Ubuntu Manpage: query_module - query the kernel for various bits pertaining to modules

NAME

       query_module - query the kernel for various bits pertaining to modules

SYNOPSIS

       #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.

DESCRIPTION

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

query_module() requests information from the kernel about loadable modules. 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 currently loaded module, some allow name to be NULL, indicating the
kernel proper.

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.

QM_MODULES
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.

QM_DEPS
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.

QM_REFS
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.

QM_SYMBOLS
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.

QM_INFO
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 current
status of the module (see the Linux kernel source file include/linux/module.h). ret is set to the
size of the module_info structure.

RETURN VALUE

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

ERRORS

       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 minimum size needed.

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

VERSIONS

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

CONFORMING TO

       query_module() is Linux-specific.

NOTES

       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 declaration 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).

COLOPHON

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