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linux/arch/alpha/kernel/signal.c
Steven Rostedt 69be8f1896 [PATCH] convert signal handling of NODEFER to act like other Unix boxes. 
It has been reported that the way Linux handles NODEFER for signals is
not consistent with the way other Unix boxes handle it.  I've written a
program to test the behavior of how this flag affects signals and had
several reports from people who ran this on various Unix boxes,
confirming that Linux seems to be unique on the way this is handled.

The way NODEFER affects signals on other Unix boxes is as follows:

1) If NODEFER is set, other signals in sa_mask are still blocked.

2) If NODEFER is set and the signal is in sa_mask, then the signal is
still blocked. (Note: this is the behavior of all tested but Linux _and_
NetBSD 2.0 *).

The way NODEFER affects signals on Linux:

1) If NODEFER is set, other signals are _not_ blocked regardless of
sa_mask (Even NetBSD doesn't do this).

2) If NODEFER is set and the signal is in sa_mask, then the signal being
handled is not blocked.

The patch converts signal handling in all current Linux architectures to
the way most Unix boxes work.

Unix boxes that were tested:  DU4, AIX 5.2, Irix 6.5, NetBSD 2.0, SFU
3.5 on WinXP, AIX 5.3, Mac OSX, and of course Linux 2.6.13-rcX.

* NetBSD was the only other Unix to behave like Linux on point #2. The
main concern was brought up by point #1 which even NetBSD isn't like
Linux.  So with this patch, we leave NetBSD as the lonely one that
behaves differently here with #2.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-08-29 10:03:11 -07:00

672 lines
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/*
* linux/arch/alpha/kernel/signal.c
*
* Copyright (C) 1995 Linus Torvalds
*
* 1997-11-02 Modified for POSIX.1b signals by Richard Henderson
*/
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/tty.h>
#include <linux/binfmts.h>
#include <linux/bitops.h>
#include <asm/uaccess.h>
#include <asm/sigcontext.h>
#include <asm/ucontext.h>
#include "proto.h"
#define DEBUG_SIG 0
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
asmlinkage void ret_from_sys_call(void);
static int do_signal(sigset_t *, struct pt_regs *, struct switch_stack *,
unsigned long, unsigned long);
/*
* The OSF/1 sigprocmask calling sequence is different from the
* C sigprocmask() sequence..
*
* how:
* 1 - SIG_BLOCK
* 2 - SIG_UNBLOCK
* 3 - SIG_SETMASK
*
* We change the range to -1 .. 1 in order to let gcc easily
* use the conditional move instructions.
*
* Note that we don't need to acquire the kernel lock for SMP
* operation, as all of this is local to this thread.
*/
asmlinkage unsigned long
do_osf_sigprocmask(int how, unsigned long newmask, struct pt_regs *regs)
{
unsigned long oldmask = -EINVAL;
if ((unsigned long)how-1 <= 2) {
long sign = how-2; /* -1 .. 1 */
unsigned long block, unblock;
newmask &= _BLOCKABLE;
spin_lock_irq(&current->sighand->siglock);
oldmask = current->blocked.sig[0];
unblock = oldmask & ~newmask;
block = oldmask | newmask;
if (!sign)
block = unblock;
if (sign <= 0)
newmask = block;
if (_NSIG_WORDS > 1 && sign > 0)
sigemptyset(&current->blocked);
current->blocked.sig[0] = newmask;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
regs->r0 = 0; /* special no error return */
}
return oldmask;
}
asmlinkage int
osf_sigaction(int sig, const struct osf_sigaction __user *act,
struct osf_sigaction __user *oact)
{
struct k_sigaction new_ka, old_ka;
int ret;
if (act) {
old_sigset_t mask;
if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
__get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
__get_user(new_ka.sa.sa_flags, &act->sa_flags))
return -EFAULT;
__get_user(mask, &act->sa_mask);
siginitset(&new_ka.sa.sa_mask, mask);
new_ka.ka_restorer = NULL;
}
ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
if (!ret && oact) {
if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
__put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
__put_user(old_ka.sa.sa_flags, &oact->sa_flags))
return -EFAULT;
__put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
}
return ret;
}
asmlinkage long
sys_rt_sigaction(int sig, const struct sigaction __user *act,
struct sigaction __user *oact,
size_t sigsetsize, void __user *restorer)
{
struct k_sigaction new_ka, old_ka;
int ret;
/* XXX: Don't preclude handling different sized sigset_t's. */
if (sigsetsize != sizeof(sigset_t))
return -EINVAL;
if (act) {
new_ka.ka_restorer = restorer;
if (copy_from_user(&new_ka.sa, act, sizeof(*act)))
return -EFAULT;
}
ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
if (!ret && oact) {
if (copy_to_user(oact, &old_ka.sa, sizeof(*oact)))
return -EFAULT;
}
return ret;
}
/*
* Atomically swap in the new signal mask, and wait for a signal.
*/
asmlinkage int
do_sigsuspend(old_sigset_t mask, struct pt_regs *regs, struct switch_stack *sw)
{
sigset_t oldset;
mask &= _BLOCKABLE;
spin_lock_irq(&current->sighand->siglock);
oldset = current->blocked;
siginitset(&current->blocked, mask);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
/* Indicate EINTR on return from any possible signal handler,
which will not come back through here, but via sigreturn. */
regs->r0 = EINTR;
regs->r19 = 1;
while (1) {
current->state = TASK_INTERRUPTIBLE;
schedule();
if (do_signal(&oldset, regs, sw, 0, 0))
return -EINTR;
}
}
asmlinkage int
do_rt_sigsuspend(sigset_t __user *uset, size_t sigsetsize,
struct pt_regs *regs, struct switch_stack *sw)
{
sigset_t oldset, set;
/* XXX: Don't preclude handling different sized sigset_t's. */
if (sigsetsize != sizeof(sigset_t))
return -EINVAL;
if (copy_from_user(&set, uset, sizeof(set)))
return -EFAULT;
sigdelsetmask(&set, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
oldset = current->blocked;
current->blocked = set;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
/* Indicate EINTR on return from any possible signal handler,
which will not come back through here, but via sigreturn. */
regs->r0 = EINTR;
regs->r19 = 1;
while (1) {
current->state = TASK_INTERRUPTIBLE;
schedule();
if (do_signal(&oldset, regs, sw, 0, 0))
return -EINTR;
}
}
asmlinkage int
sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
{
return do_sigaltstack(uss, uoss, rdusp());
}
/*
* Do a signal return; undo the signal stack.
*/
#if _NSIG_WORDS > 1
# error "Non SA_SIGINFO frame needs rearranging"
#endif
struct sigframe
{
struct sigcontext sc;
unsigned int retcode[3];
};
struct rt_sigframe
{
struct siginfo info;
struct ucontext uc;
unsigned int retcode[3];
};
/* If this changes, userland unwinders that Know Things about our signal
frame will break. Do not undertake lightly. It also implies an ABI
change wrt the size of siginfo_t, which may cause some pain. */
extern char compile_time_assert
[offsetof(struct rt_sigframe, uc.uc_mcontext) == 176 ? 1 : -1];
#define INSN_MOV_R30_R16 0x47fe0410
#define INSN_LDI_R0 0x201f0000
#define INSN_CALLSYS 0x00000083
static long
restore_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
struct switch_stack *sw)
{
unsigned long usp;
long i, err = __get_user(regs->pc, &sc->sc_pc);
sw->r26 = (unsigned long) ret_from_sys_call;
err |= __get_user(regs->r0, sc->sc_regs+0);
err |= __get_user(regs->r1, sc->sc_regs+1);
err |= __get_user(regs->r2, sc->sc_regs+2);
err |= __get_user(regs->r3, sc->sc_regs+3);
err |= __get_user(regs->r4, sc->sc_regs+4);
err |= __get_user(regs->r5, sc->sc_regs+5);
err |= __get_user(regs->r6, sc->sc_regs+6);
err |= __get_user(regs->r7, sc->sc_regs+7);
err |= __get_user(regs->r8, sc->sc_regs+8);
err |= __get_user(sw->r9, sc->sc_regs+9);
err |= __get_user(sw->r10, sc->sc_regs+10);
err |= __get_user(sw->r11, sc->sc_regs+11);
err |= __get_user(sw->r12, sc->sc_regs+12);
err |= __get_user(sw->r13, sc->sc_regs+13);
err |= __get_user(sw->r14, sc->sc_regs+14);
err |= __get_user(sw->r15, sc->sc_regs+15);
err |= __get_user(regs->r16, sc->sc_regs+16);
err |= __get_user(regs->r17, sc->sc_regs+17);
err |= __get_user(regs->r18, sc->sc_regs+18);
err |= __get_user(regs->r19, sc->sc_regs+19);
err |= __get_user(regs->r20, sc->sc_regs+20);
err |= __get_user(regs->r21, sc->sc_regs+21);
err |= __get_user(regs->r22, sc->sc_regs+22);
err |= __get_user(regs->r23, sc->sc_regs+23);
err |= __get_user(regs->r24, sc->sc_regs+24);
err |= __get_user(regs->r25, sc->sc_regs+25);
err |= __get_user(regs->r26, sc->sc_regs+26);
err |= __get_user(regs->r27, sc->sc_regs+27);
err |= __get_user(regs->r28, sc->sc_regs+28);
err |= __get_user(regs->gp, sc->sc_regs+29);
err |= __get_user(usp, sc->sc_regs+30);
wrusp(usp);
for (i = 0; i < 31; i++)
err |= __get_user(sw->fp[i], sc->sc_fpregs+i);
err |= __get_user(sw->fp[31], &sc->sc_fpcr);
return err;
}
/* Note that this syscall is also used by setcontext(3) to install
a given sigcontext. This because it's impossible to set *all*
registers and transfer control from userland. */
asmlinkage void
do_sigreturn(struct sigcontext __user *sc, struct pt_regs *regs,
struct switch_stack *sw)
{
sigset_t set;
/* Verify that it's a good sigcontext before using it */
if (!access_ok(VERIFY_READ, sc, sizeof(*sc)))
goto give_sigsegv;
if (__get_user(set.sig[0], &sc->sc_mask))
goto give_sigsegv;
sigdelsetmask(&set, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
current->blocked = set;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
if (restore_sigcontext(sc, regs, sw))
goto give_sigsegv;
/* Send SIGTRAP if we're single-stepping: */
if (ptrace_cancel_bpt (current)) {
siginfo_t info;
info.si_signo = SIGTRAP;
info.si_errno = 0;
info.si_code = TRAP_BRKPT;
info.si_addr = (void __user *) regs->pc;
info.si_trapno = 0;
send_sig_info(SIGTRAP, &info, current);
}
return;
give_sigsegv:
force_sig(SIGSEGV, current);
}
asmlinkage void
do_rt_sigreturn(struct rt_sigframe __user *frame, struct pt_regs *regs,
struct switch_stack *sw)
{
sigset_t set;
/* Verify that it's a good ucontext_t before using it */
if (!access_ok(VERIFY_READ, &frame->uc, sizeof(frame->uc)))
goto give_sigsegv;
if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
goto give_sigsegv;
sigdelsetmask(&set, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
current->blocked = set;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
if (restore_sigcontext(&frame->uc.uc_mcontext, regs, sw))
goto give_sigsegv;
/* Send SIGTRAP if we're single-stepping: */
if (ptrace_cancel_bpt (current)) {
siginfo_t info;
info.si_signo = SIGTRAP;
info.si_errno = 0;
info.si_code = TRAP_BRKPT;
info.si_addr = (void __user *) regs->pc;
info.si_trapno = 0;
send_sig_info(SIGTRAP, &info, current);
}
return;
give_sigsegv:
force_sig(SIGSEGV, current);
}
/*
* Set up a signal frame.
*/
static inline void __user *
get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
{
if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! on_sig_stack(sp))
sp = current->sas_ss_sp + current->sas_ss_size;
return (void __user *)((sp - frame_size) & -32ul);
}
static long
setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
struct switch_stack *sw, unsigned long mask, unsigned long sp)
{
long i, err = 0;
err |= __put_user(on_sig_stack((unsigned long)sc), &sc->sc_onstack);
err |= __put_user(mask, &sc->sc_mask);
err |= __put_user(regs->pc, &sc->sc_pc);
err |= __put_user(8, &sc->sc_ps);
err |= __put_user(regs->r0 , sc->sc_regs+0);
err |= __put_user(regs->r1 , sc->sc_regs+1);
err |= __put_user(regs->r2 , sc->sc_regs+2);
err |= __put_user(regs->r3 , sc->sc_regs+3);
err |= __put_user(regs->r4 , sc->sc_regs+4);
err |= __put_user(regs->r5 , sc->sc_regs+5);
err |= __put_user(regs->r6 , sc->sc_regs+6);
err |= __put_user(regs->r7 , sc->sc_regs+7);
err |= __put_user(regs->r8 , sc->sc_regs+8);
err |= __put_user(sw->r9 , sc->sc_regs+9);
err |= __put_user(sw->r10 , sc->sc_regs+10);
err |= __put_user(sw->r11 , sc->sc_regs+11);
err |= __put_user(sw->r12 , sc->sc_regs+12);
err |= __put_user(sw->r13 , sc->sc_regs+13);
err |= __put_user(sw->r14 , sc->sc_regs+14);
err |= __put_user(sw->r15 , sc->sc_regs+15);
err |= __put_user(regs->r16, sc->sc_regs+16);
err |= __put_user(regs->r17, sc->sc_regs+17);
err |= __put_user(regs->r18, sc->sc_regs+18);
err |= __put_user(regs->r19, sc->sc_regs+19);
err |= __put_user(regs->r20, sc->sc_regs+20);
err |= __put_user(regs->r21, sc->sc_regs+21);
err |= __put_user(regs->r22, sc->sc_regs+22);
err |= __put_user(regs->r23, sc->sc_regs+23);
err |= __put_user(regs->r24, sc->sc_regs+24);
err |= __put_user(regs->r25, sc->sc_regs+25);
err |= __put_user(regs->r26, sc->sc_regs+26);
err |= __put_user(regs->r27, sc->sc_regs+27);
err |= __put_user(regs->r28, sc->sc_regs+28);
err |= __put_user(regs->gp , sc->sc_regs+29);
err |= __put_user(sp, sc->sc_regs+30);
err |= __put_user(0, sc->sc_regs+31);
for (i = 0; i < 31; i++)
err |= __put_user(sw->fp[i], sc->sc_fpregs+i);
err |= __put_user(0, sc->sc_fpregs+31);
err |= __put_user(sw->fp[31], &sc->sc_fpcr);
err |= __put_user(regs->trap_a0, &sc->sc_traparg_a0);
err |= __put_user(regs->trap_a1, &sc->sc_traparg_a1);
err |= __put_user(regs->trap_a2, &sc->sc_traparg_a2);
return err;
}
static void
setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
struct pt_regs *regs, struct switch_stack * sw)
{
unsigned long oldsp, r26, err = 0;
struct sigframe __user *frame;
oldsp = rdusp();
frame = get_sigframe(ka, oldsp, sizeof(*frame));
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
goto give_sigsegv;
err |= setup_sigcontext(&frame->sc, regs, sw, set->sig[0], oldsp);
if (err)
goto give_sigsegv;
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
if (ka->ka_restorer) {
r26 = (unsigned long) ka->ka_restorer;
} else {
err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
err |= __put_user(INSN_LDI_R0+__NR_sigreturn, frame->retcode+1);
err |= __put_user(INSN_CALLSYS, frame->retcode+2);
imb();
r26 = (unsigned long) frame->retcode;
}
/* Check that everything was written properly. */
if (err)
goto give_sigsegv;
/* "Return" to the handler */
regs->r26 = r26;
regs->r27 = regs->pc = (unsigned long) ka->sa.sa_handler;
regs->r16 = sig; /* a0: signal number */
regs->r17 = 0; /* a1: exception code */
regs->r18 = (unsigned long) &frame->sc; /* a2: sigcontext pointer */
wrusp((unsigned long) frame);
#if DEBUG_SIG
printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
current->comm, current->pid, frame, regs->pc, regs->r26);
#endif
return;
give_sigsegv:
force_sigsegv(sig, current);
}
static void
setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
sigset_t *set, struct pt_regs *regs, struct switch_stack * sw)
{
unsigned long oldsp, r26, err = 0;
struct rt_sigframe __user *frame;
oldsp = rdusp();
frame = get_sigframe(ka, oldsp, sizeof(*frame));
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
goto give_sigsegv;
err |= copy_siginfo_to_user(&frame->info, info);
/* Create the ucontext. */
err |= __put_user(0, &frame->uc.uc_flags);
err |= __put_user(0, &frame->uc.uc_link);
err |= __put_user(set->sig[0], &frame->uc.uc_osf_sigmask);
err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
err |= __put_user(sas_ss_flags(oldsp), &frame->uc.uc_stack.ss_flags);
err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, sw,
set->sig[0], oldsp);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
if (err)
goto give_sigsegv;
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
if (ka->ka_restorer) {
r26 = (unsigned long) ka->ka_restorer;
} else {
err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
err |= __put_user(INSN_LDI_R0+__NR_rt_sigreturn,
frame->retcode+1);
err |= __put_user(INSN_CALLSYS, frame->retcode+2);
imb();
r26 = (unsigned long) frame->retcode;
}
if (err)
goto give_sigsegv;
/* "Return" to the handler */
regs->r26 = r26;
regs->r27 = regs->pc = (unsigned long) ka->sa.sa_handler;
regs->r16 = sig; /* a0: signal number */
regs->r17 = (unsigned long) &frame->info; /* a1: siginfo pointer */
regs->r18 = (unsigned long) &frame->uc; /* a2: ucontext pointer */
wrusp((unsigned long) frame);
#if DEBUG_SIG
printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
current->comm, current->pid, frame, regs->pc, regs->r26);
#endif
return;
give_sigsegv:
force_sigsegv(sig, current);
}
/*
* OK, we're invoking a handler.
*/
static inline void
handle_signal(int sig, struct k_sigaction *ka, siginfo_t *info,
sigset_t *oldset, struct pt_regs * regs, struct switch_stack *sw)
{
if (ka->sa.sa_flags & SA_SIGINFO)
setup_rt_frame(sig, ka, info, oldset, regs, sw);
else
setup_frame(sig, ka, oldset, regs, sw);
if (ka->sa.sa_flags & SA_RESETHAND)
ka->sa.sa_handler = SIG_DFL;
spin_lock_irq(&current->sighand->siglock);
sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
if (!(ka->sa.sa_flags & SA_NODEFER))
sigaddset(&current->blocked,sig);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
}
static inline void
syscall_restart(unsigned long r0, unsigned long r19,
struct pt_regs *regs, struct k_sigaction *ka)
{
switch (regs->r0) {
case ERESTARTSYS:
if (!(ka->sa.sa_flags & SA_RESTART)) {
case ERESTARTNOHAND:
regs->r0 = EINTR;
break;
}
/* fallthrough */
case ERESTARTNOINTR:
regs->r0 = r0; /* reset v0 and a3 and replay syscall */
regs->r19 = r19;
regs->pc -= 4;
break;
case ERESTART_RESTARTBLOCK:
current_thread_info()->restart_block.fn = do_no_restart_syscall;
regs->r0 = EINTR;
break;
}
}
/*
* Note that 'init' is a special process: it doesn't get signals it doesn't
* want to handle. Thus you cannot kill init even with a SIGKILL even by
* mistake.
*
* Note that we go through the signals twice: once to check the signals that
* the kernel can handle, and then we build all the user-level signal handling
* stack-frames in one go after that.
*
* "r0" and "r19" are the registers we need to restore for system call
* restart. "r0" is also used as an indicator whether we can restart at
* all (if we get here from anything but a syscall return, it will be 0)
*/
static int
do_signal(sigset_t *oldset, struct pt_regs * regs, struct switch_stack * sw,
unsigned long r0, unsigned long r19)
{
siginfo_t info;
int signr;
unsigned long single_stepping = ptrace_cancel_bpt(current);
struct k_sigaction ka;
if (!oldset)
oldset = &current->blocked;
/* This lets the debugger run, ... */
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
/* ... so re-check the single stepping. */
single_stepping |= ptrace_cancel_bpt(current);
if (signr > 0) {
/* Whee! Actually deliver the signal. */
if (r0) syscall_restart(r0, r19, regs, &ka);
handle_signal(signr, &ka, &info, oldset, regs, sw);
if (single_stepping)
ptrace_set_bpt(current); /* re-set bpt */
return 1;
}
if (r0) {
switch (regs->r0) {
case ERESTARTNOHAND:
case ERESTARTSYS:
case ERESTARTNOINTR:
/* Reset v0 and a3 and replay syscall. */
regs->r0 = r0;
regs->r19 = r19;
regs->pc -= 4;
break;
case ERESTART_RESTARTBLOCK:
/* Force v0 to the restart syscall and reply. */
regs->r0 = __NR_restart_syscall;
regs->pc -= 4;
break;
}
}
if (single_stepping)
ptrace_set_bpt(current); /* re-set breakpoint */
return 0;
}
void
do_notify_resume(sigset_t *oldset, struct pt_regs *regs,
struct switch_stack *sw, unsigned long r0,
unsigned long r19, unsigned long thread_info_flags)
{
if (thread_info_flags & _TIF_SIGPENDING)
do_signal(oldset, regs, sw, r0, r19);
}
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