rcfile: compile the color regexes just once

When a syntax gets parsed, store the compiled color regexes right away,
instead of compiling them a second time in color_update().

This addresses https://savannah.gnu.org/bugs/?56432.

Signed-off-by: Brand Huntsman <alpha@qzx.com>
Signed-off-by: Benno Schulenberg <bensberg@telfort.nl>

src/color.c

@@ -169,7 +169,6 @@ bool found_in_list(regexlisttype *head, const char *shibboleth)
 void color_update(void)
 {
 	syntaxtype *sint = NULL;
-	colortype *ink;
 
 	/* If the rcfiles were not read, or contained no syntaxes, get out. */
 	if (syntaxes == NULL)
@@ -281,20 +280,6 @@ void color_update(void)
 
 	openfile->syntax = sint;
 	openfile->colorstrings = (sint == NULL ? NULL : sint->color);
-
-	/* If a syntax was found, compile its specified regexes (which have
-	 * already been checked for validity when they were read in). */
-	for (ink = openfile->colorstrings; ink != NULL; ink = ink->next) {
-		if (ink->start == NULL) {
-			ink->start = (regex_t *)nmalloc(sizeof(regex_t));
-			regcomp(ink->start, ink->start_regex, ink->rex_flags);
-		}
-
-		if (ink->end_regex != NULL && ink->end == NULL) {
-			ink->end = (regex_t *)nmalloc(sizeof(regex_t));
-			regcomp(ink->end, ink->end_regex, ink->rex_flags);
-		}
-	}
 }
 
 /* Determine whether the matches of multiline regexes are still the same,

src/nano.h

@@ -192,14 +192,8 @@ typedef struct colortype {
 		 * background color. */
 	int attributes;
 		/* Pair number and brightness composed into ready-to-use attributes. */
-	int rex_flags;
-		/* The regex compilation flags (with or without REG_ICASE). */
-	char *start_regex;
-		/* The start (or all) of the regex string. */
 	regex_t *start;
 		/* The compiled start (or all) of the regex string. */
-	char *end_regex;
-		/* The end (if any) of the regex string. */
 	regex_t *end;
 		/* The compiled end (if any) of the regex string. */
 	struct colortype *next;

src/rcfile.c

@@ -269,21 +269,26 @@ char *parse_next_regex(char *ptr)
 
 /* Compile the regular expression regex to see if it's valid.  Return
  * TRUE if it is, and FALSE otherwise. */
-bool nregcomp(const char *regex, int compile_flags)
+bool nregcomp(regex_t **compiled, const char *regex, int compile_flags)
 {
-	regex_t preg;
-	int rc = regcomp(&preg, regex, compile_flags);
+	regex_t *preg = nmalloc(sizeof(regex_t));
+	int rc = regcomp(preg, regex, compile_flags);
 
 	if (rc != 0) {
-		size_t len = regerror(rc, &preg, NULL, 0);
+		size_t len = regerror(rc, preg, NULL, 0);
 		char *str = charalloc(len);
 
-		regerror(rc, &preg, str, len);
+		regerror(rc, preg, str, len);
 		rcfile_error(N_("Bad regex \"%s\": %s"), regex, str);
 		free(str);
 	}
 
-	regfree(&preg);
+	if (compiled == NULL || rc != 0) {
+		regfree(preg);
+		free(preg);
+	} else
+		*compiled = preg;
+
 	return (rc == 0);
 }
 
@@ -760,23 +765,18 @@ void parse_colors(char *ptr, int rex_flags)
 		if (*item == '\0') {
 			rcfile_error(N_("Empty regex string"));
 			goodstart = FALSE;
-		} else
-			goodstart = nregcomp(item, rex_flags);
+		} else {
+			newcolor = (colortype *)nmalloc(sizeof(colortype));
+			goodstart = nregcomp(&newcolor->start, item, rex_flags);
+		}
 
 		/* If the starting regex is valid, initialize a new color struct,
 		 * and hook it in at the tail of the linked list. */
 		if (goodstart) {
-			newcolor = (colortype *)nmalloc(sizeof(colortype));
-
 			newcolor->fg = fg;
 			newcolor->bg = bg;
 			newcolor->attributes = attributes;
-			newcolor->rex_flags = rex_flags;
 
-			newcolor->start_regex = mallocstrcpy(NULL, item);
-			newcolor->start = NULL;
-
-			newcolor->end_regex = NULL;
 			newcolor->end = NULL;
 
 			newcolor->next = NULL;
@@ -787,7 +787,8 @@ void parse_colors(char *ptr, int rex_flags)
 				lastcolor->next = newcolor;
 
 			lastcolor = newcolor;
-		}
+		} else
+			free(newcolor);
 
 		if (!expectend)
 			continue;
@@ -819,8 +820,7 @@ void parse_colors(char *ptr, int rex_flags)
 			continue;
 
 		/* If it's valid, save the ending regex string. */
-		if (nregcomp(item, rex_flags))
-			newcolor->end_regex = mallocstrcpy(NULL, item);
+		nregcomp(&newcolor->end, item, rex_flags);
 
 		/* Lame way to skip another static counter. */
 		newcolor->id = live_syntax->nmultis;
@@ -889,7 +889,7 @@ void grab_and_store(const char *kind, char *ptr, regexlisttype **storage)
 			return;
 
 		/* If the regex string is malformed, skip it. */
-		if (!nregcomp(regexstring, NANO_REG_EXTENDED | REG_NOSUB))
+		if (!nregcomp(NULL, regexstring, NANO_REG_EXTENDED | REG_NOSUB))
 			continue;
 
 		/* Copy the regex into a struct, and hook this in at the end. */