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If you have pressed CTRL+Z and a process is suspended, then you use gdb

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to attach to the process, it is surprising that the process is resumed
without inputting any gdb commands, however ptrace manual said:
  The tracing process will see the newly-traced process stop and may
  then control it as if it had been traced all along.
But the current code does not work in this way, unless traced process
received a signal later, it will continue to run as a background task.
To fix this problem, just send signal SIGSTOP to the traced process after
we resumed it, this works like that you are attaching to a running process,
it is not perfect but better than nothing.
This commit is contained in:
David Xu 2012-07-09 09:24:46 +00:00
parent 3d184db2f8
commit 5985d61556
1 changed files with 4 additions and 4 deletions
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8
sys/kern/sys_process.c
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@ -635,7 +635,7 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
struct iovec iov;
struct uio uio;
struct proc *curp, *p, *pp;
struct thread *td2 = NULL;
struct thread *td2 = NULL, *td3;
struct ptrace_io_desc *piod = NULL;
struct ptrace_lwpinfo *pl;
int error, write, tmp, num;
@ -953,10 +953,8 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
td2->td_xsig = data;
if (req == PT_DETACH) {
struct thread *td3;
FOREACH_THREAD_IN_PROC(p, td3) {
FOREACH_THREAD_IN_PROC(p, td3)
td3->td_dbgflags &= ~TDB_SUSPEND;
}
}
/*
* unsuspend all threads, to not let a thread run,
@ -967,6 +965,8 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
p->p_flag &= ~(P_STOPPED_TRACE|P_STOPPED_SIG|P_WAITED);
thread_unsuspend(p);
PROC_SUNLOCK(p);
if (req == PT_ATTACH)
kern_psignal(p, data);
} else {
if (data)
kern_psignal(p, data);