Intercept file Open/Close

base/files/file_posix.cc

Index: base/files/file_posix.cc
diff --git a/base/files/file_posix.cc b/base/files/file_posix.cc
index 43684b5dabfe3df9b2a6907cd5dfbecb8e3582c3..95cfbfb8c07ddbedb7dc90941c5f6775b0af172d 100644
--- a/base/files/file_posix.cc
+++ b/base/files/file_posix.cc
@@ -166,6 +166,27 @@ void File::Info::FromStat(const stat_wrapper_t& stat_info) {
                                   Time::kNanosecondsPerMicrosecond);
 }
 
+// Define empty hooks for blacklisting file descriptors used in base::File.
+// These functions should be declared 'weak', i.e. the functions declared in
+// a default way would have precedence over the weak ones at link time. This
+// works for both static and dynamic linking.
+//
+// With compilers other than GCC define strong no-op symbols for simplicity.

[Fabrice (no longer in Chrome), 2014/11/04 15:37:21]

Nit: other than GCC and Clang (so msvc, essentially)
COMPILER_GCC is defined for GCC and Clang.

[pasko, 2014/11/04 17:48:05]

Thanks, I did not realize COMPILER_GCC is defined for Clang. That's actually
logical. OK, since !defined(__clang__) is ugly, I'll hope for the best on both
compilers. And of course clang supports this attribute, wow!

Done.

+#if defined(COMPILER_GCC)
+#define ATTRIBUTE_WEAK __attribute__ ((weak))
+#else
+#define ATTRIBUTE_WEAK
+#endif
+BASE_EXPORT void ProtectFileDescriptor(int fd) ATTRIBUTE_WEAK;
+BASE_EXPORT void UnprotectFileDescriptor(int fd) ATTRIBUTE_WEAK;
+#undef ATTRIBUTE_WEAK
+
+void ProtectFileDescriptor(int fd) {
+}
+
+void UnprotectFileDescriptor(int fd) {
+}
+
 // NaCl doesn't implement system calls to open files directly.
 #if !defined(OS_NACL)
 // TODO(erikkay): does it make sense to support FLAG_EXCLUSIVE_* here?
@@ -252,6 +273,7 @@ void File::InitializeUnsafe(const FilePath& name, uint32 flags) {
   async_ = ((flags & FLAG_ASYNC) == FLAG_ASYNC);
   error_details_ = FILE_OK;
   file_.reset(descriptor);
+  ProtectFileDescriptor(descriptor);
 }
 #endif  // !defined(OS_NACL)
 
@@ -264,6 +286,7 @@ PlatformFile File::GetPlatformFile() const {
 }
 
 PlatformFile File::TakePlatformFile() {
+  UnprotectFileDescriptor(GetPlatformFile());
   return file_.release();
 }
 
@@ -272,6 +295,7 @@ void File::Close() {
     return;
 
   base::ThreadRestrictions::AssertIOAllowed();
+  UnprotectFileDescriptor(GetPlatformFile());
   file_.reset();
 }
 
@@ -484,8 +508,10 @@ File::Error File::OSErrorToFileError(int saved_errno) {
 }
 
 void File::SetPlatformFile(PlatformFile file) {
-  DCHECK(!file_.is_valid());
+  CHECK(!file_.is_valid());
   file_.reset(file);
+  if (file_.is_valid())
+    ProtectFileDescriptor(GetPlatformFile());
 }
 
 }  // namespace base