Delete tor binaries instead of just overwriting them

onionwrapper-core/src/main/java/org/briarproject/onionwrapper/AbstractTorWrapper.java

@@ -229,6 +229,10 @@ abstract class AbstractTorWrapper implements EventHandler, TorWrapper {
 			LOG.info("Installing Tor binary for " + architecture);
 		}
 		File torFile = getTorExecutableFile();
+		// Important: delete file here and with other binaries below to prevent
+		// problems on macOS in case the file signature changed.
+		//noinspection ResultOfMethodCallIgnored
+		torFile.delete();
 		extract(getExecutableInputStream("tor"), torFile);
 		if (!torFile.setExecutable(true, true)) throw new IOException();
 	}
@@ -238,6 +242,8 @@ abstract class AbstractTorWrapper implements EventHandler, TorWrapper {
 			LOG.info("Installing libevent binary for " + architecture);
 		}
 		File libEventFile = getLibEventFile();
+		//noinspection ResultOfMethodCallIgnored
+		libEventFile.delete();
 		extract(getExecutableInputStream("libevent-2.1.7.dylib"), libEventFile);
 	}
 
@@ -246,6 +252,8 @@ abstract class AbstractTorWrapper implements EventHandler, TorWrapper {
 			LOG.info("Installing obfs4proxy binary for " + architecture);
 		}
 		File obfs4File = getObfs4ExecutableFile();
+		//noinspection ResultOfMethodCallIgnored
+		obfs4File.delete();
 		extract(getExecutableInputStream("obfs4proxy"), obfs4File);
 		if (!obfs4File.setExecutable(true, true)) throw new IOException();
 	}
@@ -255,6 +263,8 @@ abstract class AbstractTorWrapper implements EventHandler, TorWrapper {
 			LOG.info("Installing snowflake binary for " + architecture);
 		}
 		File snowflakeFile = getSnowflakeExecutableFile();
+		//noinspection ResultOfMethodCallIgnored
+		snowflakeFile.delete();
 		extract(getExecutableInputStream("snowflake"), snowflakeFile);
 		if (!snowflakeFile.setExecutable(true, true)) throw new IOException();
 	}