QUERY_MODULE(2)           (2017-09-15)            QUERY_MODULE(2)

     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

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               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 ker-
               nel"), 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

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               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).

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

     COLOPHON
          This page is part of release 5.10 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 https://www.kernel.org/doc/man-pages/.

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