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