Don't write to a directory that contains an existing tileset.

The -f option will clear the directory now, as with mbtiles.

dirtiles.cpp

@@ -3,6 +3,8 @@
 #include <sstream>
 #include <string>
 #include <sys/stat.h>
+#include <unistd.h>
+#include <dirent.h>
 #include "dirtiles.hpp"
 
 std::string dir_read_tile(std::string pbfPath) {
@@ -24,7 +26,99 @@ void dir_write_tile(const char *outdir, int z, int tx, int ty, std::string const
 	mkdir(newdir.c_str(), S_IRWXU | S_IRWXG | S_IRWXO);
 	newdir = newdir + "/" + std::to_string(ty) + ".pbf";
 
+	struct stat st;
+	if (stat(newdir.c_str(), &st) == 0) {
+		fprintf(stderr, "Can't write tile to already existing %s\n", newdir.c_str());
+		exit(EXIT_FAILURE);
+	}
+
 	std::ofstream pbfFile(newdir, std::ios::out | std::ios::binary);
 	pbfFile.write(pbf.data(), pbf.size());
 	pbfFile.close();
 }
+
+bool numeric(const char *s) {
+	if (*s == '\0') {
+		return false;
+	}
+	for (; *s != 0; s++) {
+		if (*s < '0' || *s > '9') {
+			return false;
+		}
+	}
+	return true;
+}
+
+bool pbfname(const char *s) {
+	while (*s >= '0' && *s <= '9') {
+		s++;
+	}
+
+	return strcmp(s, ".pbf") == 0;
+}
+
+void check_dir(const char *dir, bool rm) {
+	struct stat st;
+
+	std::string meta = std::string(dir) + "/" + "metadata.json";
+	if (rm) {
+		unlink(meta.c_str());  // error OK since it may not exist;
+	} else {
+		if (stat(meta.c_str(), &st) == 0) {
+			fprintf(stderr, "%s: file exists\n", meta.c_str());
+			exit(EXIT_FAILURE);
+		}
+	}
+
+	DIR *d1 = opendir(dir);
+	if (d1 != NULL) {
+		struct dirent *dp;
+		while ((dp = readdir(d1)) != NULL) {
+			if (numeric(dp->d_name)) {
+				std::string z = std::string(dir) + "/" + dp->d_name;
+
+				DIR *d2 = opendir(z.c_str());
+				if (d2 == NULL) {
+					perror(z.c_str());
+					exit(EXIT_FAILURE);
+				}
+
+				struct dirent *dp2;
+				while ((dp2 = readdir(d2)) != NULL) {
+					if (numeric(dp2->d_name)) {
+						std::string x = z + "/" + dp2->d_name;
+
+						DIR *d3 = opendir(x.c_str());
+						if (d3 == NULL) {
+							perror(x.c_str());
+							exit(EXIT_FAILURE);
+						}
+
+						struct dirent *dp3;
+						while ((dp3 = readdir(d3)) != NULL) {
+							if (pbfname(dp3->d_name)) {
+								std::string y = x + "/" + dp3->d_name;
+
+								if (rm) {
+									if (unlink(y.c_str()) != 0) {
+										perror(y.c_str());
+										exit(EXIT_FAILURE);
+									}
+								} else {
+									fprintf(stderr, "%s: file exists\n", y.c_str());
+									exit(EXIT_FAILURE);
+								}
+							}
+						}
+
+						closedir(d3);
+					}
+				}
+
+				closedir(d2);
+			}
+		}
+
+		closedir(d1);
+	}
+}