pipe.c ( File view )

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			/*
* linux/fs/pipe.c
*
* (C) 1991 Linus Torvalds
*/

#include 		// źͷļźŷųźŽṹԼźŲԭ͡

#include 	// ȳͷļṹtask_structʼ0 ݣ
// һЩйúͻȡǶʽຯ䡣
#include  /* for get_free_page */	/* ʹеget_free_page */
// ڴͷļҳСһЩҳͷźԭ͡
#include 	// βͷļйضμĴǶʽຯ

//// ܵ
// inode ǹܵӦi ڵ㣬buf ݻָ룬count Ƕȡֽ
int
read_pipe (struct m_inode *inode, char *buf, int count)
{

  int chars, size, read = 0;

// ȡֽڼֵcount 0ѭִ²
  while (count > 0)
    {

// ǰܵû(size=0)ѵȴýڵḶ̌ûдܵߣ򷵻Ѷ
// ֽ˳ڸi ڵ˯ߣȴϢ
      while (!(size = PIPE_SIZE (*inode)))
	{

	  wake_up (&inode->i_wait);
	  ܵ(PAGE_SIZE)  ܵݳ(PIPE_SIZE)  ָtail (i_zone[1])  ָhead (i_zone[0])  ָ(i_size) if (inode->i_count != 2)	/* are there any writers? */
	    return read;
	  sleep_on (&inode->i_wait);
	
}
// ȡܵβĩ˵ֽcharsڻҪȡֽcountcount
// chars ڵǰܵкݵijsizesize
      chars = PAGE_SIZE - PIPE_TAIL (*inode);
      if (chars > count)
	chars = count;
      if (chars > size)
	chars = size;
// ֽڼȥ˴οɶֽcharsۼѶֽ
      count -= chars;
      read += chars;
// size ָܵβǰܵβָ루ǰchars ֽڣ
      size = PIPE_TAIL (*inode);
      PIPE_TAIL (*inode) += chars;
      PIPE_TAIL (*inode) &= (PAGE_SIZE - 1);
// ܵеݸƵûСڹܵi ڵ㣬i_size ֶǹָܵ롣
      while (chars-- > 0)
	put_fs_byte (((char *) inode->i_size)[size++], buf++);
    
}
// ѵȴùܵi ڵḶ̌ضȡֽ
  wake_up (&inode->i_wait);
  return read;

}

//// ܵд
// inode ǹܵӦi ڵ㣬buf ݻָ룬count ǽдֽܵ
int
write_pipe (struct m_inode *inode, char *buf, int count)
{

  int chars, size, written = 0;

// дֽڼֵcount 0ѭִ²
  while (count > 0)
    {

// ǰܵûѾ(size=0)ѵȴýڵḶ̌ûжܵߣ
// SIGPIPE źţдֽ˳д0 ֽڣ򷵻-1ڸi ڵ
// ˯ߣȴܵڳռ䡣
      while (!(size = (PAGE_SIZE - 1) - PIPE_SIZE (*inode)))
	{

	  wake_up (&inode->i_wait);
	  if (inode->i_count != 2)
	    {
			/* no readers */
	      current->signal |= (1 << (SIGPIPE - 1));
	      return written ? written : -1;
	    
}
	  sleep_on (&inode->i_wait);
	
}
// ȡܵͷĩ˿ռֽcharsڻҪдֽcount
// countchars ڵǰܵппռ䳤sizesize
      chars = PAGE_SIZE - PIPE_HEAD (*inode);
      if (chars > count)
	chars = count;
      if (chars > size)
	chars = size;
// дֽڼȥ˴οдֽcharsۼдֽwritten
      count -= chars;
      written += chars;
// size ָܵͷǰܵͷָ루ǰchars ֽڣ
      size = PIPE_HEAD (*inode);
      PIPE_HEAD (*inode) += chars;
      PIPE_HEAD (*inode) &= (PAGE_SIZE - 1);
// ûchars ֽڵܵСڹܵi ڵ㣬i_size ֶǹָܵ롣
      while (chars-- > 0)
	((char *) inode->i_size)[size++] = get_fs_byte (buf++);
    
}
// ѵȴi ڵḶ̌дֽ˳
  wake_up (&inode->i_wait);
  return written;

}

//// ܵϵͳú
// fildes ָдһļ()ļָһܵi ڵ㡣fildes[0]
// ڶܵݣfildes[1]ܵдݡ
// ɹʱ0ʱ-1
int
sys_pipe (unsigned long *fildes)
{

  struct m_inode *inode;
  struct file *f[2];
  int fd[2];
  int i, j;

// ϵͳļȡüֶΪ0 ֱüΪ1
  j = 0;
  for (i = 0; j < 2 && i < NR_FILE; i++)
    if (!file_table[i].f_count)
      (f[j++] = i + file_table)->f_count++;
// ֻһͷŸ(üλ)
  if (j == 1)
    f[0]->f_count = 0;
// ûҵ򷵻-1
  if (j < 2)
    return -1;
// ȡõļṹֱһļʹ̵ļṹֱָָ
// ļṹ
  j = 0;
  for (i = 0; j < 2 && i < NR_OPEN; i++)
    if (!current->filp[i])
      {

	current->filp[fd[j] = i] = f[j];
	j++;
      
}
// ֻһļͷŸþ
  if (j == 1)
    current->filp[fd[0]] = NULL;
// ûҵоͷȡļṹλüֵ-1
  if (j < 2)
    {

      f[0]->f_count = f[1]->f_count = 0;
      return -1;
    
}
// ܵi ڵ㣬Ϊܵ仺1 ҳڴ棩ɹӦͷļ
// ṹ-1
  if (!(inode = get_pipe_inode ()))
    {

      current->filp[fd[0]] = current->filp[fd[1]] = NULL;
      f[0]->f_count = f[1]->f_count = 0;
      return -1;
    
}
// ʼļṹָͬһi ڵ㣬дָ붼㡣1 ļṹļģʽΪ
// 2 ļṹļģʽΪд
  f[0]->f_inode = f[1]->f_inode = inode;
  f[0]->f_pos = f[1]->f_pos = 0;
  f[0]->f_mode = 1;		/* read */
  f[1]->f_mode = 2;		/* write */
// ļ鸴ƵӦûУ0˳
  put_fs_long (fd[0], 0 + fildes);
  put_fs_long (fd[1], 1 + fildes);
  return 0;

}
			
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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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