internal_statvfs.c

/* Copyright (C) 1998,1999,2000,2001,2002,2003 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C 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
   Lesser General Public License for more details.

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

#include <assert.h>
#include <errno.h>
#include <mntent.h>
#include <paths.h>
#include <stdbool.h>
#include <stdio_ext.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/statfs.h>
#include <sys/statvfs.h>
#include "linux_fsinfo.h"


void
__internal_statvfs (const char *name, struct statvfs *buf,
		    struct statfs *fsbuf, struct stat64 *st)
{
  /* Now fill in the fields we have information for.  */
  buf->f_bsize = fsbuf->f_bsize;
  /* Linux has the f_frsize size only in later version of the kernel.
     If the value is not filled in use f_bsize.  */
  buf->f_frsize = fsbuf->f_frsize ?: fsbuf->f_bsize;
  buf->f_blocks = fsbuf->f_blocks;
  buf->f_bfree = fsbuf->f_bfree;
  buf->f_bavail = fsbuf->f_bavail;
  buf->f_files = fsbuf->f_files;
  buf->f_ffree = fsbuf->f_ffree;
  if (sizeof (buf->f_fsid) == sizeof (fsbuf->f_fsid))
    buf->f_fsid = (fsbuf->f_fsid.__val[0]
		   | ((unsigned long int) fsbuf->f_fsid.__val[1]
		      << (8 * (sizeof (buf->f_fsid)
			       - sizeof (fsbuf->f_fsid.__val[0])))));
  else
    /* We cannot help here.  The statvfs element is not large enough to
       contain both words of the statfs f_fsid field.  */
    buf->f_fsid = fsbuf->f_fsid.__val[0];
#ifdef _STATVFSBUF_F_UNUSED
  buf->__f_unused = 0;
#endif
  buf->f_namemax = fsbuf->f_namelen;
  memset (buf->__f_spare, '\0', 6 * sizeof (int));

  /* What remains to do is to fill the fields f_favail and f_flag.  */

  /* XXX I have no idea how to compute f_favail.  Any idea???  */
  buf->f_favail = buf->f_ffree;

  /* Determining the flags is tricky.  We have to read /proc/mounts or
     the /etc/mtab file and search for the entry which matches the given
     file.  The way we can test for matching filesystem is using the
     device number.  */
  buf->f_flag = 0;
  if (st != NULL)
    {
      struct mntent mntbuf;
      FILE *mtab;
      const char *fsname = NULL;
      const char *fsname2 = NULL;
      bool success = false;

      /* Map the filesystem type we got from the statfs call to a string.  */
      switch (fsbuf->f_type)
	{
	case EXT2_SUPER_MAGIC:
	  fsname = "ext3";
	  fsname2 = "ext2";
	  break;
	case DEVPTS_SUPER_MAGIC:
	  fsname= "devpts";
	  break;
	case SHMFS_SUPER_MAGIC:
	  fsname = "tmpfs";
	  break;
	case PROC_SUPER_MAGIC:
	  fsname = "proc";
	  break;
	case USBDEVFS_SUPER_MAGIC:
	  fsname = "usbdevfs";
	  break;
	case AUTOFS_SUPER_MAGIC:
	  fsname = "autofs";
	  break;
	case NFS_SUPER_MAGIC:
	  fsname = "nfs";
	  break;
	}

      mtab = __setmntent ("/proc/mounts", "r");
      if (mtab == NULL)
	mtab = __setmntent (_PATH_MOUNTED, "r");

      if (mtab != NULL)
	{
	  char tmpbuf[1024];

	  /* No locking needed.  */
	  (void) __fsetlocking (mtab, FSETLOCKING_BYCALLER);

	again:
	  while (__getmntent_r (mtab, &mntbuf, tmpbuf, sizeof (tmpbuf)))
	    {
	      /* In a first round we look for a given mount point, if
		 we have a name.  */
	      if (name != NULL && strcmp (name, mntbuf.mnt_dir) != 0)
		continue;
	      /* We need to look at the entry only if the filesystem
		 name matches.  If we have a filesystem name.  */
	      else if (fsname != NULL
		  && strcmp (fsname, mntbuf.mnt_type) != 0
		  && (fsname2 == NULL
		      || strcmp (fsname2, mntbuf.mnt_type) != 0))
		continue;

	      /* Find out about the device the current entry is for.  */
	      struct stat64 fsst;
	      if (stat64 (mntbuf.mnt_dir, &fsst) >= 0
		  && st->st_dev == fsst.st_dev)
		{
		  /* Bingo, we found the entry for the device FD is on.
		     Now interpret the option string.  */
		  char *cp = mntbuf.mnt_opts;
		  char *opt;

		  while ((opt = strsep (&cp, ",")) != NULL)
		    if (strcmp (opt, "ro") == 0)
		      buf->f_flag |= ST_RDONLY;
		    else if (strcmp (opt, "nosuid") == 0)
		      buf->f_flag |= ST_NOSUID;
		    else if (strcmp (opt, "noexec") == 0)
		      buf->f_flag |= ST_NOEXEC;
		    else if (strcmp (opt, "nodev") == 0)
		      buf->f_flag |= ST_NODEV;
		    else if (strcmp (opt, "sync") == 0)
		      buf->f_flag |= ST_SYNCHRONOUS;
		    else if (strcmp (opt, "mand") == 0)
		      buf->f_flag |= ST_MANDLOCK;
		    else if (strcmp (opt, "noatime") == 0)
		      buf->f_flag |= ST_NOATIME;
		    else if (strcmp (opt, "nodiratime") == 0)
		      buf->f_flag |= ST_NODIRATIME;

		  /* We can stop looking for more entries.  */
		  success = true;
		  break;
		}
	    }
	  /* Maybe the kernel names for the filesystems changed or the
	     statvfs call got a name which was not the mount point.
	     Check again, this time without checking for name matches
	     first.  */
	  if (! success && (name != NULL || fsname != NULL))
	    {
	      if (name != NULL)
		/* Try without a mount point name.  */
		name = NULL;
	      else
		{
		  /* Try without a filesystem name.  */
		  assert (fsname != NULL);
		  fsname = fsname2 = NULL;
		}

	      /* It is not strictly allowed to use rewind here.  But
		 this code is part of the implementation so it is
		 acceptable.  */
	      rewind (mtab);

	      goto again;
	    }

	  /* Close the file.  */
	  __endmntent (mtab);

	}
    }
}