Re: read.table problem on Linux/Alpha (seg faults caused by isspace(R_EOF)) (PR#303)

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Subject: Re: read.table problem on Linux/Alpha (seg faults caused by isspace(R_EOF)) (PR#303)
From: Peter Dalgaard BSA (p.dalgaard@biostat.ku.dk)
Date: Sun 31 Oct 1999 - 22:30:01 EST


Message-ID: <x24sf7lnli.fsf@blueberry.kubism.ku.dk>

ntakebay@bio.indiana.edu writes:

> Here is a fix.
>
> --- R-0.65.1/src/main/scan.c.orig Wed Sep 29 11:11:45 1999
> +++ R-0.65.1/src/main/scan.c Fri Oct 29 17:34:22 1999
> @@ -124,7 +124,7 @@
> if (bufp >= &buffer[MAXELTSIZE - 2])
> continue;
> *bufp++ = c;
> - } while (!isspace(c = scanchar()) && c != R_EOF);
> + } while ((c = scanchar()) != R_EOF && !isspace(c));
....
> When the scanchar() returns R_EOF (=65535 #defined in src/include/Defn.h),
> isspace(R_EOF) seq-faults. By switching the order of two conditions, I could
> get around with it. I just made a test to see the behavior of isspace() by
> giving
> isspace(65535). It seg-faults in both Linux/alpha and i386 (is it supposed
> to??).
> However, R on i386 doesn't seg-faults when the last line does not have newline.

Thanks. However, perhaps a better fix would be to change R_EOF? All
the isxxx macros/functions work by indexing an array designed to take
values between -128 and +255, so passing 65535 is playing with fire,
and we have many more instances littered all over the code, where I
don't feel absolutely sure that R_EOF couldn't sneak in.

Any one remember why R_EOF is different from the customary EOF of -1??

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)             FAX: (+45) 35327907
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