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/* lexer (lexical analyzer) for control files
* Copyright (C) 1998-2001 D. Hugh Redelmeier.
*
* This program is free software; you can redistribute 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. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* RCSID $Id: lex.c,v 1.1 2002/10/22 09:07:28 dhr Exp $
*/
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <ctype.h>
#include <unistd.h>
#include <errno.h>
#include <freeswan.h>
#include "constants.h"
#include "defs.h"
#include "log.h"
#include "whack.h" /* for RC_LOG_SERIOUS */
#include "lex.h"
struct file_lex_position *flp = NULL;
/* Open a file for lexical processing.
* new_flp and name must point into storage with will live
* at least until the file is closed.
*/
bool
lexopen(struct file_lex_position *new_flp, const char *name, bool optional)
{
FILE *f = fopen(name, "r");
if (f == NULL)
{
if (!optional || errno != ENOENT)
log_errno((e, "could not open \"%s\"", name));
return FALSE;
}
else
{
new_flp->previous = flp;
flp = new_flp;
flp->filename = name;
flp->fp = f;
flp->lino = 0;
flp->bdry = B_none;
flp->cur = flp->buffer; /* nothing loaded yet */
flp->under = *flp->cur = '\0';
(void) shift(); /* prime tok */
return TRUE;
}
}
void
lexclose(void)
{
fclose(flp->fp);
flp = flp->previous;
}
/* Token decoding: shift() loads the next token into tok.
* Iff a token starts at the left margin, it is considered
* to be the first in a record. We create a special condition,
* Record Boundary (analogous to EOF), just before such a token.
* We are unwilling to shift through a record boundary:
* it must be overridden first.
* Returns FALSE iff Record Boundary or EOF (i.e. no token);
* tok will then be NULL.
*/
char *tok;
#define tokeq(s) (streq(tok, (s)))
#define tokeqword(s) (strcasecmp(tok, (s)) == 0)
bool
shift(void)
{
char *p = flp->cur;
char *sor = NULL; /* start of record for any new lines */
passert(flp->bdry == B_none);
*p = flp->under;
flp->under = '\0';
for (;;)
{
switch (*p)
{
case '\0': /* end of line */
case '#': /* comment to end of line: treat as end of line */
/* get the next line */
if (fgets(flp->buffer, sizeof(flp->buffer)-1, flp->fp) == NULL)
{
flp->bdry = B_file;
tok = flp->cur = NULL;
return FALSE;
}
else
{
/* strip trailing whitespace, including \n */
for (p = flp->buffer+strlen(flp->buffer)-1
; p>flp->buffer && isspace(p[-1]); p--)
;
*p = '\0';
flp->lino++;
sor = p = flp->buffer;
}
break; /* try again for a token */
case ' ': /* whitespace */
case '\t':
p++;
break; /* try again for a token */
case '"': /* quoted token */
case '\'':
if (p != sor)
{
/* we have a quoted token: note and advance to its end */
tok = p;
p = strchr(p+1, *p);
if (p == NULL)
{
loglog(RC_LOG_SERIOUS, "\"%s\" line %d: unterminated string"
, flp->filename, flp->lino);
p = tok + strlen(tok);
}
else
{
p++; /* include delimiter in token */
}
/* remember token delimiter and replace with '\0' */
flp->under = *p;
*p = '\0';
flp->cur = p;
return TRUE;
}
/* FALL THROUGH */
default:
if (p != sor)
{
/* we seem to have a token: note and advance to its end */
tok = p;
if (p[0] == '0' && p[1] == 't')
{
/* 0t... token goes to end of line */
p += strlen(p);
}
else
{
/* "ordinary" token: up to whitespace or end of line */
do {
p++;
} while (*p != '\0' && !isspace(*p))
;
/* fudge to separate ':' from a preceding adjacent token */
if (p-1 > tok && p[-1] == ':')
p--;
}
/* remember token delimiter and replace with '\0' */
flp->under = *p;
*p = '\0';
flp->cur = p;
return TRUE;
}
/* we have a start-of-record: return it, deferring "real" token */
flp->bdry = B_record;
tok = NULL;
flp->under = *p;
flp->cur = p;
return FALSE;
}
}
}
/* ensures we are at a Record (or File) boundary, optionally warning if not */
bool
flushline(const char *m)
{
if (flp->bdry != B_none)
{
return TRUE;
}
else
{
if (m != NULL)
loglog(RC_LOG_SERIOUS, "\"%s\" line %d: %s", flp->filename, flp->lino, m);
do ; while (shift());
return FALSE;
}
}
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