tracing program execution

[jbreazeale]

Is there a program out there like ltrace that will allow the user to determine every line of code executed by another program?

Once upon a time I created such a program on DomainOS (Apollo Computer) called 'tca' (Test Coverage Analyzer). You could execute a program then post-process the trace log to find out what lines of code where (or weren't) executed. It was an internal-only program. It would be nice to, at least, find some way of generating the PC counter history of the program execution.

Thanks!
Joel

[geskorup]

Try strace.

[jbreazeale]

I think I have what I want as an example of starting point. My version of Sandeep's "small example" outputs the instruction count and instruction pointer.

Here the URL containing Sandeep's example: http://linuxgazette.net/issue81/sandeep.html

Here's my variant showing the instruction count and instruction pointer:

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <syscall.h>
#include <sys/ptrace.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <errno.h>
#include <linux/user.h>

int main&#40;void&#41;
&#123;
        long long counter = 0;  /*  machine instruction counter */
        int wait_val;           /*  child's return value        */
        int pid;                /*  child's process id          */
        struct user_regs_struct regs;

        puts&#40;"Please wait"&#41;;

        switch &#40;pid = fork&#40;&#41;&#41; &#123;
        case -1&#58;
                perror&#40;"fork"&#41;;
                break;
        case 0&#58; /*  child process starts        */
                ptrace&#40;PTRACE_TRACEME, 0, 0, 0&#41;;
                /*
                 *  must be called in order to allow the
                 *  control over the child process
                 */
                execl&#40;"/bin/ls", "ls", NULL&#41;;
                /*
                 *  executes the program and causes
                 *  the child to stop and send a signal
                 *  to the parent, the parent can now
                 *  switch to PTRACE_SINGLESTEP
                 */
                break;
                /*  child process ends  */
        default&#58;/*  parent process starts       */
                wait&#40;&wait_val&#41;;
                /*
                 *   parent waits for child to stop at next
                 *   instruction &#40;execl&#40;&#41;&#41;
                 */
                while &#40;wait_val == 1407 &#41; &#123;
                        if &#40;ptrace&#40;PTRACE_GETREGS, pid, 0, &regs&#41; != 0&#41;
                                perror&#40;"ptrace gr"&#41;;

                        printf&#40;"%lld %08x\n", counter, regs.eip &#41;;
                        counter++;

                        if &#40;ptrace&#40;PTRACE_SINGLESTEP, pid, 0, 0&#41; != 0&#41;
                                perror&#40;"ptrace ss"&#41;;
                        /*
                         *   switch to singlestep tracing and
                         *   release child
                         *   if unable call error.
                         */
                        wait&#40;&wait_val&#41;;
                        /*   wait for next instruction to complete  */

                &#125;
                /*
                 * continue to stop, wait and release until
                 * the child is finished; wait_val != 1407
                 * Low=0177L and High=05 &#40;SIGTRAP&#41;
                 */
        &#125;
        printf&#40;"Number of machine instructions &#58; %lld\n", counter&#41;;
        return 0;
&#125;

**MOD_EDIT: added 'code' tags