nftables/0022-scanner-introduce-start-condition-stack.patch

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From 80f3c19bc1b989ab7ba2b917193e8bd3f998ba39 Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@strlen.de>
Date: Mon, 8 Mar 2021 18:18:33 +0100
Subject: [PATCH] scanner: introduce start condition stack
Add a small initial chunk of flex start conditionals.
This starts with two low-hanging fruits, numgen and j/symhash.
NUMGEN and HASH start conditions are entered from flex when
the corresponding expression token is encountered.
Flex returns to the INIT condition when the bison parser
has seen a complete numgen/hash statement.
This intentionally uses a stack rather than BEGIN()
to eventually support nested states.
The scanner_pop_start_cond() function argument is not used yet, but
will need to be used later to deal with nesting.
Signed-off-by: Florian Westphal <fw@strlen.de>
(cherry picked from commit 5896772fe3c5f01696188ea04957a825ee601b12)
---
include/parser.h | 8 ++++++++
src/parser_bison.y | 11 +++++++----
src/scanner.l | 36 +++++++++++++++++++++++++++++-------
3 files changed, 44 insertions(+), 11 deletions(-)
diff --git a/include/parser.h b/include/parser.h
index 9baa3a4db789f..b2ebd7aa226c5 100644
--- a/include/parser.h
+++ b/include/parser.h
@@ -26,6 +26,12 @@ struct parser_state {
struct list_head *cmds;
};
+enum startcond_type {
+ PARSER_SC_BEGIN,
+ PARSER_SC_EXPR_HASH,
+ PARSER_SC_EXPR_NUMGEN,
+};
+
struct mnl_socket;
extern void parser_init(struct nft_ctx *nft, struct parser_state *state,
@@ -45,4 +51,6 @@ extern void scanner_push_buffer(void *scanner,
const struct input_descriptor *indesc,
const char *buffer);
+extern void scanner_pop_start_cond(void *scanner, enum startcond_type sc);
+
#endif /* NFTABLES_PARSER_H */
diff --git a/src/parser_bison.y b/src/parser_bison.y
index 8644f66106496..da3fafcd1eeb1 100644
--- a/src/parser_bison.y
+++ b/src/parser_bison.y
@@ -857,6 +857,9 @@ opt_newline : NEWLINE
| /* empty */
;
+close_scope_hash : { scanner_pop_start_cond(nft->scanner, PARSER_SC_EXPR_HASH); };
+close_scope_numgen : { scanner_pop_start_cond(nft->scanner, PARSER_SC_EXPR_NUMGEN); };
+
common_block : INCLUDE QUOTED_STRING stmt_separator
{
if (scanner_include_file(nft, scanner, $2, &@$) < 0) {
@@ -4811,7 +4814,7 @@ numgen_type : INC { $$ = NFT_NG_INCREMENTAL; }
| RANDOM { $$ = NFT_NG_RANDOM; }
;
-numgen_expr : NUMGEN numgen_type MOD NUM offset_opt
+numgen_expr : NUMGEN numgen_type MOD NUM offset_opt close_scope_numgen
{
$$ = numgen_expr_alloc(&@$, $2, $4, $5);
}
@@ -4868,17 +4871,17 @@ xfrm_expr : IPSEC xfrm_dir xfrm_spnum xfrm_state_key
}
;
-hash_expr : JHASH expr MOD NUM SEED NUM offset_opt
+hash_expr : JHASH expr MOD NUM SEED NUM offset_opt close_scope_hash
{
$$ = hash_expr_alloc(&@$, $4, true, $6, $7, NFT_HASH_JENKINS);
$$->hash.expr = $2;
}
- | JHASH expr MOD NUM offset_opt
+ | JHASH expr MOD NUM offset_opt close_scope_hash
{
$$ = hash_expr_alloc(&@$, $4, false, 0, $5, NFT_HASH_JENKINS);
$$->hash.expr = $2;
}
- | SYMHASH MOD NUM offset_opt
+ | SYMHASH MOD NUM offset_opt close_scope_hash
{
$$ = hash_expr_alloc(&@$, $3, false, 0, $4, NFT_HASH_SYM);
}
diff --git a/src/scanner.l b/src/scanner.l
index 8bde1fbe912d8..ec8f252fbc8c8 100644
--- a/src/scanner.l
+++ b/src/scanner.l
@@ -98,6 +98,8 @@ static void reset_pos(struct parser_state *state, struct location *loc)
state->indesc->column = 1;
}
+static void scanner_push_start_cond(void *scanner, enum startcond_type type);
+
#define YY_USER_ACTION { \
update_pos(yyget_extra(yyscanner), yylloc, yyleng); \
update_offset(yyget_extra(yyscanner), yylloc, yyleng); \
@@ -193,6 +195,9 @@ addrstring ({macaddr}|{ip4addr}|{ip6addr})
%option yylineno
%option nodefault
%option warn
+%option stack
+%s SCANSTATE_EXPR_HASH
+%s SCANSTATE_EXPR_NUMGEN
%%
@@ -551,15 +556,21 @@ addrstring ({macaddr}|{ip4addr}|{ip6addr})
"state" { return STATE; }
"status" { return STATUS; }
-"numgen" { return NUMGEN; }
-"inc" { return INC; }
-"mod" { return MOD; }
-"offset" { return OFFSET; }
+"numgen" { scanner_push_start_cond(yyscanner, SCANSTATE_EXPR_NUMGEN); return NUMGEN; }
+<SCANSTATE_EXPR_NUMGEN>{
+ "inc" { return INC; }
+}
-"jhash" { return JHASH; }
-"symhash" { return SYMHASH; }
-"seed" { return SEED; }
+"jhash" { scanner_push_start_cond(yyscanner, SCANSTATE_EXPR_HASH); return JHASH; }
+"symhash" { scanner_push_start_cond(yyscanner, SCANSTATE_EXPR_HASH); return SYMHASH; }
+<SCANSTATE_EXPR_HASH>{
+ "seed" { return SEED; }
+}
+<SCANSTATE_EXPR_HASH,SCANSTATE_EXPR_NUMGEN>{
+ "mod" { return MOD; }
+ "offset" { return OFFSET; }
+}
"dup" { return DUP; }
"fwd" { return FWD; }
@@ -973,3 +984,14 @@ void scanner_destroy(struct nft_ctx *nft)
input_descriptor_list_destroy(state);
yylex_destroy(nft->scanner);
}
+
+static void scanner_push_start_cond(void *scanner, enum startcond_type type)
+{
+ yy_push_state((int)type, scanner);
+}
+
+void scanner_pop_start_cond(void *scanner, enum startcond_type t)
+{
+ yy_pop_state(scanner);
+ (void)yy_top_state(scanner); /* suppress gcc warning wrt. unused function */
+}
--
2.33.0