13ef7f1f38
file descriptor passing, PFS does some back calls to VFS. For example, to verify the validity of a path provided by a process and to tell VFS it must copy file descriptors from one process to another.
352 lines
11 KiB
C
352 lines
11 KiB
C
/* This file contains the procedures that manipulate file descriptors.
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*
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* The entry points into this file are
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* get_fd: look for free file descriptor and free filp slots
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* get_filp: look up the filp entry for a given file descriptor
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* find_filp: find a filp slot that points to a given vnode
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* inval_filp: invalidate a filp and associated fd's, only let close()
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* happen on it
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* do_verify_fd: verify whether the given file descriptor is valid for
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* the given endpoint.
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* do_set_filp: marks a filp as in-flight.
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* do_copy_filp: copies a filp to another endpoint.
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* do_put_filp: marks a filp as not in-flight anymore.
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* do_cancel_fd: cancel the transaction when something goes wrong for
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* the receiver.
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*/
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#include <sys/select.h>
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#include <minix/callnr.h>
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#include <minix/u64.h>
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#include <assert.h>
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#include "fs.h"
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#include "file.h"
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#include "fproc.h"
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#include "vnode.h"
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/*===========================================================================*
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* get_fd *
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*===========================================================================*/
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PUBLIC int get_fd(int start, mode_t bits, int *k, struct filp **fpt)
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{
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/* Look for a free file descriptor and a free filp slot. Fill in the mode word
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* in the latter, but don't claim either one yet, since the open() or creat()
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* may yet fail.
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*/
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register struct filp *f;
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register int i;
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/* Search the fproc fp_filp table for a free file descriptor. */
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for (i = start; i < OPEN_MAX; i++) {
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if (fp->fp_filp[i] == NULL && !FD_ISSET(i, &fp->fp_filp_inuse)) {
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/* A file descriptor has been located. */
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*k = i;
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break;
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}
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}
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/* Check to see if a file descriptor has been found. */
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if (i >= OPEN_MAX) return(EMFILE);
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/* Now that a file descriptor has been found, look for a free filp slot. */
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for (f = &filp[0]; f < &filp[NR_FILPS]; f++) {
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assert(f->filp_count >= 0);
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if (f->filp_count == 0) {
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f->filp_mode = bits;
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f->filp_pos = cvu64(0);
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f->filp_selectors = 0;
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f->filp_select_ops = 0;
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f->filp_pipe_select_ops = 0;
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f->filp_flags = 0;
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f->filp_state = FS_NORMAL;
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f->filp_select_flags = 0;
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*fpt = f;
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return(OK);
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}
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}
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/* If control passes here, the filp table must be full. Report that back. */
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return(ENFILE);
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}
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/*===========================================================================*
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* get_filp *
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*===========================================================================*/
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PUBLIC struct filp *get_filp(fild)
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int fild; /* file descriptor */
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{
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/* See if 'fild' refers to a valid file descr. If so, return its filp ptr. */
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return get_filp2(fp, fild);
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}
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/*===========================================================================*
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* get_filp2 *
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*===========================================================================*/
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PUBLIC struct filp *get_filp2(rfp, fild)
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register struct fproc *rfp;
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int fild; /* file descriptor */
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{
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/* See if 'fild' refers to a valid file descr. If so, return its filp ptr. */
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err_code = EBADF;
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if (fild < 0 || fild >= OPEN_MAX ) return(NULL);
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if (rfp->fp_filp[fild] == NULL && FD_ISSET(fild, &rfp->fp_filp_inuse))
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err_code = EIO; /* The filedes is not there, but is not closed either.
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*/
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return(rfp->fp_filp[fild]); /* may also be NULL */
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}
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/*===========================================================================*
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* find_filp *
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*===========================================================================*/
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PUBLIC struct filp *find_filp(register struct vnode *vp, mode_t bits)
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{
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/* Find a filp slot that refers to the vnode 'vp' in a way as described
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* by the mode bit 'bits'. Used for determining whether somebody is still
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* interested in either end of a pipe. Also used when opening a FIFO to
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* find partners to share a filp field with (to shared the file position).
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* Like 'get_fd' it performs its job by linear search through the filp table.
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*/
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register struct filp *f;
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for (f = &filp[0]; f < &filp[NR_FILPS]; f++) {
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if (f->filp_count != 0 && f->filp_vno == vp && (f->filp_mode & bits)){
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return(f);
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}
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}
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/* If control passes here, the filp wasn't there. Report that back. */
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return(NULL);
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}
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/*===========================================================================*
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* invalidate *
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*===========================================================================*/
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PUBLIC int invalidate(struct filp *fp)
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{
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/* Invalidate filp. fp_filp_inuse is not cleared, so filp can't be reused
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until it is closed first. */
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int f, fd, n = 0;
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for(f = 0; f < NR_PROCS; f++) {
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if(fproc[f].fp_pid == PID_FREE) continue;
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for(fd = 0; fd < OPEN_MAX; fd++) {
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if(fproc[f].fp_filp[fd] && fproc[f].fp_filp[fd] == fp) {
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fproc[f].fp_filp[fd] = NULL;
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n++;
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}
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}
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}
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return(n); /* Report back how often this filp has been invalidated. */
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}
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/*===========================================================================*
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* verify_fd *
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*===========================================================================*/
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PUBLIC filp_id_t verify_fd(ep, fd)
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endpoint_t ep;
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int fd;
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{
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/*
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* verify whether the given file descriptor 'fd' is valid for the
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* endpoint 'ep'. When the file descriptor is valid verify_fd returns a
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* pointer to that filp, else it returns NULL.
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*/
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int proc;
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if (isokendpt(ep, &proc) != OK) {
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return NULL;
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}
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return get_filp2(&fproc[proc], fd);
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}
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/*===========================================================================*
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* do_verify_fd *
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*===========================================================================*/
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PUBLIC int do_verify_fd(void)
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{
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m_out.ADDRESS = (void *) verify_fd(m_in.IO_ENDPT, m_in.COUNT);
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return (m_out.ADDRESS != NULL) ? OK : EINVAL;
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}
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/*===========================================================================*
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* set_filp *
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*===========================================================================*/
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PUBLIC int set_filp(sfilp)
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filp_id_t sfilp;
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{
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if (sfilp == NULL) {
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return EINVAL;
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} else {
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sfilp->filp_count++;
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return OK;
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}
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}
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/*===========================================================================*
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* do_set_filp *
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*===========================================================================*/
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PUBLIC int do_set_filp(void)
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{
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return set_filp((filp_id_t) m_in.ADDRESS);;
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}
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/*===========================================================================*
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* copy_filp *
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*===========================================================================*/
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PUBLIC int copy_filp(to_ep, cfilp)
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endpoint_t to_ep;
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filp_id_t cfilp;
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{
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int j;
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int proc;
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if (isokendpt(to_ep, &proc) != OK) {
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return EINVAL;
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}
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/* Find an open slot in fp_filp */
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for (j = 0; j < OPEN_MAX; j++) {
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if (fproc[proc].fp_filp[j] == NULL &&
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!FD_ISSET(j, &fproc[proc].fp_filp_inuse)) {
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/* Found a free slot, add descriptor */
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FD_SET(j, &fproc[proc].fp_filp_inuse);
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fproc[proc].fp_filp[j] = cfilp;
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fproc[proc].fp_filp[j]->filp_count++;
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return j;
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}
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}
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/* File Descriptor Table is Full */
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return EMFILE;
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}
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/*===========================================================================*
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* do_copy_filp *
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*===========================================================================*/
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PUBLIC int do_copy_filp(void)
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{
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return copy_filp(m_in.IO_ENDPT, (filp_id_t) m_in.ADDRESS);
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}
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/*===========================================================================*
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* put_filp *
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*===========================================================================*/
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PUBLIC int put_filp(pfilp)
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filp_id_t pfilp;
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{
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if (pfilp == NULL) {
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return EINVAL;
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} else {
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close_filp(pfilp);
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return OK;
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}
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}
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/*===========================================================================*
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* do_put_filp *
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*===========================================================================*/
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PUBLIC int do_put_filp(void)
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{
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return put_filp((filp_id_t) m_in.ADDRESS);
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}
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/*===========================================================================*
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* cancel_fd *
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*===========================================================================*/
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PUBLIC int cancel_fd(ep, fd)
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endpoint_t ep;
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int fd;
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{
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int j;
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int proc;
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if (isokendpt(ep, &proc) != OK) {
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return EINVAL;
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}
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/* Check that the input 'fd' is valid */
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if (verify_fd(ep, fd) != NULL) {
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/* Found a valid descriptor, remove it */
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FD_CLR(fd, &fproc[proc].fp_filp_inuse);
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fproc[proc].fp_filp[fd]->filp_count--;
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fproc[proc].fp_filp[fd] = NULL;
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return fd;
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}
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/* File descriptor is not valid for the endpoint. */
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return EINVAL;
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}
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/*===========================================================================*
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* do_cancel_fd *
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*===========================================================================*/
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PUBLIC int do_cancel_fd(void)
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{
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return cancel_fd(m_in.IO_ENDPT, m_in.COUNT);
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}
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/*===========================================================================*
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* close_filp *
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*===========================================================================*/
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PUBLIC void close_filp(fp)
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struct filp *fp;
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{
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int mode_word, rw;
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dev_t dev;
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struct vnode *vp;
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vp = fp->filp_vno;
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if (fp->filp_count - 1 == 0 && fp->filp_mode != FILP_CLOSED) {
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/* Check to see if the file is special. */
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mode_word = vp->v_mode & I_TYPE;
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if (mode_word == I_CHAR_SPECIAL || mode_word == I_BLOCK_SPECIAL) {
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dev = (dev_t) vp->v_sdev;
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if (mode_word == I_BLOCK_SPECIAL) {
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if (vp->v_bfs_e == ROOT_FS_E) {
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/* Invalidate the cache unless the special is
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* mounted. Assume that the root filesystem's
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* is open only for fsck.
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*/
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req_flush(vp->v_bfs_e, dev);
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}
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}
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/* Do any special processing on device close. */
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(void) dev_close(dev, fp-filp);
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/* Ignore any errors, even SUSPEND. */
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fp->filp_mode = FILP_CLOSED;
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}
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}
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/* If the inode being closed is a pipe, release everyone hanging on it. */
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if (vp->v_pipe == I_PIPE) {
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rw = (fp->filp_mode & R_BIT ? WRITE : READ);
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release(vp, rw, NR_PROCS);
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}
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/* If a write has been done, the inode is already marked as DIRTY. */
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if (--fp->filp_count == 0) {
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if (vp->v_pipe == I_PIPE) {
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/* Last reader or writer is going. Tell PFS about latest
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* pipe size.
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*/
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truncate_vnode(vp, vp->v_size);
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}
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put_vnode(fp->filp_vno);
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}
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}
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