From 3fd43cd5fcb22bb65bf2a92a25d95d801b11c9e0 Mon Sep 17 00:00:00 2001
From: Scott Gasch <scott.gasch@gmail.com>
Date: Wed, 1 Jun 2016 18:58:58 -0700
Subject: Initial checkin for typhoon chess engine.

---
 src/autoplay/child_process.cc | 188 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 188 insertions(+)
 create mode 100644 src/autoplay/child_process.cc

(limited to 'src/autoplay/child_process.cc')

diff --git a/src/autoplay/child_process.cc b/src/autoplay/child_process.cc
new file mode 100644
index 0000000..6486a0e
--- /dev/null
+++ b/src/autoplay/child_process.cc
@@ -0,0 +1,188 @@
+#include "child_process.h"
+
+#include <vector>
+#include <cstdio>
+#include <cstdlib>
+#include <unistd.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+namespace util {
+
+void ChildProcess::ParseCommandline(vector<char *> *args) {
+  char *p = commandline_;
+  bool in_quote;
+  do {
+    // Find the start of a chunk.
+    while(*p && isspace(*p)) p++;
+    if (!*p) break;
+    args->push_back(p);
+    in_quote = false;
+
+    // Find the end of the chunk.
+    while (*p) {
+      if (*p == '"') {
+        in_quote = !in_quote;
+      } else if (isspace(*p) && !in_quote) {
+        break;
+      }
+      p++;
+    }
+    if (!*p) break;
+    *p = '\0';
+    p++;
+  } while(1);
+  args->push_back(NULL);
+}
+
+static volatile bool _child_ready = false;
+static void SignalHandler(int signo) {
+  printf("SIGNAL!\n");
+  _child_ready = true;
+}
+
+void ChildProcess::Start() {
+  Stop();
+  vector<char *> args;
+  ParseCommandline(&args);
+
+  if (args.size() > 1) {
+    if (pipe(read_pipe_) != 0) {
+      perror("pipe");
+      exit(-1);
+    }
+    if (pipe(write_pipe_) != 0) {
+      perror("pipe");
+      exit(-1);
+    }
+
+    // Prepare a signal handler to tell us when the child process is
+    // ready.
+    _child_ready = false;
+    if (signal(SIGUSR1, SignalHandler) == SIG_ERR) {
+      perror("signal");
+      exit(-1);
+    }
+    sigset_t zeromask, mask, orig;
+    sigemptyset(&zeromask);
+    sigemptyset(&mask);
+    sigaddset(&mask, SIGUSR1);
+    if (sigprocmask(SIG_BLOCK, &mask, &orig) < 0) {
+      perror("sigprocmask");
+      exit(-1);
+    }
+
+    // Fork.
+    pid_ = fork();
+    if (pid_ < 0) {
+      perror("fork");
+      exit(-1);
+    }
+    if (pid_ == 0) {
+      printf("In the child process...\n");
+
+      // In the child process we do not need the pipes for parent
+      // reads and writes.
+      close(write_pipe_[1]);
+      close(read_pipe_[0]);
+      if (dup2(write_pipe_[0], fileno(stdin)) < 0) {
+        perror("dup2");
+        exit(-1);
+      }
+      close(write_pipe_[0]);
+      if (dup2(read_pipe_[1], fileno(stdout)) < 0) {
+        perror("dup2");
+        exit(-1);
+      }
+      if (dup2(fileno(stdout), fileno(stderr)) < 0) {
+        perror("dup2");
+        exit(-1);
+      }
+      close(read_pipe_[1]);
+
+      // Tell the parent that the pipes are set up then exec the child
+      // image.
+      kill(getppid(), SIGUSR1);
+      execvp(args[0], &(args[0]));
+      perror("exec");
+      exit(-1);
+    } else {
+      printf("In the parent process waiting...\n");
+      while(!_child_ready) {
+        sigsuspend(&zeromask);
+      }
+      printf("PARENT WAKEUP!\n");
+      _child_ready = false;
+      if (sigprocmask(SIG_SETMASK, &orig, NULL) < 0) {
+        perror("sigprocmask");
+        exit(-1);
+      }
+      close(write_pipe_[0]);
+      close(read_pipe_[1]);
+      from_ = fdopen(read_pipe_[0], "r");
+      to_ = fdopen(write_pipe_[1], "w");
+      setbuf(from_, NULL);
+      setbuf(to_, NULL);
+      running_ = true;
+      name_ = args[0];
+    }
+  }
+}
+
+void ChildProcess::Stop() {
+  if (!running_) {
+    return;
+  }
+  fclose(to_);
+  fclose(from_);
+  close(write_pipe_[1]);
+  close(read_pipe_[0]);
+  kill(pid_, SIGTERM);
+  int x;
+  waitpid(pid_, &x, 0);
+}
+
+void ChildProcess::Send(char *line) {
+  if (!running_) {
+    return;
+  }
+  fprintf(to_, "%s", line);
+  printf("%s sent: %s", name_, line);
+}
+
+void ChildProcess::Receive(char *line, int size) {
+  if (!size) return;
+  *line = '\0';
+  if (!running_) {
+    return;
+  }
+  if (!Poll()) {
+    return;
+  }
+  fgets(line, size, from_);
+  printf("%s recv: %s\n", name_, line);
+}
+
+bool ChildProcess::Poll() {
+  fd_set myset;
+  FD_ZERO(&myset);
+  FD_SET(read_pipe_[0], &myset);
+  timeval mytime;
+  mytime.tv_sec = 0;
+  mytime.tv_usec = 0;
+  return select(read_pipe_[0] + 1, &myset, NULL, NULL, &mytime) > 0;
+}
+
+void ChildProcess::Flush() {
+  static char line[1000];
+  while (Poll()) {
+    Receive(line, 1000);
+    printf("flush: %s", line);
+    if (!line[0]) {
+      break;
+    }
+  }
+}
+
+}  // namespace
-- 
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