signal.c ( File view )

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			/*
* linux/kernel/signal.c
*
* (C) 1991 Linus Torvalds
*/

#include 	// ȳͷļṹtask_structʼ0 ݣ
// һЩйúͻȡǶʽຯ䡣
#include 	// ںͷļһЩں˳úԭζ塣
#include 	// βͷļйضμĴǶʽຯ

#include 		// źͷļźŷųźŽṹԼźŲԭ͡

volatile void do_exit (int error_code);	// ǰ޶volatile ҪҪŻ

// ȡǰźλͼ룩
int
sys_sgetmask ()
{

  return current->blocked;

}

// µźλͼSIGKILL ܱΡֵԭźλͼ
int
sys_ssetmask (int newmask)
{

  int old = current->blocked;

  current->blocked = newmask & ~(1 << (SIGKILL - 1));
  return old;

}

// sigaction ݵfs ݶto 
static inline void
save_old (char *from, char *to)
{

  int i;

  verify_area (to, sizeof (struct sigaction));	// ֤to ڴǷ㹻
  for (i = 0; i < sizeof (struct sigaction); i++)
    {

      put_fs_byte (*from, to);	// Ƶfs ΡһûݶΡ
      from++;			// put_fs_byte()include/asm/segment.h С
      to++;
    
}

}

// sigaction ݴfs ݶfrom λøƵto 
static inline void
get_new (char *from, char *to)
{

  int i;

  for (i = 0; i < sizeof (struct sigaction); i++)
    *(to++) = get_fs_byte (from++);

}

// signal()ϵͳásigaction()ΪָźŰװµźž(źŴ)
// źžûָĺҲSIG_DFLĬϾSIG_IGNԣ
// signum --ָźţhandler -- ָľrestorer Cԭǰִеĵַλá
// ԭźž
int
sys_signal (int signum, long handler, long restorer)
{

  struct sigaction tmp;

  if (signum < 1 || signum > 32 || signum == SIGKILL)	// źֵҪڣ1-32Χڣ
    return -1;			// ҲSIGKILL
  tmp.sa_handler = (void (*)(int)) handler;	// ָźŴ
  tmp.sa_mask = 0;		// ִʱź롣
  tmp.sa_flags = SA_ONESHOT | SA_NOMASK;	// þֻʹ1 κͻָĬֵ
// źԼĴյ
  tmp.sa_restorer = (void (*)(void)) restorer;	// 淵صַ
  handler = (long) current->sigaction[signum - 1].sa_handler;
  current->sigaction[signum - 1] = tmp;
  return handler;

}

// sigaction()ϵͳáıյһźʱIJsignum dzSIGKILL κ
// źš[²(action)Ϊ]²װoldaction ָ벻Ϊգԭ
// oldactionɹ򷵻0Ϊ-1
int
sys_sigaction (int signum, const struct sigaction *action,
	       struct sigaction *oldaction)
{

  struct sigaction tmp;

// źֵҪڣ1-32ΧڣźSIGKILL Ĵܱı䡣
  if (signum < 1 || signum > 32 || signum == SIGKILL)
    return -1;
// źŵsigaction ṹµIJ
  tmp = current->sigaction[signum - 1];
  get_new ((char *) action, (char *) (signum - 1 + current->sigaction));
// oldaction ָ벻ΪյĻԭָ뱣浽oldaction ָλá
  if (oldaction)
    save_old ((char *) &tmp, (char *) oldaction);
// źԼźžյΪ0αźš
  if (current->sigaction[signum - 1].sa_flags & SA_NOMASK)
    current->sigaction[signum - 1].sa_mask = 0;
  else
    current->sigaction[signum - 1].sa_mask |= (1 << (signum - 1));
  return 0;

}

// ϵͳжϴźŴkernel/system_call.s,119 У
// öδҪǽźŵĴ뵽ûջУڱϵͳý
// غִźžȻִûij
void
do_signal (long signr, long eax, long ebx, long ecx, long edx,
	   long fs, long es, long ds,
	   long eip, long cs, long eflags, unsigned long *esp, long ss)
{

  unsigned long sa_handler;
  long old_eip = eip;
  struct sigaction *sa = current->sigaction + signr - 1;	//current->sigaction[signu-1]
  int longs;
  unsigned long *tmp_esp;

  sa_handler = (unsigned long) sa->sa_handler;
// źžΪSIG_IGN()򷵻أΪSIG_DFL(Ĭϴ)ź
// SIGCHLD 򷵻أ̵ִֹ
  if (sa_handler == 1)
    return;
  if (!sa_handler)
    {

      if (signr == SIGCHLD)
	return;
      else
	do_exit (1 << (signr - 1));	// [?? ΪʲôźλͼΪΪʲô!?]
// Ӧdo_exit(1<sa_flags & SA_ONESHOT)
    sa->sa_handler = NULL;
// δ뽫źŴ뵽ûջУͬʱҲsa_restorer,signr,(
// SA_NOMASK ûλ),eax,ecx,edx ΪԼԭϵͳõij򷵻ָ뼰־Ĵֵ
// ѹջڱϵͳж(0x80)ûʱִûźžȻ
// ټִû
// ûϵͳõĴָeip ָźŴ
  *(&eip) = sa_handler;
// źԼĴյźԼҲҪ̵ѹջ
  longs = (sa->sa_flags & SA_NOMASK) ? 7 : 8;
// ԭóûĶջָչ78֣ŵźžIJȣ
// ڴʹڴ泬ҳȣ
  *(&esp) -= longs;
  verify_area (esp, longs * 4);
// ûջдµϴsa_restorer, źsignr, blocked(SA_NOMASK λ),
// eax, ecx, edx, eflags ûԭָ롣
  tmp_esp = esp;
  put_fs_long ((long) sa->sa_restorer, tmp_esp++);
  put_fs_long (signr, tmp_esp++);
  if (!(sa->sa_flags & SA_NOMASK))
    put_fs_long (current->blocked, tmp_esp++);
  put_fs_long (eax, tmp_esp++);
  put_fs_long (ecx, tmp_esp++);
  put_fs_long (edx, tmp_esp++);
  put_fs_long (eflags, tmp_esp++);
  put_fs_long (old_eip, tmp_esp++);
  current->blocked |= sa->sa_mask;	// ()sa_mask еλ

}
			
...
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linux0.00 B0% 04-10-07
<boot>0.00 B04-10-07 15:01
bootsect.s12.49 kB08-01-04 21:38
head.s13.22 kB08-01-04 21:38
setup.s12.42 kB08-01-04 21:38
<fs>0.00 B04-10-07 15:01
bitmap.c8.46 kB02-09-04 13:12
block_dev.c3.95 kB02-09-04 13:12
buffer.c17.71 kB02-09-04 13:12
char_dev.c4.09 kB02-09-04 13:12
exec.c18.90 kB02-09-04 13:12
fcntl.c3.33 kB02-09-04 13:12
file_dev.c4.82 kB02-09-04 13:12
file_table.c209.00 B02-09-04 13:12
inode.c14.92 kB02-09-04 13:12
ioctl.c1.94 kB02-09-04 13:12
Makefile6.80 kB08-01-04 21:45
namei.c37.20 kB02-09-04 13:12
open.c10.00 kB02-09-04 13:12
pipe.c5.42 kB02-09-04 13:12
read_write.c5.86 kB02-09-04 13:12
stat.c2.69 kB02-09-04 13:12
super.c13.57 kB02-09-04 13:12
truncate.c2.46 kB02-09-04 13:12
<include>0.00 B04-10-07 15:01
a.out.h8.22 kB02-09-04 13:14
<asm>0.00 B04-10-07 15:01
io.h772.00 B02-09-04 13:14
memory.h1.03 kB08-01-04 22:13
segment.h2.50 kB02-09-04 13:14
system.h4.08 kB02-09-04 13:14
const.h589.00 B02-09-04 13:14
ctype.h1.68 kB02-09-04 13:14
errno.h2.30 kB02-09-04 13:14
fcntl.h3.30 kB02-09-04 13:14
<linux>0.00 B04-10-07 15:01
config.h2.16 kB02-09-04 13:14
fs.h9.72 kB02-09-04 13:14
hdreg.h2.94 kB02-09-04 13:14
head.h760.00 B02-09-04 13:14
kernel.h1.44 kB02-09-04 13:14
mm.h473.00 B02-09-04 13:14
sched.h13.25 kB02-09-04 13:14
sys.h5.41 kB02-09-04 13:14
tty.h3.93 kB02-09-04 13:14
signal.h4.01 kB02-09-04 13:14
stdarg.h1.77 kB02-09-04 13:14
stddef.h378.00 B02-09-04 13:14
string.h21.75 kB02-09-04 13:14
<sys>0.00 B04-10-07 15:01
stat.h2.37 kB02-09-04 13:14
times.h377.00 B02-09-04 13:14
types.h1.10 kB02-09-04 13:14
utsname.h423.00 B02-09-04 13:14
wait.h1.48 kB02-09-04 13:14
termios.h13.58 kB02-09-04 13:14
time.h1.81 kB02-09-04 13:14
unistd.h9.21 kB02-09-04 13:14
utime.h392.00 B02-09-04 13:14
<init>0.00 B04-10-07 15:01
main.c12.52 kB02-09-04 13:12
<kernel>0.00 B04-10-07 15:01
asm.s5.10 kB08-01-04 22:48
<blk_drv>0.00 B04-10-07 15:01
blk.h5.69 kB02-09-04 13:14
floppy.c23.49 kB02-09-04 13:12
hd.c17.14 kB02-09-04 13:12
ll_rw_blk.c7.59 kB02-09-04 13:12
Makefile4.25 kB08-01-04 22:53
ramdisk.c6.13 kB02-09-04 13:12
<chr_drv>0.00 B04-10-07 15:01
console.c30.91 kB02-09-04 13:12
keyboard.S21.04 kB08-01-04 22:59
Makefile4.81 kB08-01-04 22:59
rs_io.s5.75 kB08-01-04 22:59
serial.c2.91 kB02-09-04 13:12
tty_io.c18.40 kB02-09-04 13:12
tty_ioctl.c10.70 kB02-09-04 13:12
exit.c8.08 kB02-09-04 13:12
fork.c6.78 kB15-07-07 22:10
<math>0.00 B04-10-07 15:01
Makefile3.21 kB08-01-04 23:01
math_emulate.c2.08 kB02-09-04 13:12
mktime.c2.72 kB02-09-04 13:12
panic.c952.00 B02-09-04 13:12
printk.c1.75 kB02-09-04 13:12
sched.c18.57 kB16-07-07 21:23
signal.c5.61 kB02-09-04 13:12
sys.c7.62 kB02-09-04 13:12
system_call.s12.53 kB08-01-04 22:48
traps.c8.29 kB04-10-07 14:57
vsprintf.c9.96 kB02-09-04 13:12
<lib>0.00 B04-10-07 15:01
close.c397.00 B02-09-04 13:12
ctype.c1.72 kB02-09-04 13:12
dup.c401.00 B02-09-04 13:12
errno.c66.00 B02-09-04 13:12
execve.c607.00 B02-09-04 13:12
Makefile4.83 kB08-01-04 22:30
malloc.c13.50 kB02-09-04 13:12
open.c1.22 kB02-09-04 13:12
setsid.c382.00 B02-09-04 13:12
string.c199.00 B02-09-04 13:12
wait.c774.00 B02-09-04 13:12
write.c545.00 B02-09-04 13:12
_exit.c616.00 B02-09-04 13:12
Makefile8.58 kB08-01-04 22:21
<mm>0.00 B04-10-07 15:01
Makefile2.91 kB08-01-04 22:34
memory.c25.10 kB02-09-04 13:12
page.s842.00 B08-01-04 22:34
<tools>0.00 B04-10-07 15:01
build.c8.12 kB02-09-04 13:12
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