Dbx 1024 User's Guide download pdf (Page 68)

Chapter 5: Examining and Changing Data

Functions called interactively honor breakpoints. Thus you can debug a

function by setting breakpoints and then calling it interactively.

If you perform a stack trace using the where command while stopped in a

routine executed interactively, dbx displays only those activation levels

created by your interactive function call. The activation levels for your active

program are effectively invisible. For example, a stack trace looks like this

during an interactive function call:

(dbx) where

> 0 foo2(i = 9) [“/usr/var/tmp/dbx_examples/foo.c”:46, 0x10001214]

1 foo(i = 8) [“/usr/var/tmp/dbx_examples/foo.c”:40, 0x100011d4]

===== interactive function call =====

2 foo2(i = 5) [“/usr/var/tmp/dbx_examples/foo.c”:46, 0x10001214]

3 foo(i = 4) [“/usr/var/tmp/dbx_examples/foo.c”:40, 0x100011d4]

4 main(argc = 1, argv = 0xffffffad78) [“/usr/var/tmp/dbx_examples/

test4.c”:25, 0x10000fa0]

5 __start() [“/shamu/lib/libc/libc_64/csu/crt1text.s”:137, 0x10000f34]

If you stop execution of an interactively called function, you are responsible

for eventually “unstacking” the call and returning from the function call. To

unstack a call, you can complete the call using dbx commands such as cont,

resume, next, or step as many times as necessary. If you run or rerun your

program, dbx automatically unstacks all interactive function calls.

Using clearcalls

Another way to unstack an interactive function call is to execute the clearcalls

command, which clears all stopped interactive calls.

(dbx) clearcalls

When stopped or faulted within one or more nested interactive calls, the

clearcalls command removes these calls from the stack and returns the

program to its regular callstack. This command is useful when a

segmentation fault, inﬁnite loop, or other fatal error is encountered within

the interactive call.

When stopped in an interactive call, the call stack displayed by where shows

the following line at the end of each stack of interactive call instantiation.

1 2 ... 63 64 65 66 67 68 69 70 71 72 73 ... 157 158

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Dbx 1024 User's Guide Page 68