Fix "strace -oFILE -ff -p<nonexistant_pid>" behavior

* strace.c (newoutf): Set tcp->outf in non-ff mode too.
(alloctcb): This define is removed.
(alloc_tcb): Renamed to alloctcb. Does not set tcp->outf anymore.
Lost 'command_options_parsed' flag parameter.
(startup_attach): Do not say "interrupt to quit" in attach message -
^C does not work in all cases, we mislead users.
Call newoutf(tcp) after successful attach.
(startup_child): Call newoutf(tcp) after successful attach.
(trace): Call newoutf(tcp) when we picked up already attached child.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/strace.c b/strace.c
index 7446b746773f68c812bff5dafc9d7d84fdf078f2..17ee74960012555681874e8f93f0d5f915758543 100644 (file)
--- a/strace.c
+++ b/strace.c
@@ -573,10 +573,15 @@ tabto(void)
                tprints(acolumn_spaces + curcol);
 }
 
+/* Should be only called directly *after successful attach* to a tracee.
+ * Otherwise, "strace -oFILE -ff -p<nonexistant_pid>"
+ * may create bogus empty FILE.<nonexistant_pid>, and then die.
+ */
 static void
 newoutf(struct tcb *tcp)
 {
-       if (outfname && followfork >= 2) {
+       tcp->outf = outf; /* if not -ff mode, the same file is for all */
+       if (followfork >= 2) {
                char name[520 + sizeof(int) * 3];
                sprintf(name, "%.512s.%u", outfname, tcp->pid);
                tcp->outf = strace_fopen(name);
@@ -603,7 +608,7 @@ expand_tcbtab(void)
 }
 
 static struct tcb *
-alloc_tcb(int pid, int command_options_parsed)
+alloctcb(int pid)
 {
        int i;
        struct tcb *tcp;
@@ -617,21 +622,18 @@ alloc_tcb(int pid, int command_options_parsed)
                        memset(tcp, 0, sizeof(*tcp));
                        tcp->pid = pid;
                        tcp->flags = TCB_INUSE;
-                       tcp->outf = outf; /* Initialise to current out file */
+                       /* tcp->outf = outf; - not needed? */
 #if SUPPORTED_PERSONALITIES > 1
                        tcp->currpers = current_personality;
 #endif
                        nprocs++;
                        if (debug_flag)
                                fprintf(stderr, "new tcb for pid %d, active tcbs:%d\n", tcp->pid, nprocs);
-                       if (command_options_parsed)
-                               newoutf(tcp);
                        return tcp;
                }
        }
-       error_msg_and_die("bug in alloc_tcb");
+       error_msg_and_die("bug in alloctcb");
 }
-#define alloctcb(pid) alloc_tcb((pid), 1)
 
 static void
 droptcb(struct tcb *tcp)
@@ -794,7 +796,7 @@ process_opt_p_list(char *opt)
                        return;
                }
                *delim = c;
-               alloc_tcb(pid, 0);
+               alloctcb(pid);
                if (c == '\0')
                        break;
                opt = delim + 1;
@@ -846,9 +848,6 @@ startup_attach(void)
                if (tcp->flags & TCB_ATTACHED)
                        continue; /* no, we already attached it */
 
-               /* Reinitialize the output since it may have changed */
-               tcp->outf = outf;
-               newoutf(tcp);
 
                if (followfork && !daemonized_tracer) {
                        char procdir[sizeof("/proc/%d/task") + sizeof(int) * 3];
@@ -882,6 +881,7 @@ startup_attach(void)
                                        if (tid != tcp->pid)
                                                cur_tcp = alloctcb(tid);
                                        cur_tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop;
+                                       newoutf(cur_tcp);
                                }
                                closedir(dir);
                                if (interactive) {
@@ -898,8 +898,8 @@ startup_attach(void)
                                }
                                if (!qflag) {
                                        fprintf(stderr, ntid > 1
-? "Process %u attached with %u threads - interrupt to quit\n"
-: "Process %u attached - interrupt to quit\n",
+? "Process %u attached with %u threads\n"
+: "Process %u attached\n",
                                                tcp->pid, ntid);
                                }
                                if (!(tcp->flags & TCB_ATTACHED)) {
@@ -918,6 +918,7 @@ startup_attach(void)
                        continue;
                }
                tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop;
+               newoutf(tcp);
                if (debug_flag)
                        fprintf(stderr, "attach to pid %d (main) succeeded\n", tcp->pid);
 
@@ -1103,6 +1104,7 @@ startup_child(char **argv)
                        tcp->flags |= TCB_ATTACHED | TCB_STRACE_CHILD | TCB_STARTUP | post_attach_sigstop;
                else
                        tcp->flags |= TCB_ATTACHED | TCB_STRACE_CHILD | TCB_STARTUP;
+               newoutf(tcp);
        }
        else {
                /* With -D, *we* are child here, IOW: different pid. Fetch it: */
@@ -1111,6 +1113,7 @@ startup_child(char **argv)
                pid = getppid();
                alloctcb(pid);
                /* attaching will be done later, by startup_attach */
+               /* note: we don't do newoutf(tcp) here either! */
        }
 }
 
@@ -1573,7 +1576,7 @@ init(int argc, char *argv[])
        if (!followfork)
                followfork = optF;
 
-       if (followfork > 1 && cflag) {
+       if (followfork >= 2 && cflag) {
                error_msg_and_die("(-c or -C) and -ff are mutually exclusive options");
        }
 
@@ -1609,15 +1612,15 @@ init(int argc, char *argv[])
                         * We can't do the <outfname>.PID funny business
                         * when using popen, so prohibit it.
                         */
-                       if (followfork > 1)
+                       if (followfork >= 2)
                                error_msg_and_die("Piping the output and -ff are mutually exclusive");
                        outf = strace_popen(outfname + 1);
                }
-               else if (followfork <= 1)
+               else if (followfork < 2)
                        outf = strace_fopen(outfname);
        } else {
                /* -ff without -o FILE is the same as single -f */
-               if (followfork > 1)
+               if (followfork >= 2)
                        followfork = 1;
        }
 
@@ -1932,6 +1935,7 @@ trace(void)
                                   in the child.  */
                                tcp = alloctcb(pid);
                                tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop;
+                               newoutf(tcp);
                                if (!qflag)
                                        fprintf(stderr, "Process %d attached\n",
                                                pid);