man2/sysfs.2

   1 .\" Copyright (C) 1995, Thomas K. Dyas <tdyas@eden.rutgers.edu>
   2 .\"
   3 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   4 .\"
   5 .\" Created   Wed Aug  9 1995     Thomas K. Dyas <tdyas@eden.rutgers.edu>
   6 .\"
   7 .TH SYSFS 2 2021-03-22 "Linux man-pages (unreleased)"
   8 .SH NAME
   9 sysfs \- get filesystem type information
  10 .SH SYNOPSIS
  11 .nf
  12 .BI "int sysfs(int " option ", const char *" fsname );
  13 .BI "int sysfs(int " option ", unsigned int " fs_index ", char *" buf );
  14 .BI "int sysfs(int " option );
  15 .fi
  16 .SH DESCRIPTION
  17 .BR "Note" :
  18 if you are looking for information about the
  19 .B sysfs
  20 filesystem that is normally mounted at
  21 .IR /sys ,
  22 see
  23 .BR sysfs (5).
  24 .PP
  25 The (obsolete)
  26 .BR sysfs ()
  27 system call returns information about the filesystem types
  28 currently present in the kernel.
  29 The specific form of the
  30 .BR sysfs ()
  31 call and the information returned depends on the
  32 .I option
  33 in effect:
  34 .TP 3
  35 .B 1
  36 Translate the filesystem identifier string
  37 .I fsname
  38 into a filesystem type index.
  39 .TP
  40 .B 2
  41 Translate the filesystem type index
  42 .I fs_index
  43 into a null-terminated filesystem identifier string.
  44 This string will
  45 be written to the buffer pointed to by
  46 .IR buf .
  47 Make sure that
  48 .I buf
  49 has enough space to accept the string.
  50 .TP
  51 .B 3
  52 Return the total number of filesystem types currently present in the
  53 kernel.
  54 .PP
  55 The numbering of the filesystem type indexes begins with zero.
  56 .SH RETURN VALUE
  57 On success,
  58 .BR sysfs ()
  59 returns the filesystem index for option
  60 .BR 1 ,
  61 zero for option
  62 .BR 2 ,
  63 and the number of currently configured filesystems for option
  64 .BR 3 .
  65 On error, \-1 is returned, and
  66 .I errno
  67 is set to indicate the error.
  68 .SH ERRORS
  69 .TP
  70 .B EFAULT
  71 .RI "Either " fsname " or " buf
  72 is outside your accessible address space.
  73 .TP
  74 .B EINVAL
  75 .I fsname
  76 is not a valid filesystem type identifier;
  77 .I fs_index
  78 is out-of-bounds;
  79 .I option
  80 is invalid.
  81 .SH STANDARDS
  82 SVr4.
  83 .SH NOTES
  84 This System-V derived system call is obsolete; don't use it.
  85 On systems with
  86 .IR /proc ,
  87 the same information can be obtained via
  88 .IR /proc ;
  89 use that interface instead.
  90 .SH BUGS
  91 There is no libc or glibc support.
  92 There is no way to guess how large \fIbuf\fP should be.
  93 .SH SEE ALSO
  94 .BR proc (5),
  95 .BR sysfs (5)