ifctrstat: Initial structure for new applet

.gitignore

@@ -12,4 +12,5 @@ ifupdown
 ifquery
 ifup
 ifdown
+ifctrstat
 *.lock

Makefile

@@ -62,6 +62,13 @@ MULTICALL_${CONFIG_IFQUERY}_OBJ += ${IFQUERY_SRC:.c=.o}
 CMDS_${CONFIG_IFQUERY} += ifquery
 CPPFLAGS_${CONFIG_IFQUERY} += -DCONFIG_IFQUERY
 
+# enable ifctrstat applet (+9 KB)
+CONFIG_IFCTRSTAT ?= Y
+IFCTRSTAT_SRC = cmd/ifctrstat.c cmd/ifctrstat_linux.c
+MULTICALL_${CONFIG_IFCTRSTAT}_OBJ += ${IFCTRSTAT_SRC:.c=.o}
+CMDS_${CONFIG_IFCTRSTAT} += ifctrstat
+CPPFLAGS_${CONFIG_IFCTRSTAT} += -DCONFIG_IFCTRSTAT
+
 MULTICALL_OBJ += ${MULTICALL_Y_OBJ}
 CMDS += ${CMDS_Y}
 CPPFLAGS += ${CPPFLAGS_Y}

cmd/ifctrstat.c

@@ -0,0 +1,111 @@
+/*
+ * cmd/ifctrstat.c
+ * Purpose: Display statistics about interfaces on the system
+ *
+ * Copyright (c) 2020 Adélie Software in the Public Benefit, Inc.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * This software is provided 'as is' and without any warranty, express or
+ * implied.  In no event shall the authors be liable for any damages arising
+ * from the use of this software.
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <getopt.h>
+#include "libifupdown/libifupdown.h"
+#include "cmd/multicall.h"
+
+extern const char *avail_counters[];
+extern int avail_counters_count;
+
+extern const char *read_counter(const char *interface, const char *counter);
+
+static bool
+counter_is_valid(const char *candidate)
+{
+	for (int i = 0; i < avail_counters_count; i++)
+	{
+		if (strcasecmp(avail_counters[i], candidate) == 0)
+			return true;
+	}
+
+	return false;
+}
+
+void
+ifstats_list_counters(int short_opt, const struct if_option *opt,
+		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++) {
+		fprintf(stdout, "%s\n", avail_counters[i]);
+	}
+
+	exit(EXIT_SUCCESS);
+}
+
+int
+ifstats_main(int argc, char *argv[])
+{
+	if (optind >= argc)
+		generic_usage(self_applet, EXIT_FAILURE);
+
+	int idx = optind;
+	if (argc - idx < 2)
+	{
+		fprintf(stderr, "%s: interface and counter(s) required\n",
+			argv0);
+		return EXIT_FAILURE;
+	}
+
+	const char *iface = argv[idx++];
+
+	for (; idx < argc; idx++)
+	{
+		if (!counter_is_valid(argv[idx]))
+		{
+			fprintf(stderr, "%s: counter %s is not valid or not "
+					"available\n", argv0, argv[idx]);
+			return EXIT_FAILURE;
+		}
+
+		errno = 0;
+		const char *res = read_counter(iface, argv[idx]);
+		if (!res)
+		{
+			fprintf(stderr, "%s: could not determine value of "
+					"%s for interface %s: %s\n", argv0,
+					argv[idx], iface, strerror(errno));
+			return EXIT_FAILURE;
+		}
+	}
+
+	return EXIT_SUCCESS;
+}
+
+static struct if_option local_options[] = {
+	{'L', "list", NULL, "List available counters", false, ifstats_list_counters}
+};
+
+static struct if_option_group local_option_group = {
+	.desc = "Program-specific options",
+	.group_size = ARRAY_SIZE(local_options),
+	.group = local_options
+};
+
+struct if_applet ifctrstat_applet = {
+	.name = "ifctrstat",
+	.desc = "Display statistics about an interface",
+	.main = ifstats_main,
+	.usage = "ifctrstat [options] <interface> <counter>\n  ifctrstat [options] --list\n",
+	.groups = { &global_option_group, &local_option_group, NULL }
+};

cmd/ifctrstat_linux.c

@@ -0,0 +1,37 @@
+/*
+ * cmd/ifctrstat_linux.c
+ * Purpose: Implement ifstats system-specific routines for Linux
+ *
+ * Copyright (c) 2020 Adélie Software in the Public Benefit, Inc.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * This software is provided 'as is' and without any warranty, express or
+ * implied.  In no event shall the authors be liable for any damages arising
+ * from the use of this software.
+ */
+
+#include <errno.h>
+#include <stdio.h>
+
+const char *avail_counters[] = {
+	"rx.octets",
+	"rx.packets",
+	"rx.discard",
+	"rx.errors",
+	"tx.octets",
+	"tx.packets",
+	"tx.discard",
+	"tx.errors"
+};
+
+size_t avail_counters_count = sizeof(avail_counters) / sizeof(*avail_counters);
+
+const char *
+read_counter(const char *interface, const char *counter)
+{
+	errno = ENOSYS;
+	return NULL;
+}

cmd/multicall.c

@@ -32,10 +32,17 @@ extern struct if_applet ifup_applet;
 extern struct if_applet ifdown_applet;
 #endif
 
+#ifdef CONFIG_IFCTRSTAT
+extern struct if_applet ifctrstat_applet;
+#endif
+
 struct if_applet ifupdown_applet;
 const struct if_applet *self_applet = NULL;
 
 struct if_applet *applet_table[] = {
+#ifdef CONFIG_IFCTRSTAT
+	&ifctrstat_applet,
+#endif
 #ifdef CONFIG_IFUPDOWN
 	&ifdown_applet,
 #endif