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PTRACE_SEIZE can set ptrace options immediately, use this feature

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This eliminates some rare bugs, such as post-execve SIGTRAP
generation when we attach to a process, and it manages to finish
execve'ing before we set TRACEEXEC option to suppress that.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
This commit is contained in:
Denys Vlasenko 2013-07-10 14:33:05 +02:00
parent 7c41ce2878
commit c169d94718
1 changed files with 5 additions and 5 deletions
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10
strace.c
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@ -335,11 +335,11 @@ ptrace_attach_or_seize(int pid)
{
int r;
if (!use_seize)
return ptrace(PTRACE_ATTACH, pid, 0, 0);
r = ptrace(PTRACE_SEIZE, pid, 0, 0);
return ptrace(PTRACE_ATTACH, pid, 0L, 0L);
r = ptrace(PTRACE_SEIZE, pid, 0L, (unsigned long)ptrace_setoptions);
if (r)
return r;
r = ptrace(PTRACE_INTERRUPT, pid, 0, 0);
r = ptrace(PTRACE_INTERRUPT, pid, 0L, 0L);
return r;
}
#else
@ -2224,9 +2224,9 @@ trace(void)
return;
}
}
if (ptrace_setoptions) {
if (!use_seize && ptrace_setoptions) {
if (debug_flag)
fprintf(stderr, "setting opts %x on pid %d\n", ptrace_setoptions, tcp->pid);
fprintf(stderr, "setting opts 0x%x on pid %d\n", ptrace_setoptions, tcp->pid);
if (ptrace(PTRACE_SETOPTIONS, tcp->pid, NULL, ptrace_setoptions) < 0) {
if (errno != ESRCH) {
/* Should never happen, really */