Add LoggingSeekFile

util/file/file_io_win.cc

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 85 matching lines @@
       disposition = CREATE_NEW;
       break;
   }
   HANDLE file = CreateFile(path.value().c_str(), GENERIC_WRITE, 0, nullptr,
                            disposition, FILE_ATTRIBUTE_NORMAL, nullptr);
   PLOG_IF(ERROR, file == INVALID_HANDLE_VALUE) << "CreateFile "
                                                << path.value().c_str();
   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";
   return rv;
 }
 
 }  // namespace crashpad