utils: add noalloc flag to modifyString()

This should make it more straightforward for code analyzers to
tell if the function is going to allocate memory.

inotify.c

@@ -704,7 +704,7 @@ start_inotify()
 					i += EVENT_SIZE + event->len;
 					continue;
 				}
-				esc_name = modifyString(strdup(event->name), "&", "&");
+				esc_name = modifyString(strdup(event->name), "&", "&", 0);
 				snprintf(path_buf, sizeof(path_buf), "%s/%s", get_path_from_wd(event->wd), event->name);
 				if ( event->mask & IN_ISDIR && (event->mask & (IN_CREATE|IN_MOVED_TO)) )
 				{

playlist.c

@@ -236,7 +236,7 @@ found:
 				DPRINTF(E_DEBUG, L_SCANNER, "- %s not found in db\n", fname);
 				if( strchr(fname, '\\') )
 				{
-					fname = modifyString(fname, "\\", "/");
+					fname = modifyString(fname, "\\", "/", 1);
 					goto retry;
 				}
 				else if( (fname = strchr(fname, '/')) )

tivo_commands.c

@@ -118,11 +118,11 @@ SendFormats(struct upnphttp *h, const char *sformat)
 static char *
 tivo_unescape_tag(char *tag)
 {
-	modifyString(tag, "&", "&");
-	modifyString(tag, "<", "<");
-	modifyString(tag, "<", "<");
-	modifyString(tag, ">", ">");
-	modifyString(tag, ">", ">");
+	modifyString(tag, "&", "&", 1);
+	modifyString(tag, "<", "<", 1);
+	modifyString(tag, "<", "<", 1);
+	modifyString(tag, ">", ">", 1);
+	modifyString(tag, ">", ">", 1);
 	return tag;
 }
 

utils.c

@@ -31,6 +31,7 @@
 
 #include "minidlnatypes.h"
 #include "upnpglobalvars.h"
+#include "utils.h"
 #include "log.h"
 
 int
@@ -143,20 +144,27 @@ strcasestrc(const char *s, const char *p, const char t)
 } 
 
 char *
-modifyString(char * string, const char * before, const char * after)
+modifyString(char *string, const char *before, const char *after, int noalloc)
 {
 	int oldlen, newlen, chgcnt = 0;
 	char *s, *p;
 
+	/* If there is no match, just return */
+	s = strstr(string, before);
+	if (!s)
+		return string;
+
 	oldlen = strlen(before);
 	newlen = strlen(after);
-	if( newlen > oldlen )
+	if (newlen > oldlen)
 	{
-		s = string;
-		while( (p = strstr(s, before)) )
+		if (noalloc)
+			return string;
+
+		while ((p = strstr(s, before)))
 		{
 			chgcnt++;
-			s = p+oldlen;
+			s = p + oldlen;
 		}
 		s = realloc(string, strlen(string)+((newlen-oldlen)*chgcnt)+1);
 		/* If we failed to realloc, return the original alloc'd string */
@@ -167,10 +175,10 @@ modifyString(char * string, const char * before, const char * after)
 	}
 
 	s = string;
-	while( s )
+	while (s)
 	{
-		p = strcasestr(s, before);
-		if( !p )
+		p = strstr(s, before);
+		if (!p)
 			return string;
 		memmove(p + newlen, p + oldlen, strlen(p + oldlen) + 1);
 		memcpy(p, after, newlen);
@@ -189,10 +197,10 @@ unescape_tag(const char *tag, int force_alloc)
 			|| strstr(tag, """) )
 	{
 		esc_tag = strdup(tag);
-		esc_tag = modifyString(esc_tag, "&", "&");
-		esc_tag = modifyString(esc_tag, "&lt;", "<");
-		esc_tag = modifyString(esc_tag, "&gt;", ">");
-		esc_tag = modifyString(esc_tag, "&quot;", "\"");
+		esc_tag = modifyString(esc_tag, "&amp;", "&", 1);
+		esc_tag = modifyString(esc_tag, "&lt;", "<", 1);
+		esc_tag = modifyString(esc_tag, "&gt;", ">", 1);
+		esc_tag = modifyString(esc_tag, "&quot;", "\"", 1);
 	}
 	else if( force_alloc )
 		esc_tag = strdup(tag);
@@ -208,10 +216,10 @@ escape_tag(const char *tag, int force_alloc)
 	if( strchr(tag, '&') || strchr(tag, '<') || strchr(tag, '>') || strchr(tag, '"') )
 	{
 		esc_tag = strdup(tag);
-		esc_tag = modifyString(esc_tag, "&", "&amp;amp;");
-		esc_tag = modifyString(esc_tag, "<", "&amp;lt;");
-		esc_tag = modifyString(esc_tag, ">", "&amp;gt;");
-		esc_tag = modifyString(esc_tag, "\"", "&amp;quot;");
+		esc_tag = modifyString(esc_tag, "&", "&amp;amp;", 0);
+		esc_tag = modifyString(esc_tag, "<", "&amp;lt;", 0);
+		esc_tag = modifyString(esc_tag, ">", "&amp;gt;", 0);
+		esc_tag = modifyString(esc_tag, "\"", "&amp;quot;", 0);
 	}
 	else if( force_alloc )
 		esc_tag = strdup(tag);

utils.h

@@ -60,7 +60,7 @@ int ends_with(const char * haystack, const char * needle);
 char *trim(char *str);
 char *strstrc(const char *s, const char *p, const char t);
 char *strcasestrc(const char *s, const char *p, const char t);
-char *modifyString(char * string, const char * before, const char * after);
+char *modifyString(char *string, const char *before, const char *after, int noalloc);
 char *escape_tag(const char *tag, int force_alloc);
 char *unescape_tag(const char *tag, int force_alloc);
 void strip_ext(char * name);