tools: add static-nodes tool

This tool reads modules.devname from the current kernel directory and outputs
the information. By default in a human-readable format, and optionally in
machine-readable formats.

For now only the tmpfiles.d(5) format is supported, but more could easily be
added in the future if there is a need.

This means nothing but kmod needs to reads the private files under
/lib/modules/. In particular systemd-udevd can stop reading modules.devname.

Tools that used to read /lib/modules/`uname -r`/modules.devname directly, can
now move to reading 'kmod static-nodes devname'.

4 files changed, 250 insertions, 1 deletions

diff --git a/Makefile.am b/Makefile.am
index fe4c769..b1bfd59 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -110,7 +110,8 @@ noinst_SCRIPTS = tools/insmod tools/rmmod tools/lsmod \
 tools_kmod_SOURCES = tools/kmod.c tools/kmod.h tools/lsmod.c \
 		     tools/rmmod.c tools/insmod.c \
 		     tools/modinfo.c tools/modprobe.c \
-		     tools/depmod.c tools/log.h tools/log.c
+		     tools/depmod.c tools/log.h tools/log.c \
+		     tools/static-nodes.c
 tools_kmod_LDADD = libkmod/libkmod-util.la \
 		   libkmod/libkmod.la
 
diff --git a/tools/kmod.c b/tools/kmod.c
index ebb8875..347bb7d 100644
--- a/tools/kmod.c
+++ b/tools/kmod.c
@@ -37,6 +37,7 @@ static const struct kmod_cmd kmod_cmd_help;
 static const struct kmod_cmd *kmod_cmds[] = {
 	&kmod_cmd_help,
 	&kmod_cmd_list,
+	&kmod_cmd_static_nodes,
 };
 
 static const struct kmod_cmd *kmod_compat_cmds[] = {
diff --git a/tools/kmod.h b/tools/kmod.h
index 80fa4c2..68a646a 100644
--- a/tools/kmod.h
+++ b/tools/kmod.h
@@ -35,5 +35,6 @@ extern const struct kmod_cmd kmod_cmd_compat_modprobe;
 extern const struct kmod_cmd kmod_cmd_compat_depmod;
 
 extern const struct kmod_cmd kmod_cmd_list;
+extern const struct kmod_cmd kmod_cmd_static_nodes;
 
 #include "log.h"
diff --git a/tools/static-nodes.c b/tools/static-nodes.c
new file mode 100644
index 0000000..94a48c6
--- /dev/null
+++ b/tools/static-nodes.c
@@ -0,0 +1,246 @@
+/*
+ * kmod-static-nodes - manage modules.devname
+ *
+ * Copyright (C) 2004-2012 Kay Sievers <kay@vrfy.org>
+ * Copyright (C) 2011-2013  ProFUSION embedded systems
+ * Copyright (C) 2013 Tom Gundersen <teg@jklm.no>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include <getopt.h>
+#include <errno.h>
+#include <unistd.h>
+#include <string.h>
+#include <limits.h>
+#include <sys/utsname.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include "libkmod-util.h"
+
+#include "kmod.h"
+
+struct static_nodes_format {
+        const char *name;
+        int (*write)(FILE *, char[], char[], char, unsigned int, unsigned int);
+        const char *description;
+};
+
+static const struct static_nodes_format static_nodes_format_human;
+static const struct static_nodes_format static_nodes_format_tmpfiles;
+static const struct static_nodes_format static_nodes_format_devname;
+
+static const struct static_nodes_format *static_nodes_formats[] = {
+        &static_nodes_format_human,
+        &static_nodes_format_tmpfiles,
+        &static_nodes_format_devname,
+};
+
+static const char cmdopts_s[] = "o:f:h";
+static const struct option cmdopts[] = {
+        { "output", required_argument, 0, 'o'},
+        { "format", required_argument, 0, 'f'},
+        { "help", no_argument, 0, 'h'},
+        { },
+};
+
+static int write_human(FILE *out, char modname[], char devname[], char type, unsigned int maj, unsigned int min)
+{
+        int ret;
+
+        ret = fprintf(out,
+                        "Module: %s\n"
+                        "\tDevice node: /dev/%s\n"
+                        "\t\tType: %s device\n"
+                        "\t\tMajor: %u\n"
+                        "\t\tMinor: %u\n",
+                        modname, devname, (type == 'c') ? "character" : "block", maj, min);
+        if (ret >= 0)
+                return EXIT_SUCCESS;
+        else
+                return EXIT_FAILURE;
+}
+
+static const struct static_nodes_format static_nodes_format_human = {
+	.name = "human",
+	.write = write_human,
+        .description = "(default) a human readable format. Do not parse.",
+};
+
+
+static int write_tmpfiles(FILE *out, char modname[], char devname[], char type, unsigned int maj, unsigned int min)
+{
+        int ret;
+
+        ret = fprintf(out, "%c /dev/%s 0600 - - - %u:%u\n", type, devname, maj, min);
+        if (ret >= 0)
+                return EXIT_SUCCESS;
+        else
+                return EXIT_FAILURE;
+}
+
+static const struct static_nodes_format static_nodes_format_tmpfiles = {
+	.name = "tmpfiles",
+	.write = write_tmpfiles,
+        .description = "the tmpfiles.d(5) format used by systemd-tmpfiles.",
+};
+
+static int write_devname(FILE *out, char modname[], char devname[], char type, unsigned int maj, unsigned int min)
+{
+        int ret;
+
+        ret = fprintf(out, "%s %s %c%u:%u\n", modname, devname, type, maj, min);
+        if (ret >= 0)
+                return EXIT_SUCCESS;
+        else
+                return EXIT_FAILURE;
+}
+
+static const struct static_nodes_format static_nodes_format_devname = {
+	.name = "devname",
+	.write = write_devname,
+        .description = "the modules.devname format.",
+};
+
+static void help(void)
+{
+        size_t i;
+
+        printf("Usage:\n"
+                "\t%s static-nodes [options]\n"
+                "\n"
+                "kmod static-nodes outputs the static-node information of the currently running kernel.\n"
+                "\n"
+                "Options:\n"
+                "\t-f, --format=FORMAT  use a machine-readable format\n"
+                "\t-o, --output=FILE    write output to file\n"
+                "\t-h, --help           show this help\n"
+                "\n"
+                "Formats:\n",
+                program_invocation_short_name);
+
+        for (i = 0; i < ARRAY_SIZE(static_nodes_formats); i++) {
+                if (static_nodes_formats[i]->description != NULL) {
+                        printf("\t%-12s %s\n", static_nodes_formats[i]->name,
+                                        static_nodes_formats[i]->description);
+                }
+        }
+}
+
+static int do_static_nodes(int argc, char *argv[])
+{
+        struct utsname kernel;
+        char modules[PATH_MAX];
+        FILE *in = NULL, *out = stdout;
+        const struct static_nodes_format *format = &static_nodes_format_human;
+        char buf[4096];
+        int ret = EXIT_SUCCESS;
+
+        for (;;) {
+                int c, idx = 0, valid;
+                size_t i;
+
+                c = getopt_long(argc, argv, cmdopts_s, cmdopts, &idx);
+                if (c == -1) {
+                        break;
+                }
+                switch (c) {
+                case 'o':
+                        out = fopen(optarg, "we");
+                        if (out == NULL) {
+                                fprintf(stderr, "Error: could not create %s!\n", optarg);
+                                ret = EXIT_FAILURE;
+                                goto finish;
+                        }
+                        break;
+                case 'f':
+                        valid = 0;
+
+                        for (i = 0; i < ARRAY_SIZE(static_nodes_formats); i++) {
+                                if (streq(static_nodes_formats[i]->name, optarg)) {
+                                        format = static_nodes_formats[i];
+                                        valid = 1;
+                                }
+                        }
+
+                        if (!valid) {
+                                fprintf(stderr, "Unknown format: '%s'.\n", optarg);
+                                help();
+                                ret = EXIT_FAILURE;
+                                goto finish;
+                        }
+                        break;
+                case 'h':
+                        help();
+                        goto finish;
+                case '?':
+                        ret = EXIT_FAILURE;
+                        goto finish;
+                default:
+                        fprintf(stderr, "Unexpected commandline option '%c'.\n", c);
+                        help();
+                        ret = EXIT_FAILURE;
+                        goto finish;
+                }
+        }
+
+        if (uname(&kernel) < 0) {
+                fputs("Error: uname failed!\n", stderr);
+                ret = EXIT_FAILURE;
+                goto finish;
+        }
+        snprintf(modules, sizeof(modules), "/lib/modules/%s/modules.devname", kernel.release);
+        in = fopen(modules, "re");
+        if (in == NULL && errno != ENOENT) {
+                fprintf(stderr, "Error: could not open /lib/modules/%s/modules.devname!\n", kernel.release);
+                ret = EXIT_FAILURE;
+                goto finish;
+        }
+
+        while (fgets(buf, sizeof(buf), in) != NULL) {
+                char modname[PATH_MAX];
+                char devname[PATH_MAX];
+                char type;
+                unsigned int maj, min;
+                int matches;
+
+                if (buf[0] == '#')
+                        continue;
+
+                matches = sscanf(buf, "%s %s %c%u:%u", modname, devname, &type, &maj, &min);
+                if (matches != 5 || (type != 'c' && type != 'b')) {
+                        fprintf(stderr, "Error: invalid devname entry: %s", buf);
+                        ret = EXIT_FAILURE;
+                        continue;
+                }
+
+                format->write(out, modname, devname, type, maj, min);
+        }
+
+finish:
+        if (in)
+                fclose(in);
+        if (out)
+                fclose(out);
+        return ret;
+}
+
+const struct kmod_cmd kmod_cmd_static_nodes = {
+	.name = "static-nodes",
+	.cmd = do_static_nodes,
+	.help = "outputs the static-node information installed with the currently running kernel",
+};