196 lines
6.6 KiB
Diff
196 lines
6.6 KiB
Diff
From 15409324f1974d41c183904ad575da7188058c1c Mon Sep 17 00:00:00 2001
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From: Chet Ramey <chet.ramey@case.edu>
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Date: Wed, 17 Nov 2021 16:47:24 -0500
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Subject: [PATCH] Bash-5.1 patch 12: fix race condition with child processes
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and resetting trapped signals
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---
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command.h | 1 +
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execute_cmd.c | 8 +++++++-
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jobs.c | 2 ++
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nojobs.c | 2 ++
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patchlevel.h | 2 +-
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sig.c | 10 +++++++++-
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subst.c | 2 ++
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trap.c | 26 ++++++++++++++++++++++++++
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8 files changed, 50 insertions(+), 3 deletions(-)
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diff --git a/command.h b/command.h
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index 914198f9..b8477528 100644
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--- a/command.h
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+++ b/command.h
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@@ -124,6 +124,7 @@ enum command_type { cm_for, cm_case, cm_while, cm_if, cm_simple, cm_select,
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#define SUBSHELL_PROCSUB 0x20 /* subshell caused by <(command) or >(command) */
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#define SUBSHELL_COPROC 0x40 /* subshell from a coproc pipeline */
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#define SUBSHELL_RESETTRAP 0x80 /* subshell needs to reset trap strings on first call to trap */
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+#define SUBSHELL_IGNTRAP 0x100 /* subshell should reset trapped signals from trap_handler */
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/* A structure which represents a word. */
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typedef struct word_desc {
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diff --git a/execute_cmd.c b/execute_cmd.c
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index 90129e06..425679a2 100644
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--- a/execute_cmd.c
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+++ b/execute_cmd.c
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@@ -1547,6 +1547,9 @@ execute_in_subshell (command, asynchronous, pipe_in, pipe_out, fds_to_close)
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clear_pending_traps ();
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reset_signal_handlers ();
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subshell_environment |= SUBSHELL_RESETTRAP;
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+ /* Note that signal handlers have been reset, so we should no longer
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+ reset the handler and resend trapped signals to ourselves. */
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+ subshell_environment &= ~SUBSHELL_IGNTRAP;
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/* We are in a subshell, so forget that we are running a trap handler or
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that the signal handler has changed (we haven't changed it!) */
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@@ -4320,7 +4323,8 @@ execute_simple_command (simple_command, pipe_in, pipe_out, async, fds_to_close)
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already_forked = 1;
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cmdflags |= CMD_NO_FORK;
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- subshell_environment = SUBSHELL_FORK; /* XXX */
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+ /* We redo some of what make_child() does with SUBSHELL_IGNTRAP */
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+ subshell_environment = SUBSHELL_FORK|SUBSHELL_IGNTRAP; /* XXX */
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if (pipe_in != NO_PIPE || pipe_out != NO_PIPE)
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subshell_environment |= SUBSHELL_PIPE;
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if (async)
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@@ -4574,6 +4578,7 @@ run_builtin:
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trap strings if we run trap to change a signal disposition. */
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reset_signal_handlers ();
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subshell_environment |= SUBSHELL_RESETTRAP;
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+ subshell_environment &= ~SUBSHELL_IGNTRAP;
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if (async)
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{
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@@ -5514,6 +5519,7 @@ execute_disk_command (words, redirects, command_line, pipe_in, pipe_out,
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reset_terminating_signals (); /* XXX */
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/* Cancel traps, in trap.c. */
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restore_original_signals ();
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+ subshell_environment &= ~SUBSHELL_IGNTRAP;
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#if defined (JOB_CONTROL)
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FREE (p);
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diff --git a/jobs.c b/jobs.c
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index a581f305..7c3b6e83 100644
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--- a/jobs.c
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+++ b/jobs.c
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@@ -2217,6 +2217,8 @@ make_child (command, flags)
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signals to the default state for a new process. */
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pid_t mypid;
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+ subshell_environment |= SUBSHELL_IGNTRAP;
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+
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/* If this ends up being changed to modify or use `command' in the
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child process, go back and change callers who free `command' in
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the child process when this returns. */
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diff --git a/nojobs.c b/nojobs.c
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index c5fc83d9..f2563ca0 100644
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--- a/nojobs.c
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+++ b/nojobs.c
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@@ -575,6 +575,8 @@ make_child (command, flags)
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last_asynchronous_pid = getpid ();
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#endif
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+ subshell_environment |= SUBSHELL_IGNTRAP;
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+
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default_tty_job_signals ();
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}
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else
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diff --git a/patchlevel.h b/patchlevel.h
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index 8b14f289..eb2aca52 100644
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--- a/patchlevel.h
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+++ b/patchlevel.h
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@@ -25,6 +25,6 @@
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regexp `^#define[ ]*PATCHLEVEL', since that's what support/mkversion.sh
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looks for to find the patch level (for the sccs version string). */
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-#define PATCHLEVEL 11
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+#define PATCHLEVEL 12
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#endif /* _PATCHLEVEL_H_ */
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diff --git a/sig.c b/sig.c
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index 6964d862..e6537d26 100644
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--- a/sig.c
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+++ b/sig.c
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@@ -55,7 +55,8 @@
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# include "bashhist.h"
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#endif
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-extern void initialize_siglist ();
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+extern void initialize_siglist PARAMS((void));
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+extern void set_original_signal PARAMS((int, SigHandler *));
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#if !defined (JOB_CONTROL)
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extern void initialize_job_signals PARAMS((void));
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@@ -255,6 +256,13 @@ initialize_terminating_signals ()
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sigaction (XSIG (i), &act, &oact);
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XHANDLER(i) = oact.sa_handler;
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XSAFLAGS(i) = oact.sa_flags;
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+
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+#if 0
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+ set_original_signal (XSIG(i), XHANDLER(i)); /* optimization */
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+#else
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+ set_original_signal (XSIG(i), act.sa_handler); /* optimization */
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+#endif
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+
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/* Don't do anything with signals that are ignored at shell entry
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if the shell is not interactive. */
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/* XXX - should we do this for interactive shells, too? */
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diff --git a/subst.c b/subst.c
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index 462752de..327de083 100644
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--- a/subst.c
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+++ b/subst.c
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@@ -5951,6 +5951,7 @@ process_substitute (string, open_for_read_in_child)
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free_pushed_string_input ();
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/* Cancel traps, in trap.c. */
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restore_original_signals (); /* XXX - what about special builtins? bash-4.2 */
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+ subshell_environment &= ~SUBSHELL_IGNTRAP;
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QUIT; /* catch any interrupts we got post-fork */
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setup_async_signals ();
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#if 0
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@@ -6382,6 +6383,7 @@ command_substitute (string, quoted, flags)
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}
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QUIT; /* catch any interrupts we got post-fork */
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subshell_environment |= SUBSHELL_RESETTRAP;
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+ subshell_environment &= ~SUBSHELL_IGNTRAP;
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}
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#if defined (JOB_CONTROL)
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diff --git a/trap.c b/trap.c
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index c7f8ded5..1b27fb3a 100644
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--- a/trap.c
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+++ b/trap.c
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@@ -481,6 +481,32 @@ trap_handler (sig)
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SIGRETURN (0);
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}
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+ /* This means we're in a subshell, but have not yet reset the handler for
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+ trapped signals. We're not supposed to execute the trap in this situation;
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+ we should restore the original signal and resend the signal to ourselves
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+ to preserve the Posix "signal traps that are not being ignored shall be
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+ set to the default action" semantics. */
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+ if ((subshell_environment & SUBSHELL_IGNTRAP) && trap_list[sig] != (char *)IGNORE_SIG)
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+ {
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+ sigset_t mask;
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+
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+ /* Paranoia */
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+ if (original_signals[sig] == IMPOSSIBLE_TRAP_HANDLER)
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+ original_signals[sig] = SIG_DFL;
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+
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+ restore_signal (sig);
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+
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+ /* Make sure we let the signal we just caught through */
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+ sigemptyset (&mask);
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+ sigprocmask (SIG_SETMASK, (sigset_t *)NULL, &mask);
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+ sigdelset (&mask, sig);
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+ sigprocmask (SIG_SETMASK, &mask, (sigset_t *)NULL);
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+
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+ kill (getpid (), sig);
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+
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+ SIGRETURN (0);
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+ }
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+
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if ((sig >= NSIG) ||
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(trap_list[sig] == (char *)DEFAULT_SIG) ||
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(trap_list[sig] == (char *)IGNORE_SIG))
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--
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2.31.1
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