[PATCH] get rid of the PIPE_*() macros
[linux-2.6.git] / fs / fifo.c
1 /*
2  *  linux/fs/fifo.c
3  *
4  *  written by Paul H. Hargrove
5  *
6  *  Fixes:
7  *      10-06-1999, AV: fixed OOM handling in fifo_open(), moved
8  *                      initialization there, switched to external
9  *                      allocation of pipe_inode_info.
10  */
11
12 #include <linux/mm.h>
13 #include <linux/slab.h>
14 #include <linux/smp_lock.h>
15 #include <linux/fs.h>
16 #include <linux/pipe_fs_i.h>
17
18 static void wait_for_partner(struct inode* inode, unsigned int *cnt)
19 {
20         int cur = *cnt; 
21
22         while (cur == *cnt) {
23                 pipe_wait(inode->i_pipe);
24                 if (signal_pending(current))
25                         break;
26         }
27 }
28
29 static void wake_up_partner(struct inode* inode)
30 {
31         wake_up_interruptible(&inode->i_pipe->wait);
32 }
33
34 static int fifo_open(struct inode *inode, struct file *filp)
35 {
36         int ret;
37
38         mutex_lock(&inode->i_mutex);
39         if (!inode->i_pipe) {
40                 ret = -ENOMEM;
41                 inode->i_pipe = alloc_pipe_info(inode);
42                 if (!inode->i_pipe)
43                         goto err_nocleanup;
44         }
45         filp->f_version = 0;
46
47         /* We can only do regular read/write on fifos */
48         filp->f_mode &= (FMODE_READ | FMODE_WRITE);
49
50         switch (filp->f_mode) {
51         case 1:
52         /*
53          *  O_RDONLY
54          *  POSIX.1 says that O_NONBLOCK means return with the FIFO
55          *  opened, even when there is no process writing the FIFO.
56          */
57                 filp->f_op = &read_fifo_fops;
58                 inode->i_pipe->r_counter++;
59                 if (inode->i_pipe->readers++ == 0)
60                         wake_up_partner(inode);
61
62                 if (!inode->i_pipe->writers) {
63                         if ((filp->f_flags & O_NONBLOCK)) {
64                                 /* suppress POLLHUP until we have
65                                  * seen a writer */
66                                 filp->f_version = inode->i_pipe->w_counter;
67                         } else 
68                         {
69                                 wait_for_partner(inode, &inode->i_pipe->w_counter);
70                                 if(signal_pending(current))
71                                         goto err_rd;
72                         }
73                 }
74                 break;
75         
76         case 2:
77         /*
78          *  O_WRONLY
79          *  POSIX.1 says that O_NONBLOCK means return -1 with
80          *  errno=ENXIO when there is no process reading the FIFO.
81          */
82                 ret = -ENXIO;
83                 if ((filp->f_flags & O_NONBLOCK) && !inode->i_pipe->readers)
84                         goto err;
85
86                 filp->f_op = &write_fifo_fops;
87                 inode->i_pipe->w_counter++;
88                 if (!inode->i_pipe->writers++)
89                         wake_up_partner(inode);
90
91                 if (!inode->i_pipe->readers) {
92                         wait_for_partner(inode, &inode->i_pipe->r_counter);
93                         if (signal_pending(current))
94                                 goto err_wr;
95                 }
96                 break;
97         
98         case 3:
99         /*
100          *  O_RDWR
101          *  POSIX.1 leaves this case "undefined" when O_NONBLOCK is set.
102          *  This implementation will NEVER block on a O_RDWR open, since
103          *  the process can at least talk to itself.
104          */
105                 filp->f_op = &rdwr_fifo_fops;
106
107                 inode->i_pipe->readers++;
108                 inode->i_pipe->writers++;
109                 inode->i_pipe->r_counter++;
110                 inode->i_pipe->w_counter++;
111                 if (inode->i_pipe->readers == 1 || inode->i_pipe->writers == 1)
112                         wake_up_partner(inode);
113                 break;
114
115         default:
116                 ret = -EINVAL;
117                 goto err;
118         }
119
120         /* Ok! */
121         mutex_unlock(&inode->i_mutex);
122         return 0;
123
124 err_rd:
125         if (!--inode->i_pipe->readers)
126                 wake_up_interruptible(&inode->i_pipe->wait);
127         ret = -ERESTARTSYS;
128         goto err;
129
130 err_wr:
131         if (!--inode->i_pipe->writers)
132                 wake_up_interruptible(&inode->i_pipe->wait);
133         ret = -ERESTARTSYS;
134         goto err;
135
136 err:
137         if (!inode->i_pipe->readers && !inode->i_pipe->writers)
138                 free_pipe_info(inode);
139
140 err_nocleanup:
141         mutex_unlock(&inode->i_mutex);
142         return ret;
143 }
144
145 /*
146  * Dummy default file-operations: the only thing this does
147  * is contain the open that then fills in the correct operations
148  * depending on the access mode of the file...
149  */
150 const struct file_operations def_fifo_fops = {
151         .open           = fifo_open,    /* will set read or write pipe_fops */
152 };