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44daa2da55
MFC after: 3 months
563 lines
15 KiB
C
563 lines
15 KiB
C
/*-
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* Copyright (c) 2007 Robert N. M. Watson
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*-
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* Simple DDB scripting mechanism. Each script consists of a named list of
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* DDB commands to execute sequentially. A more sophisticated scripting
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* language might be desirable, but would be significantly more complex to
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* implement. A more interesting syntax might allow general use of variables
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* and extracting of useful values, such as a thread's process identifier,
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* for passing into further DDB commands. Certain scripts are run
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* automatically at kdb_enter(), if defined, based on how the debugger is
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* entered, allowing scripted responses to panics, break signals, etc.
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*
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* Scripts may be managed from within DDB using the script, scripts, and
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* unscript commands. They may also be managed from userspace using ddb(8),
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* which operates using a set of sysctls.
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*
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* TODO:
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* - Allow scripts to be defined using tunables so that they can be defined
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* before boot and be present in single-user mode without boot scripts
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* running.
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* - Memory allocation is not possible from within DDB, so we use a set of
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* statically allocated buffers to hold defined scripts. However, when
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* scripts are being defined from userspace via sysctl, we could in fact be
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* using malloc(9) and therefore not impose a static limit, giving greater
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* flexibility and avoiding hard-defined buffer limits.
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* - When scripts run automatically on entrance to DDB, placing "continue" at
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* the end still results in being in the debugger, as we unconditionally
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* run db_command_loop() after the script. There should be a way to avoid
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* this.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/kdb.h>
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#include <sys/kernel.h>
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#include <sys/libkern.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/mutex.h>
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#include <sys/sbuf.h>
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#include <sys/sysctl.h>
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#include <sys/systm.h>
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#include <ddb/ddb.h>
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#include <ddb/db_command.h>
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#include <ddb/db_lex.h>
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#include <machine/setjmp.h>
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/*
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* struct ddb_script describes an individual script.
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*/
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struct ddb_script {
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char ds_scriptname[DB_MAXSCRIPTNAME];
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char ds_script[DB_MAXSCRIPTLEN];
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};
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/*
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* Global list of scripts -- defined scripts have non-empty name fields.
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*/
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static struct ddb_script db_script_table[DB_MAXSCRIPTS];
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/*
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* While executing a script, we parse it using strsep(), so require a
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* temporary buffer that may be used destructively. Since we support weak
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* recursion of scripts (one may reference another), we need one buffer for
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* each concurrently executing script.
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*/
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static struct db_recursion_data {
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char drd_buffer[DB_MAXSCRIPTLEN];
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} db_recursion_data[DB_MAXSCRIPTRECURSION];
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static int db_recursion = -1;
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/*
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* We use a separate static buffer for script validation so that it is safe
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* to validate scripts from within a script. This is used only in
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* db_script_valid(), which should never be called reentrantly.
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*/
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static char db_static_buffer[DB_MAXSCRIPTLEN];
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/*
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* Synchronization is not required from within the debugger, as it is
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* singe-threaded (although reentrance must be carefully considered).
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* However, it is required when interacting with scripts from user space
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* processes. Sysctl procedures acquire db_script_mtx before accessing the
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* global script data structures.
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*/
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static struct mtx db_script_mtx;
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MTX_SYSINIT(db_script_mtx, &db_script_mtx, "db_script_mtx", MTX_DEF);
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/*
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* Some script names have special meaning, such as those executed
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* automatically when KDB is entered.
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*/
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#define DB_SCRIPT_KDBENTER_PREFIX "kdb.enter" /* KDB has entered. */
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#define DB_SCRIPT_KDBENTER_DEFAULT "kdb.enter.default"
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/*
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* Find the existing script slot for a named script, if any.
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*/
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static struct ddb_script *
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db_script_lookup(const char *scriptname)
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{
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int i;
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for (i = 0; i < DB_MAXSCRIPTS; i++) {
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if (strcmp(db_script_table[i].ds_scriptname, scriptname) ==
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0)
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return (&db_script_table[i]);
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}
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return (NULL);
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}
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/*
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* Find a new slot for a script, if available. Does not mark as allocated in
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* any way--this must be done by the caller.
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*/
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static struct ddb_script *
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db_script_new(void)
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{
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int i;
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for (i = 0; i < DB_MAXSCRIPTS; i++) {
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if (strlen(db_script_table[i].ds_scriptname) == 0)
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return (&db_script_table[i]);
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}
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return (NULL);
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}
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/*
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* Perform very rudimentary validation of a proposed script. It would be
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* easy to imagine something more comprehensive. The script string is
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* validated in a static buffer.
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*/
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static int
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db_script_valid(const char *scriptname, const char *script)
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{
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char *buffer, *command;
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if (strlen(scriptname) == 0)
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return (EINVAL);
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if (strlen(scriptname) >= DB_MAXSCRIPTNAME)
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return (EINVAL);
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if (strlen(script) >= DB_MAXSCRIPTLEN)
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return (EINVAL);
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buffer = db_static_buffer;
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strcpy(buffer, script);
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while ((command = strsep(&buffer, ";")) != NULL) {
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if (strlen(command) >= DB_MAXLINE)
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return (EINVAL);
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}
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return (0);
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}
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/*
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* Modify an existing script or add a new script with the specified script
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* name and contents. If there are no script slots available, an error will
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* be returned.
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*/
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static int
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db_script_set(const char *scriptname, const char *script)
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{
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struct ddb_script *dsp;
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int error;
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error = db_script_valid(scriptname, script);
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if (error)
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return (error);
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dsp = db_script_lookup(scriptname);
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if (dsp == NULL) {
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dsp = db_script_new();
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if (dsp == NULL)
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return (ENOSPC);
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strlcpy(dsp->ds_scriptname, scriptname,
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sizeof(dsp->ds_scriptname));
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}
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strlcpy(dsp->ds_script, script, sizeof(dsp->ds_script));
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return (0);
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}
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/*
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* Delete an existing script by name, if found.
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*/
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static int
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db_script_unset(const char *scriptname)
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{
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struct ddb_script *dsp;
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dsp = db_script_lookup(scriptname);
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if (dsp == NULL)
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return (ENOENT);
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strcpy(dsp->ds_scriptname, "");
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strcpy(dsp->ds_script, "");
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return (0);
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}
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/*
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* Trim leading/trailing white space in a command so that we don't pass
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* carriage returns, etc, into DDB command parser.
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*/
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static int
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db_command_trimmable(char ch)
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{
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switch (ch) {
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case ' ':
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case '\t':
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case '\n':
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case '\r':
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return (1);
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default:
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return (0);
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}
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}
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static void
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db_command_trim(char **commandp)
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{
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char *command;
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command = *commandp;
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while (db_command_trimmable(*command))
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command++;
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while ((strlen(command) > 0) &&
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db_command_trimmable(command[strlen(command) - 1]))
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command[strlen(command) - 1] = 0;
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*commandp = command;
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}
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/*
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* Execute a script, breaking it up into individual commands and passing them
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* sequentially into DDB's input processing. Use the KDB jump buffer to
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* restore control to the main script loop if things get too wonky when
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* processing a command -- i.e., traps, etc. Also, make sure we don't exceed
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* practical limits on recursion.
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*
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* XXXRW: If any individual command is too long, it will be truncated when
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* injected into the input at a lower layer. We should validate the script
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* before configuring it to avoid this scenario.
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*/
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static int
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db_script_exec(const char *scriptname, int warnifnotfound)
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{
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struct db_recursion_data *drd;
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struct ddb_script *dsp;
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char *buffer, *command;
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void *prev_jb;
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jmp_buf jb;
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dsp = db_script_lookup(scriptname);
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if (dsp == NULL) {
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if (warnifnotfound)
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db_printf("script '%s' not found\n", scriptname);
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return (ENOENT);
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}
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if (db_recursion >= DB_MAXSCRIPTRECURSION) {
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db_printf("Script stack too deep\n");
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return (E2BIG);
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}
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db_recursion++;
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drd = &db_recursion_data[db_recursion];
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/*
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* Parse script in temporary buffer, since strsep() is destructive.
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*/
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buffer = drd->drd_buffer;
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strcpy(buffer, dsp->ds_script);
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while ((command = strsep(&buffer, ";")) != NULL) {
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db_printf("db:%d:%s> %s\n", db_recursion, scriptname,
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command);
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db_command_trim(&command);
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prev_jb = kdb_jmpbuf(jb);
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if (setjmp(jb) == 0)
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db_command_script(command);
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else
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db_printf("Script command '%s' returned error\n",
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command);
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kdb_jmpbuf(prev_jb);
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}
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db_recursion--;
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return (0);
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}
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/*
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* Wrapper for exec path that is called on KDB enter. Map reason for KDB
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* enter to a script name, and don't whine if the script doesn't exist. If
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* there is no matching script, try the catch-all script.
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*/
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void
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db_script_kdbenter(const char *eventname)
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{
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char scriptname[DB_MAXSCRIPTNAME];
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snprintf(scriptname, sizeof(scriptname), "%s.%s",
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DB_SCRIPT_KDBENTER_PREFIX, eventname);
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if (db_script_exec(scriptname, 0) == ENOENT)
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(void)db_script_exec(DB_SCRIPT_KDBENTER_DEFAULT, 0);
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}
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/*-
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* DDB commands for scripting, as reached via the DDB user interface:
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*
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* scripts - lists scripts
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* run <scriptname> - run a script
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* script <scriptname> - prints script
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* script <scriptname> <script> - set a script
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* unscript <scriptname> - remove a script
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*/
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/*
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* List scripts and their contents.
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*/
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void
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db_scripts_cmd(db_expr_t addr, boolean_t have_addr, db_expr_t count,
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char *modif)
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{
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int i;
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for (i = 0; i < DB_MAXSCRIPTS; i++) {
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if (strlen(db_script_table[i].ds_scriptname) != 0) {
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db_printf("%s=%s\n",
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db_script_table[i].ds_scriptname,
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db_script_table[i].ds_script);
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}
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}
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}
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/*
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* Execute a script.
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*/
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void
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db_run_cmd(db_expr_t addr, boolean_t have_addr, db_expr_t count, char *modif)
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{
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int t;
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/*
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* Right now, we accept exactly one argument. In the future, we
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* might want to accept flags and arguments to the script itself.
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*/
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t = db_read_token();
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if (t != tIDENT)
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db_error("?\n");
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if (db_read_token() != tEOL)
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db_error("?\n");
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db_script_exec(db_tok_string, 1);
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}
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/*
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* Print or set a named script, with the set portion broken out into its own
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* function. We must directly access the remainder of the DDB line input as
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* we do not wish to use db_lex's token processing.
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*/
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void
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db_script_cmd(db_expr_t addr, boolean_t have_addr, db_expr_t count,
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char *modif)
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{
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char *buf, scriptname[DB_MAXSCRIPTNAME];
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struct ddb_script *dsp;
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int error, t;
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t = db_read_token();
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if (t != tIDENT) {
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db_printf("usage: script scriptname=script\n");
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db_skip_to_eol();
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return;
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}
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if (strlcpy(scriptname, db_tok_string, sizeof(scriptname)) >=
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sizeof(scriptname)) {
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db_printf("scriptname too long\n");
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db_skip_to_eol();
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return;
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}
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t = db_read_token();
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if (t == tEOL) {
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dsp = db_script_lookup(scriptname);
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if (dsp == NULL) {
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db_printf("script '%s' not found\n", scriptname);
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db_skip_to_eol();
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return;
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}
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db_printf("%s=%s\n", scriptname, dsp->ds_script);
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} else if (t == tEQ) {
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buf = db_get_line();
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if (buf[strlen(buf)-1] == '\n')
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buf[strlen(buf)-1] = '\0';
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error = db_script_set(scriptname, buf);
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if (error != 0)
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db_printf("Error: %d\n", error);
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} else
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db_printf("?\n");
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db_skip_to_eol();
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}
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/*
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* Remove a named script.
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*/
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void
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db_unscript_cmd(db_expr_t addr, boolean_t have_addr, db_expr_t count,
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char *modif)
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{
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int error, t;
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t = db_read_token();
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if (t != tIDENT) {
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db_printf("?\n");
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db_skip_to_eol();
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return;
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}
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error = db_script_unset(db_tok_string);
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if (error == ENOENT) {
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db_printf("script '%s' not found\n", db_tok_string);
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db_skip_to_eol();
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return;
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}
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db_skip_to_eol();
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}
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/*
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* Sysctls for managing DDB scripting:
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*
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* debug.ddb.scripting.script - Define a new script
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* debug.ddb.scripting.scripts - List of names *and* scripts
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* debug.ddb.scripting.unscript - Remove an existing script
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*
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* Since we don't want to try to manage arbitrary extensions to the sysctl
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* name space from the debugger, the script/unscript sysctls are a bit more
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* like RPCs and a bit less like normal get/set requests. The ddb(8) command
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* line tool wraps them to make things a bit more user-friendly.
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*/
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static SYSCTL_NODE(_debug_ddb, OID_AUTO, scripting, CTLFLAG_RW, 0,
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"DDB script settings");
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static int
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sysctl_debug_ddb_scripting_scripts(SYSCTL_HANDLER_ARGS)
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{
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struct sbuf sb;
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int error, i, len;
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char *buffer;
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/*
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* Make space to include a maximum-length name, = symbol,
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* maximum-length script, and carriage return for every script that
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* may be defined.
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*/
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len = DB_MAXSCRIPTS * (DB_MAXSCRIPTNAME + 1 + DB_MAXSCRIPTLEN + 1);
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buffer = malloc(len, M_TEMP, M_WAITOK);
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(void)sbuf_new(&sb, buffer, len, SBUF_FIXEDLEN);
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mtx_lock(&db_script_mtx);
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for (i = 0; i < DB_MAXSCRIPTS; i++) {
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if (strlen(db_script_table[i].ds_scriptname) == 0)
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continue;
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(void)sbuf_printf(&sb, "%s=%s\n",
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db_script_table[i].ds_scriptname,
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db_script_table[i].ds_script);
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}
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mtx_unlock(&db_script_mtx);
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sbuf_finish(&sb);
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error = SYSCTL_OUT(req, sbuf_data(&sb), sbuf_len(&sb) + 1);
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sbuf_delete(&sb);
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free(buffer, M_TEMP);
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return (error);
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}
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SYSCTL_PROC(_debug_ddb_scripting, OID_AUTO, scripts, CTLTYPE_STRING |
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CTLFLAG_RD, 0, 0, sysctl_debug_ddb_scripting_scripts, "A",
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"List of defined scripts");
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static int
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sysctl_debug_ddb_scripting_script(SYSCTL_HANDLER_ARGS)
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{
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char *buffer, *script, *scriptname;
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int error, len;
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/*
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* Maximum length for an input string is DB_MAXSCRIPTNAME + '='
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* symbol + DB_MAXSCRIPT.
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*/
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len = DB_MAXSCRIPTNAME + DB_MAXSCRIPTLEN + 1;
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buffer = malloc(len, M_TEMP, M_WAITOK | M_ZERO);
|
|
error = sysctl_handle_string(oidp, buffer, len, req);
|
|
if (error)
|
|
goto out;
|
|
|
|
/*
|
|
* Argument will be in form scriptname=script, so split into the
|
|
* scriptname and script.
|
|
*/
|
|
script = buffer;
|
|
scriptname = strsep(&script, "=");
|
|
if (script == NULL) {
|
|
error = EINVAL;
|
|
goto out;
|
|
}
|
|
mtx_lock(&db_script_mtx);
|
|
error = db_script_set(scriptname, script);
|
|
mtx_unlock(&db_script_mtx);
|
|
out:
|
|
free(buffer, M_TEMP);
|
|
return (error);
|
|
}
|
|
SYSCTL_PROC(_debug_ddb_scripting, OID_AUTO, script, CTLTYPE_STRING |
|
|
CTLFLAG_RW, 0, 0, sysctl_debug_ddb_scripting_script, "A",
|
|
"Set a script");
|
|
|
|
/*
|
|
* debug.ddb.scripting.unscript has somewhat unusual sysctl semantics -- set
|
|
* the name of the script that you want to delete.
|
|
*/
|
|
static int
|
|
sysctl_debug_ddb_scripting_unscript(SYSCTL_HANDLER_ARGS)
|
|
{
|
|
char name[DB_MAXSCRIPTNAME];
|
|
int error;
|
|
|
|
bzero(name, sizeof(name));
|
|
error = sysctl_handle_string(oidp, name, sizeof(name), req);
|
|
if (error)
|
|
return (error);
|
|
if (req->newptr == NULL)
|
|
return (0);
|
|
mtx_lock(&db_script_mtx);
|
|
error = db_script_unset(name);
|
|
mtx_unlock(&db_script_mtx);
|
|
if (error == ENOENT)
|
|
return (EINVAL); /* Don't confuse sysctl consumers. */
|
|
return (0);
|
|
}
|
|
SYSCTL_PROC(_debug_ddb_scripting, OID_AUTO, unscript, CTLTYPE_STRING |
|
|
CTLFLAG_RW, 0, 0, sysctl_debug_ddb_scripting_unscript, "A",
|
|
"Unset a script");
|