Update monet.

tools/android/file_poller/file_poller.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// When run with 2 or more arguments the file_poller tool will open a port on
+// the device, print it on its standard output and then start collect file
+// contents.  The first argument is the polling rate in Hz, and the following
+// arguments are file to poll.
+// When run with the port of an already running file_poller, the tool will
+// contact the first instance, retrieve the sample and print those on its
+// standard output. This will also terminate the first instance.
+
+#include <errno.h>
+#include <fcntl.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "base/logging.h"
+
+// Context containing the files to poll and the polling rate.
+struct Context {
+  size_t nb_files;
+  int* file_fds;
+  int poll_rate;
+};
+
+// Write from the buffer to the given file descriptor.
+void safe_write(int fd, const char* buffer, int size) {
+  const char* index = buffer;
+  size_t to_write = size;
+  while (to_write > 0) {
+    int written = write(fd, index, to_write);
+    if (written < 0)
+      PLOG(FATAL);
+    index += written;
+    to_write -= written;
+  }
+}
+
+// Transfer the content of a file descriptor to another.
+void transfer_to_fd(int fd_in, int fd_out) {
+  char buffer[1024];
+  int n;
+  while ((n = read(fd_in, buffer, sizeof(buffer))) > 0)
+    safe_write(fd_out, buffer, n);
+}
+
+// Transfer the content of a file descriptor to a buffer.
+int transfer_to_buffer(int fd_in, char* bufffer, size_t size) {
+  char* index = bufffer;
+  size_t to_read = size;
+  int n;
+  while (to_read > 0 && ((n = read(fd_in, index, to_read)) > 0)) {
+    index += n;
+    to_read -= n;
+  }
+  if (n < 0)
+    PLOG(FATAL);
+  return size - to_read;
+}
+
+// Try to open the file at the given path for reading. Exit in case of failure.
+int checked_open(const char* path) {
+  int fd = open(path, O_RDONLY);
+  if (fd < 0)
+    PLOG(FATAL);
+  return fd;
+}
+
+void transfer_measurement(int fd_in, int fd_out, bool last) {
+  char buffer[1024];
+  if (lseek(fd_in, 0, SEEK_SET) < 0)
+    PLOG(FATAL);
+  int n = transfer_to_buffer(fd_in, buffer, sizeof(buffer));
+  safe_write(fd_out, buffer, n - 1);
+  safe_write(fd_out, last ? "\n" : " ", 1);
+}
+
+// Acquire a sample and save it to the given file descriptor.
+void acquire_sample(int fd, const Context& context) {
+  struct timeval tv;
+  gettimeofday(&tv, NULL);
+  char buffer[1024];
+  int n = snprintf(buffer, sizeof(buffer), "%d.%06d ", tv.tv_sec, tv.tv_usec);
+  safe_write(fd, buffer, n);
+
+  for (int i = 0; i < context.nb_files; ++i)
+    transfer_measurement(context.file_fds[i], fd, i == (context.nb_files - 1));
+}
+
+void poll_content(const Context& context) {
+  // Create and bind the socket so that the port can be written to stdout.
+  int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+  struct sockaddr_in socket_info;
+  socket_info.sin_family = AF_INET;
+  socket_info.sin_addr.s_addr = htonl(INADDR_ANY);
+  socket_info.sin_port = htons(0);
+  if (bind(sockfd, (struct sockaddr*)&socket_info, sizeof(socket_info)) < 0)
+    PLOG(FATAL);
+  socklen_t size = sizeof(socket_info);
+  getsockname(sockfd, (struct sockaddr*)&socket_info, &size);
+  printf("%d\n", ntohs(socket_info.sin_port));
+  // Using a pipe to ensure child is diconnected from the terminal before
+  // quitting.
+  int pipes[2];
+  pipe(pipes);
+  pid_t pid = fork();
+  if (pid < 0)
+    PLOG(FATAL);
+  if (pid != 0) {
+    close(pipes[1]);
+    // Not expecting any data to be received.
+    read(pipes[0], NULL, 1);
+    signal(SIGCHLD, SIG_IGN);
+    return;
+  }
+
+  // Detach from terminal.
+  setsid();
+  close(STDIN_FILENO);
+  close(STDOUT_FILENO);
+  close(STDERR_FILENO);
+  close(pipes[0]);
+
+  // Start listening for incoming connection.
+  if (listen(sockfd, 1) < 0)
+    PLOG(FATAL);
+
+  // Signal the parent that it can now safely exit.
+  close(pipes[1]);
+
+  // Prepare file to store the samples.
+  int fd;
+  char filename[] = "/data/local/tmp/fileXXXXXX";
+  fd = mkstemp(filename);
+  unlink(filename);
+
+  // Collect samples until a client connect on the socket.
+  fd_set rfds;
+  struct timeval timeout;
+  do {
+    acquire_sample(fd, context);
+    timeout.tv_sec = 0;
+    timeout.tv_usec = 1000000 / context.poll_rate;
+    FD_ZERO(&rfds);
+    FD_SET(sockfd, &rfds);
+  } while (select(sockfd + 1, &rfds, NULL, NULL, &timeout) == 0);
+
+  // Collect a final sample.
+  acquire_sample(fd, context);
+
+  // Send the result back.
+  struct sockaddr_in remote_socket_info;
+  int rfd = accept(sockfd, (struct sockaddr*)&remote_socket_info, &size);
+  if (rfd < 0)
+    PLOG(FATAL);
+  if (lseek(fd, 0, SEEK_SET) < 0)
+    PLOG(FATAL);
+  transfer_to_fd(fd, rfd);
+}
+
+void content_collection(int port) {
+  int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+  // Connect to localhost.
+  struct sockaddr_in socket_info;
+  socket_info.sin_family = AF_INET;
+  socket_info.sin_addr.s_addr = htonl(0x7f000001);
+  socket_info.sin_port = htons(port);
+  if (connect(sockfd, (struct sockaddr*)&socket_info, sizeof(socket_info)) <
+      0) {
+    PLOG(FATAL);
+  }
+  transfer_to_fd(sockfd, STDOUT_FILENO);
+}
+
+int main(int argc, char** argv) {
+  if (argc == 1) {
+    fprintf(stderr,
+            "Usage: \n"
+            " %s port\n"
+            " %s rate FILE...\n",
+            argv[0],
+            argv[0]);
+    exit(EXIT_FAILURE);
+  }
+  if (argc == 2) {
+    // Argument is the port to connect to.
+    content_collection(atoi(argv[1]));
+  } else {
+    // First argument is the poll frequency, in Hz, following arguments are the
+    // file to poll.
+    Context context;
+    context.poll_rate = atoi(argv[1]);
+    context.nb_files = argc - 2;
+    context.file_fds = new int[context.nb_files];
+    for (int i = 2; i < argc; ++i)
+      context.file_fds[i - 2] = checked_open(argv[i]);
+    poll_content(context);
+  }
+  return EXIT_SUCCESS;
+}