ddeb562e1a
- simplify and repair UDS request handling state machine; - simplify interface used between internal modules; - implement missing support for nonblocking I/O; - fix select implementation; - clean up global variables. Change-Id: Ia82c5c6f05cc3f0a498efc9a26de14b1cde6eace
96 lines
2.6 KiB
C
96 lines
2.6 KiB
C
#include "fs.h"
|
|
#include "buf.h"
|
|
#include "inode.h"
|
|
#include <minix/com.h>
|
|
#include <string.h>
|
|
|
|
|
|
/*===========================================================================*
|
|
* fs_readwrite *
|
|
*===========================================================================*/
|
|
int fs_readwrite(message *fs_m_in, message *fs_m_out)
|
|
{
|
|
int r, rw_flag;
|
|
struct buf *bp;
|
|
cp_grant_id_t gid;
|
|
off_t position, f_size;
|
|
unsigned int nrbytes, cum_io;
|
|
pmode_t mode_word;
|
|
struct inode *rip;
|
|
pino_t inumb;
|
|
|
|
r = OK;
|
|
cum_io = 0;
|
|
inumb = (pino_t) fs_m_in->REQ_INODE_NR;
|
|
|
|
/* Find the inode referred */
|
|
if ((rip = find_inode(inumb)) == NULL) return(EINVAL);
|
|
|
|
mode_word = rip->i_mode & I_TYPE;
|
|
if (mode_word != I_NAMED_PIPE) return(EIO);
|
|
f_size = rip->i_size;
|
|
|
|
/* Get the values from the request message */
|
|
rw_flag = (fs_m_in->m_type == REQ_READ ? READING : WRITING);
|
|
gid = (cp_grant_id_t) fs_m_in->REQ_GRANT;
|
|
nrbytes = (unsigned) fs_m_in->REQ_NBYTES;
|
|
|
|
/* We can't read beyond the max file position */
|
|
if (nrbytes > PIPE_BUF) return(EFBIG);
|
|
|
|
/* Mark inode in use */
|
|
if ((get_inode(rip->i_dev, rip->i_num)) == NULL) return(err_code);
|
|
if ((bp = get_block(rip->i_dev, rip->i_num)) == NULL) return(err_code);
|
|
|
|
if (rw_flag == WRITING) {
|
|
/* Check in advance to see if file will grow too big. */
|
|
/* Casting nrbytes to signed is safe, because it's guaranteed not to
|
|
* be beyond max signed value (i.e., MAX_FILE_POS).
|
|
*/
|
|
position = rip->i_size;
|
|
if ((unsigned) position + nrbytes > PIPE_BUF) {
|
|
put_inode(rip);
|
|
put_block(rip->i_dev, rip->i_num);
|
|
return(EFBIG);
|
|
}
|
|
} else {
|
|
position = 0;
|
|
if (nrbytes > rip->i_size) {
|
|
/* There aren't that many bytes to read */
|
|
nrbytes = rip->i_size;
|
|
}
|
|
}
|
|
|
|
if (rw_flag == READING) {
|
|
/* Copy a chunk from the block buffer to user space. */
|
|
r = sys_safecopyto(fs_m_in->m_source, gid, (vir_bytes) 0,
|
|
(vir_bytes) (bp->b_data+position), (size_t) nrbytes);
|
|
} else {
|
|
/* Copy a chunk from user space to the block buffer. */
|
|
r = sys_safecopyfrom(fs_m_in->m_source, gid, (vir_bytes) 0,
|
|
(vir_bytes) (bp->b_data+position), (size_t) nrbytes);
|
|
}
|
|
|
|
if (r == OK) {
|
|
position += (signed) nrbytes; /* Update position */
|
|
cum_io += nrbytes;
|
|
}
|
|
|
|
/* On write, update file size and access time. */
|
|
if (rw_flag == WRITING) {
|
|
rip->i_size = position;
|
|
} else {
|
|
memmove(bp->b_data, bp->b_data+nrbytes, rip->i_size - nrbytes);
|
|
rip->i_size -= nrbytes;
|
|
}
|
|
|
|
if (rw_flag == READING) rip->i_update |= ATIME;
|
|
if (rw_flag == WRITING) rip->i_update |= CTIME | MTIME;
|
|
fs_m_out->RES_NBYTES = (size_t) cum_io;
|
|
fs_m_out->RES_SEEK_POS_LO = rip->i_size;
|
|
|
|
put_inode(rip);
|
|
put_block(rip->i_dev, rip->i_num);
|
|
|
|
return(r);
|
|
}
|