Fix pull request comments related to Linux kernel style.

Improved return logic and error handling of reopen_file
Renamed log file argument processing function. Improved return error codes.  Moved error handling responsibility outside of function.
Add include header for error_t

Author: Richard Young

Diff for: candump.c

@@ -62,6 +62,7 @@
 
 #include <linux/can.h>
 #include <linux/can/raw.h>
+#include <errno.h>
 
 #include "terminal.h"
 #include "lib.h"
@@ -111,18 +112,18 @@ const char anichar[MAXANI] = {'|', '/', '-', '\\'};
 const char extra_m_info[4][4] = {"- -", "B -", "- E", "B E"};
 
 #define MAXLOGNAMESZ 100
-FILE *logfile = NULL;
+static FILE *logfile = NULL;
 static char log_filename[MAXLOGNAMESZ];
 
-unsigned char silent = SILENT_INI;
+static unsigned char silent = SILENT_INI;
 
 extern int optind, opterr, optopt;
 
 static volatile int running = 1;
-static volatile int flag_reopen_file = 0;
-static volatile unsigned long sighup_count = 0;
-int is_auto_log_name = 0;
-int open_log_file(const char * filename);
+static volatile int flag_reopen_file;
+static volatile unsigned long sighup_count;
+
+static int is_auto_log_name = 0;
 
 void print_usage(char *prg)
 {
@@ -177,8 +178,7 @@ void sigterm(int signo)
 
 void sighup(int signo)
 {
-	if(signo == SIGHUP)
-	{
+	if (signo == SIGHUP && running) {
 		flag_reopen_file = 1;
 		sighup_count++;
 	}
@@ -233,14 +233,13 @@ int idx2dindex(int ifidx, int socket) {
 	return i;
 }
 
-int sprint_auto_filename_format(char * buffer)
+static int sprint_auto_filename_format(char *buffer)
 {
 	time_t currtime;
 	struct tm now;
 
 	if (time(&currtime) == (time_t)-1) {
 		perror("time");
-		//running = 0;
 		return 1;
 	}
 
@@ -259,14 +258,13 @@ int sprint_auto_filename_format(char * buffer)
 	return 0;
 }
 
-//opens file using global filehandle logfile
-int open_log_file(const char * fileName)
+/*opens file using global var logfile*/
+static int open_log_file(const char *file_name)
 {
 	if (silent != SILENT_ON)
 		fprintf(stderr, "Warning: Console output active while logging!\n");
 
-	const char * fopen_opts = (sighup_count > 0) ? "a" : "w";
-	logfile = fopen(fileName, fopen_opts);
+	logfile = fopen(file_name, "w");
 
 	if (!logfile) {
 		perror("logfile");
@@ -276,55 +274,45 @@ int open_log_file(const char * fileName)
 	return 0;
 }
 
-//flush,close then reopen log
-int reopen_file(FILE * fileHandle)
+static int reopen_file(FILE *file_handle)
 {
-	if(!fileHandle)
-		return 1;
+	const char *fopen_opts = (sighup_count > 0 && !is_auto_log_name) ? "a" : "w";
 
-	int errcode = 0;
+	if (!file_handle)
+		return 1;
 
-	if(is_auto_log_name == 1)
-	{
-		errcode = sprint_auto_filename_format(&log_filename[0]);
+	if (is_auto_log_name == 1) {
+		const int errcode = sprint_auto_filename_format(log_filename);
 
-		if(errcode != 0)
-		{
-			running = 0;
+		if (errcode != 0) {
 			return 1;
 		}
 	}
 
-	const char * fopen_opts = (sighup_count > 0) ? "a" : "w";
-	logfile = freopen(log_filename,fopen_opts,fileHandle);
+	logfile = freopen(log_filename, fopen_opts, file_handle);
 
-	running = (errcode == 0);
 	flag_reopen_file = 0;
 
-	return 0;
+	return logfile != 0;
 }
 
-void get_logname_arg(const char * arg)
+static int process_logname_arg(const char *arg)
 {
-	if(arg != 0)
-	{
-		size_t len = strnlen(arg,MAXLOGNAMESZ);
-		if(len > 0 && len < MAXLOGNAMESZ)
-		{
-			strncpy(log_filename,arg,MAXLOGNAMESZ-1);
-		}
-		else
-		{
-			//print_usage(basename(argv[0]));
-			exit(1);
+	if (arg != 0) {
+		const size_t len = strnlen(arg, MAXLOGNAMESZ);
+
+		if (len > 0 && len < MAXLOGNAMESZ) {
+			strncpy(log_filename, arg, MAXLOGNAMESZ-1);
+		} else {
+			return 1;
 		}
 		is_auto_log_name = 0;
-	}
-	else
-	{
+	} else {
 		is_auto_log_name = 1;	
-		sprint_auto_filename_format(&log_filename[0]);
+		sprint_auto_filename_format(log_filename);
 	}
+
+	return 0;
 }
 
 int main(int argc, char **argv)
@@ -361,14 +349,12 @@ int main(int argc, char **argv)
 	struct timeval tv, last_tv;
 	struct timeval timeout, timeout_config = { 0, 0 }, *timeout_current = NULL;
 
-	{
-		sigset_t sig_mask;
-		sigemptyset (&sig_mask);
+	sigset_t sig_mask;
+	sigemptyset(&sig_mask);
 
-		struct sigaction sigterm_action = {.sa_mask = sig_mask, .sa_flags = SA_RESTART, .sa_handler = sigterm};
-		sigaction (SIGHUP, &sigterm_action, NULL);
-		sigaction (SIGINT, &sigterm_action, NULL);
-	}
+	struct sigaction sigterm_action = { .sa_mask = sig_mask, .sa_flags = SA_RESTART, .sa_handler = sigterm };
+	sigaction (SIGHUP, &sigterm_action, NULL);
+	sigaction (SIGINT, &sigterm_action, NULL);
 
 	last_tv.tv_sec  = 0;
 	last_tv.tv_usec = 0;
@@ -377,9 +363,8 @@ int main(int argc, char **argv)
 
 	//Since interface is a required argument, we don't need to parse opt for final arg
 	//This enabled the -l option to take an optional filename
-	if(getoptargc > 0)
-	{
-		getoptargc = argc-1;
+	if (getoptargc > 0) {
+		getoptargc = argc - 1;
 	}
 
 	while ((opt = getopt(getoptargc, argv, ":t:HciaSs:l:DdxLn:r:he8T:?")) != -1) {
@@ -438,21 +423,26 @@ int main(int argc, char **argv)
 			{
 				log = 1;
 
-				get_logname_arg(optarg);
-				
+				if (process_logname_arg(optarg) != 0) {
+					print_usage(basename(argv[0]));
+					exit(1);
+				}
 				break;
 			}
 			default:
 				fprintf(stderr, "option -%c is missing a required argument\n", optopt);
 				return EXIT_FAILURE;
 			}		
-			
 			break;
 
 		case 'l':
 			log = 1;
 
-			get_logname_arg(optarg);
+			if (process_logname_arg(optarg) != 0) {
+				is_auto_log_name = 0;
+				print_usage(basename(argv[0]));
+				exit(1);
+			}
 
 			break;
 
@@ -511,15 +501,13 @@ int main(int argc, char **argv)
 		exit(0);
 	}
 
-	//Configure SIGHUP handler to reopen file if logging
-	{	
-		sigset_t sig_block_mask;
-		sigfillset (&sig_block_mask);
-		struct sigaction usr_action = {.sa_mask = sig_block_mask, .sa_flags = SA_RESTART};
-		usr_action.sa_handler = log ? sighup : sigterm;		
-		sigaction(SIGHUP, &usr_action, NULL);
-	}
-	
+	/*Configure SIGHUP handler to reopen file if logging*/
+	sigset_t sig_block_mask;
+	sigfillset(&sig_block_mask);
+	struct sigaction usr_action = { .sa_mask = sig_block_mask, .sa_flags = SA_RESTART };
+	usr_action.sa_handler = log ? sighup : sigterm;		
+	sigaction(SIGHUP, &usr_action, NULL);
+
 	if (logfrmt && view) {
 		fprintf(stderr, "Log file format selected: Please disable ASCII/BINARY/SWAP/RAWDLC options!\n");
 		exit(0);
@@ -734,10 +722,8 @@ int main(int argc, char **argv)
 	if (log) {
 		int result = open_log_file(log_filename);
 
-		if(result != 0)
-		{
+		if (result != 0)
 			return 1;
-		}
 	}
 
 	/* these settings are static and can be held out of the hot path */
@@ -759,20 +745,15 @@ int main(int argc, char **argv)
 		if ((ret = select(s[currmax-1]+1, &rdfs, NULL, NULL, timeout_current)) <= 0) {
 			//perror("select");
 
-			error_t serr = errno;
+			const error_t serr = errno;
 
-			if(serr == EINTR)
-			{
-				if(flag_reopen_file == 1)
-				{
-					if(reopen_file(logfile) != 0)
-					{
-						return 1;
+			if (serr == EINTR) {
+				if (flag_reopen_file == 1) {
+					if (reopen_file(logfile) != 0) {
+						return -1;
 					}
 				}
-			}
-			else
-			{
+			} else {
 				running = 0;
 			}
 
@@ -962,10 +943,8 @@ int main(int argc, char **argv)
 			fflush(stdout);
 		}
 
-		if(flag_reopen_file == 1)
-		{
-			if(reopen_file(logfile) != 0)
-			{
+		if (flag_reopen_file == 1) { 
+			if(reopen_file(logfile) != 0) {
 				return -1;
 			}
 		}