/* write 'n' bytes from 'buf' in the file referenced by 'fd' */
ssize_t fs_write(struct file_s *flip, char *buf, size_t n)
{
return fs_readwrite(flip, buf, n, FS_WRITE);
}
PRIVATE int uds_perform_write(int minor, endpoint_t m_source,
size_t size, int pretend)
{
int rc, peer, i;
message fs_m_in;
message fs_m_out;
#if DEBUG == 1
static int call_count = 0;
printf("(uds) [%d] uds_perform_write() call_count=%d\n", minor,
++call_count);
#endif
/* skip reads and writes of 0 (or less!) bytes */
if (size <= 0) {
return 0;
}
/* check if we are allowed to write */
if (!(uds_fd_table[minor].mode & S_IWUSR)) {
/* socket is shutdown for writing */
errno = EPIPE;
return -1;
}
if (size > PIPE_BUF) {
/* message is too big to ever write to the PIPE */
errno = EMSGSIZE;
return -1;
}
if (uds_fd_table[minor].type == SOCK_STREAM ||
uds_fd_table[minor].type == SOCK_SEQPACKET) {
/* if we're writing with a connection oriented socket,
* then it needs a peer to write to
*/
if (uds_fd_table[minor].peer == -1) {
if (uds_fd_table[minor].err == ECONNRESET) {
uds_fd_table[minor].err = 0;
errno = ECONNRESET;
} else {
errno = ENOTCONN;
}
return -1;
} else {
peer = uds_fd_table[minor].peer;
}
} else /* uds_fd_table[minor].type == SOCK_DGRAM */ {
peer = -1;
/* locate the "peer" we want to write to */
for (i = 0; i < NR_FDS; i++) {
/* look for a SOCK_DGRAM socket that is bound on
* the target address
*/
if (uds_fd_table[i].type == SOCK_DGRAM &&
uds_fd_table[i].addr.sun_family == AF_UNIX &&
!strncmp(uds_fd_table[minor].target.sun_path,
uds_fd_table[i].addr.sun_path, UNIX_PATH_MAX)) {
peer = i;
break;
}
}
if (peer == -1) {
errno = ENOENT;
return -1;
}
}
/* check if write would overrun buffer. check if message
* boundry preserving types (SEQPACKET and DGRAM) wouldn't write
* to an empty buffer. check if connectionless sockets have a
* target to write to.
*/
if ((uds_fd_table[peer].pos+uds_fd_table[peer].size+size > PIPE_BUF) ||
((uds_fd_table[minor].type == SOCK_SEQPACKET ||
uds_fd_table[minor].type == SOCK_DGRAM) &&
uds_fd_table[peer].size > 0) || (peer == -1)) {
if (pretend) {
return SUSPEND;
}
/* if needed revive the reader */
if (uds_fd_table[peer].suspended) {
uds_fd_table[peer].ready_to_revive = 1;
notify(m_source);
}
#if DEBUG == 1
printf("(uds) [%d] suspending write request\n", minor);
#endif
/* Process is reading from an empty pipe,
* suspend it so some bytes can be written
*/
uds_fd_table[minor].suspended = UDS_SUSPENDED_WRITE;
return SUSPEND;
}
if (pretend) {
return size;
}
/* Prepare Request to the FS side of PFS */
fs_m_in.m_type = REQ_WRITE;
fs_m_in.REQ_INODE_NR = uds_fd_table[peer].inode_nr;
fs_m_in.REQ_GRANT = uds_fd_table[minor].io_gr;
fs_m_in.REQ_SEEK_POS_HI = 0;
fs_m_in.REQ_SEEK_POS_LO = uds_fd_table[peer].pos +
uds_fd_table[peer].size;
fs_m_in.REQ_NBYTES = size;
/* Request the write */
rc = fs_readwrite(&fs_m_in, &fs_m_out);
if (rc != OK) {
perror("fs_readwrite");
return rc;
}
/* Process the response */
#if DEBUG == 1
printf("(uds) [%d] write complete\n", minor);
#endif
/* increase the count of unread bytes */
uds_fd_table[peer].size += fs_m_out.RES_NBYTES;
/* fill in the source address to be returned by recvfrom & recvmsg */
if (uds_fd_table[minor].type == SOCK_DGRAM) {
memcpy(&uds_fd_table[peer].source, &uds_fd_table[minor].addr,
sizeof(struct sockaddr_un));
}
/* revive peer that was waiting for us to write */
if (uds_fd_table[peer].suspended) {
uds_fd_table[peer].ready_to_revive = 1;
notify(m_source);
}
/* see if peer is blocked on select()*/
if (uds_fd_table[peer].selecting == 1 && fs_m_out.RES_NBYTES > 0) {
/* if the peer wants to know about data ready to read
* and it doesn't know about it already, then let the peer
* know we have data for it.
*/
if ((uds_fd_table[peer].sel_ops_in & SEL_RD) &&
!(uds_fd_table[peer].sel_ops_out & SEL_RD)) {
/* a read on peer is possible now */
uds_fd_table[peer].sel_ops_out |= SEL_RD;
uds_fd_table[peer].status_updated = 1;
notify(uds_fd_table[peer].select_proc);
}
}
return fs_m_out.RES_NBYTES; /* return number of bytes written */
}
/* read 'n' bytes from a file a put them on buf */
size_t fs_read(struct file_s *flip, char *buf, size_t n)
{
return fs_readwrite(flip, buf, n, FS_READ);
}
PRIVATE int uds_perform_read(int minor, endpoint_t m_source,
size_t size, int pretend)
{
int rc;
message fs_m_in;
message fs_m_out;
#if DEBUG == 1
static int call_count = 0;
printf("(uds) [%d] uds_perform_read() call_count=%d\n", minor,
++call_count);
#endif
/* skip reads and writes of 0 (or less!) bytes */
if (size <= 0) {
return 0;
}
/* check if we are allowed to read */
if (!(uds_fd_table[minor].mode & S_IRUSR)) {
/* socket is shutdown for reading */
errno = EPIPE;
return -1;
}
if (uds_fd_table[minor].size == 0) {
if (pretend) {
return SUSPEND;
}
/* maybe a process is blocked waiting to write? if
* needed revive the writer
*/
if (uds_fd_table[minor].peer != -1 &&
uds_fd_table[uds_fd_table[minor].peer].suspended) {
int peer = uds_fd_table[minor].peer;
uds_fd_table[peer].ready_to_revive = 1;
notify(m_source);
}
#if DEBUG == 1
printf("(uds) [%d] suspending read request\n", minor);
#endif
/* Process is reading from an empty pipe,
* suspend it so some bytes can be written
*/
uds_fd_table[minor].suspended = UDS_SUSPENDED_READ;
return SUSPEND;
}
if (pretend) {
return (size > uds_fd_table[minor].size) ?
uds_fd_table[minor].size : size;
}
/* Prepare Request to the FS side of PFS */
fs_m_in.m_type = REQ_READ;
fs_m_in.REQ_INODE_NR = uds_fd_table[minor].inode_nr;
fs_m_in.REQ_GRANT = uds_fd_table[minor].io_gr;
fs_m_in.REQ_SEEK_POS_HI = 0;
fs_m_in.REQ_SEEK_POS_LO = uds_fd_table[minor].pos;
fs_m_in.REQ_NBYTES = (size > uds_fd_table[minor].size) ?
uds_fd_table[minor].size : size;
/* perform the read */
rc = fs_readwrite(&fs_m_in, &fs_m_out);
if (rc != OK) {
perror("fs_readwrite");
return rc;
}
/* Process the response */
#if DEBUG == 1
printf("(uds) [%d] read complete\n", minor);
#endif
/* move the position of the data pointer up to data we haven't
* read yet
*/
uds_fd_table[minor].pos += fs_m_out.RES_NBYTES;
/* decrease the number of unread bytes */
uds_fd_table[minor].size -= fs_m_out.RES_NBYTES;
/* if we have 0 unread bytes, move the data pointer back to the
* start of the buffer
*/
if (uds_fd_table[minor].size == 0) {
uds_fd_table[minor].pos = 0;
}
/* maybe a big write was waiting for us to read some data, if
* needed revive the writer
*/
if (uds_fd_table[minor].peer != -1 &&
uds_fd_table[uds_fd_table[minor].peer].suspended) {
uds_fd_table[uds_fd_table[minor].peer].ready_to_revive = 1;
notify(m_source);
}
/* see if peer is blocked on select() and a write is possible
* (from peer to minor)
*/
if (uds_fd_table[minor].peer != -1 &&
uds_fd_table[uds_fd_table[minor].peer].selecting == 1 &&
(uds_fd_table[minor].size + uds_fd_table[minor].pos + 1
< PIPE_BUF)) {
int peer = uds_fd_table[minor].peer;
/* if the peer wants to know about write being possible
* and it doesn't know about it already, then let the peer know.
*/
if ((uds_fd_table[peer].sel_ops_in & SEL_WR) &&
!(uds_fd_table[peer].sel_ops_out & SEL_WR)) {
/* a write on peer is possible now */
uds_fd_table[peer].sel_ops_out |= SEL_WR;
uds_fd_table[peer].status_updated = 1;
notify(uds_fd_table[peer].select_proc);
}
}
return fs_m_out.RES_NBYTES; /* return number of bytes read */
}
