[ROOT] Segmentation violation in connection with Error("...", "...")

From: Andreas Zoglauer (zog@mpe.mpg.de)
Date: Tue Jun 19 2001 - 12:57:01 MEST 

Hi ROOTers,

The following code produces a segmentation violation in ROOT:

----------------------------------------------------

const Int_t Max = 1025;
Char_t *Text = new Char_t[Max];
for (Int_t i = 0; i < Max; i++) {
  Text[i] = '*';
}
Text[Max-1]='\0';
Error("Crash:", "%s", Text);

----------------------------------------------------

If the number of characters is 1024 or lower then there is no
segmentation violation.

The debugging output is:

#0  0x410ddfbf in strlen () from /lib/libc.so.6
#1  0x400ec9ba in DefaultErrorHandler (level=707406378, abort=1 '\001',
    location=0x2a2a2a2a <Address 0x2a2a2a2a out of bounds>,
    msg=0xbfffeb74 '*' <repeats 200 times>...) at base/src/TError.cxx:78
#2  0x400ecb9f in ErrorHandler (level=707406378, location=0x2a2a2a2a
    <Address 0x2a2a2a2a out of bounds>,
    fmt=0x2a2a2a2a <Address 0x2a2a2a2a out of bounds>, ap=0x2a2a2a2a) at
    base/src/TError.cxx:110
#3  0x2a2a2a2a in ?? ()
Cannot access memory at address 0x2a2a2a2a

or:

#0  0x410df7e5 in mempcpy () from /lib/libc.so.6
#1  0x410d5d27 in _IO_default_xsputn () from /lib/libc.so.6
#2  0x410b6c9b in vfprintf () from /lib/libc.so.6
#3  0x410cdb72 in vsprintf () from /lib/libc.so.6
#4  0x400ecafe in ErrorHandler (level=707406378, location=0x2a2a2a2a
    <Address 0x2a2a2a2a out of bounds>,
    fmt=0x2a2a2a2a <Address 0x2a2a2a2a out of bounds>, ap=0x2a2a2a2a) at
    base/src/TError.cxx:103
#5  0x2a2a2a2a in ?? ()
Cannot access memory at address 0x2a2a2a2a

or something similar


If one tests the code in the interpreter then the same error occures.

When one replaces Error(...) with
    printf("%s", Text);
then the interpreter output is:

Limitation: printf string too long. Upto 1024. Use fputs() FILE:Error.C
LINE:8

In compiled code there is no error.

I think it should be similar size-limitation-problem in TError for the
function Error(...).


Is it possible to

(a) overcome the size limitation
(b) or if (a) is not possible to catch the segentation violation by
    testing the length of the string?


Thanks

Andreas



OS:   SuSE 7.1     ROOT: 3.01.05




----------------------------------------------------------------------
Andreas Zoglauer

MPI fuer extraterrestrische Physik         Phone:    +49/89-30000-3848
Postfach 1312                              Fax:      +49/89-30000-3569
85741 Garching, Germany                    Email:    zog@mpe.mpg.de
----------------------------------------------------------------------

This archive was generated by hypermail 2b29 : Tue Jan 01 2002 - 17:50:49 MET