text: /*
   * Copyright (C) 2011 The Android Open Source Project
   *
   * 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 <unistd.h>
  #include <stdio.h>
  
  #include "sysdeps.h"
  
  #define TRACE_TAG  TRACE_ADB
  #include "adb.h"
  
  typedef struct {
      pid_t pid;
      int fd;
  } backup_harvest_params;
  
  // socketpair but do *not* mark as close_on_exec
  static int backup_socketpair(int sv[2]) {
      int rc = unix_socketpair( AF_UNIX, SOCK_STREAM, 0, sv );
      if (rc < 0)
          return -1;
  
      return 0;
  }
  
  // harvest the child process then close the read end of the socketpair
  static void* backup_child_waiter(void* args) {
      int status;
      backup_harvest_params* params = (backup_harvest_params*) args;
  
      waitpid(params->pid, &status, 0);
      adb_close(params->fd);
      free(params);
      return NULL;
  }
  
  /* returns the data socket passing the backup data here for forwarding */
  int backup_service(BackupOperation op, char* args) {
      pid_t pid;
      int s[2];
      char* operation;
      int socketnum;
  
      // Command string and choice of stdin/stdout for the pipe depend on our invocation
      if (op == BACKUP) {
          operation = "backup";
          socketnum = STDOUT_FILENO;
      } else {
          operation = "restore";
          socketnum = STDIN_FILENO;
      }
  
      D("backup_service(%s, %s)\n", operation, args);
  
      // set up the pipe from the subprocess to here
      // parent will read s[0]; child will write s[1]
      if (backup_socketpair(s)) {
          D("can't create backup/restore socketpair\n");
          fprintf(stderr, "unable to create backup/restore socketpair\n");
          return -1;
      }
  
      D("Backup/restore socket pair: (send=%d, receive=%d)\n", s[1], s[0]);
      close_on_exec(s[0]);    // only the side we hold on to
  
      // spin off the child process to run the backup command
      pid = fork();
      if (pid < 0) {
          // failure
          D("can't fork for %s\n", operation);
          fprintf(stderr, "unable to fork for %s\n", operation);
          adb_close(s[0]);
          adb_close(s[1]);
          return -1;
      }
  
      // Great, we're off and running.
      if (pid == 0) {
          // child -- actually run the backup here
          char* p;
          int argc;
          char portnum[16];
          char** bu_args;
  
          // fixed args:  [0] is 'bu', [1] is the port number, [2] is the 'operation' string
          argc = 3;
          for (p = (char*)args; p && *p; ) {
              argc++;
              while (*p && *p != ':') p++;
              if (*p == ':') p++;
          }
  
          bu_args = (char**) alloca(argc*sizeof(char*) + 1);
  
          // run through again to build the argv array
          argc = 0;
          bu_args[argc++] = "bu";
          snprintf(portnum, sizeof(portnum), "%d", s[1]);
          bu_args[argc++] = portnum;
          bu_args[argc++] = operation;
          for (p = (char*)args; p && *p; ) {
              bu_args[argc++] = p;
              while (*p && *p != ':') p++;
              if (*p == ':') {
                  *p = 0;
                  p++;
              }
          }
          bu_args[argc] = NULL;
  
          // Close the half of the socket that we don't care about, route 'bu's console
          // to the output socket, and off we go
          adb_close(s[0]);
  
          // off we go
          execvp("/system/bin/bu", (char * const *)bu_args);
          // oops error - close up shop and go home
          fprintf(stderr, "Unable to exec 'bu', bailing\n");
          exit(-1);
      } else {
          adb_thread_t t;
          backup_harvest_params* params;
  
          // parent, i.e. adbd -- close the sending half of the socket
          D("fork() returned pid %d\n", pid);
          adb_close(s[1]);
  
          // spin a thread to harvest the child process
          params = (backup_harvest_params*) malloc(sizeof(backup_harvest_params));
          params->pid = pid;
          params->fd = s[0];
          if (adb_thread_create(&t, backup_child_waiter, params)) {
              adb_close(s[0]);
              free(params);
              D("Unable to create child harvester\n");
              return -1;
          }
      }
  
      // we'll be reading from s[0] as the data is sent by the child process
      return s[0];
  }
  