90 lines
2.6 KiB
C
90 lines
2.6 KiB
C
#include "fs.h"
|
|
#include "buf.h"
|
|
#include <minix/com.h>
|
|
#include "inode.h"
|
|
|
|
|
|
/*===========================================================================*
|
|
* fs_readwrite *
|
|
*===========================================================================*/
|
|
PUBLIC int fs_readwrite(void)
|
|
{
|
|
int r, rw_flag;
|
|
struct buf *bp;
|
|
cp_grant_id_t gid;
|
|
off_t position, f_size;
|
|
unsigned int nrbytes, cum_io;
|
|
mode_t mode_word;
|
|
struct inode *rip;
|
|
ino_t inumb;
|
|
|
|
r = OK;
|
|
cum_io = 0;
|
|
inumb = (ino_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;
|
|
position = fs_m_in.REQ_SEEK_POS_LO;
|
|
nrbytes = (unsigned) fs_m_in.REQ_NBYTES;
|
|
|
|
/* We can't read beyond the max file position */
|
|
if (nrbytes > MAX_FILE_POS) return(EFBIG);
|
|
|
|
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). */
|
|
if (position > PIPE_BUF - (signed) nrbytes) 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 == READING) {
|
|
/* Copy a chunk from the block buffer to user space. */
|
|
r = sys_safecopyto(FS_PROC_NR, gid, (vir_bytes) 0,
|
|
(vir_bytes) (bp->b_data+position), (size_t) nrbytes, D);
|
|
} else {
|
|
/* Copy a chunk from user space to the block buffer. */
|
|
r = sys_safecopyfrom(FS_PROC_NR, gid, (vir_bytes) 0,
|
|
(vir_bytes) (bp->b_data+position), (size_t) nrbytes, D);
|
|
}
|
|
|
|
if (r == OK) {
|
|
position += (signed) nrbytes; /* Update position */
|
|
cum_io += nrbytes;
|
|
}
|
|
|
|
fs_m_out.RES_SEEK_POS_LO = position; /* It might change later and the VFS
|
|
has to know this value */
|
|
|
|
/* On write, update file size and access time. */
|
|
if (rw_flag == WRITING) {
|
|
if (position > f_size) rip->i_size = position;
|
|
} else {
|
|
if(position >= rip->i_size) {
|
|
/* All data in the pipe is read, so reset pipe pointers */
|
|
rip->i_size = 0; /* no data left */
|
|
position = 0; /* reset reader(s) */
|
|
}
|
|
}
|
|
|
|
bp->b_bytes = position;
|
|
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;
|
|
put_inode(rip);
|
|
put_block(rip->i_dev, rip->i_num);
|
|
|
|
return(r);
|
|
}
|
|
|