src/pluto/lex.c

@@ -0,0 +1,213 @@
+/* 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 2004/03/15 20:35:28 as 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;
+    }
+}