ifctrstat: Add ability to output counter values

Makefile

@@ -62,7 +62,7 @@ MULTICALL_${CONFIG_IFQUERY}_OBJ += ${IFQUERY_SRC:.c=.o}
 CMDS_${CONFIG_IFQUERY} += ifquery
 CPPFLAGS_${CONFIG_IFQUERY} += -DCONFIG_IFQUERY
 
-# enable ifctrstat applet (+9 KB)
+# enable ifctrstat applet (+16 KB)
 CONFIG_IFCTRSTAT ?= Y
 IFCTRSTAT_SRC = cmd/ifctrstat.c cmd/ifctrstat-${LAYOUT}.c
 MULTICALL_${CONFIG_IFCTRSTAT}_OBJ += ${IFCTRSTAT_SRC:.c=.o}

cmd/ifctrstat-linux.c

@@ -14,7 +14,9 @@
  */
 
 #include <errno.h>
+#include <limits.h>
 #include <stdio.h>
+#include <string.h>
 #include "multicall.h"
 
 const char *avail_counters[] = {
@@ -30,9 +32,69 @@ const char *avail_counters[] = {
 
 size_t avail_counters_count = ARRAY_SIZE(avail_counters);
 
-const char *
+char *
 read_counter(const char *interface, const char *counter)
 {
-	errno = ENOSYS;
+	FILE *fp;
-	return NULL;
+	const char *path;
+	char full_path[PATH_MAX];
+	char buffer[1024];
+	size_t in_count;
+
+	errno = 0;
+
+	if (strcasecmp(counter, "rx.octets") == 0)
+	{
+		path = "rx_bytes";
+	} else if (strcasecmp(counter, "rx.packets") == 0) {
+		path = "rx_packets";
+	} else if (strcasecmp(counter, "rx.discard") == 0) {
+		path = "rx_dropped";
+	} else if (strcasecmp(counter, "rx.errors") == 0) {
+		path = "rx_errors";
+	} else if (strcasecmp(counter, "tx.octets") == 0) {
+		path = "tx_bytes";
+	} else if (strcasecmp(counter, "tx.packets") == 0) {
+		path = "tx_packets";
+	} else if (strcasecmp(counter, "tx.discard") == 0) {
+		path = "tx_dropped";
+	} else if (strcasecmp(counter, "tx.errors") == 0) {
+		path = "tx_errors";
+	} else {
+		errno = ENOSYS;
+		return NULL;
+	}
+
+	if (snprintf(full_path, PATH_MAX, "/sys/class/net/%s/statistics/%s", interface, path) > PATH_MAX)
+	{
+		errno = ENOMEM;
+		return NULL;
+	}
+
+	fp = fopen(full_path, "r");
+	if (!fp)
+	{
+		return NULL;
+	}
+
+	in_count = fread(buffer, 1, sizeof(buffer), fp);
+
+	if (in_count == sizeof(buffer))
+	{
+		errno = ENOMEM;
+		fclose(fp);
+		return NULL;
+	}
+
+	if (ferror(fp))
+	{
+		return NULL;
+	}
+
+	fclose(fp);
+
+	/* take away the \n, we add our own */
+	buffer[in_count - 1] = '\0';
+
+	return strdup(buffer);
 }

cmd/ifctrstat.c

@@ -37,16 +37,44 @@ counter_is_valid(const char *candidate)
 	return false;
 }
 
+static void
+print_counter(const char *iface, const char *name, const char *value)
+{
+	fprintf(stdout, "%s: %s\n", name, value);
+}
+
+static int
+print_all_counters(const char *iface)
+{
+	int code = EXIT_SUCCESS;
+	const char *res;
+
+	for (int i = 0; i < avail_counters_count; i++) {
+		const char *ctr = avail_counters[i];
+
+		res = read_counter(iface, ctr);
+		if (!res)
+		{
+			fprintf(stderr, "%s: could not determine value of %s for interface %s: %s\n", argv0, ctr, iface, strerror(errno));
+			code = EXIT_FAILURE;
+		} else {
+			print_counter(iface, ctr, res);
+		}
+	}
+
+	return code;
+}
+
 void
-ifstats_list_counters(int short_opt, const struct if_option *opt,
+ifctrstat_list_counters(int short_opt, const struct if_option *opt, const char *opt_arg, const struct if_applet *applet)
-		const char *opt_arg, const struct if_applet *applet)
 {
 	(void) short_opt;
 	(void) opt;
 	(void) opt_arg;
 	(void) applet;
 
-	for (int i = 0; i < avail_counters_count; i++) {
+	for (int i = 0; i < avail_counters_count; i++)
+	{
 		fprintf(stdout, "%s\n", avail_counters[i]);
 	}
 
@@ -54,27 +82,31 @@ ifstats_list_counters(int short_opt, const struct if_option *opt,
 }
 
 int
-ifstats_main(int argc, char *argv[])
+ifctrstat_main(int argc, char *argv[])
 {
 	if (optind >= argc)
 		generic_usage(self_applet, EXIT_FAILURE);
 
 	int idx = optind;
-	if (argc - idx < 2)
+	if (argc - idx == 0)
 	{
-		fprintf(stderr, "%s: interface and counter(s) required\n",
+		fprintf(stderr, "%s: interface required\n",
 			argv0);
 		return EXIT_FAILURE;
 	}
 
 	const char *iface = argv[idx++];
 
+	if (argc - idx == 0)
+	{
+		return print_all_counters(iface);
+	}
+
 	for (; idx < argc; idx++)
 	{
 		if (!counter_is_valid(argv[idx]))
 		{
-			fprintf(stderr, "%s: counter %s is not valid or not "
+			fprintf(stderr, "%s: counter %s is not valid or not available\n", argv0, argv[idx]);
-					"available\n", argv0, argv[idx]);
 			return EXIT_FAILURE;
 		}
 
@@ -82,18 +114,18 @@ ifstats_main(int argc, char *argv[])
 		const char *res = read_counter(iface, argv[idx]);
 		if (!res)
 		{
-			fprintf(stderr, "%s: could not determine value of "
+			fprintf(stderr, "%s: could not determine value of %s for interface %s: %s\n", argv0, argv[idx], iface, strerror(errno));
-					"%s for interface %s: %s\n", argv0,
-					argv[idx], iface, strerror(errno));
 			return EXIT_FAILURE;
 		}
+
+		print_counter(iface, argv[idx], res);
 	}
 
 	return EXIT_SUCCESS;
 }
 
 static struct if_option local_options[] = {
-	{'L', "list", NULL, "List available counters", false, ifstats_list_counters}
+	{'L', "list", NULL, "List available counters", false, ifctrstat_list_counters}
 };
 
 static struct if_option_group local_option_group = {
@@ -105,7 +137,7 @@ static struct if_option_group local_option_group = {
 struct if_applet ifctrstat_applet = {
 	.name = "ifctrstat",
 	.desc = "Display statistics about an interface",
-	.main = ifstats_main,
+	.main = ifctrstat_main,
 	.usage = "ifctrstat [options] <interface> <counter>\n  ifctrstat [options] --list\n",
 	.groups = { &global_option_group, &local_option_group, NULL }
 };