Add LoggingSeekFile

util/file/file_io_win.cc

Index: util/file/file_io_win.cc
diff --git a/util/file/file_io_win.cc b/util/file/file_io_win.cc
index 7426737dcfe9cdaf82e5601ccd1e5f9d97af67d8..dbead0d9bd5e6ef9b39003e16cf3804647eb1d10 100644
--- a/util/file/file_io_win.cc
+++ b/util/file/file_io_win.cc
@@ -103,6 +103,33 @@ FileHandle LoggingOpenFileForWrite(const base::FilePath& path,
   return file;
 }
 
+FileOffset LoggingSeekFile(FileHandle file, FileOffset offset, int whence) {
+  CHECK(whence == SEEK_SET || whence == SEEK_CUR || whence == SEEK_END);

[Mark Mentovai, 2014/12/19 14:51:00]

I think this one would be OK as a DCHECK. It’s kind of the same thing as the
DCHECK at the top of ReadFile(), like “dummy, you shouldn’t have given that to
me as an argument!” It’s not really the kind of thing that might be passed a
different value in a production build in the field.

As an alternative, you can move this to the switch statement by doing “default:
NOTREACHED();” The style guide wants a “default:” case on switches over
non-enums, per
http://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Loops_and_Swi....

[scottmg, 2014/12/19 17:57:23]

Done.

+
+  DWORD method = 0;
+  switch (whence) {
+    case SEEK_SET:

[Mark Mentovai, 2014/12/19 14:51:00]

CL description: “both” → “bother”.

[scottmg, 2014/12/19 17:57:23]

Done.

+      method = FILE_BEGIN;
+      break;
+    case SEEK_CUR:
+      method = FILE_CURRENT;
+      break;
+    case SEEK_END:
+      method = FILE_END;
+      break;
+  }
+
+  LARGE_INTEGER li;
+  li.QuadPart = offset;
+  li.LowPart = SetFilePointer(file, li.LowPart, &li.HighPart, method);

[Mark Mentovai, 2014/12/19 14:51:00]

Wow, this is a really weird function! I had to check the documentation. It said
that SetFilePointerEx() would be less cumbersome.

It’s fine with me if you have a reason to not use that. The use of
SetFilePointer() here is correct as-is.

[scottmg, 2014/12/19 17:57:23]

Ah, for some reason I thought Ex was Vista+. Switched to the Ex version.

+  if (li.LowPart == INVALID_SET_FILE_POINTER && GetLastError() != NO_ERROR) {
+    PLOG(ERROR) << "SetFilePointer";
+    return -1;
+  }
+
+  return li.QuadPart;
+}
+
 bool LoggingCloseFile(FileHandle file) {
   BOOL rv = CloseHandle(file);
   PLOG_IF(ERROR, !rv) << "CloseHandle";