conditional gdb breakpoint after getting the char* from an function

Question

Skeleton code:

Let us say you have something like this(x.cpp):

int main() {
   char* str = <some_function_which_returns_char*>; // Such as hello, hell, hellow and it could be anything.
   // Do some work here.
}

How do you put a breakpoint in gdb if str contains "hell". This substr 'hell' can come at any location of str. Say ahell, hello etc. I have written:

b x.cpp:3 if $_regex(str, "hell") // At line number 3 of above snapshot. Right after getting the char* 

Is it the right way? OR Are there any other ways to deal with it?

Let us not worry about the leaks and anything else for now.

Answer 1

You can use the cond command to make the breakpoint conditional:

• cond x.cpp:3 strcmp(str,"hell") == 0 - for hell exactly.
• cond x.cpp:3 strncmp (str,"hell",4) - for all strings that start with hell.
• cond x.cpp:3 strstr(str, "hell") != NULL - for all strings containing hell as a substring.