rootdev: fix -d, add -c and -r. ifdefs for so use

main.c

+/* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Driver for using rootdev.c from the commandline
+ */
+#include <err.h>
+#include <errno.h>
+#include <getopt.h>
+#include <linux/limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "rootdev.h"
+
+static void print_help(const char *progname) {
+  fprintf(stderr,
+    "%s [OPTIONS] [PATH]\n"
+    "Outputs the containing device for the specified PATH.\n"
+    "With no arguments, '/' is assumed.\n"
+    "\n"
+    "Options:\n"
+    "  -h\tthis message.\n"
+    "\n"
+    "  -c\tcreate the /dev node if it cannot be found\n"
+    "  -d\treturn the block device only if possible\n"
+    "  -i\treturn path even if the node doesn't exist\n"
+    "  -s\tif possible, return the first slave of the root device\n"
+    "\n"
+    "  --block [path]\tset the path to block under the sys mount point\n"
+    "  --dev [path]\tset the path to dev mount point\n"
+    "  --major [num]\tset the major number of the rootdev\n"
+    "  --minor [num]\tset the minor number of the rootdev\n",
+    progname);
+}
+
+static int flag_help = 0;
+static int flag_use_slave = 0;
+static int flag_strip_partition = 0;
+static int flag_ignore = 0;
+static int flag_create = 0;
+static int flag_major = 0;
+static int flag_minor = 0;
+static const char *flag_path = "/";
+static char *flag_block_path = "/sys/block";
+static char *flag_dev_path = "/dev";
+
+static void parse_args(int argc, char **argv) {
+  while (1) {
+    int c;
+    int option_index = 0;
+    static const struct option long_options[] = {
+      {"c", no_argument, &flag_create, 1},
+      {"d", no_argument, &flag_strip_partition, 1},
+      {"h", no_argument, &flag_help, 1},
+      {"i", no_argument, &flag_ignore, 1},
+      {"s", no_argument, &flag_use_slave, 1},
+      /* Long arguments for testing. */
+      {"block", required_argument, NULL, 'b'},
+      {"dev", required_argument, NULL, 'd'},
+      {"major", required_argument, NULL, 'M'},
+      {"minor", required_argument, NULL, 'm'},
+      {0, 0, 0, 0}
+    };
+    c = getopt_long_only(argc, argv, "", long_options, &option_index);
+
+    if (c == -1)
+      break;
+
+    if (c == '?') {
+      flag_help = 1;
+      break;
+    }
+
+    switch (c) {
+    case 'b':
+      flag_block_path = optarg;
+      break;
+    case 'd':
+      flag_dev_path = optarg;
+      break;
+    case 'M':
+      flag_major = atoi(optarg);
+      break;
+    case 'm':
+      flag_minor = atoi(optarg);
+      break;
+    }
+
+  }
+
+  if (flag_create && flag_strip_partition) {
+    flag_help = 1;
+    warnx("-c and -d are incompatible at present.");
+    return;
+  }
+
+  if (optind < argc) {
+    flag_path = argv[optind++];
+  }
+
+  if (optind < argc) {
+    fprintf(stderr, "Too many free arguments: %d\n", argc - optind);
+    flag_help = 1;
+   }
+}
+
+int main(int argc, char **argv) {
+  struct stat path_stat;
+  char path[PATH_MAX];
+  int ret;
+  dev_t root_dev;
+  parse_args(argc, argv);
+
+  if (flag_help) {
+    print_help(argv[0]);
+    return 1;
+  }
+
+  if (flag_major || flag_minor) {
+    root_dev = makedev(flag_major, flag_minor);
+  } else {
+    /* Yields the containing dev_t in st_dev. */
+    if (stat(flag_path, &path_stat) != 0)
+      err(1, "Cannot stat(%s)", flag_path);
+    root_dev = path_stat.st_dev;
+  }
+
+  ret = rootdev_wrapper(path, sizeof(path),
+                        flag_use_slave,
+                        flag_strip_partition,
+                        &root_dev,
+                        flag_block_path,
+                        flag_dev_path);
+
+  if (ret == 1 && flag_create) {
+    /* TODO(wad) add flag_force to allow replacement */
+    ret = 0;
+    if (mknod(path, S_IFBLK | S_IRUSR | S_IWUSR, root_dev) && errno != EEXIST) {
+      warn("failed to create %s", path);
+      ret = 1;
+    }
+  }
+
+  if (flag_ignore && ret > 0)
+    ret = 0;
+
+  if (path[0] != '\0')
+    printf("%s\n", path);
+
+  return ret;
+}