Attachment 221681 Details for Bug 325451 – debugger.c

debugger.c

debugger.c (text/plain), 3.01 KB, created by Brad Hinson on 2007-10-09 19:28:50 UTC

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Creator: Brad Hinson

Created: 2007-10-09 19:28:50 UTC

Size: 3.01 KB

patch

obsolete

>#include <unistd.h>
>#include <stdio.h>
>#include <stdlib.h>
>#include <string.h>
>#include <sys/wait.h>
>#include <sys/types.h>
>#include <sys/ptrace.h>
>#include <asm/ptrace.h>
>
>#define TARGET_		"./debuggee"
>#define PTRACE_IGNORED	(void *)0
>
>static ptrace_area * pt_area = (ptrace_area *)0;
>static struct user_regs_struct * pregs = (struct user_regs_struct *)0;
>
>static void writepc(pid_t pid, unsigned long new_pc)
>{
>    int rv;
>
>    memset(pregs,0, sizeof(struct user_regs_struct));
>    memset(pt_area,0, sizeof(ptrace_area));
>    pt_area->len = sizeof(struct user_regs_struct);
>    pt_area->kernel_addr = (unsigned long)0;
>    pt_area->process_addr = (unsigned long)pregs;
>    rv = ptrace(PTRACE_PEEKUSR_AREA, pid, pt_area, 0);
>    if(rv == -1)
>    {
>	perror("PTRACE_PEEKUSR_AREA, failed\n");
>	return;
>    }
>    pregs->psw.addr = new_pc;
>    rv = ptrace(PTRACE_POKEUSR_AREA, pid, pt_area, 0);
>    if(rv == -1)
>    {
>	perror("PTRACE_POKEUSR_AREA, failed\n");
>	return;
>    }
>}
>
>static unsigned long readpc(pid_t pid)
>{
>    int rv;
>
>    memset(pregs,0, sizeof(struct user_regs_struct));
>    memset(pt_area,0, sizeof(ptrace_area));
>    pt_area->len = sizeof(struct user_regs_struct);
>    pt_area->kernel_addr = (unsigned long)0;
>    pt_area->process_addr = (unsigned long)pregs;
>    rv = ptrace(PTRACE_PEEKUSR_AREA, pid, pt_area, 0);
>    if(rv == -1)
>    {
>	perror("PTRACE_PEEKUSR_AREA, failed\n");
>	return 0;
>    }
>    return pregs->psw.addr & 0x7fffffff;
>}
>
>int main()
>{
>    int rv, status;
>    pid_t pid;
>    unsigned long pc, new_pc;
>
>    pid = fork();
>    switch(pid)
>    {
>	case -1:	/* failed fork		*/
>	    return -1;
>	case 0:		/* child process	*/
>	    ptrace(PTRACE_TRACEME,
>			PTRACE_IGNORED, PTRACE_IGNORED, PTRACE_IGNORED);
>	    execl(TARGET_, TARGET_, (const char *)0);
>	    _exit(-1);
>	    break;
>	default:	/* parent process	*/
>	    break;
>    }
>
>    pt_area = (ptrace_area *)malloc(sizeof(ptrace_area));
>    if(!pt_area)
>    {
>	ptrace(PTRACE_DETACH, pid, PTRACE_IGNORED,PTRACE_IGNORED);
>	return -1;
>    }
>    pregs = (struct user_regs_struct *)malloc(sizeof(struct user_regs_struct));
>    if(!pregs)
>    {
>	free(pt_area);
>	ptrace(PTRACE_DETACH, pid, PTRACE_IGNORED,PTRACE_IGNORED);
>	return -1;
>    }
>
>    ptrace(PTRACE_CONT, pid, PTRACE_IGNORED,PTRACE_IGNORED);
>    /* wait for process to stop 	*/
>    rv = waitpid(pid, &status, 0);
>    if(rv == -1)
>    {
>	printf("waitpid failed\n");
>	kill(pid, 9);
>	return -1;
>    }
>    if(WIFSTOPPED(status))
>    {
>	printf("process stopped\n");
>    }
>    /* adjust PC			*/
>    pc = readpc(pid);
>    new_pc = pc + 4;
>    printf("read PC = %8.8p\n", pc);
>    writepc(pid, new_pc);
>    printf("wrote PC = %8.8p\n", new_pc);
>
>    ptrace(PTRACE_CONT, pid, PTRACE_IGNORED,PTRACE_IGNORED);
>
>    /* did it work ?			*/
>
>    rv = waitpid(pid, &status, 0);
>    if(rv == -1)
>    {
>	printf("waitpid failed\n");
>	kill(pid, 9);
>	return -1;
>    }
>    if(!WIFEXITED(status))
>    {
>	pc = readpc(pid);
>	printf("read PC = %8.8p\n", pc);
>	ptrace(PTRACE_DETACH, pid, PTRACE_IGNORED,PTRACE_IGNORED);
>    }
>    free(pt_area);
>    free(pregs);
>
>    return 0;
>}
>

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