stadir.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。]

/* This file contains the code for performing four system calls relating to
 * status and directories.
 *
 * The entry points into this file are
 *   do_chdir:	perform the CHDIR system call
 *   do_chroot:	perform the CHROOT system call
 *   do_stat:	perform the STAT system call
 *   do_fstat:	perform the FSTAT system call
 *   do_fstatfs: perform the FSTATFS system call
 */

#include "fs.h"
#include <sys/stat.h>
#include <sys/statfs.h>
#include <minix/com.h>
#include "file.h"
#include "fproc.h"
#include "inode.h"
#include "param.h"
#include "super.h"

FORWARD _PROTOTYPE( int change, (struct inode **iip, char *name_ptr, int len));
FORWARD _PROTOTYPE( int change_into, (struct inode **iip, struct inode *ip));
FORWARD _PROTOTYPE( int stat_inode, (struct inode *rip, struct filp *fil_ptr,
			char *user_addr)				);

/*===========================================================================*
 *				do_fchdir				     *
 *===========================================================================*/
PUBLIC int do_fchdir()
{
	/* Change directory on already-opened fd. */
	struct filp *rfilp;

	/* Is the file descriptor valid? */
	if ( (rfilp = get_filp(m_in.fd)) == NIL_FILP) return(err_code);
	return change_into(&fp->fp_workdir, rfilp->filp_ino);
}

/*===========================================================================*
 *				do_chdir				     *
 *===========================================================================*/
PUBLIC int do_chdir()
{
/* Change directory.  This function is  also called by MM to simulate a chdir
 * in order to do EXEC, etc.  It also changes the root directory, the uids and
 * gids, and the umask. 
 */

  int r;
  register struct fproc *rfp;

  if (who == PM_PROC_NR) {
	rfp = &fproc[m_in.slot1];
	put_inode(fp->fp_rootdir);
	dup_inode(fp->fp_rootdir = rfp->fp_rootdir);
	put_inode(fp->fp_workdir);
	dup_inode(fp->fp_workdir = rfp->fp_workdir);

	/* MM uses access() to check permissions.  To make this work, pretend
	 * that the user's real ids are the same as the user's effective ids.
	 * FS calls other than access() do not use the real ids, so are not
	 * affected.
	 */
	fp->fp_realuid =
	fp->fp_effuid = rfp->fp_effuid;
	fp->fp_realgid =
	fp->fp_effgid = rfp->fp_effgid;
	fp->fp_umask = rfp->fp_umask;
	return(OK);
  }

  /* Perform the chdir(name) system call. */
  r = change(&fp->fp_workdir, m_in.name, m_in.name_length);
  return(r);
}

/*===========================================================================*
 *				do_chroot				     *
 *===========================================================================*/
PUBLIC int do_chroot()
{
/* Perform the chroot(name) system call. */

  register int r;

  if (!super_user) return(EPERM);	/* only su may chroot() */
  r = change(&fp->fp_rootdir, m_in.name, m_in.name_length);
  return(r);
}

/*===========================================================================*
 *				change					     *
 *===========================================================================*/
PRIVATE int change(iip, name_ptr, len)
struct inode **iip;		/* pointer to the inode pointer for the dir */
char *name_ptr;			/* pointer to the directory name to change to */
int len;			/* length of the directory name string */
{
/* Do the actual work for chdir() and chroot(). */
  struct inode *rip;

  /* Try to open the new directory. */
  if (fetch_name(name_ptr, len, M3) != OK) return(err_code);
  if ( (rip = eat_path(user_path)) == NIL_INODE) return(err_code);
  return change_into(iip, rip);
}

/*===========================================================================*
 *				change_into				     *
 *===========================================================================*/
PRIVATE int change_into(iip, rip)
struct inode **iip;		/* pointer to the inode pointer for the dir */
struct inode *rip;		/* this is what the inode has to become */
{
  register int r;

  /* It must be a directory and also be searchable. */
  if ( (rip->i_mode & I_TYPE) != I_DIRECTORY)
	r = ENOTDIR;
  else
	r = forbidden(rip, X_BIT);	/* check if dir is searchable */

  /* If error, return inode. */
  if (r != OK) {
	put_inode(rip);
	return(r);
  }

  /* Everything is OK.  Make the change. */
  put_inode(*iip);		/* release the old directory */
  *iip = rip;			/* acquire the new one */
  return(OK);
}

/*===========================================================================*
 *				do_stat					     *
 *===========================================================================*/
PUBLIC int do_stat()
{
/* Perform the stat(name, buf) system call. */

  register struct inode *rip;
  register int r;

  /* Both stat() and fstat() use the same routine to do the real work.  That
   * routine expects an inode, so acquire it temporarily.
   */
  if (fetch_name(m_in.name1, m_in.name1_length, M1) != OK) return(err_code);
  if ( (rip = eat_path(user_path)) == NIL_INODE) return(err_code);
  r = stat_inode(rip, NIL_FILP, m_in.name2);	/* actually do the work.*/
  put_inode(rip);		/* release the inode */
  return(r);
}

/*===========================================================================*
 *				do_fstat				     *
 *===========================================================================*/
PUBLIC int do_fstat()
{
/* Perform the fstat(fd, buf) system call. */

  register struct filp *rfilp;

  /* Is the file descriptor valid? */
  if ( (rfilp = get_filp(m_in.fd)) == NIL_FILP) return(err_code);

  return(stat_inode(rfilp->filp_ino, rfilp, m_in.buffer));
}

/*===========================================================================*
 *				stat_inode				     *
 *===========================================================================*/
PRIVATE int stat_inode(rip, fil_ptr, user_addr)
register struct inode *rip;	/* pointer to inode to stat */
struct filp *fil_ptr;		/* filp pointer, supplied by 'fstat' */
char *user_addr;		/* user space address where stat buf goes */
{
/* Common code for stat and fstat system calls. */

  struct stat statbuf;
  mode_t mo;
  int r, s;

  /* Update the atime, ctime, and mtime fields in the inode, if need be. */
  if (rip->i_update) update_times(rip);

  /* Fill in the statbuf struct. */
  mo = rip->i_mode & I_TYPE;

  /* true iff special */
  s = (mo == I_CHAR_SPECIAL || mo == I_BLOCK_SPECIAL);

  statbuf.st_dev = rip->i_dev;
  statbuf.st_ino = rip->i_num;
  statbuf.st_mode = rip->i_mode;
  statbuf.st_nlink = rip->i_nlinks;
  statbuf.st_uid = rip->i_uid;
  statbuf.st_gid = rip->i_gid;
  statbuf.st_rdev = (dev_t) (s ? rip->i_zone[0] : NO_DEV);
  statbuf.st_size = rip->i_size;

  if (rip->i_pipe == I_PIPE) {
	statbuf.st_mode &= ~I_REGULAR;	/* wipe out I_REGULAR bit for pipes */
	if (fil_ptr != NIL_FILP && fil_ptr->filp_mode & R_BIT) 
		statbuf.st_size -= fil_ptr->filp_pos;
  }

  statbuf.st_atime = rip->i_atime;
  statbuf.st_mtime = rip->i_mtime;
  statbuf.st_ctime = rip->i_ctime;

  /* Copy the struct to user space. */
  r = sys_datacopy(FS_PROC_NR, (vir_bytes) &statbuf,
  		who, (vir_bytes) user_addr, (phys_bytes) sizeof(statbuf));
  return(r);
}

/*===========================================================================*
 *				do_fstatfs				     *
 *===========================================================================*/
PUBLIC int do_fstatfs()
{
  /* Perform the fstatfs(fd, buf) system call. */
  struct statfs st;
  register struct filp *rfilp;
  int r;

  /* Is the file descriptor valid? */
  if ( (rfilp = get_filp(m_in.fd)) == NIL_FILP) return(err_code);

  st.f_bsize = rfilp->filp_ino->i_sp->s_block_size;

  r = sys_datacopy(FS_PROC_NR, (vir_bytes) &st,
  		who, (vir_bytes) m_in.buffer, (phys_bytes) sizeof(st));

   return(r);
}