From: Denys Vlasenko <dvlasenk@redhat.com>
Date: Fri, 24 Jun 2011 14:51:16 +0000 (+0200)
Subject: Add debug output in initial attachment code
X-Git-Tag: v4.7~345
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=f95397afb8aadf017b2d3d42056c5929dbf16775;p=strace

Add debug output in initial attachment code

* strace.c (startup_attach): If -d, report pid and success/failure
  of every attach attempt.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
---

diff --git a/strace.c b/strace.c
index d6788d5d..f22375ae 100644
--- a/strace.c
+++ b/strace.c
@@ -471,13 +471,20 @@ startup_attach(void)
 					if (tid <= 0)
 						continue;
 					++ntid;
-					if (ptrace(PTRACE_ATTACH, tid, (char *) 1, 0) < 0)
+					if (ptrace(PTRACE_ATTACH, tid, (char *) 1, 0) < 0) {
 						++nerr;
-					else if (tid != tcbtab[tcbi]->pid) {
-						tcp = alloctcb(tid);
-						tcp->flags |= TCB_ATTACHED|TCB_CLONE_THREAD;
-						tcbtab[tcbi]->nclone_threads++;
-						tcp->parent = tcbtab[tcbi];
+						if (debug)
+							fprintf(stderr, "attach to pid %d failed\n", tid);
+					}
+					else {
+						if (debug)
+							fprintf(stderr, "attach to pid %d succeeded\n", tid);
+						if (tid != tcbtab[tcbi]->pid) {
+							tcp = alloctcb(tid);
+							tcp->flags |= TCB_ATTACHED|TCB_CLONE_THREAD;
+							tcbtab[tcbi]->nclone_threads++;
+							tcp->parent = tcbtab[tcbi];
+						}
 					}
 					if (interactive) {
 						sigprocmask(SIG_SETMASK, &empty_set, NULL);
@@ -508,6 +515,8 @@ startup_attach(void)
 			droptcb(tcp);
 			continue;
 		}
+		if (debug)
+			fprintf(stderr, "attach to pid %d (main) succeeded\n", tcp->pid);
 		/* INTERRUPTED is going to be checked at the top of TRACE.  */
 
 		if (daemonized_tracer) {
@@ -528,7 +537,7 @@ startup_attach(void)
 			fprintf(stderr,
 				"Process %u attached - interrupt to quit\n",
 				tcp->pid);
-	}
+	} /* for each tcbtab[] */
 
 	if (interactive)
 		sigprocmask(SIG_SETMASK, &empty_set, NULL);