R devel - Jan 2001 - crash with scan(..., what=list(,,)) (PR#802)

When reading a file with scan(), the following crashes R under Solaris and
WinNT 4.0 (versions below):
> ads <- scan("Bltiadu.dat", what=list(,,))
Would an error message be more logical? Note that the followings work (the
data file has 201 lines and 3 columns):
> ads <- scan("Bltiadu.dat", what=list(0,,))
Read 603 lines
> ads <- scan("Bltiadu.dat", what=list(0,0,0))
Read 201 lines
> ads <- scan("Bltiadu.dat", what=list(0,0,))
Read 302 lines
Warning message: 
line 1 did not have 2 elements

> version
         _              
platform i386-pc-mingw32
arch     x86            
os       Win32          
system   x86, Win32     
status                  
major    1              
minor    2.0            
year     2000           
month    12             
day      15             
language R 
> version
         _
platform sparc-sun-solaris2.7
arch     sparc
os       solaris2.7
system   sparc, solaris2.7
status
major    1
minor    2.0
year     2000
month    12
day      15
language R


Emmanuel Paradis

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On Fri, 5 Jan 2001 17:11:13 +0100 (MET), you wrote in message
<200101051611.RAA27177@pubhealth.ku.dk>:
>When reading a file with scan(), the following crashes R under Solaris and
>WinNT 4.0 (versions below):
>
>> ads <- scan("Bltiadu.dat", what=list(,,))
I crash Win98 with the same sort of line; it's because list(,,) is the
same as list(), and scan isn't checking for this boundary case, I
guess...
>
>Would an error message be more logical? Note that the followings work (the
>data file has 201 lines and 3 columns):
>
>> ads <- scan("Bltiadu.dat", what=list(0,,))
>Read 603 lines
While fixing this, wouldn't it be better to change this message to 

"Read 603 cases"

since in fact, only 201 lines were read, 3 cases per line?

Duncan Murdoch
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paradis@isem.univ-montp2.fr writes:
> When reading a file with scan(), the following crashes R under Solaris and
> WinNT 4.0 (versions below):
> 
> > ads <- scan("Bltiadu.dat", what=list(,,))
Happens on Linux too. And you don't need a big file to provoke it:

$ cat > /tmp/junk
1 2 3
3 4 5
2 3 4
^D

...

Starting program: /usr/local/src/misc/r-release/BUILD/bin/R.bin
--quiet
> scan('/tmp/junk', what=list(,,))
Program received signal SIGSEGV, Segmentation fault.
0x80d5160 in scanFrame (what=0x89e8260, maxitems=0, maxlines=0, flush=0, 
    fill=0, stripwhite=0x878b0f0, blskip=1) at ../../../R/src/main/scan.c:491
491     bch = fillBuffer(buffer, TYPEOF(VECTOR_ELT(ans, ii)), strip);


-- 
   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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