Only compile regex's once

3 files changed, 126 insertions, 70 deletions

diff --git a/src/common.c b/src/common.c
index 283535f..fcb9742 100644
--- a/src/common.c
+++ b/src/common.c
@@ -1417,45 +1417,6 @@ set_boolean_if_valid (bool *out, const char *s)
 	return true;
 }
 
-static void
-regerror_to_str (int code, const regex_t *preg, struct str *out)
-{
-	size_t required = regerror (code, preg, NULL, 0);
-	str_ensure_space (out, required);
-	out->len += regerror (code, preg,
-		out->str + out->len, out->alloc - out->len) - 1;
-}
-
-static size_t regex_error_domain_tag;
-#define REGEX_ERROR (error_resolve_domain (&regex_error_domain_tag))
-
-enum
-{
-	REGEX_ERROR_COMPILATION_FAILED
-};
-
-static bool
-regex_match (const char *regex, const char *s, struct error **e)
-{
-	regex_t re;
-	int err = regcomp (&re, regex, REG_EXTENDED | REG_NOSUB);
-	if (err)
-	{
-		struct str desc;
-
-		str_init (&desc);
-		regerror_to_str (err, &re, &desc);
-		error_set (e, REGEX_ERROR, REGEX_ERROR_COMPILATION_FAILED,
-			"failed to compile regular expression: %s", desc.str);
-		str_free (&desc);
-		return false;
-	}
-
-	bool result = regexec (&re, s, 0, NULL, 0) != REG_NOMATCH;
-	regfree (&re);
-	return result;
-}
-
 static bool
 read_line (FILE *fp, struct str *s)
 {
@@ -1512,6 +1473,73 @@ xssl_get_error (SSL *ssl, int result, const char **error_info)
 	}
 }
 
+// --- Regular expressions -----------------------------------------------------
+
+static size_t regex_error_domain_tag;
+#define REGEX_ERROR (error_resolve_domain (&regex_error_domain_tag))
+
+enum
+{
+	REGEX_ERROR_COMPILATION_FAILED
+};
+
+static regex_t *
+regex_compile (const char *regex, int flags, struct error **e)
+{
+	regex_t *re = xmalloc (sizeof *re);
+	int err = regcomp (re, regex, flags);
+	if (!err)
+		return re;
+
+	struct str desc;
+	str_init (&desc);
+
+	size_t required = regerror (err, re, NULL, 0);
+	str_ensure_space (&desc, required);
+	desc.len += regerror (err, re,
+		desc.str + desc.len, desc.alloc - desc.len) - 1;
+
+	free (re);
+	error_set (e, REGEX_ERROR, REGEX_ERROR_COMPILATION_FAILED,
+		"%s: %s", "failed to compile regular expression", desc.str);
+	str_free (&desc);
+	return NULL;
+}
+
+static void
+regex_free (void *regex)
+{
+	regfree (regex);
+	free (regex);
+}
+
+// The cost of hashing a string is likely to be significantly smaller than that
+// of compiling the whole regular expression anew, so here is a simple cache.
+// Adding basic support for subgroups is easy: check `re_nsub' and output into
+// a `struct str_vector' (if all we want is the substrings).
+
+static void
+regex_cache_init (struct str_map *cache)
+{
+	str_map_init (cache);
+	cache->free = regex_free;
+}
+
+static bool
+regex_cache_match (struct str_map *cache, const char *regex, int flags,
+	const char *s, struct error **e)
+{
+	regex_t *re = str_map_find (cache, regex);
+	if (!re)
+	{
+		re = regex_compile (regex, flags, e);
+		if (!re)
+			return false;
+		str_map_set (cache, regex, re);
+	}
+	return regexec (re, s, 0, NULL, 0) != REG_NOMATCH;
+}
+
 // --- IRC utilities -----------------------------------------------------------
 
 struct irc_message
diff --git a/src/kike.c b/src/kike.c
index d5a777c..0ce7092 100644
--- a/src/kike.c
+++ b/src/kike.c
@@ -103,13 +103,24 @@ enum validation_result
 #define IRC_NICKNAME_MAX    9
 #define IRC_HOSTNAME_MAX   63
 
-// Anything to keep it as short as possible
-#define SN "[0-9A-Za-z][-0-9A-Za-z]*[0-9A-Za-z]*"
-#define N4 "[0-9]{1,3}"
-#define N6 "[0-9ABCDEFabcdef]{1,}"
+static bool
+irc_regex_match (const char *regex, const char *s)
+{
+	static struct str_map cache;
+	static bool initialized;
 
-#define LE "A-Za-z"
-#define SP "\\[\\]\\\\`_^{|}"
+	if (!initialized)
+	{
+		regex_cache_init (&cache);
+		initialized = true;
+	}
+
+	struct error *e = NULL;
+	bool result = regex_cache_match (&cache, regex,
+		REG_EXTENDED | REG_NOSUB, s, &e);
+	hard_assert (!e);
+	return result;
+}
 
 static const char *
 irc_validate_to_str (enum validation_result result)
@@ -124,14 +135,20 @@ irc_validate_to_str (enum validation_result result)
 	}
 }
 
-// TODO: at least cache the resulting `regex_t' in a `struct str_map'
+// Anything to keep it as short as possible
+#define SN "[0-9A-Za-z][-0-9A-Za-z]*[0-9A-Za-z]*"
+#define N4 "[0-9]{1,3}"
+#define N6 "[0-9ABCDEFabcdef]{1,}"
+
+#define LE "A-Za-z"
+#define SP "\\[\\]\\\\`_^{|}"
 
 static enum validation_result
 irc_validate_hostname (const char *hostname)
 {
 	if (!*hostname)
 		return VALIDATION_ERROR_EMPTY;
-	if (!regex_match ("^" SN "(\\." SN ")*$", hostname, NULL))
+	if (!irc_regex_match ("^" SN "(\\." SN ")*$", hostname))
 		return VALIDATION_ERROR_INVALID;
 	if (strlen (hostname) > IRC_HOSTNAME_MAX)
 		return VALIDATION_ERROR_TOO_LONG;
@@ -141,11 +158,11 @@ irc_validate_hostname (const char *hostname)
 static bool
 irc_is_valid_hostaddr (const char *hostaddr)
 {
-	if (regex_match ("^" N4 "\\." N4 "\\." N4 "\\." N4 "$", hostaddr, NULL)
-	 || regex_match ("^" N6 ":" N6 ":" N6 ":" N6 ":"
-		N6 ":" N6 ":" N6 ":" N6 "$", hostaddr, NULL)
-	 || regex_match ("^0:0:0:0:0:(0|[Ff]{4}):"
-		N4 "\\." N4 "\\." N4 "\\." N4 "$", hostaddr, NULL))
+	if (irc_regex_match ("^" N4 "\\." N4 "\\." N4 "\\." N4 "$", hostaddr)
+	 || irc_regex_match ("^" N6 ":" N6 ":" N6 ":" N6 ":"
+		N6 ":" N6 ":" N6 ":" N6 "$", hostaddr)
+	 || irc_regex_match ("^0:0:0:0:0:(0|[Ff]{4}):"
+		N4 "\\." N4 "\\." N4 "\\." N4 "$", hostaddr))
 		return true;
 	return false;
 }
@@ -162,7 +179,7 @@ irc_validate_nickname (const char *nickname)
 {
 	if (!*nickname)
 		return VALIDATION_ERROR_EMPTY;
-	if (!regex_match ("^[" LE SP "][-0-9" LE SP "]*$", nickname, NULL))
+	if (!irc_regex_match ("^[" LE SP "][-0-9" LE SP "]*$", nickname))
 		return VALIDATION_ERROR_INVALID;
 	if (strlen (nickname) > IRC_NICKNAME_MAX)
 		return VALIDATION_ERROR_TOO_LONG;
diff --git a/src/zyklonb.c b/src/zyklonb.c
index 69c41c1..13e7f3b 100644
--- a/src/zyklonb.c
+++ b/src/zyklonb.c
@@ -118,6 +118,7 @@ enum
 struct bot_context
 {
 	struct str_map config;              ///< User configuration
+	regex_t *admin_re;                  ///< Regex to match our administrator
 
 	int irc_fd;                         ///< Socket FD of the server
 	struct str read_buffer;             ///< Input yet to be processed
@@ -140,6 +141,7 @@ bot_context_init (struct bot_context *self)
 	str_map_init (&self->config);
 	self->config.free = free;
 	load_config_defaults (&self->config, g_config_table);
+	self->admin_re = NULL;
 
 	self->irc_fd = -1;
 	str_init (&self->read_buffer);
@@ -160,6 +162,8 @@ static void
 bot_context_free (struct bot_context *self)
 {
 	str_map_free (&self->config);
+	if (self->admin_re)
+		regex_free (self->admin_re);
 	str_free (&self->read_buffer);
 
 	// TODO: terminate the plugins properly before this is called
@@ -1110,25 +1114,10 @@ is_private_message (const struct irc_message *msg)
 static bool
 is_sent_by_admin (struct bot_context *ctx, const struct irc_message *msg)
 {
-	const char *admin = str_map_find (&ctx->config, "admin");
-
 	// No administrator set -> everyone is an administrator
-	if (!admin)
-		return true;
-
-	// TODO: precompile the regex
-	struct error *e = NULL;
-	if (regex_match (admin, msg->prefix, NULL))
-		return true;
-
-	if (e)
-	{
-		print_error ("%s: %s", "invalid admin mask", e->message);
-		error_free (e);
+	if (!ctx->admin_re)
 		return true;
-	}
-
-	return false;
+	return regexec (ctx->admin_re, msg->prefix, 0, NULL, 0) != REG_NOMATCH;
 }
 
 static void respond_to_user (struct bot_context *ctx, const struct
@@ -1591,6 +1580,26 @@ irc_connect (struct bot_context *ctx, struct error **e)
 	return true;
 }
 
+static bool
+load_admin_regex (struct bot_context *ctx)
+{
+	hard_assert (!ctx->admin_re);
+	const char *admin = str_map_find (&ctx->config, "admin");
+
+	if (!admin)
+		return true;
+
+	struct error *e = NULL;
+	ctx->admin_re = regex_compile (admin, REG_EXTENDED | REG_NOSUB, &e);
+	if (!e)
+		return true;
+
+	print_error ("invalid configuration value for `%s': %s",
+		"admin", e->message);
+	error_free (e);
+	return false;
+}
+
 static void
 on_signal_pipe_readable (const struct pollfd *fd, struct bot_context *ctx)
 {
@@ -1758,6 +1767,8 @@ main (int argc, char *argv[])
 		(poller_dispatcher_func) on_signal_pipe_readable, &ctx);
 
 	plugin_load_all_from_config (&ctx);
+	if (!load_admin_regex (&ctx))
+		exit (EXIT_FAILURE);
 	if (!irc_connect (&ctx, &e))
 	{
 		print_error ("%s", e->message);