https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109830
Bug ID: 109830
Summary: m2iso library SeqFile.mod - appending to a file
overwrites the contents
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: modula2
Assignee: gaius at gcc dot gnu.org
Reporter: gaius at gcc dot gnu.org
Target Milestone: ---
A reported on the gm2 mailing list, attempting to append data to a existing
file using the module SeqFile will overwrite the data. For example:
MODULE seqappend ;
FROM ChanConsts IMPORT OpenResults, old, raw, write, read ;
FROM IOChan IMPORT ChanId, RawWrite, RawRead ;
FROM SYSTEM IMPORT ADR;
FROM libc IMPORT exit, printf ;
FROM StrLib IMPORT StrEqual ;
IMPORT StreamFile;
IMPORT SeqFile;
PROCEDURE stress ;
VAR
cid : ChanId ;
res : OpenResults;
str : ARRAY [0..20] OF CHAR ;
actual: CARDINAL ;
code : INTEGER ;
BEGIN
code := 0 ;
str := '0123456789' ;
(* Open file and create data. *)
StreamFile.Open (cid, 'testdata', write+old+raw, res) ;
IF res = opened
THEN
(* Now write data creating new contents. *)
RawWrite (cid, ADR (str), 10) ;
StreamFile.Close(cid)
ELSE
printf ("failed to open file for write\n") ;
code := 2
END ;
str := 'abcdefghij' ;
(* Now attempt to append the alphabetic str. *)
SeqFile.OpenAppend (cid, 'testdata', write+old+raw, res) ;
IF res = opened
THEN
RawWrite (cid, ADR (str), 10);
SeqFile.Close (cid)
ELSE
printf ("failed to open file for append\n") ;
code := 3
END ;
(* And now test the file for the appended data. *)
StreamFile.Open (cid, 'testdata', read+raw, res) ;
IF res = opened
THEN
(* Now write data creating new contents. *)
RawRead (cid, ADR (str), 20, actual) ;
IF actual # 20
THEN
printf ("short read occurred: %d...\n", actual) ;
code := 5
END ;
StreamFile.Close (cid) ;
str[20] := 0C ;
IF StrEqual (str, '0123456789abcdefghij')
THEN
printf ("append test passed\n")
ELSE
printf ("append test failed\n") ;
code := 1
END
ELSE
printf ("failed to open result file\n") ;
code := 4
END ;
exit (code)
END stress ;
BEGIN
stress
END seqappend.
fails.
