[Rd] sprintf("%s\n", a) segfaults R with big a (PR#7554)
Prof Brian Ripley
ripley at stats.ox.ac.uk
Mon Jan 24 09:57:43 CET 2005
On Sat, 22 Jan 2005 webb.sprague at gmail.com wrote:
> Full_Name: Webb S.
> Version: 2.0.1
> OS: Linux Debian
> Submission from: (NULL) (126.96.36.199)
>> b = 'a small string'
>> sprintf('foo: %s\n', b)
>  "foo: a small string\n"
>> a = matrix (ncol=100, nrow=1000, data=c(1,2,3,4,5))
>> a.serial = serialize(a, NULL, ascii=TRUE)
>> sprintf('foo: %s\n', a.serial)
> Segmentation fault
> I don't have a core dump to send--sorry. If I have time, I will try to debug
> it, but I probably won't be able to....
Well, that's what C sprintf does, and R has
/* NA_STRING will be printed as `NA' */
if (strcspn(fmt, "s") >= strlen(fmt))
error("%s", "use format %s for character objects");
sprintf(bit, fmt, CHAR(STRING_ELT(CAR(args), 0)));
so no check on size of string inputs (just like C-level sprintf).
The short answer is `don't do that', but as R does guarantee to have
snprintf we will make use of it.
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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