9664ba0c4f
Added interface to select() for pipes (also named pipes), and select() stubs for regular files. Added timer library in FS that select() is the first customer of. This is unfinished, but committed anyway to get a new release out to Al and testers.
102 lines
3.3 KiB
C
102 lines
3.3 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 inode
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*/
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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 "inode.h"
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/*===========================================================================*
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* get_fd *
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*===========================================================================*/
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PUBLIC int get_fd(start, bits, k, fpt)
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int start; /* start of search (used for F_DUPFD) */
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mode_t bits; /* mode of the file to be created (RWX bits) */
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int *k; /* place to return file descriptor */
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struct filp **fpt; /* place to return filp slot */
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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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*k = -1; /* we need a way to tell if file desc found */
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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] == NIL_FILP) {
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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 (*k < 0) return(EMFILE); /* this is why we initialized k to -1 */
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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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if (f->filp_count == 0) {
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f->filp_mode = bits;
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f->filp_pos = 0L;
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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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*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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err_code = EBADF;
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if (fild < 0 || fild >= OPEN_MAX ) return(NIL_FILP);
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return(fp->fp_filp[fild]); /* may also be NIL_FILP */
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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(rip, bits)
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register struct inode *rip; /* inode referred to by the filp to be found */
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Mode_t bits; /* mode of the filp to be found (RWX bits) */
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{
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/* Find a filp slot that refers to the inode 'rip' 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_ino == rip && (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(NIL_FILP);
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}
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