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