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Diffstat (limited to 'tools/bpf/bpf_exp.y')
| -rw-r--r-- | tools/bpf/bpf_exp.y | 656 |
1 files changed, 656 insertions, 0 deletions
diff --git a/tools/bpf/bpf_exp.y b/tools/bpf/bpf_exp.y new file mode 100644 index 000000000000..56ba1de50784 --- /dev/null +++ b/tools/bpf/bpf_exp.y @@ -0,0 +1,656 @@ +/* + * 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(0); + } 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(0); + } 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(0); + } +} + +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(0); + } + + 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 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 = (uint8_t) (off - i -1); + } + } +} + +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 = (uint8_t) (off - i - 1); + } + } +} + +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); +} |