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#include <signal.h>
#include <linux/sched.h>
#include <linux/mm.h> /* for get_free_page */
#include <asm/segment.h>
int read_pipe(struct m_inode * inode, char * buf, int count)
{
char * b=buf;
while (PIPE_EMPTY(*inode)) {
wake_up(&inode->i_wait);
if (inode->i_count != 2) /* are there any writers left? */
return 0;
sleep_on(&inode->i_wait);
}
while (count>0 && !(PIPE_EMPTY(*inode))) {
count --;
put_fs_byte(((char *)inode->i_size)[PIPE_TAIL(*inode)],b++);
INC_PIPE( PIPE_TAIL(*inode) );
}
wake_up(&inode->i_wait);
return b-buf;
}
int write_pipe(struct m_inode * inode, char * buf, int count)
{
char * b=buf;
wake_up(&inode->i_wait);
if (inode->i_count != 2) { /* no readers */
current->signal |= (1<<(SIGPIPE-1));
return -1;
}
while (count-->0) {
while (PIPE_FULL(*inode)) {
wake_up(&inode->i_wait);
if (inode->i_count != 2) {
current->signal |= (1<<(SIGPIPE-1));
return b-buf;
}
sleep_on(&inode->i_wait);
}
((char *)inode->i_size)[PIPE_HEAD(*inode)] = get_fs_byte(b++);
INC_PIPE( PIPE_HEAD(*inode) );
wake_up(&inode->i_wait);
}
wake_up(&inode->i_wait);
return b-buf;
}
int sys_pipe(unsigned long * fildes)
{
struct m_inode * inode;
struct file * f[2];
int fd[2];
int i,j;
j=0;
for(i=0;j<2 && i<NR_FILE;i++)
if (!file_table[i].f_count)
(f[j++]=i+file_table)->f_count++;
if (j==1)
f[0]->f_count=0;
if (j<2)
return -1;
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=0;
return -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;
}
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 */
put_fs_long(fd[0],0+fildes);
put_fs_long(fd[1],1+fildes);
return 0;
}
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