Adding upstream version 3.4.23.upstream/3.4.23upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 873 insertions, 0 deletions

diff --git a/src/util/dict_regexp.c b/src/util/dict_regexp.c
new file mode 100644
index 0000000..81cc6dd
--- /dev/null
+++ b/src/util/dict_regexp.c
@@ -0,0 +1,873 @@
+/*++
+/* NAME
+/*	dict_regexp 3
+/* SUMMARY
+/*	dictionary manager interface to REGEXP regular expression library
+/* SYNOPSIS
+/*	#include <dict_regexp.h>
+/*
+/*	DICT	*dict_regexp_open(name, dummy, dict_flags)
+/*	const char *name;
+/*	int	dummy;
+/*	int	dict_flags;
+/* DESCRIPTION
+/*	dict_regexp_open() opens the named file and compiles the contained
+/*	regular expressions. The result object can be used to match strings
+/*	against the table.
+/* SEE ALSO
+/*	dict(3) generic dictionary manager
+/*	regexp_table(5) format of Postfix regular expression tables
+/* AUTHOR(S)
+/*	LaMont Jones
+/*	lamont@hp.com
+/*
+/*	Based on PCRE dictionary contributed by Andrew McNamara
+/*	andrewm@connect.com.au
+/*	connect.com.au Pty. Ltd.
+/*	Level 3, 213 Miller St
+/*	North Sydney, NSW, Australia
+/*
+/*	Heavily rewritten by Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*
+/*	Wietse Venema
+/*	Google, Inc.
+/*	111 8th Avenue
+/*	New York, NY 10011, USA
+/*--*/
+
+/* System library. */
+
+#include "sys_defs.h"
+
+#ifdef HAS_POSIX_REGEXP
+
+#include <sys/stat.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <ctype.h>
+#include <regex.h>
+#ifdef STRCASECMP_IN_STRINGS_H
+#include <strings.h>
+#endif
+
+/* Utility library. */
+
+#include "mymalloc.h"
+#include "msg.h"
+#include "safe.h"
+#include "vstream.h"
+#include "vstring.h"
+#include "stringops.h"
+#include "readlline.h"
+#include "dict.h"
+#include "dict_regexp.h"
+#include "mac_parse.h"
+#include "warn_stat.h"
+#include "mvect.h"
+
+ /*
+  * Support for IF/ENDIF based on an idea by Bert Driehuis.
+  */
+#define DICT_REGEXP_OP_MATCH	1	/* Match this regexp */
+#define DICT_REGEXP_OP_IF	2	/* Increase if/endif nesting on match */
+#define DICT_REGEXP_OP_ENDIF	3	/* Decrease if/endif nesting on match */
+
+ /*
+  * Regular expression before compiling.
+  */
+typedef struct {
+    char   *regexp;			/* regular expression */
+    int     options;			/* regcomp() options */
+    int     match;			/* positive or negative match */
+} DICT_REGEXP_PATTERN;
+
+ /*
+  * Compiled generic rule, and subclasses that derive from it.
+  */
+typedef struct DICT_REGEXP_RULE {
+    int     op;				/* DICT_REGEXP_OP_MATCH/IF/ENDIF */
+    int     lineno;			/* source file line number */
+    struct DICT_REGEXP_RULE *next;	/* next rule in dict */
+} DICT_REGEXP_RULE;
+
+typedef struct {
+    DICT_REGEXP_RULE rule;		/* generic part */
+    regex_t *first_exp;			/* compiled primary pattern */
+    int     first_match;		/* positive or negative match */
+    regex_t *second_exp;		/* compiled secondary pattern */
+    int     second_match;		/* positive or negative match */
+    char   *replacement;		/* replacement text */
+    size_t  max_sub;			/* largest $number in replacement */
+} DICT_REGEXP_MATCH_RULE;
+
+typedef struct {
+    DICT_REGEXP_RULE rule;		/* generic members */
+    regex_t *expr;			/* the condition */
+    int     match;			/* positive or negative match */
+    struct DICT_REGEXP_RULE *endif_rule;/* matching endif rule */
+} DICT_REGEXP_IF_RULE;
+
+ /*
+  * Regexp map.
+  */
+typedef struct {
+    DICT    dict;			/* generic members */
+    regmatch_t *pmatch;			/* matched substring info */
+    DICT_REGEXP_RULE *head;		/* first rule */
+    VSTRING *expansion_buf;		/* lookup result */
+} DICT_REGEXP;
+
+ /*
+  * Macros to make dense code more readable.
+  */
+#define NULL_SUBSTITUTIONS	(0)
+#define NULL_MATCH_RESULT	((regmatch_t *) 0)
+
+ /*
+  * Context for $number expansion callback.
+  */
+typedef struct {
+    DICT_REGEXP *dict_regexp;		/* the dictionary handle */
+    DICT_REGEXP_MATCH_RULE *match_rule;	/* the rule we matched */
+    const char *lookup_string;		/* matched text */
+} DICT_REGEXP_EXPAND_CONTEXT;
+
+ /*
+  * Context for $number pre-scan callback.
+  */
+typedef struct {
+    const char *mapname;		/* name of regexp map */
+    int     lineno;			/* where in file */
+    size_t  max_sub;			/* largest $number seen */
+    char   *literal;			/* constant result, $$ -> $ */
+} DICT_REGEXP_PRESCAN_CONTEXT;
+
+ /*
+  * Compatibility.
+  */
+#ifndef MAC_PARSE_OK
+#define MAC_PARSE_OK 0
+#endif
+
+/* dict_regexp_expand - replace $number with substring from matched text */
+
+static int dict_regexp_expand(int type, VSTRING *buf, void *ptr)
+{
+    DICT_REGEXP_EXPAND_CONTEXT *ctxt = (DICT_REGEXP_EXPAND_CONTEXT *) ptr;
+    DICT_REGEXP_MATCH_RULE *match_rule = ctxt->match_rule;
+    DICT_REGEXP *dict_regexp = ctxt->dict_regexp;
+    regmatch_t *pmatch;
+    size_t  n;
+
+    /*
+     * Replace $number by the corresponding substring from the matched text.
+     * We pre-scanned the replacement text at compile time, so any out of
+     * range $number means that something impossible has happened.
+     */
+    if (type == MAC_PARSE_VARNAME) {
+	n = atoi(vstring_str(buf));
+	if (n < 1 || n > match_rule->max_sub)
+	    msg_panic("regexp map %s, line %d: out of range replacement index \"%s\"",
+		      dict_regexp->dict.name, match_rule->rule.lineno,
+		      vstring_str(buf));
+	pmatch = dict_regexp->pmatch + n;
+	if (pmatch->rm_so < 0 || pmatch->rm_so == pmatch->rm_eo)
+	    return (MAC_PARSE_UNDEF);		/* empty or not matched */
+	vstring_strncat(dict_regexp->expansion_buf,
+			ctxt->lookup_string + pmatch->rm_so,
+			pmatch->rm_eo - pmatch->rm_so);
+	return (MAC_PARSE_OK);
+    }
+
+    /*
+     * Straight text - duplicate with no substitution.
+     */
+    else {
+	vstring_strcat(dict_regexp->expansion_buf, vstring_str(buf));
+	return (MAC_PARSE_OK);
+    }
+}
+
+/* dict_regexp_regerror - report regexp compile/execute error */
+
+static void dict_regexp_regerror(const char *mapname, int lineno, int error,
+				         const regex_t *expr)
+{
+    char    errbuf[256];
+
+    (void) regerror(error, expr, errbuf, sizeof(errbuf));
+    msg_warn("regexp map %s, line %d: %s", mapname, lineno, errbuf);
+}
+
+ /*
+  * Inlined to reduce function call overhead in the time-critical loop.
+  */
+#define DICT_REGEXP_REGEXEC(err, map, line, expr, match, str, nsub, pmatch) \
+    ((err) = regexec((expr), (str), (nsub), (pmatch), 0), \
+     ((err) == REG_NOMATCH ? !(match) : \
+      (err) == 0 ? (match) : \
+      (dict_regexp_regerror((map), (line), (err), (expr)), 0)))
+
+/* dict_regexp_lookup - match string and perform optional substitution */
+
+static const char *dict_regexp_lookup(DICT *dict, const char *lookup_string)
+{
+    DICT_REGEXP *dict_regexp = (DICT_REGEXP *) dict;
+    DICT_REGEXP_RULE *rule;
+    DICT_REGEXP_IF_RULE *if_rule;
+    DICT_REGEXP_MATCH_RULE *match_rule;
+    DICT_REGEXP_EXPAND_CONTEXT expand_context;
+    int     error;
+
+    dict->error = 0;
+
+    if (msg_verbose)
+	msg_info("dict_regexp_lookup: %s: %s", dict->name, lookup_string);
+
+    /*
+     * Optionally fold the key.
+     */
+    if (dict->flags & DICT_FLAG_FOLD_MUL) {
+	if (dict->fold_buf == 0)
+	    dict->fold_buf = vstring_alloc(10);
+	vstring_strcpy(dict->fold_buf, lookup_string);
+	lookup_string = lowercase(vstring_str(dict->fold_buf));
+    }
+    for (rule = dict_regexp->head; rule; rule = rule->next) {
+
+	switch (rule->op) {
+
+	    /*
+	     * Search for the first matching primary expression. Limit the
+	     * overhead for substring substitution to the bare minimum.
+	     */
+	case DICT_REGEXP_OP_MATCH:
+	    match_rule = (DICT_REGEXP_MATCH_RULE *) rule;
+	    if (!DICT_REGEXP_REGEXEC(error, dict->name, rule->lineno,
+				     match_rule->first_exp,
+				     match_rule->first_match,
+				     lookup_string,
+				     match_rule->max_sub > 0 ?
+				     match_rule->max_sub + 1 : 0,
+				     dict_regexp->pmatch))
+		continue;
+	    if (match_rule->second_exp
+		&& !DICT_REGEXP_REGEXEC(error, dict->name, rule->lineno,
+					match_rule->second_exp,
+					match_rule->second_match,
+					lookup_string,
+					NULL_SUBSTITUTIONS,
+					NULL_MATCH_RESULT))
+		continue;
+
+	    /*
+	     * Skip $number substitutions when the replacement text contains
+	     * no $number strings, as learned during the compile time
+	     * pre-scan. The pre-scan already replaced $$ by $.
+	     */
+	    if (match_rule->max_sub == 0)
+		return (match_rule->replacement);
+
+	    /*
+	     * Perform $number substitutions on the replacement text. We
+	     * pre-scanned the replacement text at compile time. Any macro
+	     * expansion errors at this point mean something impossible has
+	     * happened.
+	     */
+	    if (!dict_regexp->expansion_buf)
+		dict_regexp->expansion_buf = vstring_alloc(10);
+	    VSTRING_RESET(dict_regexp->expansion_buf);
+	    expand_context.lookup_string = lookup_string;
+	    expand_context.match_rule = match_rule;
+	    expand_context.dict_regexp = dict_regexp;
+
+	    if (mac_parse(match_rule->replacement, dict_regexp_expand,
+			  (void *) &expand_context) & MAC_PARSE_ERROR)
+		msg_panic("regexp map %s, line %d: bad replacement syntax",
+			  dict->name, rule->lineno);
+	    VSTRING_TERMINATE(dict_regexp->expansion_buf);
+	    return (vstring_str(dict_regexp->expansion_buf));
+
+	    /*
+	     * Conditional.
+	     */
+	case DICT_REGEXP_OP_IF:
+	    if_rule = (DICT_REGEXP_IF_RULE *) rule;
+	    if (DICT_REGEXP_REGEXEC(error, dict->name, rule->lineno,
+			       if_rule->expr, if_rule->match, lookup_string,
+				    NULL_SUBSTITUTIONS, NULL_MATCH_RESULT))
+		continue;
+	    /* An IF without matching ENDIF has no "endif" rule. */
+	    if ((rule = if_rule->endif_rule) == 0)
+		return (0);
+	    /* FALLTHROUGH */
+
+	    /*
+	     * ENDIF after IF.
+	     */
+	case DICT_REGEXP_OP_ENDIF:
+	    continue;
+
+	default:
+	    msg_panic("dict_regexp_lookup: impossible operation %d", rule->op);
+	}
+    }
+    return (0);
+}
+
+/* dict_regexp_close - close regexp dictionary */
+
+static void dict_regexp_close(DICT *dict)
+{
+    DICT_REGEXP *dict_regexp = (DICT_REGEXP *) dict;
+    DICT_REGEXP_RULE *rule;
+    DICT_REGEXP_RULE *next;
+    DICT_REGEXP_MATCH_RULE *match_rule;
+    DICT_REGEXP_IF_RULE *if_rule;
+
+    for (rule = dict_regexp->head; rule; rule = next) {
+	next = rule->next;
+	switch (rule->op) {
+	case DICT_REGEXP_OP_MATCH:
+	    match_rule = (DICT_REGEXP_MATCH_RULE *) rule;
+	    if (match_rule->first_exp) {
+		regfree(match_rule->first_exp);
+		myfree((void *) match_rule->first_exp);
+	    }
+	    if (match_rule->second_exp) {
+		regfree(match_rule->second_exp);
+		myfree((void *) match_rule->second_exp);
+	    }
+	    if (match_rule->replacement)
+		myfree((void *) match_rule->replacement);
+	    break;
+	case DICT_REGEXP_OP_IF:
+	    if_rule = (DICT_REGEXP_IF_RULE *) rule;
+	    if (if_rule->expr) {
+		regfree(if_rule->expr);
+		myfree((void *) if_rule->expr);
+	    }
+	    break;
+	case DICT_REGEXP_OP_ENDIF:
+	    break;
+	default:
+	    msg_panic("dict_regexp_close: unknown operation %d", rule->op);
+	}
+	myfree((void *) rule);
+    }
+    if (dict_regexp->pmatch)
+	myfree((void *) dict_regexp->pmatch);
+    if (dict_regexp->expansion_buf)
+	vstring_free(dict_regexp->expansion_buf);
+    if (dict->fold_buf)
+	vstring_free(dict->fold_buf);
+    dict_free(dict);
+}
+
+/* dict_regexp_get_pat - extract one pattern with options from rule */
+
+static int dict_regexp_get_pat(const char *mapname, int lineno, char **bufp,
+			               DICT_REGEXP_PATTERN *pat)
+{
+    char   *p = *bufp;
+    char    re_delim;
+
+    /*
+     * Process negation operators.
+     */
+    pat->match = 1;
+    for (;;) {
+	if (*p == '!')
+	    pat->match = !pat->match;
+	else if (!ISSPACE(*p))
+	    break;
+	p++;
+    }
+    if (*p == 0) {
+	msg_warn("regexp map %s, line %d: no regexp: skipping this rule",
+		 mapname, lineno);
+	return (0);
+    }
+
+    /*
+     * Search for the closing delimiter, handling backslash escape.
+     */
+    re_delim = *p++;
+    pat->regexp = p;
+    while (*p) {
+	if (*p == '\\') {
+	    if (p[1])
+		p++;
+	    else
+		break;
+	} else if (*p == re_delim) {
+	    break;
+	}
+	++p;
+    }
+    if (!*p) {
+	msg_warn("regexp map %s, line %d: no closing regexp delimiter \"%c\": "
+		 "skipping this rule", mapname, lineno, re_delim);
+	return (0);
+    }
+    *p++ = 0;					/* null terminate */
+
+    /*
+     * Search for options.
+     */
+    pat->options = REG_EXTENDED | REG_ICASE;
+    while (*p && !ISSPACE(*p) && *p != '!') {
+	switch (*p) {
+	case 'i':
+	    pat->options ^= REG_ICASE;
+	    break;
+	case 'm':
+	    pat->options ^= REG_NEWLINE;
+	    break;
+	case 'x':
+	    pat->options ^= REG_EXTENDED;
+	    break;
+	default:
+	    msg_warn("regexp map %s, line %d: unknown regexp option \"%c\": "
+		     "skipping this rule", mapname, lineno, *p);
+	    return (0);
+	}
+	++p;
+    }
+    *bufp = p;
+    return (1);
+}
+
+/* dict_regexp_get_pats - get the primary and second patterns and flags */
+
+static int dict_regexp_get_pats(const char *mapname, int lineno, char **p,
+				        DICT_REGEXP_PATTERN *first_pat,
+				        DICT_REGEXP_PATTERN *second_pat)
+{
+
+    /*
+     * Get the primary and optional secondary patterns and their flags.
+     */
+    if (dict_regexp_get_pat(mapname, lineno, p, first_pat) == 0)
+	return (0);
+    if (**p == '!') {
+#if 0
+	static int bitrot_warned = 0;
+
+	if (bitrot_warned == 0) {
+	    msg_warn("regexp file %s, line %d: /pattern1/!/pattern2/ goes away,"
+		 " use \"if !/pattern2/ ... /pattern1/ ... endif\" instead",
+		     mapname, lineno);
+	    bitrot_warned = 1;
+	}
+#endif
+	if (dict_regexp_get_pat(mapname, lineno, p, second_pat) == 0)
+	    return (0);
+    } else {
+	second_pat->regexp = 0;
+    }
+    return (1);
+}
+
+/* dict_regexp_prescan - find largest $number in replacement text */
+
+static int dict_regexp_prescan(int type, VSTRING *buf, void *context)
+{
+    DICT_REGEXP_PRESCAN_CONTEXT *ctxt = (DICT_REGEXP_PRESCAN_CONTEXT *) context;
+    size_t  n;
+
+    /*
+     * Keep a copy of literal text (with $$ already replaced by $) if and
+     * only if the replacement text contains no $number expression. This way
+     * we can avoid having to scan the replacement text at lookup time.
+     */
+    if (type == MAC_PARSE_VARNAME) {
+	if (ctxt->literal) {
+	    myfree(ctxt->literal);
+	    ctxt->literal = 0;
+	}
+	if (!alldig(vstring_str(buf))) {
+	    msg_warn("regexp map %s, line %d: non-numeric replacement index \"%s\"",
+		     ctxt->mapname, ctxt->lineno, vstring_str(buf));
+	    return (MAC_PARSE_ERROR);
+	}
+	n = atoi(vstring_str(buf));
+	if (n < 1) {
+	    msg_warn("regexp map %s, line %d: out-of-range replacement index \"%s\"",
+		     ctxt->mapname, ctxt->lineno, vstring_str(buf));
+	    return (MAC_PARSE_ERROR);
+	}
+	if (n > ctxt->max_sub)
+	    ctxt->max_sub = n;
+    } else if (type == MAC_PARSE_LITERAL && ctxt->max_sub == 0) {
+	if (ctxt->literal)
+	    msg_panic("regexp map %s, line %d: multiple literals but no $number",
+		      ctxt->mapname, ctxt->lineno);
+	ctxt->literal = mystrdup(vstring_str(buf));
+    }
+    return (MAC_PARSE_OK);
+}
+
+/* dict_regexp_compile_pat - compile one pattern */
+
+static regex_t *dict_regexp_compile_pat(const char *mapname, int lineno,
+					        DICT_REGEXP_PATTERN *pat)
+{
+    int     error;
+    regex_t *expr;
+
+    expr = (regex_t *) mymalloc(sizeof(*expr));
+    error = regcomp(expr, pat->regexp, pat->options);
+    if (error != 0) {
+	dict_regexp_regerror(mapname, lineno, error, expr);
+	myfree((void *) expr);
+	return (0);
+    }
+    return (expr);
+}
+
+/* dict_regexp_rule_alloc - fill in a generic rule structure */
+
+static DICT_REGEXP_RULE *dict_regexp_rule_alloc(int op, int lineno, size_t size)
+{
+    DICT_REGEXP_RULE *rule;
+
+    rule = (DICT_REGEXP_RULE *) mymalloc(size);
+    rule->op = op;
+    rule->lineno = lineno;
+    rule->next = 0;
+
+    return (rule);
+}
+
+/* dict_regexp_parseline - parse one rule */
+
+static DICT_REGEXP_RULE *dict_regexp_parseline(DICT *dict, const char *mapname,
+					             int lineno, char *line,
+					               int nesting)
+{
+    char   *p;
+
+    p = line;
+
+    /*
+     * An ordinary rule takes one or two patterns and replacement text.
+     */
+    if (!ISALNUM(*p)) {
+	DICT_REGEXP_PATTERN first_pat;
+	DICT_REGEXP_PATTERN second_pat;
+	DICT_REGEXP_PRESCAN_CONTEXT prescan_context;
+	regex_t *first_exp = 0;
+	regex_t *second_exp;
+	DICT_REGEXP_MATCH_RULE *match_rule;
+
+	/*
+	 * Get the primary and the optional secondary patterns.
+	 */
+	if (!dict_regexp_get_pats(mapname, lineno, &p, &first_pat, &second_pat))
+	    return (0);
+
+	/*
+	 * Get the replacement text.
+	 */
+	while (*p && ISSPACE(*p))
+	    ++p;
+	if (!*p) {
+	    msg_warn("regexp map %s, line %d: no replacement text: "
+		     "using empty string", mapname, lineno);
+	}
+
+	/*
+	 * Find the highest-numbered $number in the replacement text. We can
+	 * speed up pattern matching 1) by passing hints to the regexp
+	 * compiler, setting the REG_NOSUB flag when the replacement text
+	 * contains no $number string; 2) by passing hints to the regexp
+	 * execution code, limiting the amount of text that is made available
+	 * for substitution.
+	 */
+	prescan_context.mapname = mapname;
+	prescan_context.lineno = lineno;
+	prescan_context.max_sub = 0;
+	prescan_context.literal = 0;
+
+	/*
+	 * The optimizer will eliminate code duplication and/or dead code.
+	 */
+#define CREATE_MATCHOP_ERROR_RETURN(rval) do { \
+	if (first_exp) { \
+	    regfree(first_exp); \
+	    myfree((void *) first_exp); \
+	} \
+	if (prescan_context.literal) \
+	    myfree(prescan_context.literal); \
+	return (rval); \
+    } while (0)
+
+	if (dict->flags & DICT_FLAG_SRC_RHS_IS_FILE) {
+	    VSTRING *base64_buf;
+	    char   *err;
+
+	    if ((base64_buf = dict_file_to_b64(dict, p)) == 0) {
+		err = dict_file_get_error(dict);
+		msg_warn("regexp map %s, line %d: %s: skipping this rule",
+			 mapname, lineno, err);
+		myfree(err);
+		CREATE_MATCHOP_ERROR_RETURN(0);
+	    }
+	    p = vstring_str(base64_buf);
+	}
+	if (mac_parse(p, dict_regexp_prescan, (void *) &prescan_context)
+	    & MAC_PARSE_ERROR) {
+	    msg_warn("regexp map %s, line %d: bad replacement syntax: "
+		     "skipping this rule", mapname, lineno);
+	    CREATE_MATCHOP_ERROR_RETURN(0);
+	}
+
+	/*
+	 * Compile the primary and the optional secondary pattern. Speed up
+	 * execution when no matched text needs to be substituted into the
+	 * result string, or when the highest numbered substring is less than
+	 * the total number of () subpatterns.
+	 */
+	if (prescan_context.max_sub == 0)
+	    first_pat.options |= REG_NOSUB;
+	if (prescan_context.max_sub > 0 && first_pat.match == 0) {
+	    msg_warn("regexp map %s, line %d: $number found in negative match "
+		   "replacement text: skipping this rule", mapname, lineno);
+	    CREATE_MATCHOP_ERROR_RETURN(0);
+	}
+	if (prescan_context.max_sub > 0 && (dict->flags & DICT_FLAG_NO_REGSUB)) {
+	    msg_warn("regexp map %s, line %d: "
+		     "regular expression substitution is not allowed: "
+		     "skipping this rule", mapname, lineno);
+	    CREATE_MATCHOP_ERROR_RETURN(0);
+	}
+	if ((first_exp = dict_regexp_compile_pat(mapname, lineno,
+						 &first_pat)) == 0)
+	    CREATE_MATCHOP_ERROR_RETURN(0);
+	if (prescan_context.max_sub > first_exp->re_nsub) {
+	    msg_warn("regexp map %s, line %d: out of range replacement index \"%d\": "
+		     "skipping this rule", mapname, lineno,
+		     (int) prescan_context.max_sub);
+	    CREATE_MATCHOP_ERROR_RETURN(0);
+	}
+	if (second_pat.regexp != 0) {
+	    second_pat.options |= REG_NOSUB;
+	    if ((second_exp = dict_regexp_compile_pat(mapname, lineno,
+						      &second_pat)) == 0)
+		CREATE_MATCHOP_ERROR_RETURN(0);
+	} else {
+	    second_exp = 0;
+	}
+	match_rule = (DICT_REGEXP_MATCH_RULE *)
+	    dict_regexp_rule_alloc(DICT_REGEXP_OP_MATCH, lineno,
+				   sizeof(DICT_REGEXP_MATCH_RULE));
+	match_rule->first_exp = first_exp;
+	match_rule->first_match = first_pat.match;
+	match_rule->max_sub = prescan_context.max_sub;
+	match_rule->second_exp = second_exp;
+	match_rule->second_match = second_pat.match;
+	if (prescan_context.literal)
+	    match_rule->replacement = prescan_context.literal;
+	else
+	    match_rule->replacement = mystrdup(p);
+	return ((DICT_REGEXP_RULE *) match_rule);
+    }
+
+    /*
+     * The IF operator takes one pattern but no replacement text.
+     */
+    else if (strncasecmp(p, "IF", 2) == 0 && !ISALNUM(p[2])) {
+	DICT_REGEXP_PATTERN pattern;
+	regex_t *expr;
+	DICT_REGEXP_IF_RULE *if_rule;
+
+	p += 2;
+	while (*p && ISSPACE(*p))
+	    p++;
+	if (!dict_regexp_get_pat(mapname, lineno, &p, &pattern))
+	    return (0);
+	while (*p && ISSPACE(*p))
+	    ++p;
+	if (*p) {
+	    msg_warn("regexp map %s, line %d: ignoring extra text after"
+		     " IF statement: \"%s\"", mapname, lineno, p);
+	    msg_warn("regexp map %s, line %d: do not prepend whitespace"
+		     " to statements between IF and ENDIF", mapname, lineno);
+	}
+	if ((expr = dict_regexp_compile_pat(mapname, lineno, &pattern)) == 0)
+	    return (0);
+	if_rule = (DICT_REGEXP_IF_RULE *)
+	    dict_regexp_rule_alloc(DICT_REGEXP_OP_IF, lineno,
+				   sizeof(DICT_REGEXP_IF_RULE));
+	if_rule->expr = expr;
+	if_rule->match = pattern.match;
+	if_rule->endif_rule = 0;
+	return ((DICT_REGEXP_RULE *) if_rule);
+    }
+
+    /*
+     * The ENDIF operator takes no patterns and no replacement text.
+     */
+    else if (strncasecmp(p, "ENDIF", 5) == 0 && !ISALNUM(p[5])) {
+	DICT_REGEXP_RULE *rule;
+
+	p += 5;
+	if (nesting == 0) {
+	    msg_warn("regexp map %s, line %d: ignoring ENDIF without matching IF",
+		     mapname, lineno);
+	    return (0);
+	}
+	while (*p && ISSPACE(*p))
+	    ++p;
+	if (*p)
+	    msg_warn("regexp map %s, line %d: ignoring extra text after ENDIF",
+		     mapname, lineno);
+	rule = dict_regexp_rule_alloc(DICT_REGEXP_OP_ENDIF, lineno,
+				      sizeof(DICT_REGEXP_RULE));
+	return (rule);
+    }
+
+    /*
+     * Unrecognized input.
+     */
+    else {
+	msg_warn("regexp map %s, line %d: ignoring unrecognized request",
+		 mapname, lineno);
+	return (0);
+    }
+}
+
+/* dict_regexp_open - load and compile a file containing regular expressions */
+
+DICT   *dict_regexp_open(const char *mapname, int open_flags, int dict_flags)
+{
+    const char myname[] = "dict_regexp_open";
+    DICT_REGEXP *dict_regexp;
+    VSTREAM *map_fp = 0;
+    struct stat st;
+    VSTRING *line_buffer = 0;
+    DICT_REGEXP_RULE *rule;
+    DICT_REGEXP_RULE *last_rule = 0;
+    int     lineno;
+    int     last_line = 0;
+    size_t  max_sub = 0;
+    int     nesting = 0;
+    char   *p;
+    DICT_REGEXP_RULE **rule_stack = 0;
+    MVECT   mvect;
+
+    /*
+     * Let the optimizer worry about eliminating redundant code.
+     */
+#define DICT_REGEXP_OPEN_RETURN(d) do { \
+	DICT *__d = (d); \
+	if (line_buffer != 0) \
+	    vstring_free(line_buffer); \
+	if (map_fp != 0) \
+	    vstream_fclose(map_fp); \
+	return (__d); \
+    } while (0)
+
+    /*
+     * Sanity checks.
+     */
+    if (open_flags != O_RDONLY)
+	DICT_REGEXP_OPEN_RETURN(dict_surrogate(DICT_TYPE_REGEXP,
+					    mapname, open_flags, dict_flags,
+				  "%s:%s map requires O_RDONLY access mode",
+					       DICT_TYPE_REGEXP, mapname));
+
+    /*
+     * Open the configuration file.
+     */
+    if ((map_fp = vstream_fopen(mapname, O_RDONLY, 0)) == 0)
+	DICT_REGEXP_OPEN_RETURN(dict_surrogate(DICT_TYPE_REGEXP, mapname,
+					       open_flags, dict_flags,
+					       "open %s: %m", mapname));
+    if (fstat(vstream_fileno(map_fp), &st) < 0)
+	msg_fatal("fstat %s: %m", mapname);
+
+    line_buffer = vstring_alloc(100);
+
+    dict_regexp = (DICT_REGEXP *) dict_alloc(DICT_TYPE_REGEXP, mapname,
+					     sizeof(*dict_regexp));
+    dict_regexp->dict.lookup = dict_regexp_lookup;
+    dict_regexp->dict.close = dict_regexp_close;
+    dict_regexp->dict.flags = dict_flags | DICT_FLAG_PATTERN;
+    if (dict_flags & DICT_FLAG_FOLD_MUL)
+	dict_regexp->dict.fold_buf = vstring_alloc(10);
+    dict_regexp->head = 0;
+    dict_regexp->pmatch = 0;
+    dict_regexp->expansion_buf = 0;
+    dict_regexp->dict.owner.uid = st.st_uid;
+    dict_regexp->dict.owner.status = (st.st_uid != 0);
+
+    /*
+     * Parse the regexp table.
+     */
+    while (readllines(line_buffer, map_fp, &last_line, &lineno)) {
+	p = vstring_str(line_buffer);
+	trimblanks(p, 0)[0] = 0;
+	if (*p == 0)
+	    continue;
+	rule = dict_regexp_parseline(&dict_regexp->dict, mapname, lineno,
+				     p, nesting);
+	if (rule == 0)
+	    continue;
+	if (rule->op == DICT_REGEXP_OP_MATCH) {
+	    if (((DICT_REGEXP_MATCH_RULE *) rule)->max_sub > max_sub)
+		max_sub = ((DICT_REGEXP_MATCH_RULE *) rule)->max_sub;
+	} else if (rule->op == DICT_REGEXP_OP_IF) {
+	    if (rule_stack == 0)
+		rule_stack = (DICT_REGEXP_RULE **) mvect_alloc(&mvect,
+					   sizeof(*rule_stack), nesting + 1,
+						(MVECT_FN) 0, (MVECT_FN) 0);
+	    else
+		rule_stack =
+		    (DICT_REGEXP_RULE **) mvect_realloc(&mvect, nesting + 1);
+	    rule_stack[nesting] = rule;
+	    nesting++;
+	} else if (rule->op == DICT_REGEXP_OP_ENDIF) {
+	    DICT_REGEXP_IF_RULE *if_rule;
+
+	    if (nesting-- <= 0)
+		/* Already handled in dict_regexp_parseline(). */
+		msg_panic("%s: ENDIF without IF", myname);
+	    if (rule_stack[nesting]->op != DICT_REGEXP_OP_IF)
+		msg_panic("%s: unexpected rule stack element type %d",
+			  myname, rule_stack[nesting]->op);
+	    if_rule = (DICT_REGEXP_IF_RULE *) rule_stack[nesting];
+	    if_rule->endif_rule = rule;
+	}
+	if (last_rule == 0)
+	    dict_regexp->head = rule;
+	else
+	    last_rule->next = rule;
+	last_rule = rule;
+    }
+
+    while (nesting-- > 0)
+	msg_warn("regexp map %s, line %d: IF has no matching ENDIF",
+		 mapname, rule_stack[nesting]->lineno);
+
+    if (rule_stack)
+	(void) mvect_free(&mvect);
+
+    /*
+     * Allocate space for only as many matched substrings as used in the
+     * replacement text.
+     */
+    if (max_sub > 0)
+	dict_regexp->pmatch =
+	    (regmatch_t *) mymalloc(sizeof(regmatch_t) * (max_sub + 1));
+
+    dict_file_purge_buffers(&dict_regexp->dict);
+    DICT_REGEXP_OPEN_RETURN(DICT_DEBUG (&dict_regexp->dict));
+}
+
+#endif