sanchayanmaity/minix
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity
minix/servers/vfs/open.c
Philip Homburg e5df351245 Support for blocking open on char specials (due to asynch message passing), 
asynch. close, added close_filp function.
2008-02-22 13:57:11 +00:00

797 lines
21 KiB
C
Raw Blame History

/* 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 <minix/u64.h>
#include "file.h"
#include "fproc.h"
#include "lock.h"
#include "param.h"
#include <dirent.h>
#include <assert.h>
#include <minix/vfsif.h>
#include "vnode.h"
#include "vmnt.h"
#define offset_lo m2_l1
#define offset_high m2_l2
FORWARD _PROTOTYPE( int common_open, (int oflags, mode_t omode) );
FORWARD _PROTOTYPE( int create_open, (_mnx_Mode_t omode, int excl,
struct vnode **vpp, int *created) );
FORWARD _PROTOTYPE( int exists_open, (struct vnode *vp, _mnx_Mode_t bits,
int oflags));
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 b, m, r, created, found;
mode_t bits;
struct filp *fil_ptr, *filp2;
struct vnode *vp;
struct vmnt *vmp;
struct dmap *dp;
/* Remap the bottom two bits of oflags. */
m = oflags & O_ACCMODE;
switch(m) {
case O_RDONLY: bits = R_BIT; break;
case O_WRONLY: bits = W_BIT; break;
case O_RDWR: bits = R_BIT | W_BIT; break;
default: return EINVAL;
}
/* See if file descriptor and filp slots are available. */
if ((r = get_fd(0, bits, &m_in.fd, &fil_ptr)) != OK) return(r);
/* If O_CREATE, set umask */
if (oflags & O_CREAT) {
omode = I_REGULAR | (omode & ALL_MODES & fp->fp_umask);
}
if (oflags & O_CREAT)
r= create_open(omode, !!(oflags & O_EXCL), &vp, &created);
else
{
#if 0
printf("vfs:common_open: path '%s'\n", user_fullpath);
#endif
created= FALSE;
r= lookup_vp(0 /*flags*/, 0 /*!use_realuid*/, &vp);
}
if (r != OK)
return r;
if (!created)
{
r= exists_open(vp, bits, oflags);
if (r != OK)
{
put_vnode(vp);
return r;
}
}
/* 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));
if (r == SUSPEND)
suspend(XDOPEN); /* suspend caller */
break;
case I_BLOCK_SPECIAL:
/* Invoke the driver for special processing. */
r = dev_open(vp->v_sdev, who_e, bits | (oflags & ~O_ACCMODE));
if (r != OK)
break;
/* Check whether the device is mounted or not */
found = 0;
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) {
vp->v_bfs_e = vmp->m_fs_e;
}
else { /* To be handled in the root FS proc if not mounted */
vp->v_bfs_e = ROOT_FS_E;
}
/* 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);
assert(fil_ptr->filp_count == 1);
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. Claim filp. */
fil_ptr->filp_count = 1;
}
}
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);
}
/*===========================================================================*
* create_open *
*===========================================================================*/
PRIVATE int create_open(omode, excl, vpp, created)
mode_t omode;
int excl;
struct vnode **vpp;
int *created;
{
int i, r, r1;
size_t len;
struct vnode *vp, *dir_vp, *new_vp, *start_vp;
struct node_details res;
char lastc[PATH_MAX+1];
start_vp = (user_fullpath[0] == '/' ? fp->fp_rd : fp->fp_wd);
dup_vnode(start_vp);
for (i= 0; i<SYMLOOP_MAX; i++)
{
#if 0
printf("vfs:create_open: path #%d '%s'\n", i+1, user_fullpath);
#endif
r= lookup_lastdir_rel(start_vp, 0 /*!use_realuid*/, &dir_vp);
put_vnode(start_vp);
if (r != OK)
return r;
/* Save the last component of the path */
len= strlen(user_fullpath)+1;
if (len > sizeof(lastc))
{
put_vnode(dir_vp);
return ENAMETOOLONG;
}
memcpy(lastc, user_fullpath, len);
/* Get a free vnode */
new_vp = get_free_vnode(__FILE__, __LINE__);
if (new_vp == NIL_VNODE) {
put_vnode(dir_vp);
printf("vfs:create_open: no free vnode available\n");
return EINVAL;
}
r= forbidden(dir_vp, W_BIT|X_BIT, 0 /*!use_realuid*/);
if (r == OK)
{
/* Try to create the file */
r= req_create(dir_vp->v_fs_e, dir_vp->v_inode_nr,
omode, fp->fp_effuid, fp->fp_effgid, lastc,
&res);
}
if (r != EEXIST && r != EACCES)
{
put_vnode(dir_vp);
if (r != OK)
return r;
/* Check whether vnode is already in use or not */
vp = find_vnode(res.fs_e, res.inode_nr);
if (vp != NIL_VNODE) {
vp->v_ref_count++;
vp->v_fs_count++;
}
else
{
vp= new_vp;
/* Fill in the free vnode's fields */
vp->v_fs_e = res.fs_e;
vp->v_inode_nr = res.inode_nr;
vp->v_mode = res.fmode;
vp->v_size = res.fsize;
vp->v_uid = res.uid;
vp->v_gid = res.gid;
vp->v_sdev = res.dev;
vp->v_vmnt = dir_vp->v_vmnt;
vp->v_dev = vp->v_vmnt->m_dev;
vp->v_fs_count = 1;
vp->v_ref_count = 1;
}
*vpp= vp;
*created= TRUE;
return OK;
}
if (r == EEXIST && excl)
{
printf(
"vfs:create_open: creating existing file with O_EXCL\n");
put_vnode(dir_vp);
return r;
}
/* Try a regular lookup */
memcpy(user_fullpath, lastc, len);
r1= lookup_rel_vp(dir_vp, 0 /*flags*/, 0 /*!use_realuid*/, &vp);
if (r1 != ENOENT)
{
put_vnode(dir_vp);
if (r1 == OK)
{
*vpp= vp;
*created= FALSE;
}
return r1;
}
if (r == EACCES)
{
/* We cannot create a new file and the file does not
* already exist.
*/
put_vnode(dir_vp);
return r;
}
/* The create failed with EEXIST and the regular lookup
* failed with ENOENT. We have to see whether the object
* we try to access actually exists, but is a symlink that
* cannot be resolved. If the symlink exists, we start
* with the contents of the symlink.
*/
memcpy(user_fullpath, lastc, len);
r= lookup_rel_vp(dir_vp, PATH_RET_SYMLINK, 0 /*!use_realuid*/,
&vp);
if (r != OK)
{
put_vnode(dir_vp);
return r;
}
if (!S_ISLNK(vp->v_mode))
{
/* Strange, we got an object, but it is not a symlink.
* Well, just return the object.
*/
put_vnode(dir_vp);
*vpp= vp;
*created= FALSE;
return OK;
}
/* Get the contents of the link */
len= sizeof(user_fullpath);
r= req_rdlink(vp->v_fs_e, vp->v_inode_nr, FS_PROC_NR,
(vir_bytes)user_fullpath, len-1);
put_vnode(vp);
if (r < 0)
{
printf("vfs:create_open: req_rdlink failed with %d\n",
r);
put_vnode(dir_vp);
return r;
}
if (r >= len)
{
printf(
"vfs:create_open: got bad length %d from req_rdlink\n",
r);
r= len-1;
}
user_fullpath[r]= '\0';
printf("got link target '%s'\n", user_fullpath);
if (user_fullpath[0] == '/')
{
put_vnode(dir_vp);
start_vp= fp->fp_rd;
dup_vnode(start_vp);
}
else
start_vp= dir_vp;
}
put_vnode(start_vp);
return ELOOP;
}
/*===========================================================================*
* exists_open *
*===========================================================================*/
PRIVATE int exists_open(vp, bits, oflags /*, omode, lastc, vpp */)
struct vnode *vp;
mode_t bits;
int oflags;
{
int r;
/* Check protections. */
if ((r = forbidden(vp, bits, 0 /*!use_realuid*/)) != OK)
return r;
/* Opening reg. files directories and special files differ. */
switch (vp->v_mode & I_TYPE) {
case I_REGULAR:
/* Truncate regular file if O_TRUNC. */
if (oflags & O_TRUNC) {
if ((r = forbidden(vp, W_BIT, 0 /*!use_realuid*/)) !=OK) break;
truncate_vn(vp, 0);
}
break;
case I_DIRECTORY:
/* Directories may be read but not written. */
r = (bits & W_BIT ? EISDIR : OK);
break;
case I_CHAR_SPECIAL:
case I_BLOCK_SPECIAL:
if (vp->v_sdev == (dev_t)-1)
panic(__FILE__, "vfs:exists_open: bad special", NO_NUM);
break;
case I_NAMED_PIPE:
#if 0
printf("vfs:exists_open: fifo vp 0x%x, for %s\n",
vp, ((bits & W_BIT) ? "writing" : "reading"));
#endif
if (vp->v_ref_count == 1)
{
vp->v_pipe_rd_pos= 0;
vp->v_pipe_wr_pos= 0;
if (vp->v_size != 0)
r= truncate_vn(vp, 0);
}
break;
}
return(r);
}
/*===========================================================================*
* 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;
int r;
struct vnode *vp;
/* 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);
/* Request lookup */
if ((r = lookup_lastdir(0 /*!use_realuid*/, &vp)) != OK) return r;
/* Make sure that the object is a directory */
if ((vp->v_mode & I_TYPE) != I_DIRECTORY)
{
put_vnode(vp);
return ENOTDIR;
}
r= forbidden(vp, W_BIT|X_BIT, 0 /*!use_realuid*/);
if (r != OK)
{
put_vnode(vp);
return r;
}
/* Issue request */
r= req_mknod(vp->v_fs_e, vp->v_inode_nr, user_fullpath,
fp->fp_effuid, fp->fp_effgid, bits, m_in.mk_z0);
put_vnode(vp);
return r;
}
/*===========================================================================*
* do_mkdir *
*===========================================================================*/
PUBLIC int do_mkdir()
{
/* Perform the mkdir(name, mode) system call. */
mode_t bits; /* mode bits for the new inode */
int r;
struct vnode *vp;
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);
/* Request lookup */
if ((r = lookup_lastdir(0 /*!use_realuid*/, &vp)) != OK) return r;
/* Make sure that the object is a directory */
if ((vp->v_mode & I_TYPE) != I_DIRECTORY)
{
put_vnode(vp);
return ENOTDIR;
}
r= forbidden(vp, W_BIT|X_BIT, 0 /*!use_realuid*/);
if (r != OK)
{
put_vnode(vp);
return r;
}
/* Issue request */
r= req_mkdir(vp->v_fs_e, vp->v_inode_nr, user_fullpath,
fp->fp_effuid, fp->fp_effgid, bits);
put_vnode(vp);
return r;
}
/*===========================================================================*
* do_lseek *
*===========================================================================*/
PUBLIC int do_lseek()
{
/* Perform the lseek(ls_fd, offset, whence) system call. */
register struct filp *rfilp;
int r;
long offset;
u64_t pos, newpos;
/* 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 = cvu64(0); break;
case SEEK_CUR: pos = rfilp->filp_pos; break;
case SEEK_END: pos = cvul64(rfilp->filp_vno->v_size); break;
default: return(EINVAL);
}
offset= m_in.offset_lo;
if (offset >= 0)
newpos= add64ul(pos, offset);
else
newpos= sub64ul(pos, -offset);
/* Check for overflow. */
if (ex64hi(newpos) != 0)
return EINVAL;
if (cmp64(newpos, rfilp->filp_pos) != 0) { /* Inhibit read ahead request */
r = req_inhibread(rfilp->filp_vno->v_fs_e, rfilp->filp_vno->v_inode_nr);
if (r != OK) return r;
}
rfilp->filp_pos = newpos;
/* insert the new position into the output message */
m_out.reply_l1 = ex64lo(newpos);
return(OK);
}
/*===========================================================================*
* do_llseek *
*===========================================================================*/
PUBLIC int do_llseek()
{
/* Perform the llseek(ls_fd, offset, whence) system call. */
register struct filp *rfilp;
u64_t pos, newpos;
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 = cvu64(0); break;
case SEEK_CUR: pos = rfilp->filp_pos; break;
case SEEK_END: pos = cvul64(rfilp->filp_vno->v_size); break;
default: return(EINVAL);
}
newpos= add64(pos, make64(m_in.offset_lo, m_in.offset_high));
/* Check for overflow. */
if (((long)m_in.offset_high > 0) && cmp64(newpos, pos) < 0)
return(EINVAL);
if (((long)m_in.offset_high < 0) && cmp64(newpos, pos) > 0)
return(EINVAL);
if (cmp64(newpos, rfilp->filp_pos) != 0) { /* Inhibit read ahead request */
r = req_inhibread(rfilp->filp_vno->v_fs_e, rfilp->filp_vno->v_inode_nr);
if (r != OK) return r;
}
rfilp->filp_pos = newpos;
m_out.reply_l1 = ex64lo(newpos);
m_out.reply_l2 = ex64hi(newpos);
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 lock_count;
/* 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;
close_filp(rfilp);
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);
}
/*===========================================================================*
* close_filp *
*===========================================================================*/
PUBLIC void close_filp(fp)
struct filp *fp;
{
int mode_word, rw;
dev_t dev;
struct vnode *vp;
vp = fp->filp_vno;
if (fp->filp_count - 1 == 0 && fp->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) {
if (vp->v_bfs_e == ROOT_FS_E)
{
/* Invalidate the cache unless the special is
* mounted. Assume that the root filesystem's
* is open only for fsck.
*/
req_flush(vp->v_bfs_e, dev);
}
}
/* Do any special processing on device close. */
(void) dev_close(dev, fp-filp);
/* Ignore any errors, even SUSPEND. */
}
}
/* If the inode being closed is a pipe, release everyone hanging on it. */
if (vp->v_pipe == I_PIPE) {
rw = (fp->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 (--fp->filp_count == 0) {
if (vp->v_pipe == I_PIPE) {
/* Last reader or writer is going. Tell MFS about latest
* pipe size.
*/
truncate_vn(vp, vp->v_size);
}
put_vnode(fp->filp_vno);
}
}
/*===========================================================================*
* close_reply *
*===========================================================================*/
PUBLIC void close_reply()
{
/* No need to do anything */
}
Reference in a new issue View git blame Copy permalink