Add LoggingOpenFileFor{Read|Write}

util/file/file_io.h

Index: util/file/file_io.h
diff --git a/util/file/file_io.h b/util/file/file_io.h
index 927bc3cb13319ff5843a613cff77bbfd20588648..05fe7fe3c88f1be652d9284a175432795cab6cec 100644
--- a/util/file/file_io.h
+++ b/util/file/file_io.h
@@ -23,14 +23,32 @@
 #include <windows.h>
 #endif
 
+namespace base {
+class FilePath;
+}  // namespace base
+
 namespace crashpad {
 
-#if defined(OS_POSIX)
+#if defined(OS_POSIX) || DOXYGEN
+//! \brief Platform-specific alias for a low level file handle.

[Mark Mentovai, 2014/12/18 22:20:59]

nit: low-level

[scottmg, 2014/12/18 22:47:15]

Done.

 using FileHandle = int;
 #elif defined(OS_WIN)
 using FileHandle = HANDLE;
 #endif
 
+//! \brief Determines the mode that LoggingOpenFileForWrite() uses.
+enum class FileWriteMode {
+  //! \brief Opens the file if it exists, or creates a new file.
+  kReuseOrCreate,

[Mark Mentovai, 2014/12/18 22:20:58]

I agree about “reuse” but I couldn’t come up with anything better either.

+
+  //! \brief Creates a new file. If the file already exists, it will be
+  //!        overwritten.

[Mark Mentovai, 2014/12/18 22:20:58]

Hanging indents are 4 spaces. Same on the functions below.

We used to align like this but it got really bad with long parameter names.

[scottmg, 2014/12/18 22:47:15]

Done.

+  kTruncateOrCreate,
+
+  //! \brief Creates a new file. If the file already exists, the open will fail.
+  kCreateOrFail,
+};
+
 //! \brief Reads from a file, retrying when interrupted on POSIX or following a
 //!        short read.
 //!
@@ -121,6 +139,33 @@ void CheckedWriteFile(FileHandle file, const void* buffer, size_t size);
 //! \sa ReadFile
 void CheckedReadFileAtEOF(FileHandle file);
 
+//! \brief Wraps `open()` or `CreateFile()`, creating a file for output. Logs
+//!        an error if the operation fails.
+//!
+//! \a write_mode determines the style (truncate, reuse, etc.) that is used to
+//! open the file. On POSIX, if \a world_readable, `0644` will be used as
+//! `mode` permissions bits for `open()`, otherwise `0600` will be used. On
+//! Windows, the file is always opened in binary mode (that is, no CRLF
+//! translation).
+//!
+//! \return The newly opened FileHandle, or an invalid FileHandle on failure.
+//!
+//! \sa FileWriteMode
+//! \sa ScopedFD
+//! \sa ScopedFileHANDLE
+FileHandle LoggingOpenFileForWrite(const base::FilePath& path,
+                                   FileWriteMode write_mode,
+                                   bool world_readable);
+
+//! \brief Wraps `open()` or `CreateFile()`, opening an existing file for

[Mark Mentovai, 2014/12/18 22:20:59]

Nit: this file puts read ops before write ops, so swap the order of these two,
and update the .cc files to match.

[scottmg, 2014/12/18 22:47:15]

Done.

+//!        reading. Logs an error if the operation fails.
+//!
+//! \return The newly opened FileHandle, or an invalid FileHandle on failure.
+//!
+//! \sa ScopedFD
+//! \sa ScopedFileHANDLE
+FileHandle LoggingOpenFileForRead(const base::FilePath& path);
+
 //! \brief Wraps `close()` or `CloseHandle()`, logging an error if the operation
 //!        fails.
 //!