query_module - query the kernel for various bits pertaining to modules
#include <linux/module.h>
[[deprecated]] int query_module(const char *name, int which,
void buf[.bufsize], size_t bufsize,
size_t *ret);
Note: This system call is present only 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
to indicate the error.
- 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., Linux 2.6 or later).
This system call is present only up until Linux 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)