/*
 * BPF asm code parser
 *
 * This program is free software; you can distribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License,
 * or (at your option) any later version.
 *
 * Syntax kept close to:
 *
 * Steven McCanne and Van Jacobson. 1993. The BSD packet filter: a new
 * architecture for user-level packet capture. In Proceedings of the
 * USENIX Winter 1993 Conference Proceedings on USENIX Winter 1993
 * Conference Proceedings (USENIX'93). USENIX Association, Berkeley,
 * CA, USA, 2-2.
 *
 * Copyright 2013 Daniel Borkmann <borkmann@redhat.com>
 * Licensed under the GNU General Public License, version 2.0 (GPLv2)
 */

%{

#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <errno.h>
#include <assert.h>
#include <linux/filter.h>

#include "bpf_exp.yacc.h"

enum jmp_type { JTL, JFL, JKL };

extern FILE *yyin;
extern int yylineno;
extern int yylex(void);
extern void yyerror(const char *str);

extern void bpf_asm_compile(FILE *fp, bool cstyle);
static void bpf_set_curr_instr(uint16_t op, uint8_t jt, uint8_t jf, uint32_t k);
static void bpf_set_curr_label(char *label);
static void bpf_set_jmp_label(char *label, enum jmp_type type);

%}

%union {
        char *label;
        uint32_t number;
}

%token OP_LDB OP_LDH OP_LD OP_LDX OP_ST OP_STX OP_JMP OP_JEQ OP_JGT OP_JGE
%token OP_JSET OP_ADD OP_SUB OP_MUL OP_DIV OP_AND OP_OR OP_XOR OP_LSH OP_RSH
%token OP_RET OP_TAX OP_TXA OP_LDXB OP_MOD OP_NEG OP_JNEQ OP_JLT OP_JLE OP_LDI
%token OP_LDXI

%token K_PKT_LEN

%token ':' ',' '[' ']' '(' ')' 'x' 'a' '+' 'M' '*' '&' '#' '%'

%token extension number label

%type <label> label
%type <number> extension
%type <number> number

%%

prog
        : line
        | prog line
        ;

line
        : instr
        | labelled_instr
        ;

labelled_instr
        : labelled instr
        ;

instr
        : ldb
        | ldh
        | ld
        | ldi
        | ldx
        | ldxi
        | st
        | stx
        | jmp
        | jeq
        | jneq
        | jlt
        | jle
        | jgt
        | jge
        | jset
        | add
        | sub
        | mul
        | div
        | mod
        | neg
        | and
        | or
        | xor
        | lsh
        | rsh
        | ret
        | tax
        | txa
        ;

labelled
        : label ':' { bpf_set_curr_label($1); }
        ;

ldb
        : OP_LDB '[' 'x' '+' number ']' {
                bpf_set_curr_instr(BPF_LD | BPF_B | BPF_IND, 0, 0, $5); }
        | OP_LDB '[' '%' 'x' '+' number ']' {
                bpf_set_curr_instr(BPF_LD | BPF_B | BPF_IND, 0, 0, $6); }
        | OP_LDB '[' number ']' {
                bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0, $3); }
        | OP_LDB extension {
                bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
                                   SKF_AD_OFF + $2); }
        ;

ldh
        : OP_LDH '[' 'x' '+' number ']' {
                bpf_set_curr_instr(BPF_LD | BPF_H | BPF_IND, 0, 0, $5); }
        | OP_LDH '[' '%' 'x' '+' number ']' {
                bpf_set_curr_instr(BPF_LD | BPF_H | BPF_IND, 0, 0, $6); }
        | OP_LDH '[' number ']' {
                bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0, $3); }
        | OP_LDH extension {
                bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
                                   SKF_AD_OFF + $2); }
        ;

ldi
        : OP_LDI '#' number {
                bpf_set_curr_instr(BPF_LD | BPF_IMM, 0, 0, $3); }
        | OP_LDI number {
                bpf_set_curr_instr(BPF_LD | BPF_IMM, 0, 0, $2); }
        ;

ld
        : OP_LD '#' number {
                bpf_set_curr_instr(BPF_LD | BPF_IMM, 0, 0, $3); }
        | OP_LD K_PKT_LEN {
                bpf_set_curr_instr(BPF_LD | BPF_W | BPF_LEN, 0, 0, 0); }
        | OP_LD extension {
                bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
                                   SKF_AD_OFF + $2); }
        | OP_LD 'M' '[' number ']' {
                bpf_set_curr_instr(BPF_LD | BPF_MEM, 0, 0, $4); }
        | OP_LD '[' 'x' '+' number ']' {
                bpf_set_curr_instr(BPF_LD | BPF_W | BPF_IND, 0, 0, $5); }
        | OP_LD '[' '%' 'x' '+' number ']' {
                bpf_set_curr_instr(BPF_LD | BPF_W | BPF_IND, 0, 0, $6); }
        | OP_LD '[' number ']' {
                bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0, $3); }
        ;

ldxi
        : OP_LDXI '#' number {
                bpf_set_curr_instr(BPF_LDX | BPF_IMM, 0, 0, $3); }
        | OP_LDXI number {
                bpf_set_curr_instr(BPF_LDX | BPF_IMM, 0, 0, $2); }
        ;

ldx
        : OP_LDX '#' number {
                bpf_set_curr_instr(BPF_LDX | BPF_IMM, 0, 0, $3); }
        | OP_LDX K_PKT_LEN {
                bpf_set_curr_instr(BPF_LDX | BPF_W | BPF_LEN, 0, 0, 0); }
        | OP_LDX 'M' '[' number ']' {
                bpf_set_curr_instr(BPF_LDX | BPF_MEM, 0, 0, $4); }
        | OP_LDXB number '*' '(' '[' number ']' '&' number ')' {
                if ($2 != 4 || $9 != 0xf) {
                        fprintf(stderr, "ldxb offset not supported!\n");
                        exit(1);
                } else {
                        bpf_set_curr_instr(BPF_LDX | BPF_MSH | BPF_B, 0, 0, $6); } }
        | OP_LDX number '*' '(' '[' number ']' '&' number ')' {
                if ($2 != 4 || $9 != 0xf) {
                        fprintf(stderr, "ldxb offset not supported!\n");
                        exit(1);
                } else {
                        bpf_set_curr_instr(BPF_LDX | BPF_MSH | BPF_B, 0, 0, $6); } }
        ;

st
        : OP_ST 'M' '[' number ']' {
                bpf_set_curr_instr(BPF_ST, 0, 0, $4); }
        ;

stx
        : OP_STX 'M' '[' number ']' {
                bpf_set_curr_instr(BPF_STX, 0, 0, $4); }
        ;

jmp
        : OP_JMP label {
                bpf_set_jmp_label($2, JKL);
                bpf_set_curr_instr(BPF_JMP | BPF_JA, 0, 0, 0); }
        ;

jeq
        : OP_JEQ '#' number ',' label ',' label {
                bpf_set_jmp_label($5, JTL);
                bpf_set_jmp_label($7, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_K, 0, 0, $3); }
        | OP_JEQ 'x' ',' label ',' label {
                bpf_set_jmp_label($4, JTL);
                bpf_set_jmp_label($6, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
        | OP_JEQ '%' 'x' ',' label ',' label {
                bpf_set_jmp_label($5, JTL);
                bpf_set_jmp_label($7, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
        | OP_JEQ '#' number ',' label {
                bpf_set_jmp_label($5, JTL);
                bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_K, 0, 0, $3); }
        | OP_JEQ 'x' ',' label {
                bpf_set_jmp_label($4, JTL);
                bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
        | OP_JEQ '%' 'x' ',' label {
                bpf_set_jmp_label($5, JTL);
                bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
        ;

jneq
        : OP_JNEQ '#' number ',' label {
                bpf_set_jmp_label($5, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_K, 0, 0, $3); }
        | OP_JNEQ 'x' ',' label {
                bpf_set_jmp_label($4, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
        | OP_JNEQ '%' 'x' ',' label {
                bpf_set_jmp_label($5, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
        ;

jlt
        : OP_JLT '#' number ',' label {
                bpf_set_jmp_label($5, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_K, 0, 0, $3); }
        | OP_JLT 'x' ',' label {
                bpf_set_jmp_label($4, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
        | OP_JLT '%' 'x' ',' label {
                bpf_set_jmp_label($5, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
        ;

jle
        : OP_JLE '#' number ',' label {
                bpf_set_jmp_label($5, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_K, 0, 0, $3); }
        | OP_JLE 'x' ',' label {
                bpf_set_jmp_label($4, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
        | OP_JLE '%' 'x' ',' label {
                bpf_set_jmp_label($5, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
        ;

jgt
        : OP_JGT '#' number ',' label ',' label {
                bpf_set_jmp_label($5, JTL);
                bpf_set_jmp_label($7, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_K, 0, 0, $3); }
        | OP_JGT 'x' ',' label ',' label {
                bpf_set_jmp_label($4, JTL);
                bpf_set_jmp_label($6, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
        | OP_JGT '%' 'x' ',' label ',' label {
                bpf_set_jmp_label($5, JTL);
                bpf_set_jmp_label($7, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
        | OP_JGT '#' number ',' label {
                bpf_set_jmp_label($5, JTL);
                bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_K, 0, 0, $3); }
        | OP_JGT 'x' ',' label {
                bpf_set_jmp_label($4, JTL);
                bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
        | OP_JGT '%' 'x' ',' label {
                bpf_set_jmp_label($5, JTL);
                bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
        ;

jge
        : OP_JGE '#' number ',' label ',' label {
                bpf_set_jmp_label($5, JTL);
                bpf_set_jmp_label($7, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_K, 0, 0, $3); }
        | OP_JGE 'x' ',' label ',' label {
                bpf_set_jmp_label($4, JTL);
                bpf_set_jmp_label($6, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
        | OP_JGE '%' 'x' ',' label ',' label {
                bpf_set_jmp_label($5, JTL);
                bpf_set_jmp_label($7, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
        | OP_JGE '#' number ',' label {
                bpf_set_jmp_label($5, JTL);
                bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_K, 0, 0, $3); }
        | OP_JGE 'x' ',' label {
                bpf_set_jmp_label($4, JTL);
                bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
        | OP_JGE '%' 'x' ',' label {
                bpf_set_jmp_label($5, JTL);
                bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
        ;

jset
        : OP_JSET '#' number ',' label ',' label {
                bpf_set_jmp_label($5, JTL);
                bpf_set_jmp_label($7, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_K, 0, 0, $3); }
        | OP_JSET 'x' ',' label ',' label {
                bpf_set_jmp_label($4, JTL);
                bpf_set_jmp_label($6, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); }
        | OP_JSET '%' 'x' ',' label ',' label {
                bpf_set_jmp_label($5, JTL);
                bpf_set_jmp_label($7, JFL);
                bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); }
        | OP_JSET '#' number ',' label {
                bpf_set_jmp_label($5, JTL);
                bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_K, 0, 0, $3); }
        | OP_JSET 'x' ',' label {
                bpf_set_jmp_label($4, JTL);
                bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); }
        | OP_JSET '%' 'x' ',' label {
                bpf_set_jmp_label($5, JTL);
                bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); }
        ;

add
        : OP_ADD '#' number {
                bpf_set_curr_instr(BPF_ALU | BPF_ADD | BPF_K, 0, 0, $3); }
        | OP_ADD 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_ADD | BPF_X, 0, 0, 0); }
        | OP_ADD '%' 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_ADD | BPF_X, 0, 0, 0); }
        ;

sub
        : OP_SUB '#' number {
                bpf_set_curr_instr(BPF_ALU | BPF_SUB | BPF_K, 0, 0, $3); }
        | OP_SUB 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_SUB | BPF_X, 0, 0, 0); }
        | OP_SUB '%' 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_SUB | BPF_X, 0, 0, 0); }
        ;

mul
        : OP_MUL '#' number {
                bpf_set_curr_instr(BPF_ALU | BPF_MUL | BPF_K, 0, 0, $3); }
        | OP_MUL 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_MUL | BPF_X, 0, 0, 0); }
        | OP_MUL '%' 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_MUL | BPF_X, 0, 0, 0); }
        ;

div
        : OP_DIV '#' number {
                bpf_set_curr_instr(BPF_ALU | BPF_DIV | BPF_K, 0, 0, $3); }
        | OP_DIV 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_DIV | BPF_X, 0, 0, 0); }
        | OP_DIV '%' 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_DIV | BPF_X, 0, 0, 0); }
        ;

mod
        : OP_MOD '#' number {
                bpf_set_curr_instr(BPF_ALU | BPF_MOD | BPF_K, 0, 0, $3); }
        | OP_MOD 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_MOD | BPF_X, 0, 0, 0); }
        | OP_MOD '%' 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_MOD | BPF_X, 0, 0, 0); }
        ;

neg
        : OP_NEG {
                bpf_set_curr_instr(BPF_ALU | BPF_NEG, 0, 0, 0); }
        ;

and
        : OP_AND '#' number {
                bpf_set_curr_instr(BPF_ALU | BPF_AND | BPF_K, 0, 0, $3); }
        | OP_AND 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_AND | BPF_X, 0, 0, 0); }
        | OP_AND '%' 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_AND | BPF_X, 0, 0, 0); }
        ;

or
        : OP_OR '#' number {
                bpf_set_curr_instr(BPF_ALU | BPF_OR | BPF_K, 0, 0, $3); }
        | OP_OR 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_OR | BPF_X, 0, 0, 0); }
        | OP_OR '%' 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_OR | BPF_X, 0, 0, 0); }
        ;

xor
        : OP_XOR '#' number {
                bpf_set_curr_instr(BPF_ALU | BPF_XOR | BPF_K, 0, 0, $3); }
        | OP_XOR 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_XOR | BPF_X, 0, 0, 0); }
        | OP_XOR '%' 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_XOR | BPF_X, 0, 0, 0); }
        ;

lsh
        : OP_LSH '#' number {
                bpf_set_curr_instr(BPF_ALU | BPF_LSH | BPF_K, 0, 0, $3); }
        | OP_LSH 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_LSH | BPF_X, 0, 0, 0); }
        | OP_LSH '%' 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_LSH | BPF_X, 0, 0, 0); }
        ;

rsh
        : OP_RSH '#' number {
                bpf_set_curr_instr(BPF_ALU | BPF_RSH | BPF_K, 0, 0, $3); }
        | OP_RSH 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_RSH | BPF_X, 0, 0, 0); }
        | OP_RSH '%' 'x' {
                bpf_set_curr_instr(BPF_ALU | BPF_RSH | BPF_X, 0, 0, 0); }
        ;

ret
        : OP_RET 'a' {
                bpf_set_curr_instr(BPF_RET | BPF_A, 0, 0, 0); }
        | OP_RET '%' 'a' {
                bpf_set_curr_instr(BPF_RET | BPF_A, 0, 0, 0); }
        | OP_RET 'x' {
                bpf_set_curr_instr(BPF_RET | BPF_X, 0, 0, 0); }
        | OP_RET '%' 'x' {
                bpf_set_curr_instr(BPF_RET | BPF_X, 0, 0, 0); }
        | OP_RET '#' number {
                bpf_set_curr_instr(BPF_RET | BPF_K, 0, 0, $3); }
        ;

tax
        : OP_TAX {
                bpf_set_curr_instr(BPF_MISC | BPF_TAX, 0, 0, 0); }
        ;

txa
        : OP_TXA {
                bpf_set_curr_instr(BPF_MISC | BPF_TXA, 0, 0, 0); }
        ;

%%

static int curr_instr = 0;
static struct sock_filter out[BPF_MAXINSNS];
static char **labels, **labels_jt, **labels_jf, **labels_k;

static void bpf_assert_max(void)
{
        if (curr_instr >= BPF_MAXINSNS) {
                fprintf(stderr, "only max %u insns allowed!\n", BPF_MAXINSNS);
                exit(1);
        }
}

static void bpf_set_curr_instr(uint16_t code, uint8_t jt, uint8_t jf,
                               uint32_t k)
{
        bpf_assert_max();
        out[curr_instr].code = code;
        out[curr_instr].jt = jt;
        out[curr_instr].jf = jf;
        out[curr_instr].k = k;
        curr_instr++;
}

static void bpf_set_curr_label(char *label)
{
        bpf_assert_max();
        labels[curr_instr] = label;
}

static void bpf_set_jmp_label(char *label, enum jmp_type type)
{
        bpf_assert_max();
        switch (type) {
        case JTL:
                labels_jt[curr_instr] = label;
                break;
        case JFL:
                labels_jf[curr_instr] = label;
                break;
        case JKL:
                labels_k[curr_instr] = label;
                break;
        }
}

static int bpf_find_insns_offset(const char *label)
{
        int i, max = curr_instr, ret = -ENOENT;

        for (i = 0; i < max; i++) {
                if (labels[i] && !strcmp(label, labels[i])) {
                        ret = i;
                        break;
                }
        }

        if (ret == -ENOENT) {
                fprintf(stderr, "no such label \'%s\'!\n", label);
                exit(1);
        }

        return ret;
}

static void bpf_stage_1_insert_insns(void)
{
        yyparse();
}

static void bpf_reduce_k_jumps(void)
{
        int i;

        for (i = 0; i < curr_instr; i++) {
                if (labels_k[i]) {
                        int off = bpf_find_insns_offset(labels_k[i]);
                        out[i].k = (uint32_t) (off - i - 1);
                }
        }
}

static uint8_t bpf_encode_jt_jf_offset(int off, int i)
{
        int delta = off - i - 1;

        if (delta < 0 || delta > 255) {
                fprintf(stderr, "error: insn #%d jumps to insn #%d, "
                                "which is out of range\n", i, off);
                exit(1);
        }
        return (uint8_t) delta;
}

static void bpf_reduce_jt_jumps(void)
{
        int i;

        for (i = 0; i < curr_instr; i++) {
                if (labels_jt[i]) {
                        int off = bpf_find_insns_offset(labels_jt[i]);
                        out[i].jt = bpf_encode_jt_jf_offset(off, i);
                }
        }
}

static void bpf_reduce_jf_jumps(void)
{
        int i;

        for (i = 0; i < curr_instr; i++) {
                if (labels_jf[i]) {
                        int off = bpf_find_insns_offset(labels_jf[i]);
                        out[i].jf = bpf_encode_jt_jf_offset(off, i);
                }
        }
}

static void bpf_stage_2_reduce_labels(void)
{
        bpf_reduce_k_jumps();
        bpf_reduce_jt_jumps();
        bpf_reduce_jf_jumps();
}

static void bpf_pretty_print_c(void)
{
        int i;

        for (i = 0; i < curr_instr; i++)
                printf("{ %#04x, %2u, %2u, %#010x },\n", out[i].code,
                       out[i].jt, out[i].jf, out[i].k);
}

static void bpf_pretty_print(void)
{
        int i;

        printf("%u,", curr_instr);
        for (i = 0; i < curr_instr; i++)
                printf("%u %u %u %u,", out[i].code,
                       out[i].jt, out[i].jf, out[i].k);
        printf("\n");
}

static void bpf_init(void)
{
        memset(out, 0, sizeof(out));

        labels = calloc(BPF_MAXINSNS, sizeof(*labels));
        assert(labels);
        labels_jt = calloc(BPF_MAXINSNS, sizeof(*labels_jt));
        assert(labels_jt);
        labels_jf = calloc(BPF_MAXINSNS, sizeof(*labels_jf));
        assert(labels_jf);
        labels_k = calloc(BPF_MAXINSNS, sizeof(*labels_k));
        assert(labels_k);
}

static void bpf_destroy_labels(void)
{
        int i;

        for (i = 0; i < curr_instr; i++) {
                free(labels_jf[i]);
                free(labels_jt[i]);
                free(labels_k[i]);
                free(labels[i]);
        }
}

static void bpf_destroy(void)
{
        bpf_destroy_labels();
        free(labels_jt);
        free(labels_jf);
        free(labels_k);
        free(labels);
}

void bpf_asm_compile(FILE *fp, bool cstyle)
{
        yyin = fp;

        bpf_init();
        bpf_stage_1_insert_insns();
        bpf_stage_2_reduce_labels();
        bpf_destroy();

        if (cstyle)
                bpf_pretty_print_c();
        else
                bpf_pretty_print();

        if (fp != stdin)
                fclose(yyin);
}

void yyerror(const char *str)
{
        fprintf(stderr, "error: %s at line %d\n", str, yylineno);
        exit(1);
}