WindowsFile calls GetLastError via win32-api to retrieve win32 error
code but the error code may be already reset by Ruby's internal code
so that it can't retrive a correct error code. Sometimes it causes
random unrecoverable errors when in_tail plugin tries to read a
non-existent file like the following:

  2021-04-14 03:15:45 +0000 [error]: #2 Fluent::Win32Error code: 158, The segment is already unlocked.: C:/path/to/log.txt

Fiddle or FFI has a method to avoid this issue:

  * Fiddle.win32_last_error
    https://ruby-doc.org/stdlib-3.0.0/libdoc/fiddle/rdoc/Fiddle.html#method-c-win32_last_error
  * FFI::LastError.winapi_error
    https://www.rubydoc.info/github/ffi/ffi/FFI/LastError#winapi_error-instance_method

We've added an equivalent method for win32-api:

  cosmo0920/win32-api#55

This commit replaces the retrieving the error code by using it.

Signed-off-by: Takuro Ashie <ashie@clear-code.com>

WindowsFile calls GetLastError via win32-api to retrieve win32 error
code but the error code may be already reset by Ruby's internal code
so that it can't retrive a correct error code. Sometimes it causes
random unrecoverable errors when in_tail plugin tries to read a
non-existent file like the following:

  2021-04-14 03:15:45 +0000 [error]: #2 Fluent::Win32Error code: 158, The segment is already unlocked.: C:/path/to/log.txt

Fiddle or FFI has a method to avoid this issue:

  * Fiddle.win32_last_error
    https://ruby-doc.org/stdlib-3.0.0/libdoc/fiddle/rdoc/Fiddle.html#method-c-win32_last_error
  * FFI::LastError.winapi_error
    https://www.rubydoc.info/github/ffi/ffi/FFI/LastError#winapi_error-instance_method

We've added an equivalent method for win32-api:

  cosmo0920/win32-api#55

This commit replaces the retrieving the error code by using it.

Signed-off-by: Takuro Ashie <ashie@clear-code.com>

WindowsFile calls GetLastError via win32-api to retrieve win32 error
code but the error code may be already reset by Ruby's internal code
so that it can't retrive a correct error code. Sometimes it causes
random unrecoverable errors when in_tail plugin tries to read a
non-existent file like the following:

  2021-04-14 03:15:45 +0000 [error]: #2 Fluent::Win32Error code: 158, The segment is already unlocked.: C:/path/to/log.txt

Fiddle or FFI has a method to avoid this issue:

  * Fiddle.win32_last_error
    https://ruby-doc.org/stdlib-3.0.0/libdoc/fiddle/rdoc/Fiddle.html#method-c-win32_last_error
  * FFI::LastError.winapi_error
    https://www.rubydoc.info/github/ffi/ffi/FFI/LastError#winapi_error-instance_method

We've added an equivalent method for win32-api:

  cosmo0920/win32-api#55

This commit replaces the retrieving the error code with this method.

Signed-off-by: Takuro Ashie <ashie@clear-code.com>