[bug #55334] preconv fails when build with libuchardet on MS-Windows

[Eli Zaretskii]

URL:
  <https://savannah.gnu.org/bugs/?55334>

                 Summary: preconv fails when build with libuchardet on
MS-Windows
                 Project: GNU troff
            Submitted by: eliz
            Submitted on: Sun 30 Dec 2018 05:44:25 PM IST
                Category: Preprocessor preconv
                Severity: 3 - Normal
              Item Group: Incorrect behaviour
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None

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Details:

If preconv is built with libuchardet, it produces partial output, "swallowing"
the initial portion of its input.

The reason for that is that the function detect_file_encoding calls 'fstat'
and 'fseek' on the input stream, and those are non-portable when the input
stream is not a file, but a pipe or a console device.  On MS-Windows, 'fstat'
reports a small value (the size of the pipe buffer), and 'fseek' simply fails.
 So the initial portion of the inout, read by detect_file_encoding, never
shows in the output.

The solution I propose is to copy stdin to a temporary file, and read from
that file instead.  The proposed patch is in the attachment.  The changes are
currently for MS-Windows only, but maybe other platforms will need them as
well.




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File Attachments:


-------------------------------------------------------
Date: Sun 30 Dec 2018 05:44:25 PM IST  Name: preconv_decode.dif  Size: 2KiB  
By: eliz

<http://savannah.gnu.org/bugs/download.php?file_id=45792>

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