[ovs-dev] [PATCH] command-line: Add function to print all options.

[Alex Wang]

This commit adds function that extracts (both long and short)
options and returns them as string.  Right now, only ovs-appctl
command provides an option to print this function output.  And
the output is to be used by bash command-line completion script
for completion other options of the same command.

Signed-off-by: Alex Wang <alexw at nicira.com>
---
 lib/command-line.c     |   23 +++++++++++++++++++++++
 lib/command-line.h     |    1 +
 utilities/ovs-appctl.c |   18 ++++++++++++++++++
 3 files changed, 42 insertions(+)

diff --git a/lib/command-line.c b/lib/command-line.c
index cb73a25..820f3ff 100644
--- a/lib/command-line.c
+++ b/lib/command-line.c
@@ -19,6 +19,7 @@
 #include <getopt.h>
 #include <limits.h>
 #include <stdlib.h>
+#include "dynamic-string.h"
 #include "ovs-thread.h"
 #include "util.h"
 #include "vlog.h"
@@ -51,6 +52,28 @@ long_options_to_short_options(const struct option options[])
     return xstrdup(short_options);
 }
 
+/* Given the GNU-style options in 'options', returns a string which prints all
+ * options.  The caller is responsible for freeing the string. */
+char *
+print_options(const struct option options[])
+{
+    struct ds ds = DS_EMPTY_INITIALIZER;
+    char *ret;
+
+    for (; options->name; options++) {
+        const struct option *o = options;
+
+        ds_put_format(&ds, "--%s%s\n", o->name, o->has_arg ? "=ARG" : "");
+        if (o->flag == NULL && o->val > 0 && o->val <= UCHAR_MAX) {
+            ds_put_format(&ds, "-%c%s\n", o->val, o->has_arg ? " ARG" : "");
+        }
+    }
+    ret = xstrdup(ds_cstr(&ds));
+    ds_destroy(&ds);
+
+    return ret;
+}
+
 /* Runs the command designated by argv[0] within the command table specified by
  * 'commands', which must be terminated by a command whose 'name' member is a
  * null pointer.
diff --git a/lib/command-line.h b/lib/command-line.h
index bb12f72..f7d5d23 100644
--- a/lib/command-line.h
+++ b/lib/command-line.h
@@ -31,6 +31,7 @@ struct command {
 };
 
 char *long_options_to_short_options(const struct option *options);
+char *print_options(const struct option *options);
 void run_command(int argc, char *argv[], const struct command[]);
 
 void proctitle_init(int argc, char **argv);
diff --git a/utilities/ovs-appctl.c b/utilities/ovs-appctl.c
index bb17ec2..9ae5201 100644
--- a/utilities/ovs-appctl.c
+++ b/utilities/ovs-appctl.c
@@ -81,6 +81,18 @@ main(int argc, char *argv[])
 }
 
 static void
+print_appctl_options(const struct option options[])
+{
+    char *opts;
+
+    opts = print_options(options);
+    printf("%s", opts);
+    free(opts);
+
+    exit(EXIT_SUCCESS);
+}
+
+static void
 usage(void)
 {
     printf("\
@@ -110,12 +122,14 @@ static const char *
 parse_command_line(int argc, char *argv[])
 {
     enum {
+        OPT_START = UCHAR_MAX + 1,
         VLOG_OPTION_ENUMS
     };
     static const struct option long_options[] = {
         {"target", required_argument, NULL, 't'},
         {"execute", no_argument, NULL, 'e'},
         {"help", no_argument, NULL, 'h'},
+        {"option", no_argument, NULL, 'o'},
         {"version", no_argument, NULL, 'V'},
         {"timeout", required_argument, NULL, 'T'},
         VLOG_LONG_OPTIONS,
@@ -157,6 +171,10 @@ parse_command_line(int argc, char *argv[])
             usage();
             break;
 
+        case 'o':
+            print_appctl_options(long_options);
+            break;
+
         case 'T':
             time_alarm(atoi(optarg));
             break;
-- 
1.7.9.5