gen/FreeBSD/getmntinfo.3

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  28 .\"     @(#)getmntinfo.3        8.1 (Berkeley) 6/9/93
  29 .\" $FreeBSD: src/lib/libc/gen/getmntinfo.3,v 1.13 2007/01/09 00:27:54 imp Exp $
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  31 .Dd April 12, 2017
  32 .Dt GETMNTINFO 3
  33 .Os
  34 .Sh NAME
  35 .Nm getmntinfo
  36 .Nm getmntinfo_r_np
  37 .Nm getmntinfo64
  38 .Nd get information about mounted file systems
  39 .Sh SYNOPSIS
  40 .In sys/param.h
  41 .In sys/ucred.h
  42 .In sys/mount.h
  43 .Ft int
  44 .Fn getmntinfo "struct statfs **mntbufp" "int flags"
  45 .Ft int
  46 .Fn getmntinfo_r_np "struct statfs **mntbufp" "int flags"
  47 .Sh TRANSITIIONAL SYNOPSIS (NOW DEPRECATED)
  48 .Ft int
  49 .br
  50 .Fn getmntinfo64 "struct statfs64 **mntbufp" "int flags" ;
  51 .Sh DESCRIPTION
  52 The
  53 .Fn getmntinfo
  54 function
  55 returns an array of
  56 .Ft statfs
  57 structures describing each currently mounted file system (see
  58 .Xr statfs 2 ) .
  59 As
  60 .Xr statfs 2
  61 indicates, the structure is defined differently depending on
  62 whether the macro _DARWIN_FEATURE_64_BIT_INODE is defined (see
  63 .Xr stat 2
  64 for more information on this macro).
  65 .Pp
  66 The
  67 .Fn getmntinfo
  68 and
  69 .Fn getmntinfo_r_np
  70 functions
  71 pass their
  72 .Fa flags
  73 argument transparently to
  74 .Xr getfsstat 2 .
  75 .Pp
  76 The
  77 .Fn getmntinfo
  78 function maintains ownership of the results buffer it allocates,
  79 and may overwrite or free this buffer in subsequent calls to
  80 .Fn getmntinfo .
  81 For this reason,
  82 .Fn getmntinfo
  83 is not thread-safe.
  84 .Pp
  85 The
  86 .Fn getmntinfo_r_np
  87 function is a thread-safe equivalent of
  88 .Fn getmntinfo
  89 that allocates a new results buffer on every call and transfers ownership
  90 of this buffer to the caller.
  91 The caller is responsible for freeing this memory with
  92 .Xr free 3 .
  93 .Sh RETURN VALUES
  94 On successful completion,
  95 .Fn getmntinfo
  96 and
  97 .Fn getmntinfo_r_np
  98 return a count of the number of elements in the array.
  99 The pointer to the array is stored into
 100 .Fa mntbufp .
 101 .Pp
 102 If an error occurs, zero is returned and the external variable
 103 .Va errno
 104 is set to indicate the error.
 105 The
 106 .Fn getmntinfo
 107 function may modify the
 108 .Fa mbtbufp
 109 pointer even in the case of an error.
 110 In this situation, callers should consider any previous information
 111 returned by
 112 .Fn getmntinfo
 113 to be lost.
 114 The
 115 .Fn getmntinfo_r_np
 116 function will not modify the
 117 .Fa mntbufp
 118 pointer in the case of an error.
 119 .Sh ERRORS
 120 The
 121 .Fn getmntinfo
 122 and
 123 .Fn getmntinfo_r_np
 124 functions
 125 may fail and set errno for any of the errors specified for the library
 126 routines
 127 .Xr getfsstat 2
 128 or
 129 .Xr malloc 3 .
 130 .Sh TRANSITIONAL DESCRIPTION (NOW DEPRECATED)
 131 The
 132 .Fn getmntinfo64
 133 routine is equivalent to its corresponding non-64-suffixed routine,
 134 when 64-bit inodes are in effect.
 135 It was added before there was support for the symbol variants, and so is
 136 now deprecated.
 137 Instead of using it, set the
 138 .Dv _DARWIN_USE_64_BIT_INODE
 139 macro before including header files to force 64-bit inode support.
 140 .Pp
 141 The
 142 .Ft statfs64
 143 structure used by this deprecated routine is the same as the
 144 .Ft statfs
 145 structure when 64-bit inodes are in effect.
 146 .Sh SEE ALSO
 147 .Xr getfsstat 2 ,
 148 .Xr mount 2 ,
 149 .Xr stat 2 ,
 150 .Xr statfs 2 ,
 151 .Xr mount 8
 152 .Sh HISTORY
 153 The
 154 .Fn getmntinfo
 155 function first appeared in
 156 .Bx 4.4 .
 157 The
 158 .Fn getmntinfo_r_np
 159 function first appeared in macOS 10.13.
 160 .Sh BUGS
 161 The
 162 .Fn getmntinfo
 163 function writes the array of structures to an internal static object
 164 and returns
 165 a pointer to that object.
 166 Subsequent calls to
 167 .Fn getmntinfo
 168 will modify the same object.
 169 .Pp
 170 The memory allocated by
 171 .Fn getmntinfo
 172 cannot be
 173 .Xr free 3 Ns 'd
 174 by the application.