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[/] [or1k/] [trunk/] [rc203soc/] [sw/] [uClinux/] [fs/] [pipe.c] - Rev 1777
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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> #include <linux/mm.h> /* * Define this if you want SunOS compatibility wrt braindead * select behaviour on FIFO's. */ #undef FIFO_SUNOS_BRAINDAMAGE /* We don't use the head/tail construction any more. Now we use the start/len*/ /* construction providing full use of PIPE_BUF (multiple of PAGE_SIZE) */ /* Florian Coosmann (FGC) ^ current = 1 */ /* Additionally, we now use locking technique. This prevents race condition */ /* in case of paging and multiple read/write on the same pipe. (FGC) */ static int pipe_read(struct inode * inode, struct file * filp, char * buf, int count) { int chars = 0, size = 0, read = 0; char *pipebuf; if (filp->f_flags & O_NONBLOCK) { if (PIPE_LOCK(*inode)) return -EAGAIN; if (PIPE_EMPTY(*inode)) if (PIPE_WRITERS(*inode)) return -EAGAIN; else return 0; } else while (PIPE_EMPTY(*inode) || PIPE_LOCK(*inode)) { if (PIPE_EMPTY(*inode)) { if (!PIPE_WRITERS(*inode)) return 0; } if (current->signal & ~current->blocked) return -ERESTARTSYS; interruptible_sleep_on(&PIPE_WAIT(*inode)); } PIPE_LOCK(*inode)++; while (count>0 && (size = PIPE_SIZE(*inode))) { chars = PIPE_MAX_RCHUNK(*inode); if (chars > count) chars = count; if (chars > size) chars = size; read += chars; pipebuf = PIPE_BASE(*inode)+PIPE_START(*inode); PIPE_START(*inode) += chars; PIPE_START(*inode) &= (PIPE_BUF-1); PIPE_LEN(*inode) -= chars; count -= chars; memcpy_tofs(buf, pipebuf, chars ); buf += chars; } PIPE_LOCK(*inode)--; wake_up_interruptible(&PIPE_WAIT(*inode)); if (read) { UPDATE_ATIME(inode); return read; } if (PIPE_WRITERS(*inode)) return -EAGAIN; return 0; } static int pipe_write(struct inode * inode, struct file * filp, const char * buf, int count) { int chars = 0, free = 0, written = 0; char *pipebuf; if (!PIPE_READERS(*inode)) { /* no readers */ send_sig(SIGPIPE,current,0); return -EPIPE; } /* if count <= PIPE_BUF, we have to make it atomic */ if (count <= PIPE_BUF) free = count; else free = 1; /* can't do it atomically, wait for any free space */ while (count>0) { while ((PIPE_FREE(*inode) < free) || PIPE_LOCK(*inode)) { if (!PIPE_READERS(*inode)) { /* no readers */ send_sig(SIGPIPE,current,0); return written? :-EPIPE; } if (current->signal & ~current->blocked) return written? :-ERESTARTSYS; if (filp->f_flags & O_NONBLOCK) return written? :-EAGAIN; interruptible_sleep_on(&PIPE_WAIT(*inode)); } PIPE_LOCK(*inode)++; while (count>0 && (free = PIPE_FREE(*inode))) { chars = PIPE_MAX_WCHUNK(*inode); if (chars > count) chars = count; if (chars > free) chars = free; pipebuf = PIPE_BASE(*inode)+PIPE_END(*inode); written += chars; PIPE_LEN(*inode) += chars; count -= chars; memcpy_fromfs(pipebuf, buf, chars ); buf += chars; } PIPE_LOCK(*inode)--; wake_up_interruptible(&PIPE_WAIT(*inode)); free = 1; } inode->i_ctime = inode->i_mtime = CURRENT_TIME; return written; } static int pipe_lseek(struct inode * inode, struct file * file, off_t offset, int orig) { return -ESPIPE; } static int bad_pipe_r(struct inode * inode, struct file * filp, char * buf, int count) { return -EBADF; } static int bad_pipe_w(struct inode * inode, struct file * filp, const char * buf, int count) { return -EBADF; } static int pipe_ioctl(struct inode *pino, struct file * filp, unsigned int cmd, unsigned long arg) { int error; switch (cmd) { case FIONREAD: error = verify_area(VERIFY_WRITE, (void *) arg, sizeof(int)); if (!error) put_user(PIPE_SIZE(*pino),(int *) arg); return error; 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_WAIT(*inode), wait); return 0; case SEL_OUT: if (PIPE_EMPTY(*inode) || !PIPE_READERS(*inode)) return 1; select_wait(&PIPE_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; } #ifdef FIFO_SUNOS_BRAINDAMAGE /* * Arggh. Why does SunOS have to have different select() behaviour * for pipes and fifos? Hate-Hate-Hate. See difference in SEL_IN.. */ static int fifo_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait) { switch (sel_type) { case SEL_IN: if (!PIPE_EMPTY(*inode)) return 1; select_wait(&PIPE_WAIT(*inode), wait); return 0; case SEL_OUT: if (!PIPE_FULL(*inode) || !PIPE_READERS(*inode)) return 1; select_wait(&PIPE_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; } #else #define fifo_select pipe_select #endif /* FIFO_SUNOS_BRAINDAMAGE */ /* * The 'connect_xxx()' functions are needed for named pipes when * the open() code hasn't guaranteed a connection (O_NONBLOCK), * and we need to act differently until we do get a writer.. */ static int connect_read(struct inode * inode, struct file * filp, char * buf, int count) { if (PIPE_EMPTY(*inode) && !PIPE_WRITERS(*inode)) return 0; filp->f_op = &read_fifo_fops; return pipe_read(inode,filp,buf,count); } static int connect_select(struct inode * inode, struct file * filp, int sel_type, select_table * wait) { switch (sel_type) { case SEL_IN: if (!PIPE_EMPTY(*inode)) { filp->f_op = &read_fifo_fops; return 1; } if (PIPE_WRITERS(*inode)) { filp->f_op = &read_fifo_fops; } select_wait(&PIPE_WAIT(*inode), wait); return 0; case SEL_OUT: if (!PIPE_FULL(*inode)) return 1; select_wait(&PIPE_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; } static void pipe_read_release(struct inode * inode, struct file * filp) { PIPE_READERS(*inode)--; wake_up_interruptible(&PIPE_WAIT(*inode)); } static void pipe_write_release(struct inode * inode, struct file * filp) { PIPE_WRITERS(*inode)--; wake_up_interruptible(&PIPE_WAIT(*inode)); } static void pipe_rdwr_release(struct inode * inode, struct file * filp) { if (filp->f_mode & FMODE_READ) PIPE_READERS(*inode)--; if (filp->f_mode & FMODE_WRITE) PIPE_WRITERS(*inode)--; wake_up_interruptible(&PIPE_WAIT(*inode)); } static int pipe_read_open(struct inode * inode, struct file * filp) { PIPE_READERS(*inode)++; return 0; } static int pipe_write_open(struct inode * inode, struct file * filp) { PIPE_WRITERS(*inode)++; return 0; } static int pipe_rdwr_open(struct inode * inode, struct file * filp) { if (filp->f_mode & FMODE_READ) PIPE_READERS(*inode)++; if (filp->f_mode & FMODE_WRITE) PIPE_WRITERS(*inode)++; return 0; } /* * The 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 connecting_fifo_fops = { pipe_lseek, connect_read, bad_pipe_w, NULL, /* no readdir */ connect_select, pipe_ioctl, NULL, /* no mmap on pipes.. surprise */ pipe_read_open, pipe_read_release, NULL }; struct file_operations read_fifo_fops = { pipe_lseek, pipe_read, bad_pipe_w, NULL, /* no readdir */ fifo_select, pipe_ioctl, NULL, /* no mmap on pipes.. surprise */ pipe_read_open, pipe_read_release, NULL }; struct file_operations write_fifo_fops = { pipe_lseek, bad_pipe_r, pipe_write, NULL, /* no readdir */ fifo_select, pipe_ioctl, NULL, /* mmap */ pipe_write_open, pipe_write_release, NULL }; struct file_operations rdwr_fifo_fops = { pipe_lseek, pipe_read, pipe_write, NULL, /* no readdir */ fifo_select, pipe_ioctl, NULL, /* mmap */ pipe_rdwr_open, pipe_rdwr_release, NULL }; struct file_operations read_pipe_fops = { pipe_lseek, pipe_read, bad_pipe_w, NULL, /* no readdir */ pipe_select, pipe_ioctl, NULL, /* no mmap on pipes.. surprise */ pipe_read_open, pipe_read_release, NULL }; struct file_operations write_pipe_fops = { pipe_lseek, bad_pipe_r, pipe_write, NULL, /* no readdir */ pipe_select, pipe_ioctl, NULL, /* mmap */ pipe_write_open, pipe_write_release, NULL }; struct file_operations rdwr_pipe_fops = { pipe_lseek, pipe_read, pipe_write, NULL, /* no readdir */ pipe_select, pipe_ioctl, NULL, /* mmap */ pipe_rdwr_open, pipe_rdwr_release, NULL }; struct inode_operations pipe_inode_operations = { &rdwr_pipe_fops, NULL, /* create */ NULL, /* lookup */ NULL, /* link */ NULL, /* unlink */ NULL, /* symlink */ NULL, /* mkdir */ NULL, /* rmdir */ NULL, /* mknod */ NULL, /* rename */ NULL, /* readlink */ NULL, /* follow_link */ NULL, /* readpage */ NULL, /* writepage */ NULL, /* bmap */ NULL, /* truncate */ NULL /* permission */ }; int do_pipe(int *fd) { struct inode * inode; struct file *f1, *f2; int error; int i,j; error = -ENFILE; f1 = get_empty_filp(); if (!f1) goto no_files; f2 = get_empty_filp(); if (!f2) goto close_f1; inode = get_pipe_inode(); if (!inode) goto close_f12; error = get_unused_fd(); if (error < 0) goto close_f12_inode; i = error; error = get_unused_fd(); if (error < 0) goto close_f12_inode_i; j = error; f1->f_inode = f2->f_inode = inode; /* read file */ f1->f_pos = f2->f_pos = 0; f1->f_flags = O_RDONLY; f1->f_op = &read_pipe_fops; f1->f_mode = 1; /* write file */ f2->f_flags = O_WRONLY; f2->f_op = &write_pipe_fops; f2->f_mode = 2; current->files->fd[i] = f1; current->files->fd[j] = f2; fd[0] = i; fd[1] = j; return 0; close_f12_inode_i: put_unused_fd(i); close_f12_inode: inode->i_count--; iput(inode); close_f12: f2->f_count--; close_f1: f1->f_count--; no_files: return error; }
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