df.c

《linux应用开发技术详解》的配套代码

/* df - summarize free disk space
   Copyright (C) 91, 1995-2002 Free Software Foundation, Inc.

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

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

/* Written by David MacKenzie <[e-mail]>.
   --human-readable and --megabyte options added by [e-mail].
   --si and large file support added by [e-mail].  */

#ifdef _AIX
 #pragma alloca
#endif

#include <config.h>
#include <stdio.h>
#include <sys/types.h>
#include <getopt.h>
#include <assert.h>

#include "system.h"
#include "dirname.h"
#include "error.h"
#include "fsusage.h"
#include "human.h"
#include "mountlist.h"
#include "path-concat.h"
#include "quote.h"
#include "save-cwd.h"

/* The official name of this program (e.g., no `g' prefix).  */
#define PROGRAM_NAME "df"

#define AUTHORS \
  N_ ("Torbjorn Granlund, David MacKenzie, Larry McVoy, and Paul Eggert")

char *xgetcwd ();

/* Name this program was run with. */
char *program_name;

/* If nonzero, show inode information. */
static int inode_format;

/* If nonzero, show even filesystems with zero size or
   uninteresting types. */
static int show_all_fs;

/* If nonzero, show only local filesystems.  */
static int show_local_fs;

/* If nonzero, output data for each filesystem corresponding to a
   command line argument -- even if it's a dummy (automounter) entry.  */
static int show_listed_fs;

/* If positive, the units to use when printing sizes;
   if negative, the human-readable base.  */
static int output_block_size;

/* If nonzero, use the POSIX output format.  */
static int posix_format;

/* If nonzero, invoke the `sync' system call before getting any usage data.
   Using this option can make df very slow, especially with many or very
   busy disks.  Note that this may make a difference on some systems --
   SunOs4.1.3, for one.  It is *not* necessary on Linux.  */
static int require_sync = 0;

/* Nonzero if errors have occurred. */
static int exit_status;

/* A filesystem type to display. */

struct fs_type_list
{
  char *fs_name;
  struct fs_type_list *fs_next;
};

/* Linked list of filesystem types to display.
   If `fs_select_list' is NULL, list all types.
   This table is generated dynamically from command-line options,
   rather than hardcoding into the program what it thinks are the
   valid filesystem types; let the user specify any filesystem type
   they want to, and if there are any filesystems of that type, they
   will be shown.

   Some filesystem types:
   4.2 4.3 ufs nfs swap ignore io vm efs dbg */

static struct fs_type_list *fs_select_list;

/* Linked list of filesystem types to omit.
   If the list is empty, don't exclude any types.  */

static struct fs_type_list *fs_exclude_list;

/* Linked list of mounted filesystems. */
static struct mount_entry *mount_list;

/* If nonzero, print filesystem type as well.  */
static int print_type;

/* For long options that have no equivalent short option, use a
   non-character as a pseudo short option, starting with CHAR_MAX + 1.  */
enum
{
  SYNC_OPTION = CHAR_MAX + 1,
  NO_SYNC_OPTION
};

static struct option const long_options[] =
{
  {"all", no_argument, NULL, 'a'},
  {"block-size", required_argument, NULL, 'B'},
  {"inodes", no_argument, NULL, 'i'},
  {"human-readable", no_argument, NULL, 'h'},
  {"si", no_argument, NULL, 'H'},
  {"kilobytes", no_argument, NULL, 'k'}, /* long form is obsolescent */
  {"local", no_argument, NULL, 'l'},
  {"megabytes", no_argument, NULL, 'm'}, /* obsolescent */
  {"portability", no_argument, NULL, 'P'},
  {"print-type", no_argument, NULL, 'T'},
  {"sync", no_argument, NULL, SYNC_OPTION},
  {"no-sync", no_argument, NULL, NO_SYNC_OPTION},
  {"type", required_argument, NULL, 't'},
  {"exclude-type", required_argument, NULL, 'x'},
  {GETOPT_HELP_OPTION_DECL},
  {GETOPT_VERSION_OPTION_DECL},
  {NULL, 0, NULL, 0}
};

static void
print_header (void)
{
  printf (_("Filesystem "));

  if (print_type)
    printf (_("   Type"));
  else
    printf ("       ");

  if (inode_format)
    printf (_("    Inodes   IUsed   IFree IUse%%"));
  else if (output_block_size < 0)
    {
      if (output_block_size == -1000)
	printf (_("     Size   Used  Avail Use%%"));
      else
	printf (_("    Size  Used Avail Use%%"));
    }
  else if (posix_format)
    printf (_(" %4d-blocks      Used Available Capacity"), output_block_size);
  else
    {
      char buf[LONGEST_HUMAN_READABLE + 1];
      char *p = human_readable (output_block_size, buf, 1, -1024);

      /* Replace e.g. "1.0K" by "1K".  */
      size_t plen = strlen (p);
      if (3 <= plen && strncmp (p + plen - 3, ".0", 2) == 0)
	strcpy (p + plen - 3, p + plen - 1);

      printf (_(" %4s-blocks      Used Available Use%%"), p);
    }

  printf (_(" Mounted on\n"));
}

/* If FSTYPE is a type of filesystem that should be listed,
   return nonzero, else zero. */

static int
selected_fstype (const char *fstype)
{
  const struct fs_type_list *fsp;

  if (fs_select_list == NULL || fstype == NULL)
    return 1;
  for (fsp = fs_select_list; fsp; fsp = fsp->fs_next)
    if (STREQ (fstype, fsp->fs_name))
      return 1;
  return 0;
}

/* If FSTYPE is a type of filesystem that should be omitted,
   return nonzero, else zero. */

static int
excluded_fstype (const char *fstype)
{
  const struct fs_type_list *fsp;

  if (fs_exclude_list == NULL || fstype == NULL)
    return 0;
  for (fsp = fs_exclude_list; fsp; fsp = fsp->fs_next)
    if (STREQ (fstype, fsp->fs_name))
      return 1;
  return 0;
}

/* Like human_readable_inexact with a human_ceiling
   human_inexact_style, except return "-" if the argument is -1, and
   if NEGATIVE is 1 then N represents a negative number, expressed in
   two's complement.  */

static char const *
df_readable (int negative, uintmax_t n, char *buf,
	     int from_block_size, int t_output_block_size)
{
  if (n == -1)
    return "-";
  else
    {
      char *p = human_readable_inexact (negative ? - n : n,
					buf + negative, from_block_size,
					t_output_block_size,
					human_ceiling);
      if (negative)
	*--p = '-';
      return p;
    }
}

/* Since the values in a line are separated by spaces, a name cannot
 * contain a space.  Therefore some programs encode spaces in names
 * by the strings "\040".  We undo the encoding when reading an entry.
 * The decoding happens in place.  */
static char * decode_name (char *buf)
{
    char *rp = buf;
    char *wp = buf;

    do
	if (rp[0] == '\\' && rp[1] == '0' && rp[2] == '4' && rp[3] == '0') {
	    /* \040 is a SPACE.  */
	    *wp++ = ' ';
	    rp += 3;
	} else if (rp[0] == '\\' && rp[1] == '0' && rp[2] == '1' && rp[3] == '2') {
	    /* \012 is a TAB.  */
	    *wp++ = '\t';
	    rp += 3;
	} else if (rp[0] == '\\' && rp[1] == '\\') {
	    /* We have to escape \\ to be able to represent all characters.  */
	    *wp++ = '\\';
	    rp += 1;
	} else
	    *wp++ = *rp;
    while (*rp++ != '\0');

    return buf;
}

/* Display a space listing for the disk device with absolute path DISK.
   If MOUNT_POINT is non-NULL, it is the path of the root of the
   filesystem on DISK.
   If FSTYPE is non-NULL, it is the type of the filesystem on DISK.
   If MOUNT_POINT is non-NULL, then DISK may be NULL -- certain systems may
   not be able to produce statistics in this case.
   ME_DUMMY and ME_REMOTE are the mount entry flags.  */

static void
show_dev (const char *disk, const char *mount_point, const char *fstype,
	  int me_dummy, int me_remote)
{
  struct fs_usage fsu;
  const char *stat_file;
  char buf[3][LONGEST_HUMAN_READABLE + 2];
  int width;
  int use_width;
  int input_units;
  int output_units;
  uintmax_t total;
  uintmax_t available;
  int negate_available;
  uintmax_t available_to_root;
  uintmax_t used;
  int negate_used;
  double pct = -1;

  if (me_remote && show_local_fs)
    return;

  if (me_dummy && show_all_fs == 0 && !show_listed_fs)
    return;

  if (!selected_fstype (fstype) || excluded_fstype (fstype))
    return;

  /* If MOUNT_POINT is NULL, then the filesystem is not mounted, and this
     program reports on the filesystem that the special file is on.
     It would be better to report on the unmounted filesystem,
     but statfs doesn't do that on most systems.  */
  stat_file = mount_point ? decode_name((char *) mount_point) : disk;

  if (get_fs_usage (stat_file, disk, &fsu))
    {
      error (0, errno, "%s", quote (stat_file));
      exit_status = 1;
      return;
    }

  if (fsu.fsu_blocks == 0 && !show_all_fs && !show_listed_fs)
    return;

  if (! disk)
    disk = "-";			/* unknown */
  if (! fstype)
    fstype = "-";		/* unknown */

  /* df.c reserved 5 positions for fstype,
     but that does not suffice for type iso9660 */
  if (print_type)
    {
      int disk_name_len = (int) strlen (disk);
      int fstype_len = (int) strlen (fstype);
      if (disk_name_len + fstype_len + 2 < 20)
	printf ("%s%*s  ", disk, 18 - disk_name_len, fstype);
      else if (!posix_format)
	printf ("%s\n%18s  ", disk, fstype);
      else
	printf ("%s %s", disk, fstype);
    }
  else
    {
      if ((int) strlen (disk) > 20 && !posix_format)
	printf ("%s\n%20s", disk, "");
      else
	printf ("%-20s", disk);
    }

  if (inode_format)
    {
      width = 7;
      use_width = 5;
      input_units = 1;
      output_units = output_block_size < 0 ? output_block_size : 1;
      total = fsu.fsu_files;
      available = fsu.fsu_ffree;
      negate_available = 0;
      available_to_root = available;
    }
  else
    {
      width = output_block_size < 0 ? 5 + (output_block_size == -1000) : 9;
      use_width = (posix_format && 0 <= output_block_size) ? 8 : 4;
      input_units = fsu.fsu_blocksize;
      output_units = output_block_size;
      total = fsu.fsu_blocks;
      available = fsu.fsu_bavail;
      negate_available = fsu.fsu_bavail_top_bit_set;
      available_to_root = fsu.fsu_bfree;
    }

  used = -1;
  negate_used = 0;
  if (total != -1 && available_to_root != -1)
    {
      used = total - available_to_root;
      if (total < available_to_root)
	{
	  negate_used = 1;
	  used = - used;
	}
    }

  printf (" %*s %*s %*s ",
	  width, df_readable (0, total,
			      buf[0], input_units, output_units),
	  width, df_readable (negate_used, used,
			      buf[1], input_units, output_units),
	  width, df_readable (negate_available, available,
			      buf[2], input_units, output_units));

  if (used == -1 || available == -1)
    ;
  else if (!negate_used
	   && used <= TYPE_MAXIMUM (uintmax_t) / 100
	   && used + available != 0
	   && (used + available < used) == negate_available)
    {
      uintmax_t u100 = used * 100;
      uintmax_t nonroot_total = used + available;
      pct = u100 / nonroot_total + (u100 % nonroot_total != 0);
    }
  else
    {
      /* The calculation cannot be done easily with integer
	 arithmetic.  Fall back on floating point.  This can suffer
	 from minor rounding errors, but doing it exactly requires
	 multiple precision arithmetic, and it's not worth the
	 aggravation.  */
      double u = negate_used ? - (double) - used : used;
      double a = negate_available ? - (double) - available : available;
      double nonroot_total = u + a;
      if (nonroot_total)
	{
	  double ipct;
	  pct = u * 100 / nonroot_total;
	  ipct = (long) pct;

	  /* Like `pct = ceil (dpct);', but avoid ceil so that
	     the math library needn't be linked.  */
	  if (ipct - 1 < pct && pct <= ipct + 1)
	    pct = ipct + (ipct < pct);
	}
    }

  if (0 <= pct)
    printf ("%*.0f%%", use_width - 1, pct);
  else
    printf ("%*s", use_width, "- ");

  if (mount_point)
    {
#ifdef HIDE_AUTOMOUNT_PREFIX
      /* Don't print the first directory name in MOUNT_POINT if it's an
	 artifact of an automounter.  This is a bit too aggressive to be
	 the default.  */
      if (strncmp ("/auto/", mount_point, 6) == 0)
	mount_point += 5;
      else if (strncmp ("/tmp_mnt/", mount_point, 9) == 0)
	mount_point += 8;
#endif
      /* at this point mount_point should ba already decoded */
      printf (" %s", mount_point);
    }
  putchar ('\n');
}

/* Identify the directory, if any, that device
   DISK is mounted on, and show its disk usage.  */

static void
show_disk (const char *disk)
{
  struct mount_entry *me;

  for (me = mount_list; me; me = me->me_next)
    if (STREQ (disk, me->me_devname))
      {
	show_dev (me->me_devname, me->me_mountdir, me->me_type,
		  me->me_dummy, me->me_remote);
	return;
      }
  /* No filesystem is mounted on DISK. */
  show_dev (disk, (char *) NULL, (char *) NULL, 0, 0);
}

/* Return the root mountpoint of the filesystem on which FILE exists, in
   malloced storage.  FILE_STAT should be the result of stating FILE.  */
static char *
find_mount_point (const char *file, const struct stat *file_stat)
{
  struct saved_cwd cwd;
  struct stat last_stat;
  char *mp = 0;			/* The malloced mount point path.  */

  if (save_cwd (&cwd))
    return NULL;

  if (S_ISDIR (file_stat->st_mode))
    /* FILE is a directory, so just chdir there directly.  */
    {
      last_stat = *file_stat;
      if (chdir (file) < 0)
	return NULL;
    }
  else
    /* FILE is some other kind of file, we need to use its directory.  */
    {
      char *dir = dir_name (file);
      int rv = chdir (dir);
      free (dir);

      if (rv < 0)
	return NULL;

      if (stat (".", &last_stat) < 0)
	goto done;
    }

  /* Now walk up FILE's parents until we find another filesystem or /,
     chdiring as we go.  LAST_STAT holds stat information for the last place
     we visited.  */
  for (;;)
    {
      struct stat st;
      if (stat ("..", &st) < 0)