Put code to construct unique path into new utlity function uniquePath()

Two almost identical versions existed of this code.

I generalized the code by taking out the knowledge of sections.
No other uses of this code are planned, but it is easier to review in
isolation now.

src/menu.cpp

@@ -18,7 +18,6 @@
  *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
  ***************************************************************************/
 
-#include <sstream>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <dirent.h>
@@ -391,14 +390,7 @@ bool Menu::addLink(string const& path, string const& file)
 		title = title.substr(0, pos);
 	}
 
-	string linkpath = sectionDir + "/" + title;
-	int x = 2;
-	while (fileExists(linkpath)) {
-		stringstream ss;
-		ss << sectionDir << '/' << title << x;
-		ss >> linkpath;
-		x++;
-	}
+	string linkpath = uniquePath(sectionDir, title);
 	INFO("Adding link: '%s'\n", linkpath.c_str());
 
 	string dirPath = path;
@@ -541,14 +533,7 @@ bool Menu::moveSelectedLink(string const& newSection)
 		return false;
 	}
 
-	string newFileName = sectionDir + "/" + linkTitle;
-	unsigned int x = 2;
-	while (fileExists(newFileName)) {
-		string id = "";
-		stringstream ss; ss << x; ss >> id;
-		newFileName = sectionDir + "/" + linkTitle + id;
-		x++;
-	}
+	string newFileName = uniquePath(sectionDir, linkTitle);
 
 	if (rename(file.c_str(), newFileName.c_str())) {
 		WARNING("Link file move from '%s' to '%s' failed: %s\n",

src/utilities.cpp

@@ -32,6 +32,7 @@
 #include <dirent.h>
 #include <fstream>
 #include <iostream>
+#include <sstream>
 #include <strings.h>
 #include <unistd.h>
 
@@ -160,6 +161,19 @@ bool fileExists(const string &file) {
 	return access(file.c_str(), F_OK) == 0;
 }
 
+string uniquePath(string const& dir, string const& name)
+{
+	string path = dir + "/" + name;
+	unsigned int x = 2;
+	while (fileExists(path)) {
+		stringstream ss;
+		ss << dir << '/' << name << x;
+		ss >> path;
+		x++;
+	}
+	return path;
+}
+
 int constrain(int x, int imin, int imax) {
 	return min(imax, max(imin, x));
 }

src/utilities.h

@@ -80,6 +80,11 @@ inline std::string trimExtension(std::string const& filename) {
 
 bool fileExists(const std::string &file);
 
+/**
+ * Constructs a non-existing path in a given directory based on the given name.
+ */
+std::string uniquePath(std::string const& dir, std::string const& name);
+
 int constrain(int x, int imin, int imax);
 
 int evalIntConf(ConfIntHash& hash, const std::string &key, int def, int imin, int imax);