Fix duplicate process detection

src/config/toml_writer.c

@@ -43,10 +43,7 @@ bool writeFTLtoml(const bool verbose)
 	// Try to open a temporary config file for writing
 	FILE *fp;
 	if((fp = openFTLtoml("w", 0)) == NULL)
-	{
-		log_warn("Cannot write to FTL config file (%s), content not updated", strerror(errno));
 		return false;
-	}
 
 	// Write header
 	fprintf(fp, "# Pi-hole configuration file (%s)\n", get_FTL_version());

src/daemon.c

@@ -104,17 +104,27 @@ void go_daemon(void)
 		exit(EXIT_SUCCESS);
 	}
 
-	savepid();
+	savePID();
 
 	// Closing stdin, stdout and stderr is handled by dnsmasq
 }
 
-void savepid(void)
+/**
+ * @brief Save the current process ID (PID) to a file.
+ *
+ * This function retrieves the PID of the current process and writes it to a
+ * specified file. If the file cannot be opened for writing, an error is logged.
+ * Otherwise, the PID is written to the file and the file is closed. The PID is
+ * also logged for informational purposes.
+ *
+ * @return void
+ */
+void savePID(void)
 {
-	FILE *f;
 	// Get PID of the current process
 	const pid_t pid = getpid();
 	// Open file for writing
+	FILE *f = NULL;
 	if((f = fopen(config.files.pid.v.s, "w+")) == NULL)
 	{
 		// Log error
@@ -129,20 +139,39 @@ void savepid(void)
 	log_info("PID of FTL process: %i", (int)pid);
 }
 
-static void removepid(void)
+/**
+ * @brief Empties the PID file
+ *
+ * This function opens the PID file in write mode, which effectively
+ * empties its contents. If the file cannot be opened, a warning is logged.
+ *
+ * @note This function does not remove the PID file, it only empties it.
+ */
+static void removePID(void)
 {
-	// Note that this function is not really removing the PID file but
-	// rather emptying it
-	FILE *f;
-	// Open file for writing (emptying it)
+	FILE *f = NULL;
+	// Open file for writing to overwrite/empty it
 	if((f = fopen(config.files.pid.v.s, "w")) == NULL)
 	{
 		log_warn("Unable to empty PID file: %s", strerror(errno));
 		return;
 	}
 	fclose(f);
+
+	log_info("PID file emptied");
 }
 
+/**
+ * @brief Retrieves the username of the effective user ID of the calling process.
+ *
+ * This function uses the `geteuid()` function to get the effective user ID (EUID) of the calling process
+ * and then searches the user database for an entry with a matching UID using the `getpwuid()` function.
+ * If a matching entry is found, the username is returned. If no matching entry is found, the UID is
+ * returned as a string. If an error occurs during the lookup, a warning is logged.
+ *
+ * @return A dynamically allocated string containing the username or UID. The caller is responsible for
+ * freeing the allocated memory. Returns NULL if memory allocation fails.
+ */
 char *getUserName(void)
 {
 	char *name;
@@ -376,7 +405,7 @@ void cleanup(const int ret)
 	}
 
 	// Remove PID file
-	removepid();
+	removePID();
 
 	// Free regex filter memory
 	free_regex();

src/daemon.h

@@ -14,7 +14,7 @@
 extern pthread_t threads[THREADS_MAX];
 
 void go_daemon(void);
-void savepid(void);
+void savePID(void);
 char *getUserName(void);
 const char *hostname(void);
 const char *domainname(void);

src/dnsmasq_interface.c

@@ -3175,7 +3175,7 @@ void FTL_fork_and_bind_sockets(struct passwd *ent_pw, bool dnsmasq_start)
 	if(daemonmode)
 		go_daemon();
 	else
-		savepid();
+		savePID();
 
 	// Initialize query database (pihole-FTL.db)
 	db_init();

src/main.c

@@ -93,7 +93,7 @@ int main (int argc, char *argv[])
 
 	// Write PID early on so systemd cannot be fooled during DELAY_STARTUP
 	// times. The PID in this file will later be overwritten after forking
-	savepid();
+	savePID();
 
 	// Delay startup (if requested)
 	// Do this before reading the database to make this option not only