[Bug modula2/115057] New: TextIO.ReadRestLine raise an exception for insufficient buffer

[Bug modula2/115057] New: TextIO.ReadRestLine raise an exception for insufficient buffer

[dramwang at 163 dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115057

            Bug ID: 115057
           Summary: TextIO.ReadRestLine raise an exception for
                    insufficient buffer
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: modula2
          Assignee: gaius at gcc dot gnu.org
          Reporter: dramwang at 163 dot com
  Target Milestone: ---

For following code, `ReadRestLine` will raise an "attempting to read beyond end
of file" exception, which I think is incorrect:

```
MODULE test ;

IMPORT SeqFile, TextIO ;

VAR
  chan : SeqFile.ChanId ;
  line : ARRAY [0..5] OF CHAR ;
  results : SeqFile.OpenResults ;

BEGIN
  SeqFile.OpenRead (chan, "test.mod", SeqFile.read, results) ;
  TextIO.ReadRestLine (chan, line) ;
END test.
```

Tested on Debian 12, with GCC 15.0.0 20240509 (83fb5e6):

```
% gm2 test.mod && ./a.out
EXCEPTIONS.mod:65:56: In RAISE
EXCEPTIONS.mod:65:56:attempting to read beyond end of file
Aborted
```

[Bug modula2/115057] TextIO.ReadRestLine raise an exception for insufficient buffer

[gaius at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115057

Gaius Mulley <gaius at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2024-05-15

--- Comment #1 from Gaius Mulley <gaius at gcc dot gnu.org> ---
Confirmed thanks for the bug report.

[Bug modula2/115057] TextIO.ReadRestLine raise an exception for insufficient buffer

[gaius at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115057

--- Comment #2 from Gaius Mulley <gaius at gcc dot gnu.org> ---
Created attachment 58214
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=58214&action=edit
Proposed fix

Here is a proposed fix - which I'll commit (if/when) a full bootstrap
completes.

[Bug modula2/115057] TextIO.ReadRestLine raise an exception for insufficient buffer

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115057

--- Comment #3 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Gaius Mulley <gaius@gcc.gnu.org>:

https://gcc.gnu.org/g:680af0e1e90d4b80260d173636dfe15654fd470d

commit r15-516-g680af0e1e90d4b80260d173636dfe15654fd470d
Author: Gaius Mulley <gaiusmod2@gmail.com>
Date:   Wed May 15 16:58:21 2024 +0100

    PR modula2/115057 TextIO.ReadRestLine raises an exception when buffer is
exceeded

    TextIO.ReadRestLine will raise an "attempting to read beyond end of file"
    exception if the buffer is exceeded.  This bug is caused by the
    TextIO.ReadRestLine calling IOChan.Skip without a preceeding IOChan.Look.
    The Look procedure will update the status result whereas
    Skip always sets read result to allRight.

    gcc/m2/ChangeLog:

            PR modula2/115057
            * gm2-libs-iso/TextIO.mod (ReadRestLine): Use ReadChar to
            skip unwanted characters as this calls IOChan.Look and updates
            the cid result status.  A Skip without a Look does not update
            the status.  Skip always sets read result to allRight.
            * gm2-libs-iso/TextUtil.def (SkipSpaces): Improve comments.
            (CharAvailable): Improve comments.
            * gm2-libs-iso/TextUtil.mod (SkipSpaces): Improve comments.
            (CharAvailable): Improve comments.

    gcc/testsuite/ChangeLog:

            PR modula2/115057
            * gm2/isolib/run/pass/testrestline.mod: New test.
            * gm2/isolib/run/pass/testrestline2.mod: New test.
            * gm2/isolib/run/pass/testrestline3.mod: New test.

    Signed-off-by: Gaius Mulley <gaiusmod2@gmail.com>

[Bug modula2/115057] TextIO.ReadRestLine raise an exception for insufficient buffer

[gaius at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115057

Gaius Mulley <gaius at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED

--- Comment #4 from Gaius Mulley <gaius at gcc dot gnu.org> ---
Closing - thanks again for the bug report.