switch (fsbuf.f_type) { case EXT2_SUPER_MAGIC:  buf->f_frsize = 1024; break;
fstatvfs (int fd, struct statvfs *buf){  struct statfs fsbuf;  struct stat st;  /* Get as much information as possible from the system.  */  if (__fstatfs (fd, &fsbuf) < 0)    return -1;  /* Now fill in the fields we have information for.  */  buf->f_bsize = 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;  buf->f_fsid = fsbuf.f_fsid;  buf->f_namemax = fsbuf.f_namelen;  memset (buf->f_spare, '\0', 6 * sizeof (int));  /* What remains to do is to fill the fields f_frsize, f_favail,     and f_flag.  */  switch (fsbuf.f_type)    {    case EXT2_SUPER_MAGIC:      /* This is not really correct since the fragment size can vary.  */      buf->f_frsize = 1024;      break;    case ADFS_SUPER_MAGIC:    case AFFS_SUPER_MAGIC:    case CODA_SUPER_MAGIC:    case HPFS_SUPER_MAGIC:    case ISOFS_SUPER_MAGIC:    case MINIX_SUPER_MAGIC:    case MINIX_SUPER_MAGIC2:    case MINIX2_SUPER_MAGIC:    case MINIX2_SUPER_MAGIC2:    case MSDOS_SUPER_MAGIC:    case NCP_SUPER_MAGIC:    case NFS_SUPER_MAGIC:    case PROC_SUPER_MAGIC:    case SMB_SUPER_MAGIC:    case XENIX_SUPER_MAGIC:    case SYSV4_SUPER_MAGIC:    case SYSV2_SUPER_MAGIC:    case COH_SUPER_MAGIC:    case UFS_MAGIC:    case UFS_CIGAM:    default:      /* I hope it's safe to assume no fragmentation.  */      buf->f_frsize = buf->f_bsize;      break;    }  /* 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 (fstat (fd, &st) >= 0)    {      int save_errno = errno;      struct mntent mntbuf;      FILE *mtab;      mtab = __setmntent ("/proc/mounts", "r");      if (mtab == NULL)	mtab = __setmntent (_PATH_MOUNTED, "r");      if (mtab != NULL)	{	  char tmpbuf[1024];	  while (__getmntent_r (mtab, &mntbuf, tmpbuf, sizeof (tmpbuf)))	    {	      struct stat fsst;	      /* Find out about the device the current entry is for.  */	      if (stat (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.  */		  break;		}	    }	  /* Close the file.  */	  __endmntent (mtab);	}      __set_errno (save_errno);    }  /* We signal success if the statfs call succeeded.  */  return 0;}