226 lines
7.2 KiB
Diff
226 lines
7.2 KiB
Diff
Status: submitted for comments
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2004-11-12 Daniel Jacobowitz <dan@debian.org>
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* linux-nat.c (my_waitpid): New function.
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(linux_test_for_tracefork): Make more robust and verbose. Take
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an ORIGINAL_PID argument and test for PTRACE_SETOPTIONS first.
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(linux_supports_tracefork, linux_supports_tracevforkdone): Take a PID
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argument. Update calls to linux_test_for_tracefork.
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(linux_enable_event_reporting, child_follow_fork)
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(child_insert_fork_catchpoint, child_insert_vfork_catchpoint)
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(child_insert_exec_catchpoint): Update calls to
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linux_supports_tracefork and linux_supports_tracevforkdone.
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Index: gdb-6.3/gdb/linux-nat.c
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===================================================================
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--- gdb-6.3.orig/gdb/linux-nat.c 2004-10-08 16:29:47.000000000 -0400
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+++ gdb-6.3/gdb/linux-nat.c 2004-11-13 16:41:51.368720845 -0500
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@@ -150,18 +150,47 @@ linux_tracefork_child (void)
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exit (0);
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}
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-/* Determine if PTRACE_O_TRACEFORK can be used to follow fork events. We
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+/* Wrapper function for waitpid which handles EINTR. */
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+
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+static int
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+my_waitpid (int pid, int *status, int flags)
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+{
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+ int ret;
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+ do
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+ {
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+ ret = waitpid (pid, status, flags);
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+ }
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+ while (ret == -1 && errno == EINTR);
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+
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+ return ret;
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+}
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+
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+/* Determine if PTRACE_O_TRACEFORK can be used to follow fork events.
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+
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+ First, we try to enable fork tracing on ORIGINAL_PID. If this fails,
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+ we know that the feature is not available. This may change the tracing
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+ options for ORIGINAL_PID, but we'll be setting them shortly anyway.
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+
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+ However, if it succeeds, we don't know for sure that the feature is
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+ available; old versions of PTRACE_SETOPTIONS ignored unknown options. We
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create a child process, attach to it, use PTRACE_SETOPTIONS to enable
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- fork tracing, and let it fork. If the process exits, we assume that
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- we can't use TRACEFORK; if we get the fork notification, and we can
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- extract the new child's PID, then we assume that we can. */
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+ fork tracing, and let it fork. If the process exits, we assume that we
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+ can't use TRACEFORK; if we get the fork notification, and we can extract
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+ the new child's PID, then we assume that we can. */
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static void
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-linux_test_for_tracefork (void)
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+linux_test_for_tracefork (int original_pid)
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{
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int child_pid, ret, status;
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long second_pid;
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+ linux_supports_tracefork_flag = 0;
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+ linux_supports_tracevforkdone_flag = 0;
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+
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+ ret = ptrace (PTRACE_SETOPTIONS, original_pid, 0, PTRACE_O_TRACEFORK);
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+ if (ret != 0)
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+ return;
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+
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child_pid = fork ();
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if (child_pid == -1)
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perror_with_name ("linux_test_for_tracefork: fork");
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@@ -169,7 +198,7 @@ linux_test_for_tracefork (void)
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if (child_pid == 0)
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linux_tracefork_child ();
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- ret = waitpid (child_pid, &status, 0);
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+ ret = my_waitpid (child_pid, &status, 0);
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if (ret == -1)
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perror_with_name ("linux_test_for_tracefork: waitpid");
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else if (ret != child_pid)
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@@ -177,13 +206,23 @@ linux_test_for_tracefork (void)
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if (! WIFSTOPPED (status))
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error ("linux_test_for_tracefork: waitpid: unexpected status %d.", status);
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- linux_supports_tracefork_flag = 0;
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-
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ret = ptrace (PTRACE_SETOPTIONS, child_pid, 0, PTRACE_O_TRACEFORK);
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if (ret != 0)
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{
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- ptrace (PTRACE_KILL, child_pid, 0, 0);
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- waitpid (child_pid, &status, 0);
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+ ret = ptrace (PTRACE_KILL, child_pid, 0, 0);
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+ if (ret != 0)
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+ {
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+ warning ("linux_test_for_tracefork: failed to kill child");
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+ return;
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+ }
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+
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+ ret = my_waitpid (child_pid, &status, 0);
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+ if (ret != child_pid)
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+ warning ("linux_test_for_tracefork: failed to wait for killed child");
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+ else if (!WIFSIGNALED (status))
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+ warning ("linux_test_for_tracefork: unexpected wait status 0x%x from "
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+ "killed child", status);
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+
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return;
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}
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@@ -192,8 +231,12 @@ linux_test_for_tracefork (void)
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PTRACE_O_TRACEFORK | PTRACE_O_TRACEVFORKDONE);
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linux_supports_tracevforkdone_flag = (ret == 0);
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- ptrace (PTRACE_CONT, child_pid, 0, 0);
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- ret = waitpid (child_pid, &status, 0);
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+ ret = ptrace (PTRACE_CONT, child_pid, 0, 0);
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+ if (ret != 0)
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+ warning ("linux_test_for_tracefork: failed to resume child");
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+
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+ ret = my_waitpid (child_pid, &status, 0);
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+
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if (ret == child_pid && WIFSTOPPED (status)
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&& status >> 16 == PTRACE_EVENT_FORK)
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{
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@@ -204,34 +247,38 @@ linux_test_for_tracefork (void)
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int second_status;
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linux_supports_tracefork_flag = 1;
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- waitpid (second_pid, &second_status, 0);
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- ptrace (PTRACE_DETACH, second_pid, 0, 0);
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+ my_waitpid (second_pid, &second_status, 0);
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+ ret = ptrace (PTRACE_KILL, second_pid, 0, 0);
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+ if (ret != 0)
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+ warning ("linux_test_for_tracefork: failed to kill second child");
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}
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}
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+ else
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+ warning ("linux_test_for_tracefork: unexpected result from waitpid "
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+ "(%d, status 0x%x)", ret, status);
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- if (WIFSTOPPED (status))
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- {
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- ptrace (PTRACE_DETACH, child_pid, 0, 0);
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- waitpid (child_pid, &status, 0);
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- }
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+ ret = ptrace (PTRACE_KILL, child_pid, 0, 0);
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+ if (ret != 0)
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+ warning ("linux_test_for_tracefork: failed to kill child");
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+ my_waitpid (child_pid, &status, 0);
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}
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/* Return non-zero iff we have tracefork functionality available.
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This function also sets linux_supports_tracefork_flag. */
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static int
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-linux_supports_tracefork (void)
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+linux_supports_tracefork (int pid)
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{
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if (linux_supports_tracefork_flag == -1)
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- linux_test_for_tracefork ();
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+ linux_test_for_tracefork (pid);
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return linux_supports_tracefork_flag;
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}
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static int
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-linux_supports_tracevforkdone (void)
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+linux_supports_tracevforkdone (int pid)
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{
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if (linux_supports_tracefork_flag == -1)
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- linux_test_for_tracefork ();
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+ linux_test_for_tracefork (pid);
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return linux_supports_tracevforkdone_flag;
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}
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@@ -242,12 +289,12 @@ linux_enable_event_reporting (ptid_t pti
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int pid = ptid_get_pid (ptid);
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int options;
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- if (! linux_supports_tracefork ())
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+ if (! linux_supports_tracefork (pid))
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return;
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options = PTRACE_O_TRACEFORK | PTRACE_O_TRACEVFORK | PTRACE_O_TRACEEXEC
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| PTRACE_O_TRACECLONE;
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- if (linux_supports_tracevforkdone ())
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+ if (linux_supports_tracevforkdone (pid))
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options |= PTRACE_O_TRACEVFORKDONE;
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/* Do not enable PTRACE_O_TRACEEXIT until GDB is more prepared to support
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@@ -308,7 +355,8 @@ child_follow_fork (int follow_child)
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if (has_vforked)
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{
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- if (linux_supports_tracevforkdone ())
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+ gdb_assert (linux_supports_tracefork_flag >= 0);
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+ if (linux_supports_tracevforkdone (0))
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{
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int status;
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@@ -476,7 +524,7 @@ linux_handle_extended_wait (int pid, int
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int
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child_insert_fork_catchpoint (int pid)
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{
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- if (! linux_supports_tracefork ())
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+ if (! linux_supports_tracefork (pid))
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error ("Your system does not support fork catchpoints.");
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return 0;
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@@ -485,7 +533,7 @@ child_insert_fork_catchpoint (int pid)
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int
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child_insert_vfork_catchpoint (int pid)
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{
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- if (!linux_supports_tracefork ())
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+ if (!linux_supports_tracefork (pid))
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error ("Your system does not support vfork catchpoints.");
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return 0;
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@@ -494,7 +542,7 @@ child_insert_vfork_catchpoint (int pid)
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int
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child_insert_exec_catchpoint (int pid)
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{
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- if (!linux_supports_tracefork ())
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+ if (!linux_supports_tracefork (pid))
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error ("Your system does not support exec catchpoints.");
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return 0;
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