Move some parts of ProcessReader (in snapshot) to ProcessInfo (in util)

util/posix/process_util_mac.cc

-// Copyright 2014 The Crashpad Authors. All rights reserved.
-//
-// 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 "util/posix/process_util.h"
-
-#include <string.h>
-#include <sys/sysctl.h>
-#include <sys/types.h>
-
-#include "base/basictypes.h"
-
-namespace crashpad {
-
-bool ProcessArgumentsForPID(pid_t pid, std::vector<std::string>* argv) {
-  // The format of KERN_PROCARGS2 is explained in 10.9.2 adv_cmds-153/ps/print.c
-  // getproclline(). It is an int (argc) followed by the executable’s string
-  // area. The string area consists of NUL-terminated strings, beginning with
-  // the executable path, and then starting on an aligned boundary, all of the
-  // elements of argv, envp, and applev.
-
-  // It is possible for a process to exec() in between the two sysctl() calls
-  // below. If that happens, and the string area of the new program is larger
-  // than that of the old one, args_size_estimate will be too small. To detect
-  // this situation, the second sysctl() attempts to fetch args_size_estimate +
-  // 1 bytes, expecting to only receive args_size_estimate. If it gets the extra
-  // byte, it indicates that the string area has grown, and the sysctl() pair
-  // will be retried a limited number of times.
-
-  size_t args_size_estimate;
-  size_t args_size;
-  std::string args;
-  int tries = 3;
-  do {
-    int mib[] = {CTL_KERN, KERN_PROCARGS2, pid};
-    int rv =
-        sysctl(mib, arraysize(mib), nullptr, &args_size_estimate, nullptr, 0);
-    if (rv != 0) {
-      return false;
-    }
-
-    args_size = args_size_estimate + 1;
-    args.resize(args_size);
-    rv = sysctl(mib, arraysize(mib), &args[0], &args_size, nullptr, 0);
-    if (rv != 0) {
-      return false;
-    }
-  } while (args_size == args_size_estimate + 1 && tries--);
-
-  if (args_size == args_size_estimate + 1) {
-    return false;
-  }
-
-  // KERN_PROCARGS2 needs to at least contain argc.
-  if (args_size < sizeof(int)) {
-    return false;
-  }
-  args.resize(args_size);
-
-  // Get argc.
-  int argc;
-  memcpy(&argc, &args[0], sizeof(argc));
-
-  // Find the end of the executable path.
-  size_t start_pos = sizeof(argc);
-  size_t nul_pos = args.find('\0', start_pos);
-  if (nul_pos == std::string::npos) {
-    return false;
-  }
-
-  // Find the beginning of the string area.
-  start_pos = args.find_first_not_of('\0', nul_pos);
-  if (start_pos == std::string::npos) {
-    return false;
-  }
-
-  std::vector<std::string> local_argv;
-  while (argc-- && nul_pos != std::string::npos) {
-    nul_pos = args.find('\0', start_pos);
-    local_argv.push_back(args.substr(start_pos, nul_pos - start_pos));
-    start_pos = nul_pos + 1;
-  }
-
-  if (argc >= 0) {
-    // Not every argument was recovered.
-    return false;
-  }
-
-  argv->swap(local_argv);
-  return true;
-}
-
-}  // namespace crashpad