2 files changed, 41 insertions, 12 deletions

diff --git a/base/file_util.h b/base/file_util.h
index 9a590a4..8654e62 100644
--- a/base/file_util.h
+++ b/base/file_util.h
@@ -28,6 +28,10 @@
 #include "base/string16.h"
 #include "base/time.h"
 
+#if defined(OS_POSIX)
+#include "base/file_descriptor_posix.h"
+#endif
+
 namespace base {
 class Time;
 }
@@ -486,6 +490,10 @@ class MemoryMappedFile {
   // the file does not exist, or the memory mapping fails, it will return false.
   // Later we may want to allow the user to specify access.
   bool Initialize(const FilePath& file_name);
+#if defined(OS_POSIX)
+  // As above, but works with an alreay-opened file.
+  bool Initialize(const base::FileDescriptor& fd);
+#endif
 
   const uint8* data() const { return data_; }
   size_t length() const { return length_; }
@@ -498,6 +506,10 @@ class MemoryMappedFile {
   // success, false on any kind of failure. This is a helper for Initialize().
   bool MapFileToMemory(const FilePath& file_name);
 
+#if defined(OS_POSIX)
+  bool MapFileToMemoryInternal();
+#endif
+
   // Closes all open handles. Later we may want to make this public.
   void CloseHandles();
 
@@ -506,7 +518,7 @@ class MemoryMappedFile {
   HANDLE file_mapping_;
 #elif defined(OS_POSIX)
   // The file descriptor.
-  int file_;
+  base::FileDescriptor file_;
 #endif
   uint8* data_;
   size_t length_;
diff --git a/base/file_util_posix.cc b/base/file_util_posix.cc
index 6c5b86a..1a05d79 100644
--- a/base/file_util_posix.cc
+++ b/base/file_util_posix.cc
@@ -667,30 +667,47 @@ bool FileEnumerator::ReadDirectory(std::vector<DirectoryEntryInfo>* entries,
 // MemoryMappedFile
 
 MemoryMappedFile::MemoryMappedFile()
-    : file_(-1),
-      data_(NULL),
+    : data_(NULL),
       length_(0) {
 }
 
+bool MemoryMappedFile::Initialize(const base::FileDescriptor& fd) {
+  if (IsValid())
+    return false;
+
+  file_ = fd;
+
+  if (!MapFileToMemoryInternal()) {
+    CloseHandles();
+    return false;
+  }
+
+  return true;
+}
+
 bool MemoryMappedFile::MapFileToMemory(const FilePath& file_name) {
-  file_ = open(file_name.value().c_str(), O_RDONLY);
+  file_ = base::FileDescriptor(open(file_name.value().c_str(), O_RDONLY), true);
 
-  if (file_ == -1) {
+  if (file_.fd == -1) {
     LOG(ERROR) << "Couldn't open " << file_name.value();
     return false;
   }
 
+  return MapFileToMemoryInternal();
+}
+
+bool MemoryMappedFile::MapFileToMemoryInternal() {
   struct stat file_stat;
-  if (fstat(file_, &file_stat) == -1) {
-    LOG(ERROR) << "Couldn't fstat " << file_name.value() << ", errno " << errno;
+  if (fstat(file_.fd, &file_stat) == -1) {
+    LOG(ERROR) << "Couldn't fstat " << file_.fd << ", errno " << errno;
     return false;
   }
   length_ = file_stat.st_size;
 
   data_ = static_cast<uint8*>(
-      mmap(NULL, length_, PROT_READ, MAP_SHARED, file_, 0));
+      mmap(NULL, length_, PROT_READ, MAP_SHARED, file_.fd, 0));
   if (data_ == MAP_FAILED)
-    LOG(ERROR) << "Couldn't mmap " << file_name.value() << ", errno " << errno;
+    LOG(ERROR) << "Couldn't mmap " << file_.fd << ", errno " << errno;
 
   return data_ != MAP_FAILED;
 }
@@ -698,12 +715,12 @@ bool MemoryMappedFile::MapFileToMemory(const FilePath& file_name) {
 void MemoryMappedFile::CloseHandles() {
   if (data_ != NULL)
     munmap(data_, length_);
-  if (file_ != -1)
-    close(file_);
+  if (file_.auto_close && file_.fd != -1)
+    close(file_.fd);
 
   data_ = NULL;
   length_ = 0;
-  file_ = -1;
+  file_ = base::FileDescriptor();
 }
 
 } // namespace file_util