minix/servers/vfs/open.c

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/* This file contains the procedures for creating, opening, closing, and
* seeking on files.
*
* The entry points into this file are
* do_creat: perform the CREAT system call
* do_open: perform the OPEN system call
* do_mknod: perform the MKNOD system call
* do_mkdir: perform the MKDIR system call
* do_close: perform the CLOSE system call
* do_lseek: perform the LSEEK system call
*
* Changes for VFS:
* Jul 2006 (Balazs Gerofi)
*/
#include "fs.h"
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <minix/callnr.h>
#include <minix/com.h>
#include "file.h"
#include "fproc.h"
#include "lock.h"
#include "param.h"
#include <dirent.h>
#include <minix/vfsif.h>
#include "vnode.h"
#include "vmnt.h"
#define offset m2_l1
PRIVATE char mode_map[] = {R_BIT, W_BIT, R_BIT|W_BIT, 0};
FORWARD _PROTOTYPE( int common_open, (int oflags, mode_t omode) );
FORWARD _PROTOTYPE( int pipe_open, (struct vnode *vp,mode_t bits,int oflags));
/*===========================================================================*
* do_creat *
*===========================================================================*/
PUBLIC int do_creat()
{
/* Perform the creat(name, mode) system call. */
int r;
if (fetch_name(m_in.name, m_in.name_length, M3) != OK) return(err_code);
r = common_open(O_WRONLY | O_CREAT | O_TRUNC, (mode_t) m_in.mode);
return(r);
}
/*===========================================================================*
* do_open *
*===========================================================================*/
PUBLIC int do_open()
{
/* Perform the open(name, flags,...) system call. */
int create_mode = 0; /* is really mode_t but this gives problems */
int r;
/* If O_CREAT is set, open has three parameters, otherwise two. */
if (m_in.mode & O_CREAT) {
create_mode = m_in.c_mode;
r = fetch_name(m_in.c_name, m_in.name1_length, M1);
} else {
r = fetch_name(m_in.name, m_in.name_length, M3);
}
if (r != OK) {
return(err_code); /* name was bad */
}
r = common_open(m_in.mode, create_mode);
return(r);
}
/*===========================================================================*
* common_open *
*===========================================================================*/
PRIVATE int common_open(register int oflags, mode_t omode)
{
/* Common code from do_creat and do_open. */
int r, b, found;
dev_t dev;
mode_t bits;
off_t pos;
struct dmap *dp;
struct filp *fil_ptr, *filp2;
struct vnode *vp, *vp2;
struct vmnt *vmp;
char lastc[NAME_MAX];
/* Request and response structures */
struct lookup_req lookup_req;
struct open_req req;
struct node_details res;
/* Remap the bottom two bits of oflags. */
bits = (mode_t) mode_map[oflags & O_ACCMODE];
/* See if file descriptor and filp slots are available. */
if ((r = get_fd(0, bits, &m_in.fd, &fil_ptr)) != OK) return(r);
/* See if a free vnode is available */
if ((vp = get_free_vnode()) == NIL_VNODE) {
printf("VFS: no vnode available!\n");
return err_code;
}
/* If O_CREATE, set umask */
if (oflags & O_CREAT) {
omode = I_REGULAR | (omode & ALL_MODES & fp->fp_umask);
}
/* Fill in lookup request fields */
lookup_req.path = user_fullpath;
lookup_req.lastc = lastc;
lookup_req.flags = oflags&O_CREAT ? (oflags&O_EXCL ? LAST_DIR :
LAST_DIR_EATSYM) : EAT_PATH;
/* Request lookup */
if ((r = lookup(&lookup_req, &res)) != OK) return r;
/* Lookup was okay, fill in request fields for
* the actual open request. */
req.inode_nr = res.inode_nr;
req.fs_e = res.fs_e;
req.oflags = oflags;
req.omode = omode;
req.lastc = lastc;
req.uid = fp->fp_effuid;
req.gid = fp->fp_effgid;
/* Issue request */
if ((r = req_open(&req, &res)) != OK) return r;
/* Check whether the vnode is already in use */
if ((vp2 = find_vnode(res.fs_e, res.inode_nr)) != NIL_VNODE) {
vp = vp2;
vp->v_size = res.fsize;; /* In case of trunc... */
vp->v_count++;
}
/* Otherwise use the free one */
else {
vp->v_fs_e = res.fs_e;
if ( (vmp = find_vmnt(vp->v_fs_e)) == NIL_VMNT)
printf("VFS: vmnt not found by open()");
vp->v_dev = vmp->m_dev;
vp->v_inode_nr = res.inode_nr;
vp->v_mode = res.fmode;
vp->v_size = res.fsize;
vp->v_sdev = res.dev;
vp->v_count = 1;
vp->v_vmnt = vmp;
vp->v_index = res.inode_index;
}
/* Claim the file descriptor and filp slot and fill them in. */
fp->fp_filp[m_in.fd] = fil_ptr;
FD_SET(m_in.fd, &fp->fp_filp_inuse);
fil_ptr->filp_count = 1;
fil_ptr->filp_flags = oflags;
fil_ptr->filp_vno = vp;
switch (vp->v_mode & I_TYPE) {
case I_CHAR_SPECIAL:
/* Invoke the driver for special processing. */
r = dev_open(vp->v_sdev, who_e, bits | (oflags & ~O_ACCMODE));
break;
case I_BLOCK_SPECIAL:
/* Invoke the driver for special processing. */
r = dev_open(vp->v_sdev, who_e, bits | (oflags & ~O_ACCMODE));
/* Check whether the device is mounted or not */
found = 0;
if (r == OK) {
printf("VFS: opening block spec %d, handled by ", vp->v_sdev);
for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; ++vmp) {
if (vmp->m_dev == vp->v_sdev) {
found = 1;
break;
}
}
/* Who is going to be responsible for this device? */
if (found) {
printf("the FS of the mounted partition...\n");
vp->v_bfs_e = vmp->m_fs_e;
vp->v_blocksize - vmp->m_block_size;
}
else { /* To be handled in the root FS proc if not mounted */
printf("the root FS...\n");
vp->v_bfs_e = ROOT_FS_E;
vp->v_blocksize = _MIN_BLOCK_SIZE;
}
/* Get the driver endpoint of the block spec device */
dp = &dmap[(vp->v_sdev >> MAJOR) & BYTE];
if (dp->dmap_driver == NONE) {
printf("VFSblock_spec_open: driver not found for device %d\n",
vp->v_sdev);
r = EINVAL;
break;
}
/* Send the driver endpoint (even if it is known already...) */
if ((r = req_newdriver(vp->v_bfs_e, vp->v_sdev, dp->dmap_driver))
!= OK) {
printf("VFSblock_spec_open: error sending driver endpoint\n");
}
}
break;
case I_NAMED_PIPE:
vp->v_pipe = I_PIPE;
oflags |= O_APPEND; /* force append mode */
fil_ptr->filp_flags = oflags;
r = pipe_open(vp, bits, oflags);
if (r != ENXIO) {
/* See if someone else is doing a rd or wt on
* the FIFO. If so, use its filp entry so the
* file position will be automatically shared.
*/
b = (bits & R_BIT ? R_BIT : W_BIT);
fil_ptr->filp_count = 0; /* don't find self */
if ((filp2 = find_filp(vp, b)) != NIL_FILP) {
/* Co-reader or writer found. Use it.*/
fp->fp_filp[m_in.fd] = filp2;
filp2->filp_count++;
filp2->filp_vno = vp;
filp2->filp_flags = oflags;
/* v_count was incremented after the vnode has
* been found, i_count was incremented incorrectly
* by eatpath in FS, not knowing that we were going to
* use an existing filp entry. Correct this error.
*/
put_vnode(vp);
} else {
/* Nobody else found. Restore filp. */
fil_ptr->filp_count = 1;
if (fil_ptr->filp_mode == R_BIT)
fil_ptr->filp_pos = vp->v_pipe_rd_pos;
else
fil_ptr->filp_pos = vp->v_pipe_wr_pos;
}
}
break;
}
/* If error, release inode. */
if (r != OK) {
if (r == SUSPEND) return(r); /* Oops, just suspended */
fp->fp_filp[m_in.fd] = NIL_FILP;
FD_CLR(m_in.fd, &fp->fp_filp_inuse);
fil_ptr->filp_count= 0;
put_vnode(vp);
fil_ptr->filp_vno = NIL_VNODE;
return(r);
}
return(m_in.fd);
}
/*===========================================================================*
* pipe_open *
*===========================================================================*/
PRIVATE int pipe_open(register struct vnode *vp, register mode_t bits,
register int oflags)
{
/* This function is called from common_open. It checks if
* there is at least one reader/writer pair for the pipe, if not
* it suspends the caller, otherwise it revives all other blocked
* processes hanging on the pipe.
*/
vp->v_pipe = I_PIPE;
if((bits & (R_BIT|W_BIT)) == (R_BIT|W_BIT)) {
printf("pipe opened RW.\n");
return ENXIO;
}
if (find_filp(vp, bits & W_BIT ? R_BIT : W_BIT) == NIL_FILP) {
if (oflags & O_NONBLOCK) {
if (bits & W_BIT) return(ENXIO);
} else {
suspend(XPOPEN); /* suspend caller */
return(SUSPEND);
}
} else if (susp_count > 0) {/* revive blocked processes */
release(vp, OPEN, susp_count);
release(vp, CREAT, susp_count);
}
return(OK);
}
/*===========================================================================*
* do_mknod *
*===========================================================================*/
PUBLIC int do_mknod()
{
/* Perform the mknod(name, mode, addr) system call. */
register mode_t bits, mode_bits;
char lastc[NAME_MAX]; /* last component of the path */
struct mknod_req req;
struct lookup_req lookup_req;
struct node_details res;
int r;
/* Only the super_user may make nodes other than fifos. */
mode_bits = (mode_t) m_in.mk_mode; /* mode of the inode */
if (!super_user && ((mode_bits & I_TYPE) != I_NAMED_PIPE)) return(EPERM);
if (fetch_name(m_in.name1, m_in.name1_length, M1) != OK) return(err_code);
bits = (mode_bits & I_TYPE) | (mode_bits & ALL_MODES & fp->fp_umask);
/* Fill in lookup request fields */
lookup_req.path = user_fullpath;
lookup_req.lastc = lastc;
lookup_req.flags = LAST_DIR;
/* Request lookup */
if ((r = lookup(&lookup_req, &res)) != OK) return r;
/* Lookup was okay, fill in request fields for the actual
* mknod request. */
req.fs_e = res.fs_e;
req.inode_nr = res.inode_nr;
req.rmode = bits;
req.dev = m_in.mk_z0;
req.lastc = lastc;
req.uid = fp->fp_effuid;
req.gid = fp->fp_effgid;
/* Issue request */
return req_mknod(&req);
}
/*===========================================================================*
* do_mkdir *
*===========================================================================*/
PUBLIC int do_mkdir()
{
/* Perform the mkdir(name, mode) system call. */
mode_t bits; /* mode bits for the new inode */
char lastc[NAME_MAX];
struct mkdir_req req;
struct lookup_req lookup_req;
struct node_details res;
int r;
/*printf("VFS: mkdir() START:");*/
if (fetch_name(m_in.name1, m_in.name1_length, M1) != OK) return(err_code);
bits = I_DIRECTORY | (m_in.mode & RWX_MODES & fp->fp_umask);
/* Fill in lookup request fields */
lookup_req.path = user_fullpath;
lookup_req.lastc = lastc;
lookup_req.flags = LAST_DIR;
/* Request lookup */
if ((r = lookup(&lookup_req, &res)) != OK) return r;
/* Lookup was okay, fill in request message fields
* for the actual mknod request. */
req.fs_e = res.fs_e;
req.d_inode_nr = res.inode_nr;
req.rmode = bits;
req.lastc = lastc;
req.uid = fp->fp_effuid;
req.gid = fp->fp_effgid;
/* Issue request */
return req_mkdir(&req);
}
/*===========================================================================*
* do_lseek *
*===========================================================================*/
PUBLIC int do_lseek()
{
/* Perform the lseek(ls_fd, offset, whence) system call. */
register struct filp *rfilp;
register off_t pos;
struct node_req req;
int r;
/* Check to see if the file descriptor is valid. */
if ( (rfilp = get_filp(m_in.ls_fd)) == NIL_FILP) return(err_code);
/* No lseek on pipes. */
if (rfilp->filp_vno->v_pipe == I_PIPE) return(ESPIPE);
/* The value of 'whence' determines the start position to use. */
switch(m_in.whence) {
case SEEK_SET: pos = 0; break;
case SEEK_CUR: pos = rfilp->filp_pos; break;
case SEEK_END: pos = rfilp->filp_vno->v_size; break;
default: return(EINVAL);
}
/* Check for overflow. */
if (((long)m_in.offset > 0) && ((long)(pos + m_in.offset) < (long)pos))
return(EINVAL);
if (((long)m_in.offset < 0) && ((long)(pos + m_in.offset) > (long)pos))
return(EINVAL);
pos = pos + m_in.offset;
if (pos != rfilp->filp_pos) { /* Inhibit read ahead request */
/* Fill in request message */
req.fs_e = rfilp->filp_vno->v_fs_e;
req.inode_nr = rfilp->filp_vno->v_inode_nr;
/* Issue request */
if ((r = req_inhibread(&req)) != OK) return r;
}
rfilp->filp_pos = pos;
m_out.reply_l1 = pos; /* insert the long into the output message */
return(OK);
}
/*===========================================================================*
* do_close *
*===========================================================================*/
PUBLIC int do_close()
{
/* Perform the close(fd) system call. */
return close_fd(fp, m_in.fd);
}
/*===========================================================================*
* close_fd *
*===========================================================================*/
PUBLIC int close_fd(rfp, fd_nr)
struct fproc *rfp;
int fd_nr;
{
/* Perform the close(fd) system call. */
register struct filp *rfilp;
register struct vnode *vp;
struct file_lock *flp;
int rw, mode_word, lock_count;
dev_t dev;
/* First locate the vnode that belongs to the file descriptor. */
if ( (rfilp = get_filp2(rfp, fd_nr)) == NIL_FILP) return(err_code);
vp = rfilp->filp_vno;
if (rfilp->filp_count - 1 == 0 && rfilp->filp_mode != FILP_CLOSED) {
/* Check to see if the file is special. */
mode_word = vp->v_mode & I_TYPE;
if (mode_word == I_CHAR_SPECIAL || mode_word == I_BLOCK_SPECIAL) {
dev = (dev_t) vp->v_sdev;
if (mode_word == I_BLOCK_SPECIAL) {
/* Invalidate cache entries unless special is mounted
* or ROOT
*/
req_sync(vp->v_bfs_e);
printf("VFSclose: closed block spec %d\n", dev);
}
/* Do any special processing on device close. */
dev_close(dev);
}
}
/* If the inode being closed is a pipe, release everyone hanging on it. */
if (vp->v_pipe == I_PIPE) {
rw = (rfilp->filp_mode & R_BIT ? WRITE : READ);
release(vp, rw, NR_PROCS);
}
/* If a write has been done, the inode is already marked as DIRTY. */
if (--rfilp->filp_count == 0) {
if (vp->v_pipe == I_PIPE && vp->v_count > 1) {
/* Save the file position in the v-node in case needed later.
* The read and write positions are saved separately.
*/
if (rfilp->filp_mode == R_BIT)
vp->v_pipe_rd_pos = rfilp->filp_pos;
else
vp->v_pipe_wr_pos = rfilp->filp_pos;
}
else {
/* Otherwise zero the pipe position fields */
vp->v_pipe_rd_pos = 0;
vp->v_pipe_wr_pos = 0;
}
put_vnode(rfilp->filp_vno);
}
FD_CLR(fd_nr, &rfp->fp_cloexec_set);
rfp->fp_filp[fd_nr] = NIL_FILP;
FD_CLR(fd_nr, &rfp->fp_filp_inuse);
/* Check to see if the file is locked. If so, release all locks. */
if (nr_locks == 0) return(OK);
lock_count = nr_locks; /* save count of locks */
for (flp = &file_lock[0]; flp < &file_lock[NR_LOCKS]; flp++) {
if (flp->lock_type == 0) continue; /* slot not in use */
if (flp->lock_vnode == vp && flp->lock_pid == rfp->fp_pid) {
flp->lock_type = 0;
nr_locks--;
}
}
if (nr_locks < lock_count) lock_revive(); /* lock released */
return(OK);
}