Add "bootstat --output-dir" option.

bootstat.c

Index: bootstat.c
diff --git a/bootstat.c b/bootstat.c
index 573f9efe7880bb50bdfd6023022391f6890c3dc8..e13e0df3d3b061979f78da1f6b3c340bd4c7fd0b 100644
--- a/bootstat.c
+++ b/bootstat.c
@@ -1,4 +1,4 @@
-// Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+// Copyright (c) 2011 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.
 
@@ -6,26 +6,56 @@
 // 'bootstat' facility.  The command provides a command line wrapper
 // around the key functionality declared in "bootstat.h"
 
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
+#include <getopt.h>
 #include <libgen.h>
 
 #include "bootstat.h"
 
-static void usage(char* cmd)
+static void usage(const char* cmd)
 {
-  fprintf(stderr, "usage: %s <event-name>\n", basename(strdup(cmd)));
+  fprintf(stderr,
+    "usage: %s [options] <event-name>\n"
+    "Options:\n"
+    " -o/--output-dir <directory>\n"
+    "   specify alternate directory for timestamp output\n",
+    basename(strdup(cmd)));
   exit(EXIT_FAILURE);
 }
 
 
 int main(int argc, char* argv[])
 {
-  if (argc != 2)
-    usage(argv[0]);
-
-  bootstat_log(argv[1]);
+  static const struct option command_options[] = {
+    { "o", required_argument, NULL, 'o' },
+    { "output-dir", required_argument, NULL, 'o' },
+    { 0, 0, 0, 0 }
+  };
+  char *output_dir = NULL;
+
+  for (;;) {
+    int c = getopt_long_only(argc, argv, "", command_options, NULL);
+
+    if (c == -1) {
+      break;
+    }
+
+    if (c == 'o') {
+      output_dir = optarg;
+    }
+  }
+
+  if (output_dir != NULL) {
+    if (bootstat_set_output_directory(output_dir) < 0) {
+      perror(output_dir);
+      usage(argv[0]);
+    }
+  }
+
+  bootstat_log(argv[optind]);
   return EXIT_SUCCESS;
 }