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2012-02-27 Pedro Alves <palves@redhat.com>

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PR server/9684
	* linux-low.c (pid_is_stopped): New.
	(linux_attach_lwp_1): Handle attaching to 'T (stopped)' processes.
This commit is contained in:
Pedro Alves 2012-02-27 16:19:19 +00:00
parent ebbbe5c5ed
commit c14d7ab2b6
2 changed files with 64 additions and 0 deletions
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6
gdb/gdbserver/ChangeLog
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@ -1,3 +1,9 @@
2012-02-27 Pedro Alves <palves@redhat.com>
PR server/9684
* linux-low.c (pid_is_stopped): New.
(linux_attach_lwp_1): Handle attaching to 'T (stopped)' processes.
2012-02-25 Luis Machado <lgustavo@codesourcery.com>
* mem-break.c (clear_gdb_breakpoint_conditions): Fix de-allocation

58
gdb/gdbserver/linux-low.c
View file

@ -598,6 +598,37 @@ linux_create_inferior (char *program, char **allargs)
return pid;
}
/* Detect `T (stopped)' in `/proc/PID/status'.
Other states including `T (tracing stop)' are reported as false. */
static int
pid_is_stopped (pid_t pid)
{
FILE *status_file;
char buf[100];
int retval = 0;
snprintf (buf, sizeof (buf), "/proc/%d/status", (int) pid);
status_file = fopen (buf, "r");
if (status_file != NULL)
{
int have_state = 0;
while (fgets (buf, sizeof (buf), status_file))
{
if (strncmp (buf, "State:", 6) == 0)
{
have_state = 1;
break;
}
}
if (have_state && strstr (buf, "T (stopped)") != NULL)
retval = 1;
fclose (status_file);
}
return retval;
}
/* Attach to an inferior process. */
static void
@ -643,6 +674,33 @@ linux_attach_lwp_1 (unsigned long lwpid, int initial)
ptrace call on this LWP. */
new_lwp->must_set_ptrace_flags = 1;
if (pid_is_stopped (lwpid))
{
if (debug_threads)
fprintf (stderr,
"Attached to a stopped process\n");
/* The process is definitely stopped. It is in a job control
stop, unless the kernel predates the TASK_STOPPED /
TASK_TRACED distinction, in which case it might be in a
ptrace stop. Make sure it is in a ptrace stop; from there we
can kill it, signal it, et cetera.
First make sure there is a pending SIGSTOP. Since we are
already attached, the process can not transition from stopped
to running without a PTRACE_CONT; so we know this signal will
go into the queue. The SIGSTOP generated by PTRACE_ATTACH is
probably already in the queue (unless this kernel is old
enough to use TASK_STOPPED for ptrace stops); but since
SIGSTOP is not an RT signal, it can only be queued once. */
kill_lwp (lwpid, SIGSTOP);
/* Finally, resume the stopped process. This will deliver the
SIGSTOP (or a higher priority signal, just like normal
PTRACE_ATTACH), which we'll catch later on. */
ptrace (PTRACE_CONT, lwpid, 0, 0);
}
/* The next time we wait for this LWP we'll see a SIGSTOP as PTRACE_ATTACH
brings it to a halt.