sanchayanmaity/minix
1
0
Fork 0
Code Issues Pull requests Packages Projects Releases Wiki Activity
minix/servers/vfs/open.c
Thomas Veerman 958b25be50 - Introduce support for sticky bit. 
- Revise VFS-FS protocol and update VFS/MFS/ISOFS accordingly.
- Clean up MFS by removing old, dead code (backwards compatibility is broken by
  the new VFS-FS protocol, anyway) and rewrite other parts. Also, make sure all
  functions have proper banners and prototypes.
- VFS should always provide a (syntactically) valid path to the FS; no need for
  the FS to do sanity checks when leaving/entering mount points.
- Fix several bugs in MFS:
  - Several path lookup bugs in MFS.
  - A link can be too big for the path buffer.
  - A mountpoint can become inaccessible when the creation of a new inode
    fails, because the inode already exists and is a mountpoint.
- Introduce support for supplemental groups.
- Add test 46 to test supplemental group functionality (and removed obsolete
  suppl. tests from test 2).
- Clean up VFS (not everything is done yet).
- ISOFS now opens device read-only. This makes the -r flag in the mount command
  unnecessary (but will still report to be mounted read-write).
- Introduce PipeFS. PipeFS is a new FS that handles all anonymous and
  named pipes. However, named pipes still reside on the (M)FS, as they are part
  of the file system on disk. To make this work VFS now has a concept of
  'mapped' inodes, which causes read, write, truncate and stat requests to be
  redirected to the mapped FS, and all other requests to the original FS.
2009-12-20 20:27:14 +00:00

669 lines
19 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
*/
#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"
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( struct vnode *new_node, (mode_t bits) );
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, r, exist = TRUE;
dev_t dev;
mode_t bits;
struct filp *fil_ptr, *filp2;
struct vnode *vp;
struct vmnt *vmp;
struct dmap *dp;
/* Remap the bottom two bits of oflags. */
bits = (mode_t) mode_map[oflags & O_ACCMODE];
if (!bits) 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 is set, try to make the file. */
if (oflags & O_CREAT) {
omode = I_REGULAR | (omode & ALL_MODES & fp->fp_umask);
vp = new_node(omode);
r = err_code;
if (r == OK) exist = FALSE; /* We just created the file */
else if (r != EEXIST) return(r); /* other error */
else exist = !(oflags & O_EXCL); /* file exists, if the O_EXCL
flag is set this is an error */
} else {
/* Scan path name */
if ((vp = eat_path(PATH_NOFLAGS)) == NIL_VNODE) return(err_code);
}
/* 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_vno = vp;
fil_ptr->filp_flags = oflags;
/* Only do the normal open code if didn't just create the file. */
if(exist) {
/* Check protections. */
if ((r = forbidden(vp, bits)) == OK) {
/* 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)) != OK)
break;
truncate_vnode(vp, 0);
}
break;
case I_DIRECTORY:
/* Directories may be read but not written. */
r = (bits & W_BIT ? EISDIR : OK);
break;
case I_CHAR_SPECIAL:
/* Invoke the driver for special processing. */
dev = (dev_t) vp->v_sdev;
r = dev_open(dev, who_e, bits | (oflags & ~O_ACCMODE));
if (r == SUSPEND) suspend(FP_BLOCKED_ON_DOPEN);
break;
case I_BLOCK_SPECIAL:
/* Invoke the driver for special processing. */
dev = (dev_t) vp->v_sdev;
r = dev_open(dev, who_e, bits | (oflags & ~O_ACCMODE));
/* Check whether the device is mounted or not. If so,
then that FS is responsible for this device. Else
we default to ROOT_FS. */
vp->v_bfs_e = ROOT_FS_E; /* By default */
for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; ++vmp)
if (vmp->m_dev == vp->v_sdev)
vp->v_bfs_e = vmp->m_fs_e;
/* Get the driver endpoint of the block spec device */
dp = &dmap[(vp->v_sdev >> MAJOR) & BYTE];
if (dp->dmap_driver == NONE) {
printf("VFS: driver not found for device %d\n",
vp->v_sdev);
r = ENXIO;
break;
}
/* Send the driver endpoint (even when known already)*/
if ((r = req_newdriver(vp->v_bfs_e, vp->v_sdev,
dp->dmap_driver)) != OK) {
printf("VFS: error sending driver endpoint\n");
r = ENXIO;
}
break;
case I_NAMED_PIPE:
/* Create a mapped inode on PFS which handles reads
and writes to this named pipe. */
r = map_vnode(vp);
if (r == OK) {
vp->v_pipe = I_PIPE;
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_vnode(vp, 0);
}
oflags |= O_APPEND; /* force append mode */
fil_ptr->filp_flags = oflags;
}
if (r == OK) {
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 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;
}
}
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);
}
/*===========================================================================*
* new_node *
*===========================================================================*/
PRIVATE struct vnode *new_node(mode_t bits)
{
struct vnode *dirp, *vp;
int r;
struct node_details res;
struct vnode *rest;
/* See if the path can be opened down to the last directory. */
if ((dirp = last_dir()) == NIL_VNODE) return(NIL_VNODE);
/* The final directory is accessible. Get final component of the path. */
vp = advance(dirp, 0);
if (vp == NIL_VNODE && err_code == ENOENT) {
/* Last path component does not exist. Make a new directory entry. */
if ((vp = get_free_vnode()) == NIL_VNODE) {
/* Can't create new vnode: out of vnodes. */
put_vnode(dirp);
return(NIL_VNODE);
}
if ((r = forbidden(dirp, W_BIT|X_BIT)) != OK ||
(r = req_create(dirp->v_fs_e, dirp->v_inode_nr,bits, fp->fp_effuid,
fp->fp_effgid, user_fullpath, &res)) != OK ) {
/* Can't create new directory entry: either no permission or
something else is wrong. */
put_vnode(dirp);
err_code = r;
return(NIL_VNODE);
}
/* Store results and mark vnode in use */
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 = dirp->v_vmnt;
vp->v_dev = vp->v_vmnt->m_dev;
vp->v_fs_count = 1;
vp->v_ref_count = 1;
} else {
/* Either last component exists, or there is some other problem. */
if (vp != NIL_VNODE)
r = EEXIST;
else
r = err_code;
}
err_code = r;
put_vnode(dirp);
return(vp);
}
/*===========================================================================*
* 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)) 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(FP_BLOCKED_ON_POPEN); /* 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);
bits = (mode_bits & I_TYPE) | (mode_bits & ALL_MODES & fp->fp_umask);
/* Open directory that's going to hold the new node. */
if(fetch_name(m_in.name1, m_in.name1_length, M1) != OK) return(err_code);
if((vp = last_dir()) == NIL_VNODE) return(err_code);
/* Make sure that the object is a directory */
if((vp->v_mode & I_TYPE) != I_DIRECTORY) {
put_vnode(vp);
return(ENOTDIR);
}
if ((r = forbidden(vp, W_BIT|X_BIT)) == OK) {
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((vp = last_dir()) == NIL_VNODE) return(err_code);
/* Make sure that the object is a directory */
if ((vp->v_mode & I_TYPE) != I_DIRECTORY) {
put_vnode(vp);
return(ENOTDIR);
}
if ((r = forbidden(vp, W_BIT|X_BIT)) == OK) {
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_vnode(vp, vp->v_size);
}
put_vnode(fp->filp_vno);
}
}
/*===========================================================================*
* close_reply *
*===========================================================================*/
PUBLIC void close_reply()
{
/* No need to do anything */
}
/*===========================================================================*
* do_vm_open *
*===========================================================================*/
PUBLIC int do_vm_open()
{
int len, r, n;
endpoint_t ep;
len = m_in.VMVO_NAME_LENGTH;
m_out.VMV_ENDPOINT = ep = m_in.VMVO_ENDPOINT;
/* Do open() call on behalf of any process, performed by VM. */
if(len < 2 || len > sizeof(user_fullpath)) {
printf("do_vm_open: strange length %d\n", len);
m_out.VMVRO_FD = EINVAL;
return(VM_VFS_REPLY_OPEN);
}
/* Do open on behalf of which process? */
if(isokendpt(ep, &n) != OK) {
printf("do_vm_open: strange endpoint %d\n", ep);
m_out.VMVRO_FD = EINVAL;
return(VM_VFS_REPLY_OPEN);
}
/* XXX - do open on behalf of this process */
fp = &fproc[n];
/* Get path name from VM address space. */
if((r=sys_safecopyfrom(VM_PROC_NR, m_in.VMVO_NAME_GRANT, 0,
(vir_bytes) user_fullpath, len, D)) != OK) {
printf("do_vm_open: sys_safecopyfrom failed: %d\n", r);
m_out.VMVRO_FD = EPERM;
return(VM_VFS_REPLY_OPEN);
}
/* Check if path is null-terminated. */
if(user_fullpath[len-1] != '\0') {
printf("do_vm_open: name (len %d) not 0-terminated\n", len);
m_out.VMVRO_FD = EINVAL;
return(VM_VFS_REPLY_OPEN);
}
/* Perform open(). */
m_out.VMVRO_FD = common_open(m_in.VMVO_FLAGS, m_in.VMVO_MODE);
m_out.VMV_ENDPOINT = ep;
/* Send open() reply. */
return(VM_VFS_REPLY_OPEN);
}
/*===========================================================================*
* do_vm_close *
*===========================================================================*/
PUBLIC int do_vm_close()
{
int len, r, n;
endpoint_t ep;
len = m_in.VMVO_NAME_LENGTH;
/* Do close() call on behalf of any process, performed by VM. */
m_out.VMV_ENDPOINT = ep = m_in.VMVC_ENDPOINT;
if(isokendpt(ep, &n) != OK) {
printf("do_vm_close: strange endpoint %d\n", ep);
return(VM_VFS_REPLY_CLOSE);
}
/* Perform close(). */
r = close_fd(&fproc[n], m_in.VMVC_FD);
return(VM_VFS_REPLY_CLOSE);
}
Reference in a new issue View git blame Copy permalink