device.c

Minix3.11的源码。[MINIX 3是一个为高可靠性应用而设计的自由且简洁的类UNIX系统。]

/* When a needed block is not in the cache, it must be fetched from the disk.
 * Special character files also require I/O.  The routines for these are here.
 *
 * The entry points in this file are:
 *   dev_open:   FS opens a device
 *   dev_close:  FS closes a device
 *   dev_io:	 FS does a read or write on a device
 *   dev_status: FS processes callback request alert
 *   gen_opcl:   generic call to a task to perform an open/close
 *   gen_io:     generic call to a task to perform an I/O operation
 *   no_dev:     open/close processing for devices that don't exist
 *   no_dev_io:  i/o processing for devices that don't exist
 *   tty_opcl:   perform tty-specific processing for open/close
 *   ctty_opcl:  perform controlling-tty-specific processing for open/close
 *   ctty_io:    perform controlling-tty-specific processing for I/O
 *   do_ioctl:	 perform the IOCTL system call
 *   do_setsid:	 perform the SETSID system call (FS side)
 */

#include "fs.h"
#include <fcntl.h>
#include <minix/callnr.h>
#include <minix/com.h>
#include "file.h"
#include "fproc.h"
#include "inode.h"
#include "param.h"
#include "super.h"

#define ELEMENTS(a) (sizeof(a)/sizeof((a)[0]))

extern int dmap_size;

/*===========================================================================*
 *				dev_open				     *
 *===========================================================================*/
PUBLIC int dev_open(dev, proc, flags)
dev_t dev;			/* device to open */
int proc;			/* process to open for */
int flags;			/* mode bits and flags */
{
  int major, r;
  struct dmap *dp;

  /* Determine the major device number call the device class specific
   * open/close routine.  (This is the only routine that must check the
   * device number for being in range.  All others can trust this check.)
   */
  major = (dev >> MAJOR) & BYTE;
  if (major >= NR_DEVICES) major = 0;
  dp = &dmap[major];
  if (dp->dmap_driver == NONE) return ENXIO;
  r = (*dp->dmap_opcl)(DEV_OPEN, dev, proc, flags);
  if (r == SUSPEND) panic(__FILE__,"suspend on open from", dp->dmap_driver);
  return(r);
}

/*===========================================================================*
 *				dev_close				     *
 *===========================================================================*/
PUBLIC void dev_close(dev)
dev_t dev;			/* device to close */
{
  /* See if driver is roughly valid. */
  if (dmap[(dev >> MAJOR)].dmap_driver == NONE) {
	return;
  }
  (void) (*dmap[(dev >> MAJOR) & BYTE].dmap_opcl)(DEV_CLOSE, dev, 0, 0);
}

/*===========================================================================*
 *				dev_status					*
 *===========================================================================*/
PUBLIC void dev_status(message *m)
{
	message st;
	int d, get_more = 1;

	for(d = 0; d < NR_DEVICES; d++)
		if (dmap[d].dmap_driver != NONE &&
		    dmap[d].dmap_driver == m->m_source)
			break;

	if (d >= NR_DEVICES)
		return;

	do {
		int r;
		st.m_type = DEV_STATUS;
		if ((r=sendrec(m->m_source, &st)) != OK) {
			if (r == EDEADSRCDST) return;
			if (r == EDSTDIED) return;
			if (r == ESRCDIED) return;
			panic(__FILE__,"couldn't sendrec for DEV_STATUS", r);
		}

		switch(st.m_type) {
			case DEV_REVIVE:
				revive(st.REP_PROC_NR, st.REP_STATUS);
				break;
			case DEV_IO_READY:
				select_notified(d, st.DEV_MINOR, st.DEV_SEL_OPS);
				break;
			default:
				printf("FS: unrecognized reply %d to DEV_STATUS\n", st.m_type);
				/* Fall through. */
			case DEV_NO_STATUS:
				get_more = 0;
				break;
		}
	} while(get_more);

	return;
}

/*===========================================================================*
 *				dev_io					     *
 *===========================================================================*/
PUBLIC int dev_io(op, dev, proc, buf, pos, bytes, flags)
int op;				/* DEV_READ, DEV_WRITE, DEV_IOCTL, etc. */
dev_t dev;			/* major-minor device number */
int proc;			/* in whose address space is buf? */
void *buf;			/* virtual address of the buffer */
off_t pos;			/* byte position */
int bytes;			/* how many bytes to transfer */
int flags;			/* special flags, like O_NONBLOCK */
{
/* Read or write from a device.  The parameter 'dev' tells which one. */
  struct dmap *dp;
  message dev_mess;

  /* Determine task dmap. */
  dp = &dmap[(dev >> MAJOR) & BYTE];

  /* See if driver is roughly valid. */
  if (dp->dmap_driver == NONE) return ENXIO;

  /* Set up the message passed to task. */
  dev_mess.m_type   = op;
  dev_mess.DEVICE   = (dev >> MINOR) & BYTE;
  dev_mess.POSITION = pos;
  dev_mess.PROC_NR  = proc;
  dev_mess.ADDRESS  = buf;
  dev_mess.COUNT    = bytes;
  dev_mess.TTY_FLAGS = flags;

  /* Call the task. */
  (*dp->dmap_io)(dp->dmap_driver, &dev_mess);

  /* Task has completed.  See if call completed. */
  if (dev_mess.REP_STATUS == SUSPEND) {
	if (flags & O_NONBLOCK) {
		/* Not supposed to block. */
		dev_mess.m_type = CANCEL;
		dev_mess.PROC_NR = proc;
		dev_mess.DEVICE = (dev >> MINOR) & BYTE;
		(*dp->dmap_io)(dp->dmap_driver, &dev_mess);
		if (dev_mess.REP_STATUS == EINTR) dev_mess.REP_STATUS = EAGAIN;
	} else {
		/* Suspend user. */
		suspend(dp->dmap_driver);
		return(SUSPEND);
	}
  }
  return(dev_mess.REP_STATUS);
}

/*===========================================================================*
 *				gen_opcl				     *
 *===========================================================================*/
PUBLIC int gen_opcl(op, dev, proc, flags)
int op;				/* operation, DEV_OPEN or DEV_CLOSE */
dev_t dev;			/* device to open or close */
int proc;			/* process to open/close for */
int flags;			/* mode bits and flags */
{
/* Called from the dmap struct in table.c on opens & closes of special files.*/
  struct dmap *dp;
  message dev_mess;

  /* Determine task dmap. */
  dp = &dmap[(dev >> MAJOR) & BYTE];

  dev_mess.m_type   = op;
  dev_mess.DEVICE   = (dev >> MINOR) & BYTE;
  dev_mess.PROC_NR  = proc;
  dev_mess.COUNT    = flags;

  /* Call the task. */
  (*dp->dmap_io)(dp->dmap_driver, &dev_mess);

  return(dev_mess.REP_STATUS);
}

/*===========================================================================*
 *				tty_opcl				     *
 *===========================================================================*/
PUBLIC int tty_opcl(op, dev, proc, flags)
int op;				/* operation, DEV_OPEN or DEV_CLOSE */
dev_t dev;			/* device to open or close */
int proc;			/* process to open/close for */
int flags;			/* mode bits and flags */
{
/* This procedure is called from the dmap struct on tty open/close. */
 
  int r;
  register struct fproc *rfp;

  /* Add O_NOCTTY to the flags if this process is not a session leader, or
   * if it already has a controlling tty, or if it is someone elses
   * controlling tty.
   */
  if (!fp->fp_sesldr || fp->fp_tty != 0) {
	flags |= O_NOCTTY;
  } else {
	for (rfp = &fproc[0]; rfp < &fproc[NR_PROCS]; rfp++) {
		if (rfp->fp_tty == dev) flags |= O_NOCTTY;
	}
  }

  r = gen_opcl(op, dev, proc, flags);

  /* Did this call make the tty the controlling tty? */
  if (r == 1) {
	fp->fp_tty = dev;
	r = OK;
  }
  return(r);
}

/*===========================================================================*
 *				ctty_opcl				     *
 *===========================================================================*/
PUBLIC int ctty_opcl(op, dev, proc, flags)
int op;				/* operation, DEV_OPEN or DEV_CLOSE */
dev_t dev;			/* device to open or close */
int proc;			/* process to open/close for */
int flags;			/* mode bits and flags */
{
/* This procedure is called from the dmap struct in table.c on opening/closing
 * /dev/tty, the magic device that translates to the controlling tty.
 */
 
  return(fp->fp_tty == 0 ? ENXIO : OK);
}

/*===========================================================================*
 *				do_setsid				     *
 *===========================================================================*/
PUBLIC int do_setsid()
{
/* Perform the FS side of the SETSID call, i.e. get rid of the controlling
 * terminal of a process, and make the process a session leader.
 */
  register struct fproc *rfp;

  /* Only MM may do the SETSID call directly. */
  if (who != PM_PROC_NR) return(ENOSYS);

  /* Make the process a session leader with no controlling tty. */
  rfp = &fproc[m_in.slot1];
  rfp->fp_sesldr = TRUE;
  rfp->fp_tty = 0;
  return(OK);
}

/*===========================================================================*
 *				do_ioctl				     *
 *===========================================================================*/
PUBLIC int do_ioctl()
{
/* Perform the ioctl(ls_fd, request, argx) system call (uses m2 fmt). */