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lvm2/libdm/regex/parse_rx.c

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2007-04-27 22:40:23 +04:00
/*
* Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
* Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
*
* This file is part of the device-mapper userspace tools.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU Lesser General Public License v.2.1.
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*
* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, write to the Free Software Foundation,
* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "dmlib.h"
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#include "parse_rx.h"
struct parse_sp { /* scratch pad for the parsing process */
struct dm_pool *mem;
int type; /* token type, 0 indicates a charset */
dm_bitset_t charset; /* The current charset */
const char *cursor; /* where we are in the regex */
const char *rx_end; /* 1pte for the expression being parsed */
};
static struct rx_node *_or_term(struct parse_sp *ps);
static void _single_char(struct parse_sp *ps, unsigned int c, const char *ptr)
{
ps->type = 0;
ps->cursor = ptr + 1;
dm_bit_clear_all(ps->charset);
dm_bit_set(ps->charset, c);
}
/*
* Get the next token from the regular expression.
* Returns: 1 success, 0 end of input, -1 error.
*/
static int _rx_get_token(struct parse_sp *ps)
{
int neg = 0, range = 0;
char c, lc = 0;
const char *ptr = ps->cursor;
if (ptr == ps->rx_end) { /* end of input ? */
ps->type = -1;
return 0;
}
switch (*ptr) {
/* charsets and ncharsets */
case '[':
ptr++;
if (*ptr == '^') {
dm_bit_set_all(ps->charset);
/* never transition on zero */
dm_bit_clear(ps->charset, 0);
neg = 1;
ptr++;
} else
dm_bit_clear_all(ps->charset);
while ((ptr < ps->rx_end) && (*ptr != ']')) {
if (*ptr == '\\') {
/* an escaped character */
ptr++;
switch (*ptr) {
case 'n':
c = '\n';
break;
case 'r':
c = '\r';
break;
case 't':
c = '\t';
break;
default:
c = *ptr;
}
} else if (*ptr == '-' && lc) {
/* we've got a range on our hands */
range = 1;
ptr++;
if (ptr == ps->rx_end) {
log_error("Incomplete range"
"specification");
return -1;
}
c = *ptr;
} else
c = *ptr;
if (range) {
/* add lc - c into the bitset */
if (lc > c) {
char tmp = c;
c = lc;
lc = tmp;
}
for (; lc <= c; lc++) {
if (neg)
dm_bit_clear(ps->charset, lc);
else
dm_bit_set(ps->charset, lc);
}
range = 0;
} else {
/* add c into the bitset */
if (neg)
dm_bit_clear(ps->charset, c);
else
dm_bit_set(ps->charset, c);
}
ptr++;
lc = c;
}
if (ptr >= ps->rx_end) {
ps->type = -1;
return -1;
}
ps->type = 0;
ps->cursor = ptr + 1;
break;
/* These characters are special, we just return their ASCII
codes as the type. Sorted into ascending order to help the
compiler */
case '(':
case ')':
case '*':
case '+':
case '?':
case '|':
ps->type = (int) *ptr;
ps->cursor = ptr + 1;
break;
case '^':
_single_char(ps, HAT_CHAR, ptr);
break;
case '$':
_single_char(ps, DOLLAR_CHAR, ptr);
break;
case '.':
/* The 'all but newline' character set */
ps->type = 0;
ps->cursor = ptr + 1;
dm_bit_set_all(ps->charset);
dm_bit_clear(ps->charset, (int) '\n');
dm_bit_clear(ps->charset, (int) '\r');
dm_bit_clear(ps->charset, 0);
break;
case '\\':
/* escaped character */
ptr++;
if (ptr >= ps->rx_end) {
log_error("Badly quoted character at end "
"of expression");
ps->type = -1;
return -1;
}
ps->type = 0;
ps->cursor = ptr + 1;
dm_bit_clear_all(ps->charset);
switch (*ptr) {
case 'n':
dm_bit_set(ps->charset, (int) '\n');
break;
case 'r':
dm_bit_set(ps->charset, (int) '\r');
break;
case 't':
dm_bit_set(ps->charset, (int) '\t');
break;
default:
dm_bit_set(ps->charset, (int) *ptr);
}
break;
default:
/* add a single character to the bitset */
ps->type = 0;
ps->cursor = ptr + 1;
dm_bit_clear_all(ps->charset);
dm_bit_set(ps->charset, (int) *ptr);
break;
}
return 1;
}
static struct rx_node *_node(struct dm_pool *mem, int type,
struct rx_node *l, struct rx_node *r)
{
struct rx_node *n = dm_pool_zalloc(mem, sizeof(*n));
if (n) {
if (!(n->charset = dm_bitset_create(mem, 256))) {
dm_pool_free(mem, n);
return NULL;
}
n->type = type;
n->left = l;
n->right = r;
}
return n;
}
static struct rx_node *_term(struct parse_sp *ps)
{
struct rx_node *n;
switch (ps->type) {
case 0:
if (!(n = _node(ps->mem, CHARSET, NULL, NULL))) {
stack;
return NULL;
}
dm_bit_copy(n->charset, ps->charset);
_rx_get_token(ps); /* match charset */
break;
case '(':
_rx_get_token(ps); /* match '(' */
n = _or_term(ps);
if (ps->type != ')') {
log_error("missing ')' in regular expression");
return 0;
}
_rx_get_token(ps); /* match ')' */
break;
default:
n = 0;
}
return n;
}
static struct rx_node *_closure_term(struct parse_sp *ps)
{
struct rx_node *l, *n;
if (!(l = _term(ps)))
return NULL;
for (;;) {
switch (ps->type) {
case '*':
n = _node(ps->mem, STAR, l, NULL);
break;
case '+':
n = _node(ps->mem, PLUS, l, NULL);
break;
case '?':
n = _node(ps->mem, QUEST, l, NULL);
break;
default:
return l;
}
if (!n) {
stack;
return NULL;
}
_rx_get_token(ps);
l = n;
}
return n;
}
static struct rx_node *_cat_term(struct parse_sp *ps)
{
struct rx_node *l, *r, *n;
if (!(l = _closure_term(ps)))
return NULL;
if (ps->type == '|')
return l;
if (!(r = _cat_term(ps)))
return l;
if (!(n = _node(ps->mem, CAT, l, r)))
stack;
return n;
}
static struct rx_node *_or_term(struct parse_sp *ps)
{
struct rx_node *l, *r, *n;
if (!(l = _cat_term(ps)))
return NULL;
if (ps->type != '|')
return l;
_rx_get_token(ps); /* match '|' */
if (!(r = _or_term(ps))) {
log_error("Badly formed 'or' expression");
return NULL;
}
if (!(n = _node(ps->mem, OR, l, r)))
stack;
return n;
}
struct rx_node *rx_parse_tok(struct dm_pool *mem,
const char *begin, const char *end)
{
struct rx_node *r;
struct parse_sp *ps = dm_pool_zalloc(mem, sizeof(*ps));
if (!ps) {
stack;
return NULL;
}
ps->mem = mem;
ps->charset = dm_bitset_create(mem, 256);
ps->cursor = begin;
ps->rx_end = end;
_rx_get_token(ps); /* load the first token */
if (!(r = _or_term(ps))) {
log_error("Parse error in regex");
dm_pool_free(mem, ps);
}
return r;
}
struct rx_node *rx_parse_str(struct dm_pool *mem, const char *str)
{
return rx_parse_tok(mem, str, str + strlen(str));
}