Report the name of ptrace command when ptrace_attach_or_seize fails.

* strace.c (ptrace_attach_cmd): New variable.
(ptrace_attach_or_seize): Save last ptrace command's name
to ptrace_attach_cmd.
(attach_tcb, startup_child): Use it in error diagnostics.

diff --git a/strace.c b/strace.c
index b0f4d5b82bea7a4040612aa9824c8a5ea1cd67fd..185d669fbe891fdec8141a828638b685be712d0a 100644 (file)
--- a/strace.c
+++ b/strace.c
@@ -360,22 +360,26 @@ error_opt_arg(int opt, const char *arg)
        error_msg_and_help("invalid -%c argument: '%s'", opt, arg);
 }
 
-#if USE_SEIZE
+static const char *ptrace_attach_cmd;
+
 static int
 ptrace_attach_or_seize(int pid)
 {
+#if USE_SEIZE
        int r;
        if (!use_seize)
-               return ptrace(PTRACE_ATTACH, pid, 0L, 0L);
+               return ptrace_attach_cmd = "PTRACE_ATTACH",
+                      ptrace(PTRACE_ATTACH, pid, 0L, 0L);
        r = ptrace(PTRACE_SEIZE, pid, 0L, (unsigned long) ptrace_setoptions);
        if (r)
-               return r;
+               return ptrace_attach_cmd = "PTRACE_SEIZE", r;
        r = ptrace(PTRACE_INTERRUPT, pid, 0L, 0L);
-       return r;
-}
+       return ptrace_attach_cmd = "PTRACE_INTERRUPT", r;
 #else
-# define ptrace_attach_or_seize(pid) ptrace(PTRACE_ATTACH, (pid), 0, 0)
+               return ptrace_attach_cmd = "PTRACE_ATTACH",
+                      ptrace(PTRACE_ATTACH, pid, 0L, 0L);
 #endif
+}
 
 /*
  * Used when we want to unblock stopped traced process.
@@ -1034,7 +1038,8 @@ attach_tcb(struct tcb *const tcp)
                                if (ptrace_attach_or_seize(tid) < 0) {
                                        ++nerr;
                                        if (debug_flag)
-                                               error_msg("attach to pid %d failed", tid);
+                                               perror_msg("attach: ptrace(%s, %d)",
+                                                          ptrace_attach_cmd, tid);
                                        continue;
                                }
                                if (debug_flag)
@@ -1078,7 +1083,8 @@ attach_tcb(struct tcb *const tcp)
        } /* if (-f) */
 
        if (ptrace_attach_or_seize(tcp->pid) < 0) {
-               perror_msg("attach: ptrace(PTRACE_ATTACH, ...)");
+               perror_msg("attach: ptrace(%s, %d)",
+                          ptrace_attach_cmd, tcp->pid);
                droptcb(tcp);
                return;
        }
@@ -1375,7 +1381,8 @@ startup_child(char **argv)
 
                        if (ptrace_attach_or_seize(pid)) {
                                kill_save_errno(pid, SIGKILL);
-                               perror_msg_and_die("Can't attach to %d", pid);
+                               perror_msg_and_die("attach: ptrace(%s, %d)",
+                                                  ptrace_attach_cmd, pid);
                        }
                        if (!NOMMU_SYSTEM)
                                kill(pid, SIGCONT);