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 2012-10-09 "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 Note :
  20 This system call is present only in kernels before Linux 2.6.
  21
  22 .BR query_module ()
  23 requests information from the kernel about loadable modules.
  24 The returned information is placed in the buffer pointed to by
  25 .IR buf .
  26 The caller must specify the size of
  27 .I buf
  28 in
  29 .IR bufsize .
  30 The precise nature and format of the returned information
  31 depend on the operation specified by
  32 .IR which .
  33 Some operations require
  34 .I name
  35 to identify a currently loaded module, some allow
  36 .I name
  37 to be NULL, indicating the kernel proper.
  38
  39 The following values can be specified for
  40 .IR which :
  41 .TP
  42 .B 0
  43 Returns success, if the kernel supports
  44 .BR query_module ().
  45 Used to probe for availability of the system call.
  46 .TP
  47 .B QM_MODULES
  48 Returns the names of all loaded modules.
  49 The returned buffer consists of a sequence of null-terminated strings;
  50 .I ret
  51 is set to the number of
  52 modules.
  53 .\" ret is set on ENOSPC
  54 .TP
  55 .B QM_DEPS
  56 Returns the names of all modules used by the indicated module.
  57 The returned buffer consists of a sequence of null-terminated strings;
  58 .I ret
  59 is set to the number of modules.
  60 .\" ret is set on ENOSPC
  61 .TP
  62 .B QM_REFS
  63 Returns the names of all modules using the indicated module.
  64 This is the inverse of
  65 .BR QM_DEPS .
  66 The returned buffer consists of a sequence of null-terminated strings;
  67 .I ret
  68 is set to the number of modules.
  69 .\" ret is set on ENOSPC
  70 .TP
  71 .B QM_SYMBOLS
  72 Returns the symbols and values exported by the kernel or the indicated
  73 module.
  74 The returned buffer is an array of structures of the following form
  75 .\" ret is set on ENOSPC
  76 .in +4n
  77 .nf
  78
  79 struct module_symbol {
  80     unsigned long value;
  81     unsigned long name;
  82 };
  83 .fi
  84 .in
  85 .IP
  86 followed by null-terminated strings.
  87 The value of
  88 .I name
  89 is the character offset of the string relative to the start of
  90 .IR buf ;
  91 .I ret
  92 is set to the number of symbols.
  93 .TP
  94 .B QM_INFO
  95 Returns miscellaneous information about the indicated module.
  96 The output buffer format is:
  97 .in +4n
  98 .nf
  99
 100 struct module_info {
 101     unsigned long address;
 102     unsigned long size;
 103     unsigned long flags;
 104 };
 105 .fi
 106 .in
 107 .IP
 108 where
 109 .I address
 110 is the kernel address at which the module resides,
 111 .I size
 112 is the size of the module in bytes, and
 113 .I flags
 114 is a mask of
 115 .BR MOD_RUNNING ,
 116 .BR MOD_AUTOCLEAN ,
 117 etc., that indicates the current status of the module
 118 (see the Linux kernel source file
 119 .IR include/linux/module.h ).
 120 .I ret
 121 is set to the size of the
 122 .I module_info
 123 structure.
 124 .SH "RETURN VALUE"
 125 On success, zero is returned.
 126 On error, \-1 is returned and
 127 .I errno
 128 is set appropriately.
 129 .SH ERRORS
 130 .TP
 131 .B EFAULT
 132 At least one of
 133 .IR name ,
 134 .IR buf ,
 135 or
 136 .I ret
 137 was outside the program's accessible address space.
 138 .TP
 139 .B EINVAL
 140 Invalid
 141 .IR which ;
 142 or
 143 .I name
 144 is NULL (indicating "the kernel"),
 145 but this is not permitted with the specified value of
 146 .IR which .
 147 .\" Not permitted with QM_DEPS, QM_REFS, or QM_INFO.
 148 .TP
 149 .B ENOENT
 150 No module by that
 151 .I name
 152 exists.
 153 .TP
 154 .B ENOSPC
 155 The buffer size provided was too small.
 156 .I ret
 157 is set to the minimum size needed.
 158 .TP
 159 .B ENOSYS
 160 .BR query_module ()
 161 is not supported in this version of the kernel.
 162 .SH "CONFORMING TO"
 163 .BR query_module ()
 164 is Linux-specific.
 165 .SH NOTES
 166 This system call is only present on Linux up until kernel 2.4;
 167 it was removed in Linux 2.6.
 168 .\" Removed in Linux 2.5.48
 169 Some of the information that was available via
 170 .BR query_module ()
 171 can be obtained from
 172 .IR /proc/modules ,
 173 .IR /proc/kallsyms ,
 174 and the files under the directory
 175 .IR /sys/module .
 176 .SH "SEE ALSO"
 177 .BR create_module (2),
 178 .BR delete_module (2),
 179 .BR get_kernel_syms (2),
 180 .BR init_module (2),
 181 .BR lsmod (8),
 182 .BR modinfo (8)