Re: g77 bug report

[Toon Moene <toon at moene dot indiv dot nluug dot nl>]

Theodore W. Hall wrote:

> First, THANK YOU for making g77 available on Mac OS X!
Appreciate the thanks !

> SYSTEM
> ------
>
> % uname -a
> Darwin ted.arch.cuhk.edu.hk 6.1 Darwin Kernel Version 6.1: Fri Sep  6 
> 23:24:34 PDT 2002; root:xnu/xnu-344.2.obj~2/RELEASE_PPC  Power Macintosh 
> powerpc
>
> % g77 -v
> Reading specs from /usr/local/lib/gcc-lib/powerpc-apple-darwin5.4/3.1/specs
> Configured with: ../gcc3/configure --enable-pfe --disable-nls 
> --enable-languages=c,f77
> Thread model: single
> Apple Computer, Inc. GCC version 1110, based on gcc version 3.1 20020420 
> (prerelease)
>
>
>
> BUG
> ---
>
> In a series of SEQUENTIAL UNFORMATTED writes to an external file, each
> subsequent WRITE over-writes the previous.  This is not a problem for
> FORMATTED writes; only UNFORMATTED.
>
>
>
> TEST PROGRAM
> ------------
>
> % cat testwrite.f
>       PRINT *, 'Writing sequential unformatted data ...'
>       OPEN  (UNIT   = 1,
>      &       FILE   = 'bin.dat',
>      &       STATUS = 'UNKNOWN',
>      &       ACCESS = 'SEQUENTIAL',
>      &       FORM   = 'UNFORMATTED',
>      &       ERR    = 91)
>       WRITE (UNIT   = 1, ERR    = 92) 1, 2, 3
>       WRITE (UNIT   = 1, ERR    = 92) 4, 5
>       WRITE (UNIT   = 1, ERR    = 92) 6
>       CLOSE (UNIT   = 1,
>      &       STATUS = 'KEEP',
>      &       ERR    = 93)
>       PRINT *, 'Writing sequential formatted data ...'
>       OPEN  (UNIT   = 1,
>      &       FILE   = 'txt.dat',
>      &       STATUS = 'UNKNOWN',
>      &       ACCESS = 'SEQUENTIAL',
>      &       FORM   = 'FORMATTED',
>      &       ERR    = 91)
>       WRITE (UNIT   = 1, FMT    = 1, ERR    = 92) 1, 2, 3
>       WRITE (UNIT   = 1, FMT    = 1, ERR    = 92) 4, 5
>       WRITE (UNIT   = 1, FMT    = 1, ERR    = 92) 6
>       CLOSE (UNIT   = 1,
>      &       STATUS = 'KEEP',
>      &       ERR    = 93)
>     1 FORMAT (3I4)
>       PRINT *, 'Done.'
>       STOP
>    91 PRINT *, 'OPEN error.'
>       STOP
>    92 PRINT *, 'WRITE error.'
>       STOP
>    93 PRINT *, 'CLOSE error.'
>       STOP
>       END
>
> % g77 -W -Wall -O -o testwrite testwrite.f
> %
>
> % ./testwrite
>  Writing sequential unformatted data ...
>  Writing sequential formatted data ...
>  Done.
> %
>
> % cat txt.dat
>    1   2   3
>    4   5
>    6
>
> % hexdump -C bin.dat
> 00000000  00 00 00 04 00 00 00 06  00 00 00 04 00 00 00 08  
> |................|
> 00000010  00 00 00 0c                                       |....|
> 00000014
> %
>
>
>
> EXPECTED RESULT
> ---------------
>
> % hexdump -C bin.dat
> 00000000  00 00 00 0c 00 00 00 01  00 00 00 02 00 00 00 03  
> |................|
> 00000010  00 00 00 0c 00 00 00 08  00 00 00 04 00 00 00 05  
> |................|
> 00000020  00 00 00 08 00 00 00 04  00 00 00 06 00 00 00 04  
> |................|
> %
>
> That is,
>
>    record length   00 00 00 0c
>    data            00 00 00 01   00 00 00 02   00 00 00 03
>    record length   00 00 00 0c
>
>    record length   00 00 00 08
>    data            00 00 00 04   00 00 00 05
>    record length   00 00 00 08
>
>    record length   00 00 00 04
>    data            00 00 00 06
>    record length   00 00 00 04
>
> Note that in the actual output, following the last record
>
>    00 00 00 04   00 00 00 06   00 00 00 04
>
> are the trailing record lengths of the two previous records
>
>    00 00 00 08   00 00 00 0c
> which seems to indicate that the earlier longer records were over-written
> by the later shorter ones.
g77-3.2 seems to produce the correct results on 
powerpc-unknown-linux-gnu.  Perhaps there's a problem in the coupling 
between the libf2c.{so|a} - the run time library of g77 - and the 
underlying libc/OS.

It might be helpful to post this problem to a Darwin specific mailing list.

Hope this helps,

--
Toon Moene - mailto:toon@moene.indiv.nluug.nl - phoneto: +31 346 214290
Saturnushof 14, 3738 XG  Maartensdijk, The Netherlands
Maintainer, GNU Fortran 77: http://gcc.gnu.org/onlinedocs/g77_news.html
Join GNU Fortran 95: http://g95.sourceforge.net/ (under construction)