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grub/grub-core/script/parser.y
Glenn Washburn ac301e4dd0 script: Do not allow a delimiter between function name and block start 
Currently the following is valid syntax but should be a syntax error:

  grub> function f; { echo HERE; }
  grub> f
  HERE

This fix is not backward compatible, but current syntax is not documented
either and has no functional value. So any scripts with this unintended
syntax are technically syntactically incorrect and should not be relying
on this behavior.

Signed-off-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2020-09-18 22:31:30 +02:00

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/* parser.y - The scripting parser. */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2005,2006,2007,2008,2009,2010 Free Software Foundation, Inc.
*
* GRUB is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GRUB is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
%{
#include <grub/script_sh.h>
#include <grub/mm.h>
#include <grub/misc.h>
#include <grub/i18n.h>
#define YYFREE grub_free
#define YYMALLOC grub_malloc
#define YYLTYPE_IS_TRIVIAL 0
#define YYENABLE_NLS 0
#include "grub_script.tab.h"
#pragma GCC diagnostic ignored "-Wmissing-declarations"
%}
%union {
struct grub_script_cmd *cmd;
struct grub_script_arglist *arglist;
struct grub_script_arg *arg;
char *string;
struct {
unsigned offset;
struct grub_script_mem *memory;
struct grub_script *scripts;
};
}
%token GRUB_PARSER_TOKEN_BAD
%token GRUB_PARSER_TOKEN_EOF 0 "end-of-input"
%token GRUB_PARSER_TOKEN_NEWLINE "\n"
%token GRUB_PARSER_TOKEN_AND "&&"
%token GRUB_PARSER_TOKEN_OR "||"
%token GRUB_PARSER_TOKEN_SEMI2 ";;"
%token GRUB_PARSER_TOKEN_PIPE "|"
%token GRUB_PARSER_TOKEN_AMP "&"
%token GRUB_PARSER_TOKEN_SEMI ";"
%token GRUB_PARSER_TOKEN_LBR "{"
%token GRUB_PARSER_TOKEN_RBR "}"
%token GRUB_PARSER_TOKEN_NOT "!"
%token GRUB_PARSER_TOKEN_LSQBR2 "["
%token GRUB_PARSER_TOKEN_RSQBR2 "]"
%token GRUB_PARSER_TOKEN_LT "<"
%token GRUB_PARSER_TOKEN_GT ">"
%token <arg> GRUB_PARSER_TOKEN_CASE "case"
%token <arg> GRUB_PARSER_TOKEN_DO "do"
%token <arg> GRUB_PARSER_TOKEN_DONE "done"
%token <arg> GRUB_PARSER_TOKEN_ELIF "elif"
%token <arg> GRUB_PARSER_TOKEN_ELSE "else"
%token <arg> GRUB_PARSER_TOKEN_ESAC "esac"
%token <arg> GRUB_PARSER_TOKEN_FI "fi"
%token <arg> GRUB_PARSER_TOKEN_FOR "for"
%token <arg> GRUB_PARSER_TOKEN_IF "if"
%token <arg> GRUB_PARSER_TOKEN_IN "in"
%token <arg> GRUB_PARSER_TOKEN_SELECT "select"
%token <arg> GRUB_PARSER_TOKEN_THEN "then"
%token <arg> GRUB_PARSER_TOKEN_UNTIL "until"
%token <arg> GRUB_PARSER_TOKEN_WHILE "while"
%token <arg> GRUB_PARSER_TOKEN_FUNCTION "function"
%token <arg> GRUB_PARSER_TOKEN_NAME "name"
%token <arg> GRUB_PARSER_TOKEN_WORD "word"
%type <arg> block block0
%type <arglist> word argument arguments0 arguments1
%type <cmd> script_init script
%type <cmd> grubcmd ifclause ifcmd forcmd whilecmd untilcmd
%type <cmd> command commands1 statement
%pure-parser
%lex-param { struct grub_parser_param *state };
%parse-param { struct grub_parser_param *state };
%start script_init
%%
/* It should be possible to do this in a clean way... */
script_init: { state->err = 0; } script { state->parsed = $2; state->err = 0; }
;
script: newlines0
{
$$ = 0;
}
| script statement delimiter newlines0
{
$$ = grub_script_append_cmd (state, $1, $2);
}
| error
{
$$ = 0;
yyerror (state, N_("Incorrect command"));
yyerrok;
}
;
newlines0: /* Empty */ | newlines1 ;
newlines1: newlines0 "\n" ;
delimiter: ";"
| "\n"
;
delimiters0: /* Empty */ | delimiters1 ;
delimiters1: delimiter
| delimiters1 "\n"
;
word: GRUB_PARSER_TOKEN_NAME { $$ = grub_script_add_arglist (state, 0, $1); }
| GRUB_PARSER_TOKEN_WORD { $$ = grub_script_add_arglist (state, 0, $1); }
;
statement: command { $$ = $1; }
| function { $$ = 0; }
;
argument : "case" { $$ = grub_script_add_arglist (state, 0, $1); }
| "do" { $$ = grub_script_add_arglist (state, 0, $1); }
| "done" { $$ = grub_script_add_arglist (state, 0, $1); }
| "elif" { $$ = grub_script_add_arglist (state, 0, $1); }
| "else" { $$ = grub_script_add_arglist (state, 0, $1); }
| "esac" { $$ = grub_script_add_arglist (state, 0, $1); }
| "fi" { $$ = grub_script_add_arglist (state, 0, $1); }
| "for" { $$ = grub_script_add_arglist (state, 0, $1); }
| "if" { $$ = grub_script_add_arglist (state, 0, $1); }
| "in" { $$ = grub_script_add_arglist (state, 0, $1); }
| "select" { $$ = grub_script_add_arglist (state, 0, $1); }
| "then" { $$ = grub_script_add_arglist (state, 0, $1); }
| "until" { $$ = grub_script_add_arglist (state, 0, $1); }
| "while" { $$ = grub_script_add_arglist (state, 0, $1); }
| "function" { $$ = grub_script_add_arglist (state, 0, $1); }
| word { $$ = $1; }
;
/*
Block parameter is passed to commands in two forms: as unparsed
string and as pre-parsed grub_script object. Passing as grub_script
object makes memory management difficult, because:
(1) Command may want to keep a reference to grub_script objects for
later use, so script framework may not free the grub_script
object after command completes.
(2) Command may get called multiple times with same grub_script
object under loops, so we should not let command implementation
to free the grub_script object.
To solve above problems, we rely on reference counting for
grub_script objects. Commands that want to keep the grub_script
object must take a reference to it.
Other complexity comes with arbitrary nesting of grub_script
objects: a grub_script object may have commands with several block
parameters, and each block parameter may further contain multiple
block parameters nested. We use temporary variable, state->scripts
to collect nested child scripts (that are linked by siblings and
children members), and will build grub_scripts tree from bottom.
*/
block: "{"
{
grub_script_lexer_ref (state->lexerstate);
$<offset>$ = grub_script_lexer_record_start (state);
$<memory>$ = grub_script_mem_record (state);
/* save currently known scripts. */
$<scripts>$ = state->scripts;
state->scripts = 0;
}
commands1 delimiters0 "}"
{
char *p;
struct grub_script_mem *memory;
struct grub_script *s = $<scripts>2;
memory = grub_script_mem_record_stop (state, $<memory>2);
if ((p = grub_script_lexer_record_stop (state, $<offset>2)))
*grub_strrchr (p, '}') = '\0';
$$ = grub_script_arg_add (state, 0, GRUB_SCRIPT_ARG_TYPE_BLOCK, p);
if (! $$ || ! ($$->script = grub_script_create ($3, memory)))
grub_script_mem_free (memory);
else {
/* attach nested scripts to $$->script as children */
$$->script->children = state->scripts;
/* restore old scripts; append $$->script to siblings. */
state->scripts = $<scripts>2 ?: $$->script;
if (s) {
while (s->next_siblings)
s = s->next_siblings;
s->next_siblings = $$->script;
}
}
grub_script_lexer_deref (state->lexerstate);
}
;
block0: /* Empty */ { $$ = 0; }
| block { $$ = $1; }
;
arguments0: /* Empty */ { $$ = 0; }
| arguments1 { $$ = $1; }
;
arguments1: argument arguments0
{
if ($1 && $2)
{
$1->next = $2;
$1->argcount += $2->argcount;
$2->argcount = 0;
}
$$ = $1;
}
;
grubcmd: word arguments0 block0
{
struct grub_script_arglist *x = $2;
if ($3)
x = grub_script_add_arglist (state, $2, $3);
if ($1 && x) {
$1->next = x;
$1->argcount += x->argcount;
x->argcount = 0;
}
$$ = grub_script_create_cmdline (state, $1);
}
;
/* A single command. */
command: grubcmd { $$ = $1; }
| ifcmd { $$ = $1; }
| forcmd { $$ = $1; }
| whilecmd { $$ = $1; }
| untilcmd { $$ = $1; }
;
/* A list of commands. */
commands1: newlines0 command
{
$$ = grub_script_append_cmd (state, 0, $2);
}
| commands1 delimiters1 command
{
$$ = grub_script_append_cmd (state, $1, $3);
}
;
function: "function" "name"
{
grub_script_lexer_ref (state->lexerstate);
state->func_mem = grub_script_mem_record (state);
$<scripts>$ = state->scripts;
state->scripts = 0;
}
newlines0 "{" commands1 delimiters1 "}"
{
struct grub_script *script;
state->func_mem = grub_script_mem_record_stop (state,
state->func_mem);
script = grub_script_create ($6, state->func_mem);
if (! script)
grub_script_mem_free (state->func_mem);
else {
script->children = state->scripts;
if (!grub_script_function_create ($2, script))
grub_script_free (script);
}
state->scripts = $<scripts>3;
grub_script_lexer_deref (state->lexerstate);
}
;
ifcmd: "if"
{
grub_script_lexer_ref (state->lexerstate);
}
ifclause "fi"
{
$$ = $3;
grub_script_lexer_deref (state->lexerstate);
}
;
ifclause: commands1 delimiters1 "then" commands1 delimiters1
{
$$ = grub_script_create_cmdif (state, $1, $4, 0);
}
| commands1 delimiters1 "then" commands1 delimiters1 "else" commands1 delimiters1
{
$$ = grub_script_create_cmdif (state, $1, $4, $7);
}
| commands1 delimiters1 "then" commands1 delimiters1 "elif" ifclause
{
$$ = grub_script_create_cmdif (state, $1, $4, $7);
}
;
forcmd: "for" "name"
{
grub_script_lexer_ref (state->lexerstate);
}
"in" arguments0 delimiters1 "do" commands1 delimiters1 "done"
{
$$ = grub_script_create_cmdfor (state, $2, $5, $8);
grub_script_lexer_deref (state->lexerstate);
}
;
whilecmd: "while"
{
grub_script_lexer_ref (state->lexerstate);
}
commands1 delimiters1 "do" commands1 delimiters1 "done"
{
$$ = grub_script_create_cmdwhile (state, $3, $6, 0);
grub_script_lexer_deref (state->lexerstate);
}
;
untilcmd: "until"
{
grub_script_lexer_ref (state->lexerstate);
}
commands1 delimiters1 "do" commands1 delimiters1 "done"
{
$$ = grub_script_create_cmdwhile (state, $3, $6, 1);
grub_script_lexer_deref (state->lexerstate);
}
;
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