mac: Remove POSIX shared memory.

base/memory/shared_memory_mac.cc

Index: base/memory/shared_memory_mac.cc
diff --git a/base/memory/shared_memory_mac.cc b/base/memory/shared_memory_mac.cc
index 6dd957621c78add7ec9840839e9efa8ed5d4b3b8..c9882fd0153e646e99556654df4641532f3e7f82 100644
--- a/base/memory/shared_memory_mac.cc
+++ b/base/memory/shared_memory_mac.cc
@@ -4,33 +4,22 @@
 
 #include "base/memory/shared_memory.h"
 
-#include <errno.h>
-#include <fcntl.h>
 #include <mach/mach_vm.h>
-#include <stddef.h>
-#include <sys/mman.h>
-#include <sys/stat.h>
-#include <unistd.h>
 
 #include "base/files/file_util.h"
 #include "base/files/scoped_file.h"
 #include "base/logging.h"
+#include "base/mac/foundation_util.h"
 #include "base/mac/mac_util.h"
 #include "base/mac/scoped_mach_vm.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
-#include "base/posix/eintr_wrapper.h"
-#include "base/posix/safe_strerror.h"
 #include "base/process/process_metrics.h"
 #include "base/profiler/scoped_tracker.h"
 #include "base/scoped_generic.h"
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
 
-#if defined(OS_MACOSX)
-#include "base/mac/foundation_util.h"
-#endif  // OS_MACOSX
-
 namespace base {
 
 namespace {
@@ -78,81 +67,15 @@ bool MakeMachSharedMemoryHandleReadOnly(SharedMemoryHandle* new_handle,
   return true;
 }
 
-struct ScopedPathUnlinkerTraits {
-  static FilePath* InvalidValue() { return nullptr; }
-
-  static void Free(FilePath* path) {
-    // TODO(erikchen): Remove ScopedTracker below once http://crbug.com/466437
-    // is fixed.
-    tracked_objects::ScopedTracker tracking_profile(
-        FROM_HERE_WITH_EXPLICIT_FUNCTION(
-            "466437 SharedMemory::Create::Unlink"));
-    if (unlink(path->value().c_str()))
-      PLOG(WARNING) << "unlink";
-  }
-};
-
-// Unlinks the FilePath when the object is destroyed.
-typedef ScopedGeneric<FilePath*, ScopedPathUnlinkerTraits> ScopedPathUnlinker;
-
-// Makes a temporary file, fdopens it, and then unlinks it. |fp| is populated
-// with the fdopened FILE. |readonly_fd| is populated with the opened fd if
-// options.share_read_only is true. |path| is populated with the location of
-// the file before it was unlinked.
-// Returns false if there's an unhandled failure.
-bool CreateAnonymousSharedMemory(const SharedMemoryCreateOptions& options,
-                                 ScopedFILE* fp,
-                                 ScopedFD* readonly_fd,
-                                 FilePath* path) {
-  // Q: Why not use the shm_open() etc. APIs?
-  // A: Because they're limited to 4mb on OS X.  FFFFFFFUUUUUUUUUUU
-  FilePath directory;
-  ScopedPathUnlinker path_unlinker;
-  if (GetShmemTempDir(options.executable, &directory)) {
-    // TODO(erikchen): Remove ScopedTracker below once http://crbug.com/466437
-    // is fixed.
-    tracked_objects::ScopedTracker tracking_profile(
-        FROM_HERE_WITH_EXPLICIT_FUNCTION(
-            "466437 SharedMemory::Create::OpenTemporaryFile"));
-    fp->reset(CreateAndOpenTemporaryFileInDir(directory, path));
-
-    // Deleting the file prevents anyone else from mapping it in (making it
-    // private), and prevents the need for cleanup (once the last fd is
-    // closed, it is truly freed).
-    if (*fp)
-      path_unlinker.reset(path);
-  }
-
-  if (*fp) {
-    if (options.share_read_only) {
-      // TODO(erikchen): Remove ScopedTracker below once
-      // http://crbug.com/466437 is fixed.
-      tracked_objects::ScopedTracker tracking_profile(
-          FROM_HERE_WITH_EXPLICIT_FUNCTION(
-              "466437 SharedMemory::Create::OpenReadonly"));
-      // Also open as readonly so that we can ShareReadOnlyToProcess.
-      readonly_fd->reset(HANDLE_EINTR(open(path->value().c_str(), O_RDONLY)));
-      if (!readonly_fd->is_valid()) {
-        DPLOG(ERROR) << "open(\"" << path->value() << "\", O_RDONLY) failed";
-        fp->reset();
-        return false;
-      }
-    }
-  }
-  return true;
-}
-
 }  // namespace
 
 SharedMemoryCreateOptions::SharedMemoryCreateOptions()
-    : type(SharedMemoryHandle::MACH),
-      size(0),
+    : size(0),
       executable(false),
       share_read_only(false) {}
 
 SharedMemory::SharedMemory()
-    : mapped_memory_mechanism_(SharedMemoryHandle::POSIX),
-      readonly_mapped_file_(-1),
+    : readonly_mapped_file_(-1),
       mapped_size_(0),
       memory_(NULL),
       read_only_(false),
@@ -160,7 +83,6 @@ SharedMemory::SharedMemory()
 
 SharedMemory::SharedMemory(const SharedMemoryHandle& handle, bool read_only)
     : shm_(handle),
-      mapped_memory_mechanism_(SharedMemoryHandle::POSIX),
       readonly_mapped_file_(-1),
       mapped_size_(0),
       memory_(NULL),
@@ -189,7 +111,8 @@ void SharedMemory::CloseHandle(const SharedMemoryHandle& handle) {
 
 // static
 size_t SharedMemory::GetHandleLimit() {
-  return GetMaxFds();
+  // This should be effectively unlimited on OS X.
+  return 10000;
 }
 
 // static
@@ -198,27 +121,10 @@ SharedMemoryHandle SharedMemory::DuplicateHandle(
   return handle.Duplicate();
 }
 
-// static
-int SharedMemory::GetFdFromSharedMemoryHandle(
-    const SharedMemoryHandle& handle) {
-  return handle.GetFileDescriptor().fd;
-}
-
 bool SharedMemory::CreateAndMapAnonymous(size_t size) {
   return CreateAnonymous(size) && Map(size);
 }
 
-bool SharedMemory::CreateAndMapAnonymousPosix(size_t size) {
-  return CreateAnonymousPosix(size) && Map(size);
-}
-
-bool SharedMemory::CreateAnonymousPosix(size_t size) {
-  SharedMemoryCreateOptions options;
-  options.type = SharedMemoryHandle::POSIX;
-  options.size = size;
-  return Create(options);
-}
-
 // static
 bool SharedMemory::GetSizeFromSharedMemoryHandle(
     const SharedMemoryHandle& handle,
@@ -240,42 +146,9 @@ bool SharedMemory::Create(const SharedMemoryCreateOptions& options) {
   if (options.size > static_cast<size_t>(std::numeric_limits<int>::max()))
     return false;
 
-  if (options.type == SharedMemoryHandle::MACH) {
-    shm_ = SharedMemoryHandle(options.size);
-    requested_size_ = options.size;
-    return shm_.IsValid();
-  }
-
-  // This function theoretically can block on the disk. Both profiling of real
-  // users and local instrumentation shows that this is a real problem.
-  // https://code.google.com/p/chromium/issues/detail?id=466437
-  base::ThreadRestrictions::ScopedAllowIO allow_io;
-
-  ScopedFILE fp;
-  ScopedFD readonly_fd;
-
-  FilePath path;
-  bool result = CreateAnonymousSharedMemory(options, &fp, &readonly_fd, &path);
-  if (!result)
-    return false;
-
-  if (!fp) {
-    PLOG(ERROR) << "Creating shared memory in " << path.value() << " failed";
-    return false;
-  }
-
-  // Get current size.
-  struct stat stat;
-  if (fstat(fileno(fp.get()), &stat) != 0)
-    return false;
-  const size_t current_size = stat.st_size;
-  if (current_size != options.size) {
-    if (HANDLE_EINTR(ftruncate(fileno(fp.get()), options.size)) != 0)
-      return false;
-  }
+  shm_ = SharedMemoryHandle(options.size);
   requested_size_ = options.size;
-
-  return PrepareMapFile(std::move(fp), std::move(readonly_fd));
+  return shm_.IsValid();
 }
 
 bool SharedMemory::MapAt(off_t offset, size_t bytes) {
@@ -291,7 +164,6 @@ bool SharedMemory::MapAt(off_t offset, size_t bytes) {
     mapped_size_ = bytes;
     DCHECK_EQ(0U, reinterpret_cast<uintptr_t>(memory_) &
                       (SharedMemory::MAP_MINIMUM_ALIGNMENT - 1));
-    mapped_memory_mechanism_ = shm_.GetType();
   } else {
     memory_ = NULL;
   }
@@ -303,142 +175,49 @@ bool SharedMemory::Unmap() {
   if (memory_ == NULL)
     return false;
 
-  switch (mapped_memory_mechanism_) {
-    case SharedMemoryHandle::POSIX:
-      munmap(memory_, mapped_size_);
-      break;
-    case SharedMemoryHandle::MACH:
-      mach_vm_deallocate(mach_task_self(),
-                         reinterpret_cast<mach_vm_address_t>(memory_),
-                         mapped_size_);
-      break;
-  }
-
+  mach_vm_deallocate(mach_task_self(),
+                     reinterpret_cast<mach_vm_address_t>(memory_),
+                     mapped_size_);
   memory_ = NULL;
   mapped_size_ = 0;
   return true;
 }
 
 SharedMemoryHandle SharedMemory::handle() const {
-  switch (shm_.GetType()) {
-    case SharedMemoryHandle::POSIX:
-      return SharedMemoryHandle(shm_.GetFileDescriptor().fd, false);
-    case SharedMemoryHandle::MACH:
-      return shm_;
-  }
+  return shm_;
 }
 
 void SharedMemory::Close() {
   shm_.Close();
   shm_ = SharedMemoryHandle();
-  if (shm_.GetType() == SharedMemoryHandle::POSIX) {
-    if (readonly_mapped_file_ > 0) {
-      if (IGNORE_EINTR(close(readonly_mapped_file_)) < 0)
-        PLOG(ERROR) << "close";
-      readonly_mapped_file_ = -1;
-    }
-  }
-}
-
-bool SharedMemory::PrepareMapFile(ScopedFILE fp, ScopedFD readonly_fd) {
-  DCHECK(!shm_.IsValid());
-  DCHECK_EQ(-1, readonly_mapped_file_);
-  if (fp == NULL)
-    return false;
-
-  // This function theoretically can block on the disk, but realistically
-  // the temporary files we create will just go into the buffer cache
-  // and be deleted before they ever make it out to disk.
-  base::ThreadRestrictions::ScopedAllowIO allow_io;
-
-  struct stat st = {};
-  if (fstat(fileno(fp.get()), &st))
-    NOTREACHED();
-  if (readonly_fd.is_valid()) {
-    struct stat readonly_st = {};
-    if (fstat(readonly_fd.get(), &readonly_st))
-      NOTREACHED();
-    if (st.st_dev != readonly_st.st_dev || st.st_ino != readonly_st.st_ino) {
-      LOG(ERROR) << "writable and read-only inodes don't match; bailing";
-      return false;
-    }
-  }
-
-  int mapped_file = HANDLE_EINTR(dup(fileno(fp.get())));
-  if (mapped_file == -1) {
-    if (errno == EMFILE) {
-      LOG(WARNING) << "Shared memory creation failed; out of file descriptors";
-      return false;
-    } else {
-      NOTREACHED() << "Call to dup failed, errno=" << errno;
-    }
-  }
-  shm_ = SharedMemoryHandle(mapped_file, false);
-  readonly_mapped_file_ = readonly_fd.release();
-
-  return true;
 }
 
 bool SharedMemory::ShareToProcessCommon(ProcessHandle process,
                                         SharedMemoryHandle* new_handle,
                                         bool close_self,
                                         ShareMode share_mode) {
-  if (shm_.GetType() == SharedMemoryHandle::MACH) {
-    DCHECK(shm_.IsValid());
-
-    bool success = false;
-    switch (share_mode) {
-      case SHARE_CURRENT_MODE:
-        *new_handle = shm_.Duplicate();
-        success = true;
-        break;
-      case SHARE_READONLY:
-        success = MakeMachSharedMemoryHandleReadOnly(new_handle, shm_, memory_);
-        break;
-    }
-
-    if (success)
-      new_handle->SetOwnershipPassesToIPC(true);
-
-    if (close_self) {
-      Unmap();
-      Close();
-    }
-
-    return success;
-  }
+  DCHECK(shm_.IsValid());
 
-  int handle_to_dup = -1;
+  bool success = false;
   switch (share_mode) {
     case SHARE_CURRENT_MODE:
-      handle_to_dup = shm_.GetFileDescriptor().fd;
+      *new_handle = shm_.Duplicate();
+      success = true;
       break;
     case SHARE_READONLY:
-      // We could imagine re-opening the file from /dev/fd, but that can't make
-      // it readonly on Mac: https://codereview.chromium.org/27265002/#msg10
-      CHECK_GE(readonly_mapped_file_, 0);
-      handle_to_dup = readonly_mapped_file_;
+      success = MakeMachSharedMemoryHandleReadOnly(new_handle, shm_, memory_);
       break;
   }
 
-  const int new_fd = HANDLE_EINTR(dup(handle_to_dup));
-  if (new_fd < 0) {
-    if (close_self) {
-      Unmap();
-      Close();
-    }
-    DPLOG(ERROR) << "dup() failed.";
-    return false;
-  }
-
-  new_handle->SetFileHandle(new_fd, true);
+  if (success)
+    new_handle->SetOwnershipPassesToIPC(true);
 
   if (close_self) {
     Unmap();
     Close();
   }
 
-  return true;
+  return success;
 }
 
 }  // namespace base