man2/query_module.2

   1 .\" Copyright (C) 1996 Free Software Foundation, Inc.
   2 .\" This file is distributed according to the GNU General Public License.
   3 .\" See the file COPYING in the top level source directory for details.
   4 .\"
   5 .\" 2006-02-09, some reformatting by Luc Van Oostenryck; some
   6 .\" reformatting and rewordings by mtk
   7 .\"
   8 .TH QUERY_MODULE 2 2007-06-03 "Linux" "Linux Programmer's Manual"
   9 .SH NAME
  10 query_module \- query the kernel for various bits pertaining to modules
  11 .SH SYNOPSIS
  12 .nf
  13 .B #include <linux/module.h>
  14 .sp
  15 .BI "int query_module(const char *" name ", int " which ", void *" buf ,
  16 .BI "                 size_t " bufsize ", size_t *" ret );
  17 .fi
  18 .SH DESCRIPTION
  19 .BR query_module ()
  20 requests information from the kernel about loadable modules.
  21 The returned information is placed in the buffer pointed to by
  22 .IR buf .
  23 The caller must specify the size of
  24 .I buf
  25 in
  26 .IR bufsize .
  27 The precise nature and format of the returned information
  28 depend on the operation specified by
  29 .IR which .
  30 Some operations require
  31 .I name
  32 to identify a currently loaded module, some allow
  33 .I name
  34 to be NULL, indicating the kernel proper.
  35
  36 The following values can be specified for
  37 .IR which :
  38 .TP
  39 .B 0
  40 Returns success, if the kernel supports
  41 .BR query_module ().
  42 Used to probe for availability of the system call.
  43 .TP
  44 .B QM_MODULES
  45 Returns the names of all loaded modules.
  46 The returned buffer consists of a sequence of null-terminated strings;
  47 .I ret
  48 is set to the number of
  49 modules.
  50 .\" ret is set on ENOSPC
  51 .TP
  52 .B QM_DEPS
  53 Returns the names of all modules used by the indicated module.
  54 The returned buffer consists of a sequence of null-terminated strings;
  55 .I ret
  56 is set to the number of modules.
  57 .\" ret is set on ENOSPC
  58 .TP
  59 .B QM_REFS
  60 Returns the names of all modules using the indicated module.
  61 This is the inverse of
  62 .BR QM_DEPS .
  63 The returned buffer consists of a sequence of null-terminated strings;
  64 .I ret
  65 is set to the number of modules.
  66 .\" ret is set on ENOSPC
  67 .TP
  68 .B QM_SYMBOLS
  69 Returns the symbols and values exported by the kernel or the indicated
  70 module.
  71 The returned buffer is an array of structures of the following form
  72 .\" ret is set on ENOSPC
  73 .in +4n
  74 .nf
  75
  76 struct module_symbol {
  77     unsigned long value;
  78     unsigned long name;
  79 };
  80 .fi
  81 .in
  82 .IP
  83 followed by null-terminated strings.
  84 The value of
  85 .I name
  86 is the character offset of the string relative to the start of
  87 .IR buf ;
  88 .I ret
  89 is set to the number of symbols.
  90 .TP
  91 .B QM_INFO
  92 Returns miscellaneous information about the indicated module.
  93 The output buffer format is:
  94 .in +4n
  95 .nf
  96
  97 struct module_info {
  98     unsigned long address;
  99     unsigned long size;
 100     unsigned long flags;
 101 };
 102 .fi
 103 .in
 104 .IP
 105 where
 106 .I address
 107 is the kernel address at which the module resides,
 108 .I size
 109 is the size of the module in bytes, and
 110 .I flags
 111 is a mask of
 112 .BR MOD_RUNNING ,
 113 .BR MOD_AUTOCLEAN ,
 114 etc. that indicates the current status of the module
 115 (see the kernel source file
 116 .IR include/linux/module.h ).
 117 .I ret
 118 is set to the size of the
 119 .I module_info
 120 structure.
 121 .RE
 122 .SH "RETURN VALUE"
 123 On success, zero is returned.
 124 On error, \-1 is returned and
 125 .I errno
 126 is set appropriately.
 127 .SH ERRORS
 128 .TP
 129 .B EFAULT
 130 At least one of
 131 .IR name ,
 132 .IR buf ,
 133 or
 134 .I ret
 135 was outside the program's accessible address space.
 136 .TP
 137 .B EINVAL
 138 Invalid
 139 .IR which ;
 140 or
 141 .I name
 142 is NULL (indicating "the kernel"),
 143 but this is not permitted with the specified value of
 144 .IR which .
 145 .\" Not permitted with QM_DEPS, QM_REFS, or QM_INFO.
 146 .TP
 147 .B ENOENT
 148 No module by that
 149 .I name
 150 exists.
 151 .TP
 152 .B ENOSPC
 153 The buffer size provided was too small.
 154 .I ret
 155 is set to the minimum size needed.
 156 .TP
 157 .B ENOSYS
 158 .BR query_module ()
 159 is not supported in this version of the kernel.
 160 .SH "CONFORMING TO"
 161 .BR query_module ()
 162 is Linux-specific.
 163 .SH NOTES
 164 This system call is only present on Linux up until kernel 2.4;
 165 it was removed in Linux 2.6.
 166 .\" Removed in Linux 2.5.48
 167 Some of the information that was available via
 168 .BR query_module ()
 169 can be obtained from
 170 .IR /proc/modules ,
 171 .IR /proc/kallsyms ,
 172 and
 173 .IR /sys/modules .
 174 .SH "SEE ALSO"
 175 .BR create_module (2),
 176 .BR delete_module (2),
 177 .BR get_kernel_syms (2),
 178 .BR init_module (2)