From: Denys Vlasenko <dvlasenk@redhat.com>
Date: Wed, 10 Jul 2013 12:33:05 +0000 (+0200)
Subject: PTRACE_SEIZE can set ptrace options immediately, use this feature
X-Git-Tag: v4.9~199
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=c169d94718e0c3a980dbf352010e615daf2f4332;p=strace

PTRACE_SEIZE can set ptrace options immediately, use this feature

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>
---

diff --git a/strace.c b/strace.c
index 42cfcb99..94706ad0 100644
--- a/strace.c
+++ b/strace.c
@@ -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 */