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 2013-01-27 "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
  19 .IR Note :
  20 There is no glibc wrapper for this system call; see NOTES.
  21 .SH DESCRIPTION
  22 .BR Note :
  23 This system call is present only in kernels before Linux 2.6.
  24
  25 .BR query_module ()
  26 requests information from the kernel about loadable modules.
  27 The returned information is placed in the buffer pointed to by
  28 .IR buf .
  29 The caller must specify the size of
  30 .I buf
  31 in
  32 .IR bufsize .
  33 The precise nature and format of the returned information
  34 depend on the operation specified by
  35 .IR which .
  36 Some operations require
  37 .I name
  38 to identify a currently loaded module, some allow
  39 .I name
  40 to be NULL, indicating the kernel proper.
  41
  42 The following values can be specified for
  43 .IR which :
  44 .TP
  45 .B 0
  46 Returns success, if the kernel supports
  47 .BR query_module ().
  48 Used to probe for availability of the system call.
  49 .TP
  50 .B QM_MODULES
  51 Returns the names of all loaded modules.
  52 The returned buffer consists of a sequence of null-terminated strings;
  53 .I ret
  54 is set to the number of
  55 modules.
  56 .\" ret is set on ENOSPC
  57 .TP
  58 .B QM_DEPS
  59 Returns the names of all modules used by the indicated module.
  60 The returned buffer consists of a sequence of null-terminated strings;
  61 .I ret
  62 is set to the number of modules.
  63 .\" ret is set on ENOSPC
  64 .TP
  65 .B QM_REFS
  66 Returns the names of all modules using the indicated module.
  67 This is the inverse of
  68 .BR QM_DEPS .
  69 The returned buffer consists of a sequence of null-terminated strings;
  70 .I ret
  71 is set to the number of modules.
  72 .\" ret is set on ENOSPC
  73 .TP
  74 .B QM_SYMBOLS
  75 Returns the symbols and values exported by the kernel or the indicated
  76 module.
  77 The returned buffer is an array of structures of the following form
  78 .\" ret is set on ENOSPC
  79 .in +4n
  80 .nf
  81
  82 struct module_symbol {
  83     unsigned long value;
  84     unsigned long name;
  85 };
  86 .fi
  87 .in
  88 .IP
  89 followed by null-terminated strings.
  90 The value of
  91 .I name
  92 is the character offset of the string relative to the start of
  93 .IR buf ;
  94 .I ret
  95 is set to the number of symbols.
  96 .TP
  97 .B QM_INFO
  98 Returns miscellaneous information about the indicated module.
  99 The output buffer format is:
 100 .in +4n
 101 .nf
 102
 103 struct module_info {
 104     unsigned long address;
 105     unsigned long size;
 106     unsigned long flags;
 107 };
 108 .fi
 109 .in
 110 .IP
 111 where
 112 .I address
 113 is the kernel address at which the module resides,
 114 .I size
 115 is the size of the module in bytes, and
 116 .I flags
 117 is a mask of
 118 .BR MOD_RUNNING ,
 119 .BR MOD_AUTOCLEAN ,
 120 etc., that indicates the current status of the module
 121 (see the Linux kernel source file
 122 .IR include/linux/module.h ).
 123 .I ret
 124 is set to the size of the
 125 .I module_info
 126 structure.
 127 .SH RETURN VALUE
 128 On success, zero is returned.
 129 On error, \-1 is returned and
 130 .I errno
 131 is set appropriately.
 132 .SH ERRORS
 133 .TP
 134 .B EFAULT
 135 At least one of
 136 .IR name ,
 137 .IR buf ,
 138 or
 139 .I ret
 140 was outside the program's accessible address space.
 141 .TP
 142 .B EINVAL
 143 Invalid
 144 .IR which ;
 145 or
 146 .I name
 147 is NULL (indicating "the kernel"),
 148 but this is not permitted with the specified value of
 149 .IR which .
 150 .\" Not permitted with QM_DEPS, QM_REFS, or QM_INFO.
 151 .TP
 152 .B ENOENT
 153 No module by that
 154 .I name
 155 exists.
 156 .TP
 157 .B ENOSPC
 158 The buffer size provided was too small.
 159 .I ret
 160 is set to the minimum size needed.
 161 .TP
 162 .B ENOSYS
 163 .BR query_module ()
 164 is not supported in this version of the kernel
 165 (e.g., the kernel is version 2.6 or later).
 166 .SH VERSIONS
 167 This system call is only present on Linux up until kernel 2.4;
 168 it was removed in Linux 2.6.
 169 .\" Removed in Linux 2.5.48
 170 .SH CONFORMING TO
 171 .BR query_module ()
 172 is Linux-specific.
 173 .SH NOTES
 174 Some of the information that was formerly available via
 175 .BR query_module ()
 176 can be obtained from
 177 .IR /proc/modules ,
 178 .IR /proc/kallsyms ,
 179 and the files under the directory
 180 .IR /sys/module .
 181
 182 Glibc does not provide a wrapper for this system call;
 183 in the unlikely event that you need to use it on an old kernel, use
 184 .BR syscall (2).
 185 .SH SEE ALSO
 186 .BR create_module (2),
 187 .BR delete_module (2),
 188 .BR get_kernel_syms (2),
 189 .BR init_module (2),
 190 .BR lsmod (8),
 191 .BR modinfo (8)