jack@cwi.nl (Jack Jansen) (12/02/88)
The following is probably not a bug in GCC, but in Ultrix (and maybe
other) stdio. However, gcc triggers the bug because it stores
strings in read-only space.
What happens is that the following program will dump core:
--------
main() {
int i;
short j;
i = sscanf("1", "%hd", &j);
printf("i=%d, j=%d\n", i, j);
}
---------
What happens is the following: sscanf sets up a dummy FILE * structure,
points the buffer/pointer to the argument string "1" and calls _doscan.
Doscan, however, will call ungetc() at some point. Ungetc will try to
stuff a character back into the input buffer. BANG!
Just thought I'd warn the rest of the net....
--
Fight war, not wars | Jack Jansen, jack@cwi.nl
Destroy power, not people! -- Crass | (or mcvax!jack)weening@Gang-of-Four.Stanford.EDU (Joe Weening) (12/03/88)
In article <7747@boring.cwi.nl>, jack@cwi (Jack Jansen) writes: > >The following is probably not a bug in GCC, but in Ultrix (and maybe >other) stdio. However, gcc triggers the bug because it stores >strings in read-only space. > ... I encountered this when compiling the window manager "twm" for X11R3, and it may happen on other X11 programs as well. This was under Sun OS 4.0, by the way. Adding "-fwritable-strings" to the GCC options avoids the problems, however. -- Joe Weening Computer Science Dept. weening@Gang-of-Four.Stanford.EDU Stanford University