query_module manpage

Search topic Section

QUERY_MODULE(2)		   Linux Programmer's Manual	       QUERY_MODULE(2)

       query_module - query the kernel for various bits pertaining to modules

       #include <linux/module.h>

       int query_module(const char *name, int which, void *buf,
			size_t bufsize, size_t *ret);

       Note:  No declaration of this system call is provided in glibc headers;
       see NOTES.

       Note: This system call is present only in kernels before Linux 2.6.

       query_module() requests information from the kernel about loadable mod-
       ules.   The  returned information is placed in the buffer pointed to by
       buf.  The caller must specify the size of buf in bufsize.  The  precise
       nature  and  format of the returned information depend on the operation
       specified by which.  Some operations require name to  identify  a  cur-
       rently loaded module, some allow name to be NULL, indicating the kernel

       The following values can be specified for which:

       0      Returns success, if the kernel supports query_module().  Used to
	      probe for availability of the system call.

	      Returns  the  names  of all loaded modules.  The returned buffer
	      consists of a sequence of null-terminated strings; ret is set to
	      the number of modules.

	      Returns  the  names of all modules used by the indicated module.
	      The returned buffer consists of a	 sequence  of  null-terminated
	      strings; ret is set to the number of modules.

	      Returns  the  names  of  all modules using the indicated module.
	      This is the inverse of QM_DEPS.  The returned buffer consists of
	      a	 sequence of null-terminated strings; ret is set to the number
	      of modules.

	      Returns the symbols and values exported by  the  kernel  or  the
	      indicated module.	 The returned buffer is an array of structures
	      of the following form

		  struct module_symbol {
		      unsigned long value;
		      unsigned long name;

	      followed by null-terminated strings.  The value of name  is  the
	      character offset of the string relative to the start of buf; ret
	      is set to the number of symbols.

	      Returns miscellaneous information about  the  indicated  module.
	      The output buffer format is:

		  struct module_info {
		      unsigned long address;
		      unsigned long size;
		      unsigned long flags;

	      where address is the kernel address at which the module resides,
	      size is the size of the module in bytes, and flags is a mask  of
	      MOD_RUNNING,  MOD_AUTOCLEAN,  and so on, that indicates the cur-
	      rent status of the module (see  the  Linux  kernel  source  file
	      include/linux/module.h).	 ret  is  set  to the size of the mod-
	      ule_info structure.

       On success, zero is returned.  On error, -1 is returned	and  errno  is
       set appropriately.

       EFAULT At  least	 one  of  name,	 buf, or ret was outside the program's
	      accessible address space.

       EINVAL Invalid which; or name is NULL (indicating  "the	kernel"),  but
	      this is not permitted with the specified value of which.

       ENOENT No module by that name exists.

       ENOSPC The buffer size provided was too small.  ret is set to the mini-
	      mum size needed.

       ENOSYS query_module() is not supported in this version  of  the	kernel
	      (e.g., the kernel is version 2.6 or later).

       This  system  call is present on Linux only up until kernel 2.4; it was
       removed in Linux 2.6.

       query_module() is Linux-specific.

       Some of the information that was formerly available via	query_module()
       can be obtained from /proc/modules, /proc/kallsyms, and the files under
       the directory /sys/module.

       The query_module() system call is not supported by glibc.  No  declara-
       tion  is	 provided  in  glibc headers, but, through a quirk of history,
       glibc does export an ABI for this system call.  Therefore, in order  to
       employ  this  system  call,  it	is  sufficient to manually declare the
       interface in your code; alternatively, you can invoke the  system  call
       using syscall(2).

       create_module(2), delete_module(2), get_kernel_syms(2), init_module(2),
       lsmod(8), modinfo(8)

       This page is part of release 4.10 of the Linux  man-pages  project.   A
       description  of	the project, information about reporting bugs, and the
       latest	 version    of	  this	  page,	   can	   be	  found	    at

Linux				  2014-05-10		       QUERY_MODULE(2)