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Diffstat (limited to 'share/examples/lkm/misc/module/miscmod.c')
-rw-r--r-- | share/examples/lkm/misc/module/miscmod.c | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/share/examples/lkm/misc/module/miscmod.c b/share/examples/lkm/misc/module/miscmod.c new file mode 100644 index 0000000..04aa07c --- /dev/null +++ b/share/examples/lkm/misc/module/miscmod.c @@ -0,0 +1,189 @@ +/* 25 May 93*/ +/* + * Makefile for miscmod + * + * 05 Jun 93 Terry Lambert Split mycall.c out + * 25 May 93 Terry Lambert Original + * + * Copyright (c) 1993 Terrence R. Lambert. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by Terrence R. Lambert. + * 4. The name Terrence R. Lambert may not be used to endorse or promote + * products derived from this software without specific prior written + * permission. + * + * THIS SOFTWARE IS PROVIDED BY TERRENCE R. LAMBERT ``AS IS'' AND ANY + * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE TERRENCE R. LAMBERT BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + */ +#include <sys/param.h> +#include <sys/ioctl.h> +#include <sys/systm.h> +#include <sys/conf.h> +#include <sys/mount.h> +#include <sys/exec.h> +#include <sys/lkm.h> +#include <a.out.h> +#include <sys/file.h> +#include <sys/errno.h> + + +extern int misccall(); + +/* + * These two entries define our system call and module information. We + * have 0 arguments to our system call. + */ +static struct sysent newent = { + 0, misccall /* # of args, function pointer*/ +}; + +/* + * Miscellaneous modules must have their own save areas... + */ +static struct sysent oldent; /* save are for old callslot entry*/ + +MOD_MISC( "miscmod") + + +/* + * This function is called each time the module is loaded or unloaded. + * Since we are a miscellaneous module, we have to provide whatever + * code is necessary to patch ourselves into the area we are being + * loaded to change. + * + * For the system call table, we duplicate the code in the kern_lkm.c + * file for patching into the system call table. We can tell what + * has been allocated, etc. by virtue of the fact that we know the + * criteria used by the system call loader interface. We still + * kick out the copyright to the console here (to give an example). + * + * The stat information is basically common to all modules, so there + * is no real issue involved with stat; we will leave it nosys(), + * cince we don't have to do anything about it. + */ +static int +miscmod_handle( lkmtp, cmd) +struct lkm_table *lkmtp; +int cmd; +{ + int i; + struct lkm_misc *args = lkmtp->private.lkm_misc; + int err = 0; /* default = success*/ + extern int nsysent; /* init_sysent.c*/ + extern int lkmnosys(); /* allocable slot*/ + + switch( cmd) { + case LKM_E_LOAD: + + /* + * Don't load twice! (lkmexists() is exported by kern_lkm.c) + */ + if( lkmexists( lkmtp)) + return( EEXIST); + + /* + * This is where we would express a slot preference if + * we had one; since we don't, we will simply duplicate + * the "auto" code and forget the other. + */ + + /* + * Search the table looking for a slot... + */ + for( i = 0; i < nsysent; i++) + if( sysent[ i].sy_call == lkmnosys) + break; /* found it!*/ + /* out of allocable slots?*/ + if( i == nsysent) { + err = ENFILE; + break; + } + + /* save old -- we must provide our own data area*/ + bcopy( &sysent[ i], &oldent, sizeof( struct sysent)); + + /* replace with new*/ + bcopy( &newent, &sysent[ i], sizeof( struct sysent)); + + /* done!*/ + args->lkm_offset = i; /* slot in sysent[]*/ + + + /* if we make it to here, print copyright on console*/ + printf( "\nSample Loaded miscellaneous module (system call)\n"); + printf( "Copyright (c) 1993\n"); + printf( "Terrence R. Lambert\n"); + printf( "All rights reserved\n"); + + break; /* Success*/ + + case LKM_E_UNLOAD: + /* current slot...*/ + i = args->lkm_offset; + + /* replace current slot contents with old contents*/ + bcopy( &oldent, &sysent[ i], sizeof( struct sysent)); + + break; /* Success*/ + + default: /* we only understand load/unload*/ + err = EINVAL; + break; + } + + return( err); +} + + +/* + * External entry point; should generally match name of .o file. The + * arguments are always the same for all loaded modules. The "load", + * "unload", and "stat" functions in "DISPATCH" will be called under + * their respective circumstances unless their value is "nosys". If + * called, they are called with the same arguments (cmd is included to + * allow the use of a single function, ver is included for version + * matching between modules and the kernel loader for the modules). + * + * Since we expect to link in the kernel and add external symbols to + * the kernel symbol name space in a future version, generally all + * functions used in the implementation of a particular module should + * be static unless they are expected to be seen in other modules or + * to resolve unresolved symbols alread existing in the kernel (the + * second case is not likely to ever occur). + * + * The entry point should return 0 unless it is refusing load (in which + * case it should return an errno from errno.h). + */ +miscmod( lkmtp, cmd, ver) +struct lkm_table *lkmtp; +int cmd; +int ver; +{ + DISPATCH(lkmtp,cmd,ver,miscmod_handle,miscmod_handle,nosys) +} + + +/* + * EOF -- This file has not been truncated. + */ |