lib: add pr_debug() macro

Add the pr_debug() macro so that:

  #ifdef DEBUG
  	printf("foo");
  #endif

can be replaced by:

  	pr_debug("foo");

Apply the pr_debug() macro wherever relevant.

Currently, there is no consensus whether debug messages should be
printed on stdout or stderr. Most of the modules: canbusload.c,
candump.c and canlogserver.c use stdout but
mcp251xfd/mcp251xfd-dev-coredump.c uses stderr. Harmonize the behavior
by following the major trend and make
mcp251xfd/mcp251xfd-dev-coredump.c also output to stdout.

slcanpty.c does a #define DEBUG, meaning that debug is always turned
on for this file. Remove this and make debug an option like every
other files.

Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://lore.kernel.org/all/20221114163848.3398-5-mailhol.vincent@wanadoo.fr
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Makefile

@@ -46,6 +46,7 @@ MAKEFLAGS := -k
 CFLAGS := -O2 -Wall -Wno-parentheses
 
 CPPFLAGS += \
+	-I. \
 	-Iinclude \
 	-DAF_CAN=PF_CAN \
 	-DPF_CAN=29 \

canbusload.c

@@ -61,6 +61,7 @@
 #include <linux/can.h>
 #include <linux/can/raw.h>
 
+#include "lib.h"
 #include "terminal.h"
 #include "canframelen.h"
 
@@ -310,9 +311,7 @@ int main(int argc, char **argv)
 			return 1;
 		}
 
-#ifdef DEBUG
-		printf("open %d '%s'.\n", i, ptr);
-#endif
+		pr_debug("open %d '%s'.\n", i, ptr);
 
 		s[i] = socket(PF_CAN, SOCK_RAW, CAN_RAW);
 		if (s[i] < 0) {
@@ -358,10 +357,8 @@ int main(int argc, char **argv)
 		if (nbytes > max_bitrate_len)
 			max_bitrate_len = nbytes; /* for nice printing */
 
+		pr_debug("using interface name '%s'.\n", ifr.ifr_name);
 
-#ifdef DEBUG
-		printf("using interface name '%s'.\n", ifr.ifr_name);
-#endif
 		/* try to switch the socket into CAN FD mode */
 		const int canfd_on = 1;
 		setsockopt(s[i], SOL_CAN_RAW, CAN_RAW_FD_FRAMES, &canfd_on, sizeof(canfd_on));

candump.c

@@ -216,9 +216,7 @@ static int idx2dindex(int ifidx, int socket)
 
 	strcpy(devname[i], ifr.ifr_name);
 
-#ifdef DEBUG
-	printf("new index %d (%s)\n", i, devname[i]);
-#endif
+	pr_debug("new index %d (%s)\n", i, devname[i]);
 
 	return i;
 }
@@ -477,9 +475,7 @@ int main(int argc, char **argv)
 		ptr = argv[optind+i];
 		nptr = strchr(ptr, ',');
 
-#ifdef DEBUG
-		printf("open %d '%s'.\n", i, ptr);
-#endif
+		pr_debug("open %d '%s'.\n", i, ptr);
 
 		obj->s = socket(PF_CAN, SOCK_RAW, CAN_RAW);
 		if (obj->s < 0) {
@@ -513,9 +509,7 @@ int main(int argc, char **argv)
 		memset(&ifr.ifr_name, 0, sizeof(ifr.ifr_name));
 		strncpy(ifr.ifr_name, ptr, nbytes);
 
-#ifdef DEBUG
-		printf("using interface name '%s'.\n", ifr.ifr_name);
-#endif
+		pr_debug("using interface name '%s'.\n", ifr.ifr_name);
 
 		if (strcmp(ANYDEV, ifr.ifr_name) != 0) {
 			if (ioctl(obj->s, SIOCGIFINDEX, &ifr) < 0) {
@@ -605,9 +599,7 @@ int main(int argc, char **argv)
 			/* try SO_RCVBUFFORCE first, if we run with CAP_NET_ADMIN */
 			if (setsockopt(obj->s, SOL_SOCKET, SO_RCVBUFFORCE,
 				       &rcvbuf_size, sizeof(rcvbuf_size)) < 0) {
-#ifdef DEBUG
-				printf("SO_RCVBUFFORCE failed so try SO_RCVBUF ...\n");
-#endif
+				pr_debug("SO_RCVBUFFORCE failed so try SO_RCVBUF ...\n");
 				if (setsockopt(obj->s, SOL_SOCKET, SO_RCVBUF,
 					       &rcvbuf_size, sizeof(rcvbuf_size)) < 0) {
 					perror("setsockopt SO_RCVBUF");

canlogserver.c

@@ -145,9 +145,7 @@ int idx2dindex(int ifidx, int socket)
 
 	strcpy(devname[i], ifr.ifr_name);
 
-#ifdef DEBUG
-	printf("new index %d (%s)\n", i, devname[i]);
-#endif
+	pr_debug("new index %d (%s)\n", i, devname[i]);
 
 	return i;
 }
@@ -310,11 +308,9 @@ int main(int argc, char **argv)
 
 	for (i=0; i<currmax; i++) {
 
-#ifdef DEBUG
-		printf("open %d '%s' m%08X v%08X i%d e%d.\n",
-		       i, argv[optind+i], mask[i], value[i],
-		       inv_filter[i], err_mask[i]);
-#endif
+		pr_debug("open %d '%s' m%08X v%08X i%d e%d.\n",
+		      i, argv[optind+i], mask[i], value[i],
+		      inv_filter[i], err_mask[i]);
 
 		if ((s[i] = socket(PF_CAN, SOCK_RAW, CAN_RAW)) < 0) {
 			perror("socket");

lib.h

@@ -47,6 +47,13 @@
 
 #include <stdio.h>
 
+#ifdef DEBUG
+#define pr_debug(fmt, args...) printf(fmt, ##args)
+#else
+__attribute__((format (printf, 1, 2)))
+static inline int pr_debug(const char* fmt, ...) {return 0;}
+#endif
+
 /* buffer sizes for CAN frame string representations */
 
 #define CL_ID (sizeof("12345678##1"))

mcp251xfd/mcp251xfd-dev-coredump.c

@@ -17,18 +17,10 @@
 
 #include <linux/kernel.h>
 
+#include "lib.h"
 #include "mcp251xfd.h"
 #include "mcp251xfd-dump-userspace.h"
 
-#define pr_err(fmt, args...)    fprintf(stderr, fmt, ##args)
-#define pr_no(fmt, args...)     while (0) { fprintf(stdout, fmt, ##args); }
-
-#ifdef DEBUG
-#define pr_debug(fmt, args...) pr_err(fmt, ##args)
-#else
-#define pr_debug(fmt, args...) pr_no(fmt, ##args)
-#endif
-
 
 struct mcp251xfd_dump_iter {
 	const void *start;

slcanpty.c

@@ -49,8 +49,6 @@
 #define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
 #define DEVICE_NAME_PTMX "/dev/ptmx"
 
-#define DEBUG
-
 /* read data from pty, send CAN frames to CAN socket and answer commands */
 int pty2can(int pty, int socket, struct can_filter *fi,
 	    int *is_open, int *tstamp)
@@ -106,14 +104,12 @@ rx_restart:
 	cmd = buf[0];
 	buf[nbytes] = 0;
 
-#ifdef DEBUG
 	for (tmp = 0; tmp < nbytes; tmp++)
 		if (buf[tmp] == '\r')
-			putchar('@');
+			pr_debug("@");
 		else
-			putchar(buf[tmp]);
-	printf("\n");
-#endif
+			pr_debug("%c", buf[tmp]);
+	pr_debug("\n");
 
 	/* check for filter configuration commands */
 	if (cmd == 'm' || cmd == 'M') {