projects / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 1da177e4 LT |
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 | while(cur == *cnt) { | |
| 22 | pipe_wait(inode); | |
| 23 | if(signal_pending(current)) | |
| 24 | break; | |
| 25 | } | |
| 26 | } | |
| 27 | ||
| 28 | static void wake_up_partner(struct inode* inode) | |
| 29 | { | |
| 30 | wake_up_interruptible(PIPE_WAIT(*inode)); | |
| 31 | } | |
| 32 | ||
| 33 | static int fifo_open(struct inode *inode, struct file *filp) | |
| 34 | { | |
| 35 | int ret; | |
| 36 | ||
| 37 | ret = -ERESTARTSYS; | |
| 38 | if (down_interruptible(PIPE_SEM(*inode))) | |
| 39 | goto err_nolock_nocleanup; | |
| 40 | ||
| 41 | if (!inode->i_pipe) { | |
| 42 | ret = -ENOMEM; | |
| 43 | if(!pipe_new(inode)) | |
| 44 | goto err_nocleanup; | |
| 45 | } | |
| 46 | filp->f_version = 0; | |
| 47 | ||
| 48 | /* We can only do regular read/write on fifos */ | |
| 49 | filp->f_mode &= (FMODE_READ | FMODE_WRITE); | |
| 50 | ||
| 51 | switch (filp->f_mode) { | |
| 52 | case 1: | |
| 53 | /* | |
| 54 | * O_RDONLY | |
| 55 | * POSIX.1 says that O_NONBLOCK means return with the FIFO | |
| 56 | * opened, even when there is no process writing the FIFO. | |
| 57 | */ | |
| 58 | filp->f_op = &read_fifo_fops; | |
| 59 | PIPE_RCOUNTER(*inode)++; | |
| 60 | if (PIPE_READERS(*inode)++ == 0) | |
| 61 | wake_up_partner(inode); | |
| 62 | ||
| 63 | if (!PIPE_WRITERS(*inode)) { | |
| 64 | if ((filp->f_flags & O_NONBLOCK)) { | |
| 65 | /* suppress POLLHUP until we have | |
| 66 | * seen a writer */ | |
| 67 | filp->f_version = PIPE_WCOUNTER(*inode); | |
| 68 | } else | |
| 69 | { | |
| 70 | wait_for_partner(inode, &PIPE_WCOUNTER(*inode)); | |
| 71 | if(signal_pending(current)) | |
| 72 | goto err_rd; | |
| 73 | } | |
| 74 | } | |
| 75 | break; | |
| 76 | ||
| 77 | case 2: | |
| 78 | /* | |
| 79 | * O_WRONLY | |
| 80 | * POSIX.1 says that O_NONBLOCK means return -1 with | |
| 81 | * errno=ENXIO when there is no process reading the FIFO. | |
| 82 | */ | |
| 83 | ret = -ENXIO; | |
| 84 | if ((filp->f_flags & O_NONBLOCK) && !PIPE_READERS(*inode)) | |
| 85 | goto err; | |
| 86 | ||
| 87 | filp->f_op = &write_fifo_fops; | |
| 88 | PIPE_WCOUNTER(*inode)++; | |
| 89 | if (!PIPE_WRITERS(*inode)++) | |
| 90 | wake_up_partner(inode); | |
| 91 | ||
| 92 | if (!PIPE_READERS(*inode)) { | |
| 93 | wait_for_partner(inode, &PIPE_RCOUNTER(*inode)); | |
| 94 | if (signal_pending(current)) | |
| 95 | goto err_wr; | |
| 96 | } | |
| 97 | break; | |
| 98 | ||
| 99 | case 3: | |
| 100 | /* | |
| 101 | * O_RDWR | |
| 102 | * POSIX.1 leaves this case "undefined" when O_NONBLOCK is set. | |
| 103 | * This implementation will NEVER block on a O_RDWR open, since | |
| 104 | * the process can at least talk to itself. | |
| 105 | */ | |
| 106 | filp->f_op = &rdwr_fifo_fops; | |
| 107 | ||
| 108 | PIPE_READERS(*inode)++; | |
| 109 | PIPE_WRITERS(*inode)++; | |
| 110 | PIPE_RCOUNTER(*inode)++; | |
| 111 | PIPE_WCOUNTER(*inode)++; | |
| 112 | if (PIPE_READERS(*inode) == 1 || PIPE_WRITERS(*inode) == 1) | |
| 113 | wake_up_partner(inode); | |
| 114 | break; | |
| 115 | ||
| 116 | default: | |
| 117 | ret = -EINVAL; | |
| 118 | goto err; | |
| 119 | } | |
| 120 | ||
| 121 | /* Ok! */ | |
| 122 | up(PIPE_SEM(*inode)); | |
| 123 | return 0; | |
| 124 | ||
| 125 | err_rd: | |
| 126 | if (!--PIPE_READERS(*inode)) | |
| 127 | wake_up_interruptible(PIPE_WAIT(*inode)); | |
| 128 | ret = -ERESTARTSYS; | |
| 129 | goto err; | |
| 130 | ||
| 131 | err_wr: | |
| 132 | if (!--PIPE_WRITERS(*inode)) | |
| 133 | wake_up_interruptible(PIPE_WAIT(*inode)); | |
| 134 | ret = -ERESTARTSYS; | |
| 135 | goto err; | |
| 136 | ||
| 137 | err: | |
| 138 | if (!PIPE_READERS(*inode) && !PIPE_WRITERS(*inode)) | |
| 139 | free_pipe_info(inode); | |
| 140 | ||
| 141 | err_nocleanup: | |
| 142 | up(PIPE_SEM(*inode)); | |
| 143 | ||
| 144 | err_nolock_nocleanup: | |
| 145 | return ret; | |
| 146 | } | |
| 147 | ||
| 148 | /* | |
| 149 | * Dummy default file-operations: the only thing this does | |
| 150 | * is contain the open that then fills in the correct operations | |
| 151 | * depending on the access mode of the file... | |
| 152 | */ | |
| 153 | struct file_operations def_fifo_fops = { | |
| 154 | .open = fifo_open, /* will set read or write pipe_fops */ | |
| 155 | }; |