util.c

Linux内核源代码 为压缩文件 是<<Linux内核>>一书中的源代码

/*  devfs (Device FileSystem) utilities.

    Copyright (C) 1999-2000  Richard Gooch

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

    Richard Gooch may be reached by email at  [e-mail]
    The postal address is:
      Richard Gooch, c/o ATNF, P. O. Box 76, Epping, N.S.W., 2121, Australia.

    ChangeLog

    19991031   Richard Gooch <[e-mail]>
               Created.
    19991103   Richard Gooch <[e-mail]>
               Created <_devfs_convert_name> and supported SCSI and IDE CD-ROMs
    20000203   Richard Gooch <[e-mail]>
               Changed operations pointer type to void *.
    20000621   Richard Gooch <[e-mail]>
               Changed interface to <devfs_register_series>.
    20000622   Richard Gooch <[e-mail]>
               Took account of interface change to <devfs_mk_symlink>.
               Took account of interface change to <devfs_mk_dir>.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/locks.h>
#include <linux/kdev_t.h>
#include <linux/devfs_fs_kernel.h>


/*  Private functions follow  */

/**
 *	_devfs_convert_name - Convert from an old style location-based name to new style.
 *	@new: The new name will be written here.
 *	@old: The old name.
 *	@disc: If true, disc partitioning information should be processed.
 */

static void __init _devfs_convert_name (char *new, const char *old, int disc)
{
    int host, bus, target, lun;
    char *ptr;
    char part[8];

    /*  Decode "c#b#t#u#"  */
    if (old[0] != 'c') return;
    host = simple_strtol (old + 1, &ptr, 10);
    if (ptr[0] != 'b') return;
    bus = simple_strtol (ptr + 1, &ptr, 10);
    if (ptr[0] != 't') return;
    target = simple_strtol (ptr + 1, &ptr, 10);
    if (ptr[0] != 'u') return;
    lun = simple_strtol (ptr + 1, &ptr, 10);
    if (disc)
    {
	/*  Decode "p#"  */
	if (ptr[0] == 'p') sprintf (part, "part%s", ptr + 1);
	else strcpy (part, "disc");
    }
    else part[0] = '\0';
    sprintf (new, "/host%d/bus%d/target%d/lun%d/%s",
	     host, bus, target, lun, part);
}   /*  End Function _devfs_convert_name  */


/*  Public functions follow  */

/**
 *	devfs_make_root - Create the root FS device entry if required.
 *	@name: The name of the root FS device, as passed by "root=".
 */

void __init devfs_make_root (const char *name)
{
    char dest[64];

    if ( (strncmp (name, "sd/", 3) == 0) || (strncmp (name, "sr/", 3) == 0) )
    {
	strcpy (dest, "../scsi");
	_devfs_convert_name (dest + 7, name + 3, (name[1] == 'd') ? 1 : 0);
    }
    else if ( (strncmp (name, "ide/hd/", 7) == 0) ||
	      (strncmp (name, "ide/cd/", 7) == 0) )
    {
	strcpy (dest, "..");
	_devfs_convert_name (dest + 2, name + 7, (name[4] == 'h') ? 1 : 0);
    }
    else return;
    devfs_mk_symlink (NULL, name, DEVFS_FL_DEFAULT, dest, NULL, NULL);
}   /*  End Function devfs_make_root  */


/**
 *	devfs_register_tape - Register a tape device in the "/dev/tapes" hierarchy.
 *	@de: Any tape device entry in the device directory.
 */

void devfs_register_tape (devfs_handle_t de)
{
    int pos;
    devfs_handle_t parent, slave;
    char name[16], dest[64];
    static unsigned int tape_counter;
    static devfs_handle_t tape_dir;

    if (tape_dir == NULL) tape_dir = devfs_mk_dir (NULL, "tapes", NULL);
    parent = devfs_get_parent (de);
    pos = devfs_generate_path (parent, dest + 3, sizeof dest - 3);
    if (pos < 0) return;
    strncpy (dest + pos, "../", 3);
    sprintf (name, "tape%u", tape_counter++);
    devfs_mk_symlink (tape_dir, name, DEVFS_FL_DEFAULT, dest + pos,
		      &slave, NULL);
    devfs_auto_unregister (de, slave);
}   /*  End Function devfs_register_tape  */
EXPORT_SYMBOL(devfs_register_tape);


/**
 *	devfs_register_series - Register a sequence of device entries.
 *	@dir: The handle to the parent devfs directory entry. If this is %NULL the
 *		new names are relative to the root of the devfs.
 *	@format: The printf-style format string. A single "\%u" is allowed.
 *	@flags: A set of bitwise-ORed flags (DEVFS_FL_*).
 *	@major: The major number. Not needed for regular files.
 *	@minor_start: The starting minor number. Not needed for regular files.
 *	@mode: The default file mode.
 *	@ops: The &file_operations or &block_device_operations structure.
 *		This must not be externally deallocated.
 *	@info: An arbitrary pointer which will be written to the private_data
 *		field of the &file structure passed to the device driver. You can set
 *		this to whatever you like, and change it once the file is opened (the next
 *		file opened will not see this change).
 */

void devfs_register_series (devfs_handle_t dir, const char *format,
			    unsigned int num_entries, unsigned int flags,
			    unsigned int major, unsigned int minor_start,
			    umode_t mode, void *ops, void *info)
{
    unsigned int count;
    char devname[128];

    for (count = 0; count < num_entries; ++count)
    {
	sprintf (devname, format, count);
	devfs_register (dir, devname, flags, major, minor_start + count,
			mode, ops, info);
    }
}   /*  End Function devfs_register_series  */
EXPORT_SYMBOL(devfs_register_series);