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831dca8de8
Reading a bitmap from a binary file stream where the stream is already at EOF
causes an abort rather than returning an empty bitmap in the case where the
file is a regular file. (The case where the stream is not a regular file is
already handled correctly.)
library/io.m:
Fix the above problem.
tests/hard_coded/read_bitmap_size.{m,exp}:
Extend this test case to check for the above.
105 lines
3.2 KiB
Mathematica
105 lines
3.2 KiB
Mathematica
%---------------------------------------------------------------------------%
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% vim: ft=mercury ts=4 sw=4 et
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%---------------------------------------------------------------------------%
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% This a regression test for the issue in commit 3e3dbab
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% (Github pull req #76): when reading a bitmap from a binary file stream the
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% size of the result bitmap was being set based on the size of the file
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% without regard for our current position in the stream. This was leading
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% to an abort since less bytes than % expected ended up being read from
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% the stream.
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%---------------------------------------------------------------------------%
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:- module read_bitmap_size.
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:- interface.
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:- import_module io.
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:- pred main(io::di, io::uo) is det.
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%---------------------------------------------------------------------------%
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%---------------------------------------------------------------------------%
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:- implementation.
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:- import_module bitmap.
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:- import_module exception.
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:- import_module int.
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:- import_module list.
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:- import_module string.
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%---------------------------------------------------------------------------%
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main(!IO) :-
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io.open_binary_output(test_file, OpenResult, !IO),
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(
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OpenResult = ok(TestFile),
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list.foldl(write_binary_uint8(TestFile),
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[1u8, 2u8, 4u8, 8u8, 16u8, 32u8, 64u8, 128u8, 255u8], !IO),
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io.close_binary_output(TestFile, !IO),
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do_test(0, !IO),
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do_test(1, !IO),
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do_test(2, !IO),
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do_test(4, !IO),
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do_test(8, !IO),
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do_test(9, !IO)
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;
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OpenResult = error(IOError),
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io.error_message(IOError, Msg),
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io.print_line(Msg, !IO)
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),
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io.remove_file(test_file, _, !IO).
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:- pred do_test(int::in, io::di, io::uo) is det.
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do_test(N, !IO) :-
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io.format("SKIP %d: ", [i(N)], !IO),
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io.open_binary_input(test_file, OpenResult, !IO),
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(
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OpenResult = ok(File),
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read_and_discard(File, N, !IO),
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io.read_binary_file_as_bitmap(File, ReadRes, !IO),
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(
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ReadRes = ok(Bitmap),
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ByteString = bitmap.to_byte_string(Bitmap),
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io.print_line(ByteString, !IO),
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io.close_binary_input(File, !IO)
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;
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ReadRes = error(IOError),
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io.error_message(IOError, Msg),
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io.print_line(Msg, !IO)
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)
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;
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OpenResult = error(IOError),
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io.error_message(IOError, Msg),
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io.print_line(Msg, !IO)
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).
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% We could use seek here, but that isn't supported properly
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% by all backends.
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:- pred read_and_discard(io.binary_input_stream::in, int::in,
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io::di, io::uo) is det.
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read_and_discard(File, N, !IO) :-
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( if N > 0 then
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read_binary_uint8(File, ReadResult, !IO),
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(
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ReadResult = ok(_),
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read_and_discard(File, N - 1, !IO)
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;
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ReadResult = eof
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;
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ReadResult = error(IOError),
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throw(software_error(io.error_message(IOError)))
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)
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else
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true
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).
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:- func test_file = string.
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test_file = "read_bitmap_size.bin".
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%---------------------------------------------------------------------------%
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:- end_module read_bitmap_size.
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%---------------------------------------------------------------------------%
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