freebsd-dev/sys/ddb/db_script.c
Pedro F. Giffuni 753c4e83fc sys/ddb: further adoption of SPDX licensing ID tags.
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
2017-11-27 15:14:46 +00:00

565 lines
15 KiB
C

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