
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