CloseMultipleNowOrOnExec(): promote out of test

util/test/posix/close_multiple.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/test/posix/close_multiple.h"
-
-#include <dirent.h>
-#include <errno.h>
-#include <fcntl.h>
-#include <limits.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-
-#include <algorithm>
-
-#include "base/basictypes.h"
-#include "base/logging.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/posix/eintr_wrapper.h"
-#include "build/build_config.h"
-#include "util/numeric/safe_assignment.h"
-
-// Everything in this file is expected to execute between fork() and exec(),
-// so everything called here must be acceptable in this context. However,
-// logging code that is not expected to execute under normal circumstances is
-// currently permitted.
-
-namespace crashpad {
-namespace {
-
-// This function attempts to close |fd| or mark it as close-on-exec. On systems
-// where close-on-exec is attempted, a failure to mark it close-on-exec will be
-// followed by an attempt to close it. |ebadf_ok| should be set to |true| if
-// the caller is attempting to close the file descriptor “blind,” that is,
-// without knowledge that it is or is not a valid file descriptor.
-void CloseNowOrOnExec(int fd, bool ebadf_ok) {
-  int rv;
-
-#if defined(OS_MACOSX)
-  // Try to set close-on-exec, to avoid attempting to close a guarded FD with
-  // a close guard set.
-  rv = fcntl(fd, F_SETFD, FD_CLOEXEC);
-  if (rv != -1 || (ebadf_ok && errno == EBADF)) {
-    return;
-  }
-  PLOG(WARNING) << "fcntl";
-#endif
-
-  rv = IGNORE_EINTR(close(fd));
-  if (rv != 0 && !(ebadf_ok && errno == EBADF)) {
-    PLOG(WARNING) << "close";
-  }
-}
-
-struct ScopedDIRCloser {
-  void operator()(DIR* dir) const {
-    if (dir) {
-      if (closedir(dir) < 0) {
-        PLOG(ERROR) << "closedir";
-      }
-    }
-  }
-};
-
-using ScopedDIR = scoped_ptr<DIR, ScopedDIRCloser>;
-
-// This function implements CloseMultipleNowOrOnExec() using an operating
-// system-specific FD directory to determine which file descriptors are open.
-// This is an advantage over looping over all possible file descriptors, because
-// no attempt needs to be made to close file descriptors that are not open.
-bool CloseMultipleNowOrOnExecUsingFDDir(int fd, int preserve_fd) {
-#if defined(OS_MACOSX)
-  const char kFDDir[] = "/dev/fd";
-#elif defined(OS_LINUX)
-  const char kFDDir[] = "/proc/self/fd";
-#endif
-
-  DIR* dir = opendir(kFDDir);
-  if (!dir) {
-    PLOG(WARNING) << "opendir";
-    return false;
-  }
-
-  ScopedDIR dir_owner(dir);
-
-  int dir_fd = dirfd(dir);
-  if (dir_fd == -1) {
-    PLOG(WARNING) << "dirfd";
-    return false;
-  }
-
-  dirent entry;
-  dirent* result;
-  int rv;
-  while ((rv = readdir_r(dir, &entry, &result)) == 0 && result != nullptr) {
-    const char* entry_name = &(*result->d_name);
-    if (strcmp(entry_name, ".") == 0 || strcmp(entry_name, "..") == 0) {
-      continue;
-    }
-
-    char* end;
-    long entry_fd_long = strtol(entry_name, &end, 10);
-    if (entry_name[0] == '\0' || *end) {
-      LOG(ERROR) << "unexpected entry " << entry_name;
-      return false;
-    }
-
-    int entry_fd;
-    if (!AssignIfInRange(&entry_fd, entry_fd_long)) {
-      LOG(ERROR) << "out-of-range fd " << entry_name;
-      return false;
-    }
-
-    if (entry_fd >= fd && entry_fd != preserve_fd && entry_fd != dir_fd) {
-      CloseNowOrOnExec(entry_fd, false);
-    }
-  }
-
-  return true;
-}
-
-}  // namespace
-
-void CloseMultipleNowOrOnExec(int fd, int preserve_fd) {
-  if (CloseMultipleNowOrOnExecUsingFDDir(fd, preserve_fd)) {
-    return;
-  }
-
-  // Fallback: close every file descriptor starting at |fd| and ending at the
-  // system’s file descriptor limit. Check a few values and use the highest as
-  // the limit, because these may be based on the file descriptor limit set by
-  // setrlimit(), and higher-numbered file descriptors may have been opened
-  // prior to the limit being lowered. For Mac OS X, see 10.9.2
-  // Libc-997.90.3/gen/FreeBSD/sysconf.c sysconf() and 10.9.4
-  // xnu-2422.110.17/bsd/kern/kern_descrip.c getdtablesize(), which both return
-  // the current RLIMIT_NOFILE value, not the maximum possible file descriptor.
-  int max_fd = std::max(implicit_cast<int>(sysconf(_SC_OPEN_MAX)), OPEN_MAX);
-  max_fd = std::max(max_fd, getdtablesize());
-
-  for (int entry_fd = fd; entry_fd < max_fd; ++entry_fd) {
-    if (entry_fd != preserve_fd) {
-      CloseNowOrOnExec(entry_fd, true);
-    }
-  }
-}
-
-}  // namespace crashpad