0000375: io.seek_binary_output(Stream, set, 32, Out3, Out4), % rec1 NOT working

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Date Submitted

Last Update

0000375

mercury

Bug

public

2015-01-19 14:52

2015-01-21 01:07

Reporter

lpimmes

Assigned To

Priority

urgent

Severity

major

Reproducibility

always

Status

new

Resolution

open

Platform

OSx 10.9

OS Version

Product Version

Target Version

Fixed in Version

Summary

0000375: io.seek_binary_output(Stream, set, 32, Out3, Out4), % rec1 NOT working

Description

Seeking to an offset, the second record, in binTest file and then writing new results only writes a single record.
Initially three records present; now only a single record remains.
Any ideas? Thanks.
This invites the question: overwrite record at position, versus insert new record at seek position.

Steps To Reproduce

Change true/false switches in main/2 to achieve results for test:
1 write binTest, true, false
2 false, true read binTest at offset, record 2, OK
3 false, false write to binTest at offset, record 2; fails.

                                % ioBinFile 522>which mmc
                % /usr/local/mercury-14.01/bin/mmc

                % ioBinFile 511>./ioBinFile
                % Opened 'binTest' successfully.
                % Offsets rec0: 0, rec1: 32, rec2: 62.
                % ioBinFile 513>cat binTest
                % rec("The man ran home.", 3092).
                % rec("The girl saw me.", 312).
                % rec("Each person saw you.", 532).

                % set to false, recompile main/2
                % ioBinFile 517>./ioBinFile
                % Opened 'binTest' successfully.
                % Offset after seek: 32.
                % Read record: rec('The girl saw me.', 312)

                % Not working, just record output; first and third one removed.
                % false, false; default last term in if / then / else
                % ioBinFile 521>./ioBinFile
                % Opened 'binTest' successfully for seek writing.
                % Stream name: binTest; seek to position: 32.
                % ioBinFile 521>cat binTest
                % rec("Dr. Smith", 3).

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Attached Files

ioBinFile.m (4,993 bytes) 2015-01-19 14:52

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Notes
~0000805 juliensf (administrator) 2015-01-20 12:33	The call to io.open_binary_output/4 in the predicate writeSeek/3 will truncate the file. You probably meant to call io.open_binary_append/4.

~0000806 lpimmes (reporter) 2015-01-21 01:07	Yes, I agree, and testing shows that o.open_binary_append/4 in writeSeek/3 will (not surprisingly) append new text to end of existing text. Code and example shown below. But, how do overwrite/insert at a particular seek position in this file? Reading from a position after seek works fine. Thanks. :- pred writeSeek(string::in, io::di, io::uo) is det. writeSeek(Fname, In, Out) :- io.open_binary_append(Fname, Result, In, Out2), % file may / may not exist (if Result = ok(Stream) % Offsets rec0: 0, rec1: 32, rec2: 62. then io.format("Opened '%s' successfully for seek writing.\n", [s(Fname) ], Out2, Out3), io.seek_binary_output(Stream, set, 32, Out3, Out4), % rec1 io.binary_output_stream_offset(Stream, Offset, Out4, Out5), io.binary_output_stream_name(Stream, Name, Out5, Out6), io.format("Stream name: %s; seek to position: %i.\n", [s(Name), i(Offset) ], Out6, Out7), % should be 32, OK Rec0 = rec("Dr. Smith", 3), io.write_binary(Stream, Rec0, Out7, Out8), io.close_binary_output(Stream, Out8, Out) else if Result = io.error(Code) then io.format("Failed to open %s because of: %s.\n", [ s(Fname), s(io.error_message(Code)) ], Out2, Out) else io.format( "Fail to unify io.error(Code).\n", [], Out2, Out) ). ----- ioBinFile 508>./ioBinFile Opened 'binTest' successfully for seek writing. Stream name: binTest; seek to position: 32. ioBinFile 509>cat binTest rec("The man ran home.", 3092). rec("The girl saw me.", 312). rec("Each person saw you.", 532). rec("Dr. Smith", 3).

Notes

Date Modified	Username	Field
Issue History
2015-01-19 14:52	lpimmes	New Issue
2015-01-19 14:52	lpimmes	File Added: ioBinFile.m
2015-01-20 12:33	juliensf	Note Added: 0000805
2015-01-21 01:07	lpimmes	Note Added: 0000806

Issue History