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minix/servers/vfs/open.c
Thomas Veerman 992799b91f VFS: make all IPC asynchronous 
By decoupling synchronous drivers from VFS, we are a big step closer to
supporting driver crashes under all circumstances. That is, VFS can't
become stuck on IPC with a synchronous driver (e.g., INET) and can
recover from crashing block drivers during open/close/ioctl or during
communication with an FS.

In order to maintain serialized communication with a synchronous driver,
the communication is wrapped by a mutex on a per driver basis (not major
numbers as there can be multiple majors with identical endpoints). Majors
that share a driver endpoint point to a single mutex object.

In order to support crashes from block drivers, the file reopen tactic
had to be changed; first reopen files associated with the crashed
driver, then send the new driver endpoint to FSes. This solves a
deadlock between the FS and the block driver;
  - VFS would send REQ_NEW_DRIVER to an FS, but he FS only receives it
    after retrying the current request to the newly started driver.
  - The block driver would refuse the retried request until all files
    had been reopened.
  - VFS would reopen files only after getting a reply from the initial
    REQ_NEW_DRIVER.

When a character special driver crashes, all associated files have to
be marked invalid and closed (or reopened if flagged as such). However,
they can only be closed if a thread holds exclusive access to it. To
obtain exclusive access, the worker thread (which handles the new driver
endpoint event from DS) schedules a new job to garbage collect invalid
files. This way, we can signal the worker thread that was talking to the
crashed driver and will release exclusive access to a file associated
with the crashed driver and prevent the garbage collecting worker thread
from dead locking on that file.

Also, when a character special driver crashes, RS will unmap the driver
and remap it upon restart. During unmapping, associated files are marked
invalid instead of waiting for an endpoint up event from DS, as that
event might come later than new read/write/select requests and thus
cause confusion in the freshly started driver.

When locking a filp, the usage counters are no longer checked. The usage
counter can legally go down to zero during filp invalidation while there
are locks pending.

DS events are handled by a separate worker thread instead of the main
thread as reopening files could lead to another crash and a stuck thread.
An additional worker thread is then necessary to unlock it.

Finally, with everything asynchronous a race condition in do_select
surfaced. A select entry was only marked in use after succesfully sending
initial select requests to drivers and having to wait. When multiple
select() calls were handled there was opportunity that these entries
were overwritten. This had as effect that some select results were
ignored (and select() remained blocking instead if returning) or do_select
tried to access filps that were not present (because thrown away by
secondary select()). This bug manifested itself with sendrecs, but was
very hard to reproduce. However, it became awfully easy to trigger with
asynsends only.
2012-09-17 11:01:45 +00:00

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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
* do_llseek: perform the LLSEEK 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 "scratchpad.h"
#include "dmap.h"
#include "lock.h"
#include "param.h"
#include <dirent.h>
#include <assert.h>
#include <minix/vfsif.h>
#include "vnode.h"
#include "vmnt.h"
#include "path.h"
char mode_map[] = {R_BIT, W_BIT, R_BIT|W_BIT, 0};
static struct vnode *new_node(struct lookup *resolve, int oflags,
mode_t bits);
static int pipe_open(struct vnode *vp, mode_t bits, int oflags);
/*===========================================================================*
* do_creat *
*===========================================================================*/
int do_creat()
{
/* Perform the creat(name, mode) system call.
* syscall might provide 'name' embedded in the message.
*/
char fullpath[PATH_MAX];
vir_bytes vname;
size_t vname_length;
mode_t open_mode;
vname = (vir_bytes) job_m_in.name;
vname_length = (size_t) job_m_in.name_length;
open_mode = (mode_t) job_m_in.mode;
if (copy_name(vname_length, fullpath) != OK) {
/* Direct copy failed, try fetching from user space */
if (fetch_name(vname, vname_length, fullpath) != OK)
return(err_code);
}
return common_open(fullpath, O_WRONLY | O_CREAT | O_TRUNC, open_mode);
}
/*===========================================================================*
* do_open *
*===========================================================================*/
int do_open()
{
/* Perform the open(name, flags,...) system call.
* syscall might provide 'name' embedded in message when not creating file */
int create_mode; /* is really mode_t but this gives problems */
int open_mode = 0; /* is really mode_t but this gives problems */
int r = OK;
char fullpath[PATH_MAX];
vir_bytes vname;
size_t vname_length;
open_mode = (mode_t) job_m_in.mode;
create_mode = job_m_in.c_mode;
/* If O_CREAT is set, open has three parameters, otherwise two. */
if (open_mode & O_CREAT) {
vname = (vir_bytes) job_m_in.name1;
vname_length = (size_t) job_m_in.name1_length;
r = fetch_name(vname, vname_length, fullpath);
} else {
vname = (vir_bytes) job_m_in.name;
vname_length = (size_t) job_m_in.name_length;
create_mode = 0;
if (copy_name(vname_length, fullpath) != OK) {
/* Direct copy failed, try fetching from user space */
if (fetch_name(vname, vname_length, fullpath) != OK)
r = err_code;
}
}
if (r != OK) return(err_code); /* name was bad */
return common_open(fullpath, open_mode, create_mode);
}
/*===========================================================================*
* common_open *
*===========================================================================*/
int common_open(char path[PATH_MAX], int oflags, mode_t omode)
{
/* Common code from do_creat and do_open. */
int b, r, exist = TRUE, major_dev;
dev_t dev;
mode_t bits;
struct filp *filp, *filp2;
struct vnode *vp;
struct vmnt *vmp;
struct dmap *dp;
struct lookup resolve;
/* 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, &(scratch(fp).file.fd_nr), &filp)) != OK) return(r);
lookup_init(&resolve, path, PATH_NOFLAGS, &vmp, &vp);
/* If O_CREATE is set, try to make the file. */
if (oflags & O_CREAT) {
omode = I_REGULAR | (omode & ALLPERMS & fp->fp_umask);
vp = new_node(&resolve, oflags, omode);
r = err_code;
if (r == OK) exist = FALSE; /* We just created the file */
else if (r != EEXIST) { /* other error */
if (vp) unlock_vnode(vp);
unlock_filp(filp);
return(r);
}
else exist = !(oflags & O_EXCL);/* file exists, if the O_EXCL
flag is set this is an error */
} else {
/* Scan path name */
resolve.l_vmnt_lock = VMNT_READ;
resolve.l_vnode_lock = VNODE_OPCL;
if ((vp = eat_path(&resolve, fp)) == NULL) {
unlock_filp(filp);
return(err_code);
}
if (vmp != NULL) unlock_vmnt(vmp);
}
/* Claim the file descriptor and filp slot and fill them in. */
fp->fp_filp[scratch(fp).file.fd_nr] = filp;
FD_SET(scratch(fp).file.fd_nr, &fp->fp_filp_inuse);
filp->filp_count = 1;
filp->filp_vno = vp;
filp->filp_flags = oflags;
/* Only do the normal open code if we didn't just create the file. */
if (exist) {
/* Check protections. */
if ((r = forbidden(fp, vp, bits)) == OK) {
/* Opening reg. files, directories, and special files differ */
switch (vp->v_mode & S_IFMT) {
case S_IFREG:
/* Truncate regular file if O_TRUNC. */
if (oflags & O_TRUNC) {
if ((r = forbidden(fp, vp, W_BIT)) != OK)
break;
truncate_vnode(vp, 0);
}
break;
case S_IFDIR:
/* Directories may be read but not written. */
r = (bits & W_BIT ? EISDIR : OK);
break;
case S_IFCHR:
/* Invoke the driver for special processing. */
dev = (dev_t) vp->v_sdev;
/* TTY needs to know about the O_NOCTTY flag. */
r = dev_open(dev, who_e, bits | (oflags & O_NOCTTY));
if (r == SUSPEND) suspend(FP_BLOCKED_ON_DOPEN);
else vp = filp->filp_vno; /* Might be updated by
* dev_open/clone_opcl */
break;
case S_IFBLK:
lock_bsf();
/* Invoke the driver for special processing. */
dev = (dev_t) vp->v_sdev;
r = bdev_open(dev, bits);
if (r != OK) {
unlock_bsf();
break;
}
major_dev = major(vp->v_sdev);
dp = &dmap[major_dev];
if (dp->dmap_driver == NONE) {
printf("VFS: block driver disappeared!\n");
unlock_bsf();
r = ENXIO;
break;
}
/* Check whether the device is mounted or not. If so,
* then that FS is responsible for this device.
* Otherwise 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 &&
!(vmp->m_flags & VMNT_FORCEROOTBSF)) {
vp->v_bfs_e = vmp->m_fs_e;
}
/* Send the driver label to the file system that will
* handle the block I/O requests (even when its label
* and endpoint are known already), but only when it is
* the root file system. Other file systems will
* already have it anyway.
*/
if (vp->v_bfs_e != ROOT_FS_E) {
unlock_bsf();
break;
}
if (req_newdriver(vp->v_bfs_e, vp->v_sdev,
dp->dmap_label) != OK) {
printf("VFS: error sending driver label\n");
bdev_close(dev);
r = ENXIO;
}
unlock_bsf();
break;
case S_IFIFO:
/* Create a mapped inode on PFS which handles reads
and writes to this named pipe. */
tll_upgrade(&vp->v_lock);
r = map_vnode(vp, PFS_PROC_NR);
if (r == OK) {
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 */
filp->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);
filp->filp_count = 0; /* don't find self */
if ((filp2 = find_filp(vp, b)) != NULL) {
/* Co-reader or writer found. Use it.*/
fp->fp_filp[scratch(fp).file.fd_nr] = 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.
*/
unlock_vnode(vp);
put_vnode(vp);
} else {
/* Nobody else found. Restore filp. */
filp->filp_count = 1;
}
}
break;
}
}
}
unlock_filp(filp);
/* If error, release inode. */
if (r != OK) {
if (r != SUSPEND) {
fp->fp_filp[scratch(fp).file.fd_nr] = NULL;
FD_CLR(scratch(fp).file.fd_nr, &fp->fp_filp_inuse);
filp->filp_count = 0;
filp->filp_vno = NULL;
filp->filp_state &= ~FS_INVALIDATED; /* Prevent garbage col. */
put_vnode(vp);
}
} else {
r = scratch(fp).file.fd_nr;
}
return(r);
}
/*===========================================================================*
* new_node *
*===========================================================================*/
static struct vnode *new_node(struct lookup *resolve, int oflags, mode_t bits)
{
/* Try to create a new inode and return a pointer to it. If the inode already
exists, return a pointer to it as well, but set err_code accordingly.
NULL is returned if the path cannot be resolved up to the last
directory, or when the inode cannot be created due to permissions or
otherwise. */
struct vnode *dirp, *vp;
struct vmnt *dir_vmp, *vp_vmp;
int r;
struct node_details res;
struct lookup findnode;
char *path;
path = resolve->l_path; /* For easy access */
lookup_init(&findnode, path, resolve->l_flags, &dir_vmp, &dirp);
findnode.l_vmnt_lock = VMNT_WRITE;
findnode.l_vnode_lock = VNODE_WRITE; /* dir node */
/* When O_CREAT and O_EXCL flags are set, the path may not be named by a
* symbolic link. */
if (oflags & O_EXCL) findnode.l_flags |= PATH_RET_SYMLINK;
/* See if the path can be opened down to the last directory. */
if ((dirp = last_dir(&findnode, fp)) == NULL) return(NULL);
/* The final directory is accessible. Get final component of the path. */
lookup_init(&findnode, findnode.l_path, findnode.l_flags, &vp_vmp, &vp);
findnode.l_vmnt_lock = VMNT_WRITE;
findnode.l_vnode_lock = (oflags & O_TRUNC) ? VNODE_WRITE : VNODE_OPCL;
vp = advance(dirp, &findnode, fp);
assert(vp_vmp == NULL); /* Lookup to last dir should have yielded lock
* on vmp or final component does not exist.
* Either way, vp_vmp ought to be not set.
*/
/* The combination of a symlink with absolute path followed by a danglink
* symlink results in a new path that needs to be re-resolved entirely. */
if (path[0] == '/') {
unlock_vnode(dirp);
unlock_vmnt(dir_vmp);
put_vnode(dirp);
if (vp != NULL) {
unlock_vnode(vp);
put_vnode(vp);
}
return new_node(resolve, oflags, bits);
}
if (vp == NULL && err_code == ENOENT) {
/* Last path component does not exist. Make a new directory entry. */
if ((vp = get_free_vnode()) == NULL) {
/* Can't create new entry: out of vnodes. */
unlock_vnode(dirp);
unlock_vmnt(dir_vmp);
put_vnode(dirp);
return(NULL);
}
lock_vnode(vp, VNODE_OPCL);
if ((r = forbidden(fp, dirp, W_BIT|X_BIT)) != OK ||
(r = req_create(dirp->v_fs_e, dirp->v_inode_nr,bits, fp->fp_effuid,
fp->fp_effgid, path, &res)) != OK ) {
/* Can't create inode either due to permissions or some other
* problem. In case r is EEXIST, we might be dealing with a
* dangling symlink.*/
if (r == EEXIST) {
struct vnode *slp, *old_wd;
/* Resolve path up to symlink */
findnode.l_flags = PATH_RET_SYMLINK;
findnode.l_vnode_lock = VNODE_READ;
findnode.l_vnode = &slp;
slp = advance(dirp, &findnode, fp);
if (slp != NULL) {
if (S_ISLNK(slp->v_mode)) {
/* Get contents of link */
r = req_rdlink(slp->v_fs_e,
slp->v_inode_nr,
VFS_PROC_NR,
(vir_bytes) path,
PATH_MAX - 1, 0);
if (r < 0) {
/* Failed to read link */
unlock_vnode(slp);
unlock_vnode(dirp);
unlock_vmnt(dir_vmp);
put_vnode(slp);
put_vnode(dirp);
err_code = r;
return(NULL);
}
path[r] = '\0'; /* Terminate path */
}
unlock_vnode(slp);
put_vnode(slp);
}
/* Try to create the inode the dangling symlink was
* pointing to. We have to use dirp as starting point
* as there might be multiple successive symlinks
* crossing multiple mountpoints.
* Unlock vnodes and vmnts as we're going to recurse.
*/
unlock_vnode(dirp);
unlock_vnode(vp);
unlock_vmnt(dir_vmp);
old_wd = fp->fp_wd; /* Save orig. working dirp */
fp->fp_wd = dirp;
vp = new_node(resolve, oflags, bits);
fp->fp_wd = old_wd; /* Restore */
if (vp != NULL) {
put_vnode(dirp);
*(resolve->l_vnode) = vp;
return(vp);
}
r = err_code;
}
if (r == EEXIST)
err_code = EIO; /* Impossible, we have verified that
* the last component doesn't exist and
* is not a dangling symlink. */
else
err_code = r;
unlock_vnode(dirp);
unlock_vnode(vp);
unlock_vmnt(dir_vmp);
put_vnode(dirp);
return(NULL);
}
/* 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 != NULL) {
r = EEXIST; /* File exists or a symlink names a file while
* O_EXCL is set. */
} else
r = err_code; /* Other problem. */
}
err_code = r;
/* When dirp equals vp, we shouldn't release the lock as a vp is locked only
* once. Releasing the lock would cause the resulting vp not be locked and
* cause mayhem later on. */
if (dirp != vp) {
unlock_vnode(dirp);
}
unlock_vmnt(dir_vmp);
put_vnode(dirp);
*(resolve->l_vnode) = vp;
return(vp);
}
/*===========================================================================*
* pipe_open *
*===========================================================================*/
static int pipe_open(struct vnode *vp, mode_t bits, 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.
*/
if ((bits & (R_BIT|W_BIT)) == (R_BIT|W_BIT)) return(ENXIO);
/* Find the reader/writer at the other end of the pipe */
if (find_filp(vp, bits & W_BIT ? R_BIT : W_BIT) == NULL) {
/* Not found */
if (oflags & O_NONBLOCK) {
if (bits & W_BIT) return(ENXIO);
} else {
/* Let's wait for the other side to show up */
suspend(FP_BLOCKED_ON_POPEN);
return(SUSPEND);
}
} else if (susp_count > 0) { /* revive blocked processes */
release(vp, OPEN, susp_count);
release(vp, CREAT, susp_count);
}
return(OK);
}
/*===========================================================================*
* do_mknod *
*===========================================================================*/
int do_mknod()
{
/* Perform the mknod(name, mode, addr) system call. */
register mode_t bits, mode_bits;
int r;
struct vnode *vp;
struct vmnt *vmp;
char fullpath[PATH_MAX];
struct lookup resolve;
vir_bytes vname1;
size_t vname1_length;
dev_t dev;
vname1 = (vir_bytes) job_m_in.name1;
vname1_length = (size_t) job_m_in.name1_length;
mode_bits = (mode_t) job_m_in.mk_mode; /* mode of the inode */
dev = job_m_in.m1_i3;
lookup_init(&resolve, fullpath, PATH_NOFLAGS, &vmp, &vp);
resolve.l_vmnt_lock = VMNT_WRITE;
resolve.l_vnode_lock = VNODE_READ;
/* Only the super_user may make nodes other than fifos. */
if (!super_user && (!S_ISFIFO(mode_bits) && !S_ISSOCK(mode_bits))) {
return(EPERM);
}
bits = (mode_bits & S_IFMT) | (mode_bits & ACCESSPERMS & fp->fp_umask);
/* Open directory that's going to hold the new node. */
if (fetch_name(vname1, vname1_length, fullpath) != OK) return(err_code);
if ((vp = last_dir(&resolve, fp)) == NULL) return(err_code);
/* Make sure that the object is a directory */
if (!S_ISDIR(vp->v_mode)) {
r = ENOTDIR;
} else if ((r = forbidden(fp, vp, W_BIT|X_BIT)) == OK) {
r = req_mknod(vp->v_fs_e, vp->v_inode_nr, fullpath, fp->fp_effuid,
fp->fp_effgid, bits, dev);
}
unlock_vnode(vp);
unlock_vmnt(vmp);
put_vnode(vp);
return(r);
}
/*===========================================================================*
* do_mkdir *
*===========================================================================*/
int do_mkdir()
{
/* Perform the mkdir(name, mode) system call. */
mode_t bits; /* mode bits for the new inode */
int r;
struct vnode *vp;
struct vmnt *vmp;
char fullpath[PATH_MAX];
struct lookup resolve;
vir_bytes vname1;
size_t vname1_length;
mode_t dirmode;
vname1 = (vir_bytes) job_m_in.name1;
vname1_length = (size_t) job_m_in.name1_length;
dirmode = (mode_t) job_m_in.mode;
lookup_init(&resolve, fullpath, PATH_NOFLAGS, &vmp, &vp);
resolve.l_vmnt_lock = VMNT_WRITE;
resolve.l_vnode_lock = VNODE_READ;
if (fetch_name(vname1, vname1_length, fullpath) != OK) return(err_code);
bits = I_DIRECTORY | (dirmode & RWX_MODES & fp->fp_umask);
if ((vp = last_dir(&resolve, fp)) == NULL) return(err_code);
/* Make sure that the object is a directory */
if (!S_ISDIR(vp->v_mode)) {
r = ENOTDIR;
} else if ((r = forbidden(fp, vp, W_BIT|X_BIT)) == OK) {
r = req_mkdir(vp->v_fs_e, vp->v_inode_nr, fullpath, fp->fp_effuid,
fp->fp_effgid, bits);
}
unlock_vnode(vp);
unlock_vmnt(vmp);
put_vnode(vp);
return(r);
}
/*===========================================================================*
* do_lseek *
*===========================================================================*/
int do_lseek()
{
/* Perform the lseek(ls_fd, offset, whence) system call. */
register struct filp *rfilp;
int r = OK, seekfd, seekwhence;
off_t offset;
u64_t pos, newpos;
seekfd = job_m_in.ls_fd;
seekwhence = job_m_in.whence;
offset = (off_t) job_m_in.offset_lo;
/* Check to see if the file descriptor is valid. */
if ( (rfilp = get_filp(seekfd, VNODE_READ)) == NULL) return(err_code);
/* No lseek on pipes. */
if (S_ISFIFO(rfilp->filp_vno->v_mode)) {
unlock_filp(rfilp);
return(ESPIPE);
}
/* The value of 'whence' determines the start position to use. */
switch(seekwhence) {
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: unlock_filp(rfilp); return(EINVAL);
}
if (offset >= 0)
newpos = add64ul(pos, offset);
else
newpos = sub64ul(pos, -offset);
/* Check for overflow. */
if (ex64hi(newpos) != 0) {
r = EOVERFLOW;
} else if ((off_t) ex64lo(newpos) < 0) { /* no negative file size */
r = EOVERFLOW;
} else {
/* insert the new position into the output message */
m_out.reply_l1 = ex64lo(newpos);
if (cmp64(newpos, rfilp->filp_pos) != 0) {
rfilp->filp_pos = newpos;
/* Inhibit read ahead request */
r = req_inhibread(rfilp->filp_vno->v_fs_e,
rfilp->filp_vno->v_inode_nr);
}
}
unlock_filp(rfilp);
return(r);
}
/*===========================================================================*
* do_llseek *
*===========================================================================*/
int do_llseek()
{
/* Perform the llseek(ls_fd, offset, whence) system call. */
register struct filp *rfilp;
u64_t pos, newpos;
int r = OK, seekfd, seekwhence;
long off_hi, off_lo;
seekfd = job_m_in.ls_fd;
seekwhence = job_m_in.whence;
off_hi = job_m_in.offset_high;
off_lo = job_m_in.offset_lo;
/* Check to see if the file descriptor is valid. */
if ( (rfilp = get_filp(seekfd, VNODE_READ)) == NULL) return(err_code);
/* No lseek on pipes. */
if (S_ISFIFO(rfilp->filp_vno->v_mode)) {
unlock_filp(rfilp);
return(ESPIPE);
}
/* The value of 'whence' determines the start position to use. */
switch(seekwhence) {
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: unlock_filp(rfilp); return(EINVAL);
}
newpos = add64(pos, make64(off_lo, off_hi));
/* Check for overflow. */
if ((off_hi > 0) && cmp64(newpos, pos) < 0)
r = EINVAL;
else if ((off_hi < 0) && cmp64(newpos, pos) > 0)
r = EINVAL;
else {
/* insert the new position into the output message */
m_out.reply_l1 = ex64lo(newpos);
m_out.reply_l2 = ex64hi(newpos);
if (cmp64(newpos, rfilp->filp_pos) != 0) {
rfilp->filp_pos = newpos;
/* Inhibit read ahead request */
r = req_inhibread(rfilp->filp_vno->v_fs_e,
rfilp->filp_vno->v_inode_nr);
}
}
unlock_filp(rfilp);
return(r);
}
/*===========================================================================*
* do_close *
*===========================================================================*/
int do_close()
{
/* Perform the close(fd) system call. */
scratch(fp).file.fd_nr = job_m_in.fd;
return close_fd(fp, scratch(fp).file.fd_nr);
}
/*===========================================================================*
* close_fd *
*===========================================================================*/
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, VNODE_OPCL)) == NULL) return(err_code);
vp = rfilp->filp_vno;
close_filp(rfilp);
rfp->fp_filp[fd_nr] = NULL;
FD_CLR(fd_nr, &rfp->fp_cloexec_set);
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) {
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(); /* one or more locks released */
}
return(OK);
}
/*===========================================================================*
* close_reply *
*===========================================================================*/
void close_reply()
{
/* No need to do anything */
}
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