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* linux/fs/pipe.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
#include <asm/segment.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/fcntl.h>
#include <linux/termios.h>
static int pipe_read(struct inode * inode, struct file * filp, char * buf, int count)
{
int chars, size, read = 0;
if (!(filp->f_flags & O_NONBLOCK))
while (!PIPE_SIZE(*inode)) {
wake_up(& PIPE_WRITE_WAIT(*inode));
if (!PIPE_WRITERS(*inode)) /* are there any writers? */
return 0;
if (current->signal & ~current->blocked)
return -ERESTARTSYS;
interruptible_sleep_on(& PIPE_READ_WAIT(*inode));
}
while (count>0 && (size = PIPE_SIZE(*inode))) {
chars = PAGE_SIZE-PIPE_TAIL(*inode);
if (chars > count)
chars = count;
if (chars > size)
chars = size;
memcpy_tofs(buf, PIPE_BASE(*inode)+PIPE_TAIL(*inode), chars );
read += chars;
PIPE_TAIL(*inode) += chars;
PIPE_TAIL(*inode) &= (PAGE_SIZE-1);
count -= chars;
buf += chars;
}
wake_up(& PIPE_WRITE_WAIT(*inode));
return read?read:-EAGAIN;
}
static int pipe_write(struct inode * inode, struct file * filp, char * buf, int count)
{
int chars, size, written = 0;
if (!PIPE_READERS(*inode)) { /* no readers */
send_sig(SIGPIPE,current,0);
return -EPIPE;
}
/* if count < PAGE_SIZE, we have to make it atomic */
if (count < PAGE_SIZE)
size = PAGE_SIZE-count;
else
size = PAGE_SIZE-1;
while (count>0) {
while (PIPE_SIZE(*inode) >= size) {
if (!PIPE_READERS(*inode)) { /* no readers */
send_sig(SIGPIPE,current,0);
return written?written:-EPIPE;
}
if (current->signal & ~current->blocked)
return written?written:-ERESTARTSYS;
if (filp->f_flags & O_NONBLOCK)
return -EAGAIN;
else
interruptible_sleep_on(&PIPE_WRITE_WAIT(*inode));
}
while (count>0 && (size = (PAGE_SIZE-1)-PIPE_SIZE(*inode))) {
chars = PAGE_SIZE-PIPE_HEAD(*inode);
if (chars > count)
chars = count;
if (chars > size)
chars = size;
memcpy_fromfs(PIPE_BASE(*inode)+PIPE_HEAD(*inode), buf, chars );
written += chars;
PIPE_HEAD(*inode) += chars;
PIPE_HEAD(*inode) &= (PAGE_SIZE-1);
count -= chars;
buf += chars;
}
wake_up(& PIPE_READ_WAIT(*inode));
size = PAGE_SIZE-1;
}
return written;
}
static int pipe_lseek(struct inode * inode, struct file * file, off_t offset, int orig)
{
return -ESPIPE;
}
static int pipe_readdir(struct inode * inode, struct file * file, struct dirent * de, int count)
{
return -ENOTDIR;
}
static int bad_pipe_rw(struct inode * inode, struct file * filp, char * buf, int count)
{
return -EBADF;
}
static int pipe_ioctl(struct inode *pino, struct file * filp,
unsigned int cmd, unsigned int arg)
{
switch (cmd) {
case FIONREAD:
verify_area((void *) arg,4);
put_fs_long(PIPE_SIZE(*pino),(unsigned long *) arg);
return 0;
default:
return -EINVAL;
}
}
static int pipe_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait)
{
switch (sel_type) {
case SEL_IN:
if (!PIPE_EMPTY(*inode) || !PIPE_WRITERS(*inode))
return 1;
select_wait(&PIPE_READ_WAIT(*inode), wait);
return 0;
case SEL_OUT:
if (!PIPE_FULL(*inode) || !PIPE_WRITERS(*inode))
return 1;
select_wait(&PIPE_WRITE_WAIT(*inode), wait);
return 0;
case SEL_EX:
if (!PIPE_READERS(*inode) || !PIPE_WRITERS(*inode))
return 1;
select_wait(&inode->i_wait,wait);
return 0;
}
return 0;
}
/*
* Ok, these three routines NOW keep track of readers/writers,
* Linus previously did it with inode->i_count checking.
*/
static void pipe_read_release(struct inode * inode, struct file * filp)
{
PIPE_READERS(*inode)--;
wake_up(&PIPE_WRITE_WAIT(*inode));
}
static void pipe_write_release(struct inode * inode, struct file * filp)
{
PIPE_WRITERS(*inode)--;
wake_up(&PIPE_READ_WAIT(*inode));
}
static void pipe_rdwr_release(struct inode * inode, struct file * filp)
{
PIPE_READERS(*inode)--;
PIPE_WRITERS(*inode)--;
wake_up(&PIPE_READ_WAIT(*inode));
wake_up(&PIPE_WRITE_WAIT(*inode));
}
/*
* The three file_operations structs are not static because they
* are also used in linux/fs/fifo.c to do operations on fifo's.
*/
struct file_operations read_pipe_fops = {
pipe_lseek,
pipe_read,
bad_pipe_rw,
pipe_readdir,
pipe_select,
pipe_ioctl,
NULL, /* no mmap on pipes.. surprise */
NULL, /* no special open code */
pipe_read_release
};
struct file_operations write_pipe_fops = {
pipe_lseek,
bad_pipe_rw,
pipe_write,
pipe_readdir,
pipe_select,
pipe_ioctl,
NULL, /* mmap */
NULL, /* no special open code */
pipe_write_release
};
struct file_operations rdwr_pipe_fops = {
pipe_lseek,
pipe_read,
pipe_write,
pipe_readdir,
pipe_select,
pipe_ioctl,
NULL, /* mmap */
NULL, /* no special open code */
pipe_rdwr_release
};
int sys_pipe(unsigned long * fildes)
{
struct inode * inode;
struct file * f[2];
int fd[2];
int i,j;
verify_area(fildes,8);
for(j=0 ; j<2 ; j++)
if (!(f[j] = get_empty_filp()))
break;
if (j==1)
f[0]->f_count--;
if (j<2)
return -ENFILE;
j=0;
for(i=0;j<2 && i<NR_OPEN;i++)
if (!current->filp[i]) {
current->filp[ fd[j]=i ] = f[j];
j++;
}
if (j==1)
current->filp[fd[0]]=NULL;
if (j<2) {
f[0]->f_count--;
f[1]->f_count--;
return -EMFILE;
}
if (!(inode=get_pipe_inode())) {
current->filp[fd[0]] = NULL;
current->filp[fd[1]] = NULL;
f[0]->f_count--;
f[1]->f_count--;
return -ENFILE;
}
f[0]->f_inode = f[1]->f_inode = inode;
f[0]->f_pos = f[1]->f_pos = 0;
f[0]->f_flags = f[1]->f_flags = 0;
f[0]->f_op = &read_pipe_fops;
f[0]->f_mode = 1; /* read */
f[1]->f_op = &write_pipe_fops;
f[1]->f_mode = 2; /* write */
put_fs_long(fd[0],0+fildes);
put_fs_long(fd[1],1+fildes);
return 0;
}
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