man2/sysfs.2

   1 .\" Copyright (C) 1995, Thomas K. Dyas <tdyas@eden.rutgers.edu>
   2 .\"
   3 .\" %%%LICENSE_START(VERBATIM)
   4 .\" Permission is granted to make and distribute verbatim copies of this
   5 .\" manual provided the copyright notice and this permission notice are
   6 .\" preserved on all copies.
   7 .\"
   8 .\" Permission is granted to copy and distribute modified versions of this
   9 .\" manual under the conditions for verbatim copying, provided that the
  10 .\" entire resulting derived work is distributed under the terms of a
  11 .\" permission notice identical to this one.
  12 .\"
  13 .\" Since the Linux kernel and libraries are constantly changing, this
  14 .\" manual page may be incorrect or out-of-date.  The author(s) assume no
  15 .\" responsibility for errors or omissions, or for damages resulting from
  16 .\" the use of the information contained herein.  The author(s) may not
  17 .\" have taken the same level of care in the production of this manual,
  18 .\" which is licensed free of charge, as they might when working
  19 .\" professionally.
  20 .\"
  21 .\" Formatted or processed versions of this manual, if unaccompanied by
  22 .\" the source, must acknowledge the copyright and authors of this work.
  23 .\" %%%LICENSE_END
  24 .\"
  25 .\" Created   Wed Aug  9 1995     Thomas K. Dyas <tdyas@eden.rutgers.edu>
  26 .\"
  27 .TH SYSFS 2 2017-09-15 "Linux" "Linux Programmer's Manual"
  28 .SH NAME
  29 sysfs \- get filesystem type information
  30 .SH SYNOPSIS
  31 .BI "int sysfs(int " option ", const char *" fsname );
  32 .PP
  33 .BI "int sysfs(int " option ", unsigned int " fs_index ", char *" buf );
  34 .PP
  35 .BI "int sysfs(int " option );
  36 .SH DESCRIPTION
  37 .BR "Note" :
  38 if you are looking for information about the
  39 .B sysfs
  40 filesystem that is normally mounted at
  41 .IR /sys ,
  42 see
  43 .BR sysfs (5).
  44 .PP
  45 The (obsolete)
  46 .BR sysfs ()
  47 system call returns information about the filesystem types
  48 currently present in the kernel.
  49 The specific form of the
  50 .BR sysfs ()
  51 call and the information returned depends on the
  52 .I option
  53 in effect:
  54 .TP 3
  55 .B 1
  56 Translate the filesystem identifier string
  57 .I fsname
  58 into a filesystem type index.
  59 .TP
  60 .B 2
  61 Translate the filesystem type index
  62 .I fs_index
  63 into a null-terminated filesystem identifier string.
  64 This string will
  65 be written to the buffer pointed to by
  66 .IR buf .
  67 Make sure that
  68 .I buf
  69 has enough space to accept the string.
  70 .TP
  71 .B 3
  72 Return the total number of filesystem types currently present in the
  73 kernel.
  74 .PP
  75 The numbering of the filesystem type indexes begins with zero.
  76 .SH RETURN VALUE
  77 On success,
  78 .BR sysfs ()
  79 returns the filesystem index for option
  80 .BR 1 ,
  81 zero for option
  82 .BR 2 ,
  83 and the number of currently configured filesystems for option
  84 .BR 3 .
  85 On error, \-1 is returned, and
  86 .I errno
  87 is set appropriately.
  88 .SH ERRORS
  89 .TP
  90 .B EFAULT
  91 .RI "Either " fsname " or " buf
  92 is outside your accessible address space.
  93 .TP
  94 .B EINVAL
  95 .I fsname
  96 is not a valid filesystem type identifier;
  97 .I fs_index
  98 is out-of-bounds;
  99 .I option
 100 is invalid.
 101 .SH CONFORMING TO
 102 SVr4.
 103 .SH NOTES
 104 This System-V derived system call is obsolete; don't use it.
 105 On systems with
 106 .IR /proc ,
 107 the same information can be obtained via
 108 .IR /proc/filesystems ;
 109 use that interface instead.
 110 .SH BUGS
 111 There is no libc or glibc support.
 112 There is no way to guess how large \fIbuf\fP should be.