minix/servers/vfs/utility.c

/* This file contains a few general purpose utility routines.
 *
 * The entry points into this file are
 *   clock_timespec: ask the clock task for the real time
 *   copy:	  copy a block of data
 *   fetch_name:  go get a path name from user space
 *   no_sys:      reject a system call that FS does not handle
 *   panic:       something awful has occurred;  MINIX cannot continue
 *   conv2:	  do byte swapping on a 16-bit int
 *   conv4:	  do byte swapping on a 32-bit long
 *   in_group:    determines if group 'grp' is in rfp->fp_sgroups[]
 */

#include "fs.h"
#include <minix/com.h>
#include <minix/endpoint.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <time.h>
#include "file.h"
#include "param.h"
#include "vmnt.h"

/*===========================================================================*
 *				copy_name				     *
 *===========================================================================*/
inline int copy_name( size_t len, char *dest)
{
/* Go get path and put it in 'dest'.
 */
  if (len > PATH_MAX) {	/* 'len' includes terminating-nul */
	err_code = ENAMETOOLONG;
	return(EGENERIC);
  }

  /* Check name length for validity. */
  if (len > SSIZE_MAX) {
	err_code = EINVAL;
	return(EGENERIC);
  }

  if (len <= M3_STRING) {
	/* Just copy the path from the message */
	strncpy(dest, job_m_in.pathname, len);
  } else {
	/* String is not contained in the message. */
	err_code = EINVAL;
	return(EGENERIC);
  }

  if (dest[len - 1] != '\0') {
	err_code = ENAMETOOLONG;
	return(EGENERIC);
  }

  return(OK);
}

/*===========================================================================*
 *				fetch_name				     *
 *===========================================================================*/
int fetch_name(vir_bytes path, size_t len, char *dest)
{
/* Go get path and put it in 'dest'.  */
  int r;

  if (len > PATH_MAX) {	/* 'len' includes terminating-nul */
	err_code = ENAMETOOLONG;
	return(EGENERIC);
  }

  /* Check name length for validity. */
  if (len > SSIZE_MAX) {
	err_code = EINVAL;
	return(EGENERIC);
  }

  /* String is not contained in the message.  Get it from user space. */
  r = sys_datacopy(who_e, path, VFS_PROC_NR, (vir_bytes) dest, len);
  if (r != OK) {
	err_code = EINVAL;
	return(r);
  }

  if (dest[len - 1] != '\0') {
	err_code = ENAMETOOLONG;
	return(EGENERIC);
  }

  return(OK);
}


/*===========================================================================*
 *				no_sys					     *
 *===========================================================================*/
int no_sys(message *UNUSED(m_out))
{
/* Somebody has used an illegal system call number */
  return(ENOSYS);
}


/*===========================================================================*
 *				isokendpt_f				     *
 *===========================================================================*/
int isokendpt_f(char *file, int line, endpoint_t endpoint, int *proc,
       int fatal)
{
  int failed = 0;
  endpoint_t ke;
  *proc = _ENDPOINT_P(endpoint);
  if (endpoint == NONE) {
	printf("VFS %s:%d: endpoint is NONE\n", file, line);
	failed = 1;
  } else if (*proc < 0 || *proc >= NR_PROCS) {
	printf("VFS %s:%d: proc (%d) from endpoint (%d) out of range\n",
		file, line, *proc, endpoint);
	failed = 1;
  } else if ((ke = fproc[*proc].fp_endpoint) != endpoint) {
	if(ke == NONE) {
		assert(fproc[*proc].fp_pid == PID_FREE);
	} else {
		printf("VFS %s:%d: proc (%d) from endpoint (%d) doesn't match "
			"known endpoint (%d)\n", file, line, *proc, endpoint,
			fproc[*proc].fp_endpoint);
		assert(fproc[*proc].fp_pid != PID_FREE);
	}
	failed = 1;
  }

  if(failed && fatal)
	panic("isokendpt_f failed");

  return(failed ? EDEADEPT : OK);
}


/*===========================================================================*
 *				clock_timespec				     *
 *===========================================================================*/
struct timespec clock_timespec(void)
{
/* This routine returns the time in seconds since 1.1.1970.  MINIX is an
 * astrophysically naive system that assumes the earth rotates at a constant
 * rate and that such things as leap seconds do not exist.
 */

  register int r;
  struct timespec tv;
  clock_t uptime;
  clock_t realtime;
  time_t boottime;

  r = getuptime(&uptime, &realtime, &boottime);
  if (r != OK)
	panic("clock_timespec err: %d", r);

  tv.tv_sec = (time_t) (boottime + (realtime/system_hz));
  /* We do not want to overflow, and system_hz can be as high as 50kHz */
  assert(system_hz < LONG_MAX/40000);
  tv.tv_nsec = (realtime%system_hz) * 40000 / system_hz * 25000;
  return tv;
}

/*===========================================================================*
 *                              in_group                                     *
 *===========================================================================*/
int in_group(struct fproc *rfp, gid_t grp)
{
  int i;

  for (i = 0; i < rfp->fp_ngroups; i++)
	if (rfp->fp_sgroups[i] == grp)
		return(OK);

  return(EINVAL);
}