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/* Copyright (c) 2002-2013 Pigeonhole authors, see the included COPYING file
*/
#include "lib.h"
#include "istream.h"
#include "failures.h"
#include "sieve-common.h"
#include "sieve-limits.h"
#include "sieve-script.h"
#include "sieve-lexer.h"
#include "sieve-parser.h"
#include "sieve-error.h"
#include "sieve-ast.h"
/*
* Forward declarations
*/
inline static void sieve_parser_error
(struct sieve_parser *parser, const char *fmt, ...) ATTR_FORMAT(2, 3);
inline static void sieve_parser_warning
(struct sieve_parser *parser, const char *fmt, ...) ATTR_FORMAT(2, 3);
static int sieve_parser_recover
(struct sieve_parser *parser, enum sieve_token_type end_token);
/*
* Parser object
*/
struct sieve_parser {
pool_t pool;
bool valid;
struct sieve_script *script;
struct sieve_error_handler *ehandler;
const struct sieve_lexer *lexer;
struct sieve_ast *ast;
};
struct sieve_parser *sieve_parser_create
(struct sieve_script *script, struct sieve_error_handler *ehandler,
enum sieve_error *error_r)
{
struct sieve_parser *parser;
const struct sieve_lexer *lexer;
lexer = sieve_lexer_create(script, ehandler, error_r);
if ( lexer != NULL ) {
pool_t pool = pool_alloconly_create("sieve_parser", 4096);
parser = p_new(pool, struct sieve_parser, 1);
parser->pool = pool;
parser->valid = TRUE;
parser->ehandler = ehandler;
sieve_error_handler_ref(ehandler);
parser->script = script;
sieve_script_ref(script);
parser->lexer = lexer;
parser->ast = NULL;
return parser;
}
return NULL;
}
void sieve_parser_free(struct sieve_parser **parser)
{
if ((*parser)->ast != NULL)
sieve_ast_unref(&(*parser)->ast);
sieve_lexer_free(&(*parser)->lexer);
sieve_script_unref(&(*parser)->script);
sieve_error_handler_unref(&(*parser)->ehandler);
pool_unref(&(*parser)->pool);
*parser = NULL;
}
/*
* Internal error handling
*/
inline static void sieve_parser_error
(struct sieve_parser *parser, const char *fmt, ...)
{
va_list args;
va_start(args, fmt);
/* Don't report a parse error if the lexer complained already */
if ( sieve_lexer_token_type(parser->lexer) != STT_ERROR )
{
T_BEGIN {
sieve_verror(parser->ehandler,
sieve_error_script_location(parser->script,
sieve_lexer_token_line(parser->lexer)),
fmt, args);
} T_END;
}
parser->valid = FALSE;
va_end(args);
}
inline static void sieve_parser_warning
(struct sieve_parser *parser, const char *fmt, ...)
{
va_list args;
va_start(args, fmt);
T_BEGIN {
sieve_vwarning(parser->ehandler,
sieve_error_script_location(parser->script,
sieve_lexer_token_line(parser->lexer)),
fmt, args);
} T_END;
va_end(args);
}
/*
* Sieve grammar parsing
*/
/* sieve_parse_arguments():
*
* Parses both command arguments and sub-tests:
* arguments = *argument [test / test-list]
* argument = string-list / number / tag
* string = quoted-string / multi-line [[implicitly handled in lexer]]
* string-list = "[" string *("," string) "]" / string ;; if
* there is only a single string, the brackets are optional
* test-list = "(" test *("," test) ")"
* test = identifier arguments
*/
static int sieve_parse_arguments
(struct sieve_parser *parser, struct sieve_ast_node *node, unsigned int depth)
{
const struct sieve_lexer *lexer = parser->lexer;
struct sieve_ast_node *test = NULL;
bool test_present = TRUE;
bool arg_present = TRUE;
int result = TRUE; /* Indicates whether the parser is in a defined, not
necessarily error-free state */
/* Parse arguments */
while ( arg_present && result > 0 ) {
struct sieve_ast_argument *arg;
if ( !parser->valid && !sieve_errors_more_allowed(parser->ehandler) ) {
result = 0;
break;
}
switch ( sieve_lexer_token_type(lexer) ) {
/* String list */
case STT_LSQUARE:
/* Create stinglist object */
arg = sieve_ast_argument_stringlist_create
(node, sieve_lexer_token_line(parser->lexer));
if ( arg == NULL ) break;
sieve_lexer_skip_token(lexer);
if ( sieve_lexer_token_type(lexer) == STT_STRING ) {
bool add_failed = FALSE;
/* Add the string to the list */
if ( !sieve_ast_stringlist_add
(arg, sieve_lexer_token_str(lexer),
sieve_lexer_token_line(parser->lexer)) )
add_failed = TRUE;
sieve_lexer_skip_token(lexer);
while ( !add_failed && sieve_lexer_token_type(lexer) == STT_COMMA ) {
sieve_lexer_skip_token(lexer);
/* Check parser status */
if ( !parser->valid && !sieve_errors_more_allowed(parser->ehandler) ) {
result = sieve_parser_recover(parser, STT_RSQUARE);
break;
}
if ( sieve_lexer_token_type(lexer) == STT_STRING ) {
/* Add the string to the list */
if ( !sieve_ast_stringlist_add
(arg, sieve_lexer_token_str(lexer),
sieve_lexer_token_line(parser->lexer)) )
add_failed = TRUE;
sieve_lexer_skip_token(lexer);
} else {
sieve_parser_error(parser,
"expecting string after ',' in string list, but found %s",
sieve_lexer_token_description(lexer));
result = sieve_parser_recover(parser, STT_RSQUARE);
break;
}
}
if ( add_failed ) {
sieve_parser_error(parser,
"failed to accept more items in string list");
return -1;
}
} else {
sieve_parser_error(parser,
"expecting string after '[' in string list, but found %s",
sieve_lexer_token_description(lexer));
result = sieve_parser_recover(parser, STT_RSQUARE);
}
/* Finish the string list */
if ( sieve_lexer_token_type(lexer) == STT_RSQUARE ) {
sieve_lexer_skip_token(lexer);
} else {
sieve_parser_error(parser,
"expecting ',' or end of string list ']', but found %s",
sieve_lexer_token_description(lexer));
if ( (result=sieve_parser_recover(parser, STT_RSQUARE)) == TRUE )
sieve_lexer_skip_token(lexer);
}
break;
/* Single string */
case STT_STRING:
arg = sieve_ast_argument_string_create
(node, sieve_lexer_token_str(lexer),
sieve_lexer_token_line(parser->lexer));
sieve_lexer_skip_token(lexer);
break;
/* Number */
case STT_NUMBER:
arg = sieve_ast_argument_number_create
(node, sieve_lexer_token_int(lexer),
sieve_lexer_token_line(parser->lexer));
sieve_lexer_skip_token(lexer);
break;
/* Tag */
case STT_TAG:
arg = sieve_ast_argument_tag_create
(node, sieve_lexer_token_ident(lexer),
sieve_lexer_token_line(parser->lexer));
sieve_lexer_skip_token(lexer);
break;
/* End of argument list, continue with tests */
default:
arg_present = FALSE;
break;
}
if ( arg_present && arg == NULL ) {
sieve_parser_error(parser,
"failed to accept more arguments for command '%s'", node->identifier);
return -1;
}
if ( sieve_ast_argument_count(node) > SIEVE_MAX_COMMAND_ARGUMENTS ) {
sieve_parser_error(parser,
"too many arguments for command '%s'", node->identifier);
return FALSE;
}
}
if ( result <= 0 ) return result; /* Defer recovery to caller */
/* --> [ test / test-list ]
* test-list = "(" test *("," test) ")"
* test = identifier arguments
*/
switch ( sieve_lexer_token_type(lexer) ) {
/* Single test */
case STT_IDENTIFIER:
if ( depth+1 > SIEVE_MAX_TEST_NESTING ) {
sieve_parser_error(parser,
"cannot nest tests deeper than %u levels",
SIEVE_MAX_TEST_NESTING);
return FALSE;
}
test = sieve_ast_test_create
(node, sieve_lexer_token_ident(lexer),
sieve_lexer_token_line(parser->lexer));
sieve_lexer_skip_token(lexer);
/* Theoretically, test can be NULL */
if ( test == NULL ) break;
/* Parse test arguments, which may include more tests (recurse) */
if ( !sieve_parse_arguments(parser, test, depth+1) ) {
return FALSE; /* Defer recovery to caller */
}
break;
/* Test list */
case STT_LBRACKET:
sieve_lexer_skip_token(lexer);
if ( depth+1 > SIEVE_MAX_TEST_NESTING ) {
sieve_parser_error(parser,
"cannot nest tests deeper than %u levels",
SIEVE_MAX_TEST_NESTING);
result = sieve_parser_recover(parser, STT_RBRACKET);
if ( result ) sieve_lexer_skip_token(lexer);
return result;
}
node->test_list = TRUE;
/* Test starts with identifier */
if ( sieve_lexer_token_type(lexer) == STT_IDENTIFIER ) {
test = sieve_ast_test_create
(node, sieve_lexer_token_ident(lexer),
sieve_lexer_token_line(parser->lexer));
sieve_lexer_skip_token(lexer);
if ( test == NULL ) break;
/* Parse test arguments, which may include more tests (recurse) */
if ( (result=sieve_parse_arguments(parser, test, depth+1)) > 0 ) {
/* More tests ? */
while ( sieve_lexer_token_type(lexer) == STT_COMMA ) {
sieve_lexer_skip_token(lexer);
/* Check parser status */
if ( !parser->valid && !sieve_errors_more_allowed(parser->ehandler) ) {
result = sieve_parser_recover(parser, STT_RBRACKET);
break;
}
/* Test starts with identifier */
if ( sieve_lexer_token_type(lexer) == STT_IDENTIFIER ) {
test = sieve_ast_test_create
(node, sieve_lexer_token_ident(lexer),
sieve_lexer_token_line(parser->lexer));
sieve_lexer_skip_token(lexer);
if ( test == NULL ) break;
/* Parse test arguments, which may include more tests (recurse) */
if ( (result=sieve_parse_arguments(parser, test, depth+1)) <= 0 ) {
if ( result < 0 ) return result;
result = sieve_parser_recover(parser, STT_RBRACKET);
break;
}
} else {
sieve_parser_error(parser,
"expecting test identifier after ',' in test list, but found %s",
sieve_lexer_token_description(lexer));
result = sieve_parser_recover(parser, STT_RBRACKET);
break;
}
}
if ( test == NULL ) break;
} else {
if ( result < 0 ) return result;
result = sieve_parser_recover(parser, STT_RBRACKET);
}
} else {
sieve_parser_error(parser,
"expecting test identifier after '(' in test list, but found %s",
sieve_lexer_token_description(lexer));
result = sieve_parser_recover(parser, STT_RBRACKET);
}
/* The next token should be a ')', indicating the end of the test list
* --> previous sieve_parser_recover calls try to restore this situation
* after parse errors.
*/
if ( sieve_lexer_token_type(lexer) == STT_RBRACKET ) {
sieve_lexer_skip_token(lexer);
} else {
sieve_parser_error(parser,
"expecting ',' or end of test list ')', but found %s",
sieve_lexer_token_description(lexer));
/* Recover function tries to make next token equal to ')'. If it succeeds
* we need to skip it.
*/
if ( (result=sieve_parser_recover(parser, STT_RBRACKET)) == TRUE )
sieve_lexer_skip_token(lexer);
}
break;
default:
/* Not an error: test / test-list is optional
* --> any errors are detected by the caller
*/
test_present = FALSE;
break;
}
if ( test_present && test == NULL ) {
sieve_parser_error(parser,
"failed to accept more tests for command '%s'", node->identifier);
return -1;
}
return result;
}
/* commands = *command
* command = identifier arguments ( ";" / block )
* block = "{" commands "}"
*/
static int sieve_parse_commands
(struct sieve_parser *parser, struct sieve_ast_node *block, unsigned int depth)
{
const struct sieve_lexer *lexer = parser->lexer;
int result = TRUE;
while ( result > 0 &&
sieve_lexer_token_type(lexer) == STT_IDENTIFIER ) {
struct sieve_ast_node *command;
/* Check parser status */
if ( !parser->valid && !sieve_errors_more_allowed(parser->ehandler) ) {
result = sieve_parser_recover(parser, STT_SEMICOLON);
break;
}
/* Create command node */
command = sieve_ast_command_create
(block, sieve_lexer_token_ident(lexer),
sieve_lexer_token_line(parser->lexer));
sieve_lexer_skip_token(lexer);
if ( command == NULL ) {
sieve_parser_error(parser,
"failed to accept more commands inside the block of command '%s'",
block->identifier);
return -1;
}
result = sieve_parse_arguments(parser, command, 1);
/* Check whether the command is properly terminated
* (i.e. with ; or a new block)
*/
if ( result > 0 &&
sieve_lexer_token_type(lexer) != STT_SEMICOLON &&
sieve_lexer_token_type(lexer) != STT_LCURLY ) {
sieve_parser_error(parser,
"expected end of command ';' or the beginning of a compound block '{', "
"but found %s",
sieve_lexer_token_description(lexer));
result = FALSE;
}
/* Try to recover from parse errors to reacquire a defined state */
if ( result == 0 ) {
result = sieve_parser_recover(parser, STT_SEMICOLON);
}
/* Don't bother to continue if we are not in a defined state */
if ( result <= 0 ) {
return result;
}
switch ( sieve_lexer_token_type(lexer) ) {
/* End of the command */
case STT_SEMICOLON:
sieve_lexer_skip_token(lexer);
break;
/* Command has a block {...} */
case STT_LCURLY:
sieve_lexer_skip_token(lexer);
/* Check current depth first */
if ( depth+1 > SIEVE_MAX_BLOCK_NESTING ) {
sieve_parser_error(parser,
"cannot nest command blocks deeper than %u levels",
SIEVE_MAX_BLOCK_NESTING);
result = sieve_parser_recover(parser, STT_RCURLY);
if ( result > 0 )
sieve_lexer_skip_token(lexer);
break;
}
command->block = TRUE;
if ( (result=sieve_parse_commands(parser, command, depth+1)) > 0 ) {
if ( sieve_lexer_token_type(lexer) != STT_RCURLY ) {
sieve_parser_error(parser,
"expected end of compound block '}', but found %s",
sieve_lexer_token_description(lexer));
result = sieve_parser_recover(parser, STT_RCURLY);
} else
sieve_lexer_skip_token(lexer);
} else {
if ( result < 0 ) return result;
if ( (result=sieve_parser_recover(parser, STT_RCURLY)) > 0 )
sieve_lexer_skip_token(lexer);
}
break;
default:
/* Recovered previously, so this cannot happen */
i_unreached();
}
}
return result;
}
bool sieve_parser_run
(struct sieve_parser *parser, struct sieve_ast **ast)
{
if ( parser->ast != NULL )
sieve_ast_unref(&parser->ast);
/* Create AST object if none is provided */
if ( *ast == NULL )
*ast = sieve_ast_create(parser->script);
else
sieve_ast_ref(*ast);
parser->ast = *ast;
/* Scan first token */
sieve_lexer_skip_token(parser->lexer);
/* Parse */
if ( sieve_parse_commands(parser, sieve_ast_root(parser->ast), 1) > 0 &&
parser->valid ) {
/* Parsed right to EOF ? */
if ( sieve_lexer_token_type(parser->lexer) != STT_EOF ) {
sieve_parser_error(parser,
"unexpected %s found at (the presumed) end of file",
sieve_lexer_token_description(parser->lexer));
parser->valid = FALSE;
}
} else parser->valid = FALSE;
/* Clean up AST if parse failed */
if ( !parser->valid ) {
parser->ast = NULL;
sieve_ast_unref(ast);
}
return parser->valid;
}
/* Error recovery:
* To continue parsing after an error it is important to find the next
* parsible item in the stream. The recover function skips over the remaining
* garbage after an error. It tries to find the end of the failed syntax
* structure and takes nesting of structures into account.
*/
/* Assign useful names to priorities for readability */
enum sieve_grammatical_prio {
SGP_BLOCK = 3,
SGP_COMMAND = 2,
SGP_TEST_LIST = 1,
SGP_STRING_LIST = 0,
SGP_OTHER = -1
};
static inline enum sieve_grammatical_prio __get_token_priority
(enum sieve_token_type token)
{
switch ( token ) {
case STT_LCURLY:
case STT_RCURLY:
return SGP_BLOCK;
case STT_SEMICOLON:
return SGP_COMMAND;
case STT_LBRACKET:
case STT_RBRACKET:
return SGP_TEST_LIST;
case STT_LSQUARE:
case STT_RSQUARE:
return SGP_STRING_LIST;
default:
break;
}
return SGP_OTHER;
}
static int sieve_parser_recover
(struct sieve_parser *parser, enum sieve_token_type end_token)
{
/* The tokens that begin/end a specific block/command/list in order
* of ascending grammatical priority.
*/
static const enum sieve_token_type begin_tokens[4] =
{ STT_LSQUARE, STT_LBRACKET, STT_NONE, STT_LCURLY };
static const enum sieve_token_type end_tokens[4] =
{ STT_RSQUARE, STT_RBRACKET, STT_SEMICOLON, STT_RCURLY};
const struct sieve_lexer *lexer = parser->lexer;
int nesting = 1;
enum sieve_grammatical_prio end_priority = __get_token_priority(end_token);
i_assert( end_priority != SGP_OTHER );
while ( sieve_lexer_token_type(lexer) != STT_EOF &&
__get_token_priority(sieve_lexer_token_type(lexer)) <= end_priority ) {
if ( sieve_lexer_token_type(lexer) == begin_tokens[end_priority] ) {
nesting++;
sieve_lexer_skip_token(lexer);
continue;
}
if ( sieve_lexer_token_type(lexer) == end_tokens[end_priority] ) {
nesting--;
if ( nesting == 0 ) {
/* Next character is the end */
return TRUE;
}
}
sieve_lexer_skip_token(lexer);
}
/* Special case: COMMAND */
if (end_token == STT_SEMICOLON &&
sieve_lexer_token_type(lexer) == STT_LCURLY) {
return TRUE;
}
/* End not found before eof or end of surrounding grammatical structure
*/
return FALSE;
}
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