Merge pull request #11 from zerotier/snprintf-into-self

Avoid using the same source and destination in snprintf()

one.cpp

@@ -1196,12 +1196,13 @@ static int cli(int argc, char** argv)
 			return 0;
 		}
 
-		snprintf((char*)path, sizeof(path), "%s%szerotier_dump.txt", (char*)path, ZT_PATH_SEPARATOR_S);
+		char dumpfile[PATH_MAX];
+		snprintf(dumpfile, sizeof(dumpfile), "%s%szerotier_dump.txt", (char*)path, ZT_PATH_SEPARATOR_S);
 
-		fprintf(stdout, "Writing dump to: %s\n", path);
-		int fd = open((char*)path, O_CREAT | O_RDWR, 0664);
+		fprintf(stdout, "Writing dump to: %s\n", dumpfile);
+		int fd = open(dumpfile, O_CREAT | O_WRONLY | O_TRUNC, 0664);
 		if (fd == -1) {
-			fprintf(stderr, "Error creating file.\n");
+			perror("Error creating file");
 			return 1;
 		}
 		write(fd, dump.str().c_str(), dump.str().size());
@@ -1346,12 +1347,15 @@ static int cli(int argc, char** argv)
 		}
 		close(sock);
 		char cwd[16384];
-		getcwd(cwd, sizeof(cwd));
-		snprintf(cwd, sizeof(cwd), "%s%szerotier_dump.txt", cwd, ZT_PATH_SEPARATOR_S);
-		fprintf(stdout, "Writing dump to: %s\n", cwd);
-		int fd = open(cwd, O_CREAT | O_RDWR, 0664);
+		if (getcwd(cwd, sizeof(cwd)) == nullptr) {
+			strcpy(cwd, ".");
+		}
+		char dumpfile[sizeof(cwd) + 32];
+		snprintf(dumpfile, sizeof(dumpfile), "%s%szerotier_dump.txt", cwd, ZT_PATH_SEPARATOR_S);
+		fprintf(stdout, "Writing dump to: %s\n", dumpfile);
+		int fd = open(dumpfile, O_CREAT | O_WRONLY | O_TRUNC, 0664);
 		if (fd == -1) {
-			fprintf(stderr, "Error creating file.\n");
+			perror("Error creating file");
 			return 1;
 		}
 		write(fd, dump.str().c_str(), dump.str().size());