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lvm2/lib/regex/matcher.c

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o First pass at the regex code. lib/regex/matcher takes an array of regex's and builds a *very* efficient engine that will tell you which regex a string matches with only a single pass through the string. To be used in the config file when specifying devices. o Anchor's aren't supported yet (^ and $) but that won't take long. o Also when we get some realistic config files we may want to consider adding an extra level of indirection to the dfa state in order to compress the table. It all depends on how large typical tables get.
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/*
* Copyright (C) 2001 Sistina Software (UK) Limited.
*
* This file is released under the GPL.
*/
#include "matcher.h"
#include "parse_rx.h"
#include "log.h"
#include "ttree.h"
#include "bitset.h"
#include <string.h>
#include <stdio.h>
#include <assert.h>
struct dfa_state {
int final;
struct dfa_state *lookup[256];
};
struct state_queue {
struct dfa_state *s;
bitset_t bits;
struct state_queue *next;
};
struct matcher { /* Instance variables for the lexer */
struct dfa_state *start;
int num_nodes, nodes_entered;
struct rx_node **nodes;
struct pool *scratch, *mem;
};
#define TARGET_TRANS '\0'
static int _count_nodes(struct rx_node *rx)
{
int r = 1;
if(rx->left)
r += _count_nodes(rx->left);
if(rx->right)
r += _count_nodes(rx->right);
return r;
}
static void _fill_table(struct matcher *m, struct rx_node *rx)
{
assert((rx->type != OR) || (rx->left && rx->right));
if(rx->left)
_fill_table(m, rx->left);
if(rx->right)
_fill_table(m, rx->right);
m->nodes[m->nodes_entered++] = rx;
}
static void _create_bitsets(struct matcher *m)
{
int i;
for(i = 0; i < m->num_nodes; i++) {
struct rx_node *n = m->nodes[i];
n->firstpos = bitset_create(m->scratch, m->num_nodes);
n->lastpos = bitset_create(m->scratch, m->num_nodes);
n->followpos = bitset_create(m->scratch, m->num_nodes);
}
}
static void _calc_functions(struct matcher *m)
{
int i, j, final = 1;
struct rx_node *rx, *c1, *c2;
for(i = 0; i < m->num_nodes; i++) {
rx = m->nodes[i];
c1 = rx->left;
c2 = rx->right;
if(bit(rx->charset, TARGET_TRANS))
rx->final = final++;
switch(rx->type) {
case CAT:
if(c1->nullable)
bit_union(rx->firstpos,
c1->firstpos, c2->firstpos);
else
bit_copy(rx->firstpos, c1->firstpos);
if(c2->nullable)
bit_union(rx->lastpos,
c1->lastpos, c2->lastpos);
else
bit_copy(rx->lastpos, c2->lastpos);
rx->nullable = c1->nullable && c2->nullable;
break;
case PLUS:
bit_copy(rx->firstpos, c1->firstpos);
bit_copy(rx->lastpos, c1->lastpos);
rx->nullable = c1->nullable;
break;
case OR:
bit_union(rx->firstpos, c1->firstpos, c2->firstpos);
bit_union(rx->lastpos, c1->lastpos, c2->lastpos);
rx->nullable = c1->nullable || c2->nullable;
break;
case QUEST:
case STAR:
bit_copy(rx->firstpos, c1->firstpos);
bit_copy(rx->lastpos, c1->lastpos);
rx->nullable = 1;
break;
case CHARSET:
bit_set(rx->firstpos, i);
bit_set(rx->lastpos, i);
rx->nullable = 0;
break;
default:
log_debug("unknown node type");
}
/*
* followpos has it's own switch
* because PLUS and STAR do the
* same thing.
*/
switch(rx->type) {
case CAT:
for(j = 0; j < m->num_nodes; j++) {
if(bit(c1->lastpos, j)) {
struct rx_node *n = m->nodes[j];
bit_union(n->followpos,
n->followpos, c2->firstpos);
}
}
break;
case PLUS:
case STAR:
for(j = 0; j < m->num_nodes; j++) {
if(bit(rx->lastpos, j)) {
struct rx_node *n = m->nodes[j];
bit_union(n->followpos,
n->followpos, rx->firstpos);
}
}
break;
}
}
}
static inline struct dfa_state *_create_dfa_state(struct pool *mem)
{
return pool_zalloc(mem, sizeof(struct dfa_state));
}
static struct state_queue *_create_state_queue(struct pool *mem,
struct dfa_state *dfa,
bitset_t bits)
{
struct state_queue *r = pool_alloc(mem, sizeof(*r));
if (!r) {
stack;
return NULL;
}
r->s = dfa;
r->bits = bitset_create(mem, bits[0]); /* first element is the size */
bit_copy(r->bits, bits);
r->next = 0;
return r;
}
static int _calc_states(struct matcher *m, struct rx_node *rx)
{
int iwidth = (m->num_nodes / BITS_PER_INT) + 1;
struct ttree *tt = ttree_create(m->scratch, iwidth);
struct state_queue *h, *t, *tmp;
struct dfa_state *dfa, *ldfa;
int i, a, set_bits = 0, count = 0;
bitset_t bs = bitset_create(m->scratch, m->num_nodes), dfa_bits;
if (!tt) {
stack;
return 0;
}
if (!bs) {
stack;
return 0;
}
/* create first state */
dfa = _create_dfa_state(m->mem);
m->start = dfa;
o Filter for the dev cache that takes values from config file: devices { # first match is final, eg. /dev/ide/cdrom # get's rejected due to the first pattern filter=["r/cdrom/", # don't touch the music ! "a/hd[a-d][0-9]+/", "a/ide/", "a/sd/", "a/md/", "a|loop/[0-9]+|", # accept devfs style loop back "r/loop/", # and reject old style "a/dasd/", "a/dac960/", "a/nbd/", "a/ida/", "a/cciss/", "a/ubd/", "r/.*/"] # reject all others } Alasdair this is ready to roll into the tools now.
2001-10-19 22:20:37 +04:00
ttree_insert(tt, rx->firstpos + 1, dfa);
o First pass at the regex code. lib/regex/matcher takes an array of regex's and builds a *very* efficient engine that will tell you which regex a string matches with only a single pass through the string. To be used in the config file when specifying devices. o Anchor's aren't supported yet (^ and $) but that won't take long. o Also when we get some realistic config files we may want to consider adding an extra level of indirection to the dfa state in order to compress the table. It all depends on how large typical tables get.
2001-10-19 18:36:57 +04:00
/* prime the queue */
h = t = _create_state_queue(m->scratch, dfa, rx->firstpos);
o Filter for the dev cache that takes values from config file: devices { # first match is final, eg. /dev/ide/cdrom # get's rejected due to the first pattern filter=["r/cdrom/", # don't touch the music ! "a/hd[a-d][0-9]+/", "a/ide/", "a/sd/", "a/md/", "a|loop/[0-9]+|", # accept devfs style loop back "r/loop/", # and reject old style "a/dasd/", "a/dac960/", "a/nbd/", "a/ida/", "a/cciss/", "a/ubd/", "r/.*/"] # reject all others } Alasdair this is ready to roll into the tools now.
2001-10-19 22:20:37 +04:00
while (h) {
o First pass at the regex code. lib/regex/matcher takes an array of regex's and builds a *very* efficient engine that will tell you which regex a string matches with only a single pass through the string. To be used in the config file when specifying devices. o Anchor's aren't supported yet (^ and $) but that won't take long. o Also when we get some realistic config files we may want to consider adding an extra level of indirection to the dfa state in order to compress the table. It all depends on how large typical tables get.
2001-10-19 18:36:57 +04:00
/* pop state off front of the queue */
dfa = h->s;
dfa_bits = h->bits;
h = h->next;
/* iterate through all the inputs for this state */
bit_clear_all(bs);
for(a = 0; a < 256; a++) {
/* iterate through all the states in firstpos */
for(i = bit_get_first(dfa_bits);
i >=0;
i = bit_get_next(dfa_bits, i)) {
if(bit(m->nodes[i]->charset, a)) {
if(a == TARGET_TRANS)
dfa->final = m->nodes[i]->final;
bit_union(bs, bs, m->nodes[i]->followpos);
set_bits = 1;
}
}
if(set_bits) {
ldfa = ttree_lookup(tt, bs + 1);
if(!ldfa) {
/* push */
ldfa = _create_dfa_state(m->mem);
ttree_insert(tt, bs + 1, ldfa);
tmp = _create_state_queue(m->scratch, ldfa, bs);
if(!h)
h = t = tmp;
else {
t->next = tmp;
t = tmp;
}
count++;
}
dfa->lookup[a] = ldfa;
set_bits = 0;
bit_clear_all(bs);
}
}
}
o Filter for the dev cache that takes values from config file: devices { # first match is final, eg. /dev/ide/cdrom # get's rejected due to the first pattern filter=["r/cdrom/", # don't touch the music ! "a/hd[a-d][0-9]+/", "a/ide/", "a/sd/", "a/md/", "a|loop/[0-9]+|", # accept devfs style loop back "r/loop/", # and reject old style "a/dasd/", "a/dac960/", "a/nbd/", "a/ida/", "a/cciss/", "a/ubd/", "r/.*/"] # reject all others } Alasdair this is ready to roll into the tools now.
2001-10-19 22:20:37 +04:00
log_debug("Matcher built with %d dfa states", count);
o First pass at the regex code. lib/regex/matcher takes an array of regex's and builds a *very* efficient engine that will tell you which regex a string matches with only a single pass through the string. To be used in the config file when specifying devices. o Anchor's aren't supported yet (^ and $) but that won't take long. o Also when we get some realistic config files we may want to consider adding an extra level of indirection to the dfa state in order to compress the table. It all depends on how large typical tables get.
2001-10-19 18:36:57 +04:00
return 1;
}
struct matcher *matcher_create(struct pool *mem,
const char **patterns, int num)
{
char *all, *ptr;
int i, len = 0;
struct rx_node *rx;
struct pool *scratch = pool_create(10 * 1024);
struct matcher *m;
if (!scratch) {
stack;
return NULL;
}
if (!(m = pool_alloc(mem, sizeof(*m)))) {
stack;
return NULL;
}
memset(m, 0, sizeof(*m));
/* join the regexps together, delimiting with zero */
for(i = 0; i < num; i++)
len += strlen(patterns[i]) + 8;
ptr = all = pool_alloc(scratch, len + 1);
if (!all) {
stack;
goto bad;
}
for(i = 0; i < num; i++) {
ptr += sprintf(ptr, "(.*(%s)%c)", patterns[i],
TARGET_TRANS);
if(i < (num - 1))
*ptr++ = '|';
}
/* parse this expression */
if(!(rx = rx_parse_tok(scratch, all, ptr))) {
log_debug("Couldn't parse the regex");
goto bad;
}
m->mem = mem;
m->scratch = scratch;
m->num_nodes = _count_nodes(rx);
m->nodes = pool_alloc(scratch, sizeof(*m->nodes) * m->num_nodes);
if (!m->nodes) {
stack;
goto bad;
}
_fill_table(m, rx);
_create_bitsets(m);
_calc_functions(m);
_calc_states(m, rx);
pool_destroy(scratch);
m->scratch = NULL;
return m;
bad:
pool_destroy(scratch);
pool_destroy(mem);
return NULL;
}
o Filter for the dev cache that takes values from config file: devices { # first match is final, eg. /dev/ide/cdrom # get's rejected due to the first pattern filter=["r/cdrom/", # don't touch the music ! "a/hd[a-d][0-9]+/", "a/ide/", "a/sd/", "a/md/", "a|loop/[0-9]+|", # accept devfs style loop back "r/loop/", # and reject old style "a/dasd/", "a/dac960/", "a/nbd/", "a/ida/", "a/cciss/", "a/ubd/", "r/.*/"] # reject all others } Alasdair this is ready to roll into the tools now.
2001-10-19 22:20:37 +04:00
int matcher_run(struct matcher *m, const char *b)
o First pass at the regex code. lib/regex/matcher takes an array of regex's and builds a *very* efficient engine that will tell you which regex a string matches with only a single pass through the string. To be used in the config file when specifying devices. o Anchor's aren't supported yet (^ and $) but that won't take long. o Also when we get some realistic config files we may want to consider adding an extra level of indirection to the dfa state in order to compress the table. It all depends on how large typical tables get.
2001-10-19 18:36:57 +04:00
{
struct dfa_state *cs = m->start;
o Filter for the dev cache that takes values from config file: devices { # first match is final, eg. /dev/ide/cdrom # get's rejected due to the first pattern filter=["r/cdrom/", # don't touch the music ! "a/hd[a-d][0-9]+/", "a/ide/", "a/sd/", "a/md/", "a|loop/[0-9]+|", # accept devfs style loop back "r/loop/", # and reject old style "a/dasd/", "a/dac960/", "a/nbd/", "a/ida/", "a/cciss/", "a/ubd/", "r/.*/"] # reject all others } Alasdair this is ready to roll into the tools now.
2001-10-19 22:20:37 +04:00
int r = 0;
o First pass at the regex code. lib/regex/matcher takes an array of regex's and builds a *very* efficient engine that will tell you which regex a string matches with only a single pass through the string. To be used in the config file when specifying devices. o Anchor's aren't supported yet (^ and $) but that won't take long. o Also when we get some realistic config files we may want to consider adding an extra level of indirection to the dfa state in order to compress the table. It all depends on how large typical tables get.
2001-10-19 18:36:57 +04:00
o Filter for the dev cache that takes values from config file: devices { # first match is final, eg. /dev/ide/cdrom # get's rejected due to the first pattern filter=["r/cdrom/", # don't touch the music ! "a/hd[a-d][0-9]+/", "a/ide/", "a/sd/", "a/md/", "a|loop/[0-9]+|", # accept devfs style loop back "r/loop/", # and reject old style "a/dasd/", "a/dac960/", "a/nbd/", "a/ida/", "a/cciss/", "a/ubd/", "r/.*/"] # reject all others } Alasdair this is ready to roll into the tools now.
2001-10-19 22:20:37 +04:00
for (; *b; b++) {
o First pass at the regex code. lib/regex/matcher takes an array of regex's and builds a *very* efficient engine that will tell you which regex a string matches with only a single pass through the string. To be used in the config file when specifying devices. o Anchor's aren't supported yet (^ and $) but that won't take long. o Also when we get some realistic config files we may want to consider adding an extra level of indirection to the dfa state in order to compress the table. It all depends on how large typical tables get.
2001-10-19 18:36:57 +04:00
if (!(cs = cs->lookup[(int) (unsigned char) *b]))
break;
o tidying
2001-10-21 14:24:10 +04:00
if (cs->final && (cs->final > r))
o First pass at the regex code. lib/regex/matcher takes an array of regex's and builds a *very* efficient engine that will tell you which regex a string matches with only a single pass through the string. To be used in the config file when specifying devices. o Anchor's aren't supported yet (^ and $) but that won't take long. o Also when we get some realistic config files we may want to consider adding an extra level of indirection to the dfa state in order to compress the table. It all depends on how large typical tables get.
2001-10-19 18:36:57 +04:00
r = cs->final;
}
/* subtract 1 to get back to zero index */
o Filter for the dev cache that takes values from config file: devices { # first match is final, eg. /dev/ide/cdrom # get's rejected due to the first pattern filter=["r/cdrom/", # don't touch the music ! "a/hd[a-d][0-9]+/", "a/ide/", "a/sd/", "a/md/", "a|loop/[0-9]+|", # accept devfs style loop back "r/loop/", # and reject old style "a/dasd/", "a/dac960/", "a/nbd/", "a/ida/", "a/cciss/", "a/ubd/", "r/.*/"] # reject all others } Alasdair this is ready to roll into the tools now.
2001-10-19 22:20:37 +04:00
return r - 1;
o First pass at the regex code. lib/regex/matcher takes an array of regex's and builds a *very* efficient engine that will tell you which regex a string matches with only a single pass through the string. To be used in the config file when specifying devices. o Anchor's aren't supported yet (^ and $) but that won't take long. o Also when we get some realistic config files we may want to consider adding an extra level of indirection to the dfa state in order to compress the table. It all depends on how large typical tables get.
2001-10-19 18:36:57 +04:00
}
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