363 lines
10 KiB
C
363 lines
10 KiB
C
/* This file contains the heart of the mechanism used to read (and write)
|
|
* files. Read and write requests are split up into chunks that do not cross
|
|
* block boundaries. Each chunk is then processed in turn. Reads on special
|
|
* files are also detected and handled.
|
|
*
|
|
* The entry points into this file are
|
|
* do_read: perform the READ system call by calling read_write
|
|
* do_getdents: read entries from a directory (GETDENTS)
|
|
* read_write: actually do the work of READ and WRITE
|
|
*
|
|
* Changes for VFS:
|
|
* Jul 2006 (Balazs Gerofi)
|
|
*/
|
|
|
|
#include "fs.h"
|
|
#include <fcntl.h>
|
|
#include <unistd.h>
|
|
#include <minix/com.h>
|
|
#include <minix/u64.h>
|
|
#include "file.h"
|
|
#include "fproc.h"
|
|
#include "param.h"
|
|
#include <dirent.h>
|
|
|
|
#include <minix/vfsif.h>
|
|
#include "vnode.h"
|
|
#include "vmnt.h"
|
|
|
|
|
|
/*===========================================================================*
|
|
* do_read *
|
|
*===========================================================================*/
|
|
PUBLIC int do_read()
|
|
{
|
|
return(read_write(READING));
|
|
}
|
|
|
|
|
|
/*===========================================================================*
|
|
* read_write *
|
|
*===========================================================================*/
|
|
PUBLIC int read_write(rw_flag)
|
|
int rw_flag; /* READING or WRITING */
|
|
{
|
|
/* Perform read(fd, buffer, nbytes) or write(fd, buffer, nbytes) call. */
|
|
register struct filp *f;
|
|
register struct vnode *vp;
|
|
off_t bytes_left, f_size;
|
|
u64_t position;
|
|
unsigned int off, cum_io;
|
|
int op, oflags, r, chunk, usr, seg, block_spec, char_spec;
|
|
int regular, partial_pipe = 0, partial_cnt = 0;
|
|
mode_t mode_word;
|
|
struct filp *wf;
|
|
phys_bytes p;
|
|
struct dmap *dp;
|
|
|
|
/* Request and response structures */
|
|
struct readwrite_req req;
|
|
struct readwrite_res res;
|
|
|
|
/* For block spec files */
|
|
struct breadwrite_req breq;
|
|
|
|
/* PM loads segments by putting funny things in other bits of the
|
|
* message, indicated by a high bit in fd. */
|
|
if (who_e == PM_PROC_NR && (m_in.fd & _PM_SEG_FLAG)) {
|
|
seg = (int) m_in.m1_p2;
|
|
usr = (int) m_in.m1_p3;
|
|
m_in.fd &= ~(_PM_SEG_FLAG); /* get rid of flag bit */
|
|
}
|
|
else {
|
|
usr = who_e; /* normal case */
|
|
seg = D;
|
|
}
|
|
|
|
/* If the file descriptor is valid, get the vnode, size and mode. */
|
|
if (m_in.nbytes < 0) return(EINVAL);
|
|
if ((f = get_filp(m_in.fd)) == NIL_FILP) return(err_code);
|
|
if (((f->filp_mode) & (rw_flag == READING ? R_BIT : W_BIT)) == 0) {
|
|
return(f->filp_mode == FILP_CLOSED ? EIO : EBADF);
|
|
}
|
|
|
|
if (m_in.nbytes == 0)
|
|
return(0); /* so char special files need not check for 0*/
|
|
|
|
/* check if user process has the memory it needs.
|
|
* if not, copying will fail later.
|
|
* do this after 0-check above because umap doesn't want to map 0 bytes. */
|
|
if ((r = sys_umap(usr, seg, (vir_bytes) m_in.buffer, m_in.nbytes, &p)) != OK)
|
|
{
|
|
printf("VFS: read_write: umap failed for process %d\n", usr);
|
|
return r;
|
|
}
|
|
|
|
position = f->filp_pos;
|
|
oflags = f->filp_flags;
|
|
|
|
vp = f->filp_vno;
|
|
f_size = vp->v_size;
|
|
|
|
r = OK;
|
|
if (vp->v_pipe == I_PIPE) {
|
|
/* fp->fp_cum_io_partial is only nonzero when doing partial writes */
|
|
cum_io = fp->fp_cum_io_partial;
|
|
}
|
|
else {
|
|
cum_io = 0;
|
|
}
|
|
|
|
op = (rw_flag == READING ? DEV_READ : DEV_WRITE);
|
|
mode_word = vp->v_mode & I_TYPE;
|
|
regular = mode_word == I_REGULAR || mode_word == I_NAMED_PIPE;
|
|
|
|
if ((char_spec = (mode_word == I_CHAR_SPECIAL ? 1 : 0))) {
|
|
if (vp->v_sdev == NO_DEV)
|
|
panic(__FILE__,"read_write tries to read from "
|
|
"character device NO_DEV", NO_NUM);
|
|
}
|
|
|
|
if ((block_spec = (mode_word == I_BLOCK_SPECIAL ? 1 : 0))) {
|
|
f_size = ULONG_MAX;
|
|
if (vp->v_sdev == NO_DEV)
|
|
panic(__FILE__,"read_write tries to read from "
|
|
" block device NO_DEV", NO_NUM);
|
|
}
|
|
|
|
/* Character special files. */
|
|
if (char_spec) {
|
|
dev_t dev;
|
|
/*dev = (dev_t) f->filp_ino->i_zone[0];*/
|
|
dev = (dev_t) vp->v_sdev;
|
|
r = dev_io(op, dev, usr, m_in.buffer, position, m_in.nbytes, oflags);
|
|
if (r >= 0) {
|
|
cum_io = r;
|
|
position = add64ul(position, r);
|
|
r = OK;
|
|
}
|
|
}
|
|
/* Block special files. */
|
|
else if (block_spec) {
|
|
/* Fill in the fields of the request */
|
|
breq.rw_flag = rw_flag;
|
|
breq.fs_e = vp->v_bfs_e;
|
|
breq.blocksize = vp->v_blocksize;
|
|
breq.dev = vp->v_sdev;
|
|
breq.user_e = usr;
|
|
breq.pos = position;
|
|
breq.num_of_bytes = m_in.nbytes;
|
|
breq.user_addr = m_in.buffer;
|
|
|
|
/* Issue request */
|
|
r = req_breadwrite(&breq, &res);
|
|
|
|
position = res.new_pos;
|
|
cum_io += res.cum_io;
|
|
}
|
|
/* Regular files */
|
|
else {
|
|
if (rw_flag == WRITING && block_spec == 0) {
|
|
/* Check for O_APPEND flag. */
|
|
if (oflags & O_APPEND) position = cvul64(f_size);
|
|
|
|
/* Check in advance to see if file will grow too big. */
|
|
if (cmp64ul(position, vp->v_vmnt->m_max_file_size - m_in.nbytes) > 0)
|
|
return(EFBIG);
|
|
|
|
}
|
|
|
|
/* Pipes are a little different. Check. */
|
|
if (vp->v_pipe == I_PIPE) {
|
|
r = pipe_check(vp, rw_flag, oflags,
|
|
m_in.nbytes, position, &partial_cnt, 0);
|
|
if (r <= 0) return(r);
|
|
}
|
|
|
|
if (partial_cnt > 0) {
|
|
/* So taht we don't need to deal with partial count
|
|
* in the FS process */
|
|
m_in.nbytes = MIN(m_in.nbytes, partial_cnt);
|
|
partial_pipe = 1;
|
|
}
|
|
|
|
/* Fill in request structure */
|
|
req.fs_e = vp->v_fs_e;
|
|
req.rw_flag = rw_flag;
|
|
req.inode_nr = vp->v_inode_nr;
|
|
req.user_e = usr;
|
|
req.seg = seg;
|
|
req.pos = position;
|
|
req.num_of_bytes = m_in.nbytes;
|
|
req.user_addr = m_in.buffer;
|
|
req.inode_index = vp->v_index;
|
|
|
|
if (vp->v_isfifo)
|
|
{
|
|
printf("read_write: %s for FIFO @ %u size %u\n",
|
|
(rw_flag == READING) ? "read" : "write",
|
|
ex64lo(position), m_in.nbytes);
|
|
}
|
|
|
|
/* Issue request */
|
|
r = req_readwrite(&req, &res);
|
|
|
|
if (r >= 0)
|
|
{
|
|
if (ex64hi(res.new_pos))
|
|
panic(__FILE__, "read_write: bad new pos", NO_NUM);
|
|
|
|
position = res.new_pos;
|
|
cum_io += res.cum_io;
|
|
}
|
|
}
|
|
|
|
/* On write, update file size and access time. */
|
|
if (rw_flag == WRITING) {
|
|
if (regular || mode_word == I_DIRECTORY) {
|
|
if (cmp64ul(position, f_size) > 0)
|
|
{
|
|
if (ex64hi(position) != 0)
|
|
{
|
|
panic(__FILE__,
|
|
"read_write: file size too big for v_size",
|
|
NO_NUM);
|
|
}
|
|
vp->v_size = ex64lo(position);
|
|
}
|
|
}
|
|
}
|
|
else {
|
|
if (vp->v_pipe == I_PIPE) {
|
|
if (cmp64ul(position, vp->v_size) >= 0) {
|
|
/* Reset pipe pointers */
|
|
vp->v_size = 0;
|
|
position = cvu64(0);
|
|
wf = find_filp(vp, W_BIT);
|
|
if (wf != NIL_FILP) wf->filp_pos = cvu64(0);
|
|
}
|
|
}
|
|
}
|
|
|
|
f->filp_pos = position;
|
|
|
|
if (r == OK) {
|
|
if (partial_pipe) {
|
|
partial_pipe = 0;
|
|
/* partial write on pipe with */
|
|
/* O_NONBLOCK, return write count */
|
|
if (!(oflags & O_NONBLOCK)) {
|
|
fp->fp_cum_io_partial = cum_io;
|
|
suspend(XPIPE); /* partial write on pipe with */
|
|
return(SUSPEND); /* nbyte > PIPE_SIZE - non-atomic */
|
|
}
|
|
}
|
|
fp->fp_cum_io_partial = 0;
|
|
return cum_io;
|
|
}
|
|
|
|
return r;
|
|
}
|
|
|
|
|
|
/* Original "uncached" code for block spec files */
|
|
#if 0
|
|
else if (block_spec) {
|
|
char buf[_MIN_BLOCK_SIZE];
|
|
block_t b;
|
|
int bleft = m_in.nbytes;
|
|
dev_t dev = vp->v_sdev;
|
|
|
|
b = position / _MIN_BLOCK_SIZE;
|
|
off = position % _MIN_BLOCK_SIZE;
|
|
|
|
while (bleft) {
|
|
/* First read the whole block */
|
|
r = dev_bio(DEV_READ, dev, FS_PROC_NR, buf, b * _MIN_BLOCK_SIZE,
|
|
_MIN_BLOCK_SIZE);
|
|
|
|
if (r != _MIN_BLOCK_SIZE)
|
|
break;
|
|
|
|
/* How many bytes to copy? */
|
|
chunk = MIN(bleft, _MIN_BLOCK_SIZE - off);
|
|
|
|
if (rw_flag == READING) {
|
|
/* Copy a chunk from the buffer to user space. */
|
|
r = sys_vircopy(FS_PROC_NR, D, (phys_bytes) (&buf[off]),
|
|
usr, seg, (phys_bytes) m_in.buffer,
|
|
(phys_bytes) chunk);
|
|
}
|
|
else {
|
|
/* Copy a chunk from user space to the buffer. */
|
|
r = sys_vircopy(usr, seg, (phys_bytes) m_in.buffer,
|
|
FS_PROC_NR, D, (phys_bytes) (&buf[off]),
|
|
(phys_bytes) chunk);
|
|
}
|
|
|
|
/* Write back if WRITE */
|
|
if (rw_flag == WRITING) {
|
|
r = dev_bio(DEV_WRITE, dev, FS_PROC_NR, buf,
|
|
b * _MIN_BLOCK_SIZE, _MIN_BLOCK_SIZE);
|
|
|
|
if (r != _MIN_BLOCK_SIZE)
|
|
break;
|
|
}
|
|
|
|
bleft -= chunk;
|
|
m_in.buffer += chunk;
|
|
|
|
/* 0 offset in the next block */
|
|
b++;
|
|
off = 0;
|
|
}
|
|
|
|
cum_io = m_in.nbytes - bleft;
|
|
position += cum_io;
|
|
r = OK;
|
|
}
|
|
#endif
|
|
|
|
|
|
/*===========================================================================*
|
|
* do_getdents *
|
|
*===========================================================================*/
|
|
PUBLIC int do_getdents()
|
|
{
|
|
/* Perform the getdents(fd, buf, size) system call. */
|
|
int r;
|
|
off_t pos_change;
|
|
cp_grant_id_t gid;
|
|
register struct filp *rfilp;
|
|
|
|
/* Is the file descriptor valid? */
|
|
if ( (rfilp = get_filp(m_in.fd)) == NIL_FILP) {
|
|
return(err_code);
|
|
}
|
|
|
|
if (!(rfilp->filp_mode & R_BIT))
|
|
return EBADF;
|
|
|
|
if ((rfilp->filp_vno->v_mode & I_TYPE) != I_DIRECTORY)
|
|
return EBADF;
|
|
|
|
gid=cpf_grant_magic(rfilp->filp_vno->v_fs_e, who_e, (vir_bytes) m_in.buffer,
|
|
m_in.nbytes, CPF_WRITE);
|
|
if (gid < 0) panic(__FILE__, "cpf_grant_magic failed", gid);
|
|
|
|
/* Issue request */
|
|
if (ex64hi(rfilp->filp_pos) != 0)
|
|
panic(__FILE__, "do_getdents: should handle large offsets", NO_NUM);
|
|
|
|
r= req_getdents(rfilp->filp_vno->v_fs_e, rfilp->filp_vno->v_inode_nr,
|
|
ex64lo(rfilp->filp_pos), gid, m_in.nbytes, &pos_change);
|
|
|
|
cpf_revoke(gid);
|
|
|
|
if (r > 0)
|
|
rfilp->filp_pos= add64ul(rfilp->filp_pos, pos_change);
|
|
return r;
|
|
}
|
|
|
|
|
|
|