A variable is declared similar to this:
static char * avar = "some string";
Then an attempt to change the value like this will throw a SIGSEGV:
avar[4] = '_';
The problem occurs when the variable is declared locally in a function, and
when the variable is declared globally. Adding a cast to the assignment (as
suggested in another bug solution I found during my search) does not alter the
behavior:
avar[4] = (unsigned char)'_';
Changing the way the variable is declared does work around the problem:
static char * avar = NULL; // Local or global
...
if(avar == NULL) avar = "some string"; // In a function
...
avar[4] = '_'; // Now this will work
I am seeing this problem using Linux Kernel 2.6.21.5 and gcc version 4.1.2.
I am using the gcc build from the Slackware 12.0 distribution.
--
Summary: Variables declared as 'static char * avar = "some
string";' cannot be modified
Product: gcc
Version: 4.1.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: Quinlan at ACM dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35384
