Debugging attached process with gdb - how to escape from a loop

I am debugging code that looks like this:

while (true){
   // do something ...
   size_t i = foo();  // <- bp set here
   if (flag_set) break;
}

// More code follows here ...

I want to break at the foo() function call, invoke it a few times and then jump out of the while loop completely (lets assume that we are guaranteed that the flag will be set - so we can break out of the loop.

How do I break out of the loop completely?开发者_C百科. finish simply runs to the next iteration. What I want to do is to exit the current "code chunk" (in this case, the while loop)

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You want the advance command, which takes the same arguments as the break command. Using your code as an example (but with line numbers added):

10 while (true){
11   // do something ...
12   size_t i = foo();  // <- bp set here
13   if (flag_set) break;
14 }
15 
16 // More code follows here ...
17 someFunction();

Say your original breakpoint on line 12 was breakpoint 1, and after breaking a few times you wanted to skip to line 17, you would type something like:

disable 1

advance 17

which would disable breakpoint 1 (so it doesn't get hit for the rest of the loop) and then keep executing the program until it hit line 17.

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Set a breakpoint before the loop. Then cursor to the foo() call, and use Debug|Run to Line. This is so useful that I have dedicated a function key to it.

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Set a second breakpoint after the loop. disable the breakpoint inside the loop. cont. enable the breakpoint again.

I don't know of any easier way.

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Try using the jump command. Per gdb help, on this system at least:

jump -- Continue program being debugged at specified line or address

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What you need is until command. This is the easiest way to avoid stepping through the loop. From gdb manual:

Continue running until a source line past the current line, in the current stack frame, is reached. This command is used to avoid single stepping through a loop more than once. It is like the next command, except that when until encounters a jump, it automatically continues execution until the program counter is greater than the address of the jump.