Improve error messages in detach()
* strace.c (detach): Change return type from int to void.
Improve error meesages: show PID, tell exactly which operation fails.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
diff --git a/strace.c b/strace.c
index e94ca31..ae24db1 100644
--- a/strace.c
+++ b/strace.c
@@ -157,7 +157,7 @@
unsigned os_release; /* generated from uname()'s u.release */
-static int detach(struct tcb *tcp);
+static void detach(struct tcb *tcp);
static int trace(void);
static void cleanup(void);
static void interrupt(int sig);
@@ -729,7 +729,7 @@
* attached-unstopped processes give the same ESRCH. For unattached process we
* would SIGSTOP it and wait for its SIGSTOP notification forever.
*/
-static int
+static void
detach(struct tcb *tcp)
{
int error;
@@ -764,14 +764,14 @@
}
else if (errno != ESRCH) {
/* Shouldn't happen. */
- perror_msg("detach: ptrace(PTRACE_DETACH, ...)");
+ perror_msg("detach: ptrace(%u,PTRACE_DETACH)", tcp->pid);
}
else
/* ESRCH: process is either not stopped or doesn't exist. */
if (my_tkill(tcp->pid, 0) < 0) {
if (errno != ESRCH)
/* Shouldn't happen. */
- perror_msg("detach: checking sanity");
+ perror_msg("detach: tkill(%u,0)", tcp->pid);
/* else: process doesn't exist. */
}
else
@@ -788,17 +788,15 @@
error = ptrace(PTRACE_INTERRUPT, tcp->pid, 0, 0);
if (!error)
interrupt_done = 1;
+ else if (errno != ESRCH)
+ perror_msg("detach: ptrace(%u,PTRACE_INTERRUPT)", tcp->pid);
}
else {
error = my_tkill(tcp->pid, SIGSTOP);
if (!error)
sigstop_expected = 1;
- }
- if (error && errno != ESRCH) {
- if (use_seize)
- perror_msg("detach: ptrace(PTRACE_INTERRUPT, ...)");
- else
- perror_msg("detach: stopping child");
+ else if (errno != ESRCH)
+ perror_msg("detach: tkill(%u,SIGSTOP)", tcp->pid);
}
}
}
@@ -811,7 +809,7 @@
continue;
if (errno == ECHILD) /* Already gone. */
break;
- perror_msg("detach: waiting");
+ perror_msg("detach: waitpid(%u)", tcp->pid);
break;
}
if (!WIFSTOPPED(status)) {
@@ -870,8 +868,6 @@
fprintf(stderr, "Process %u detached\n", tcp->pid);
droptcb(tcp);
-
- return error;
}
static void