command-line: add ovs_cmdl_context

I started working on a new command line utility that used this shared
code.  I wanted the ability to pass some data from common
initialization code to all of the commands.  You can find a similar
pattern in ovs-vsctl.

This patch updates the command handler to take a new struct,
ovs_cmdl_context, instead of argc and argv directly.  It includes argc
and argv, but also includes an opaque type (void *), where the user of
this API can attach its custom data it wants passed along to command
handlers.

This patch affected the ovstest sub-programs, as well.  The patch
includes a bit of an odd hack to OVSTEST_REGISTER() to avoid making
the main() function of the sub-programs take a ovs_cmdl_context.
The test main() functions still receive argc and argv directly, as
that seems more natural.  The test-subprograms themselves are able to
make use of a context internally, though.

Signed-off-by: Russell Bryant <[email protected]>
Signed-off-by: Ben Pfaff <[email protected]>

lib/command-line.c

@@ -92,27 +92,33 @@ ovs_cmdl_print_options(const struct option options[])
  * null pointer.
  *
  * Command-line options should be stripped off, so that a typical invocation
- * looks like "run_command(argc - optind, argv + optind, my_commands);". */
+ * looks like:
+ *    struct ovs_cmdl_context ctx = {
+ *        .argc = argc - optind,
+ *        .argv = argv + optind,
+ *    };
+ *    ovs_cmdl_run_command(&ctx, my_commands);
+ * */
 void
-ovs_cmdl_run_command(int argc, char *argv[], const struct ovs_cmdl_command commands[])
+ovs_cmdl_run_command(struct ovs_cmdl_context *ctx, const struct ovs_cmdl_command commands[])
 {
     const struct ovs_cmdl_command *p;
 
-    if (argc < 1) {
+    if (ctx->argc < 1) {
         ovs_fatal(0, "missing command name; use --help for help");
     }
 
     for (p = commands; p->name != NULL; p++) {
-        if (!strcmp(p->name, argv[0])) {
-            int n_arg = argc - 1;
+        if (!strcmp(p->name, ctx->argv[0])) {
+            int n_arg = ctx->argc - 1;
             if (n_arg < p->min_args) {
                 VLOG_FATAL( "'%s' command requires at least %d arguments",
                             p->name, p->min_args);
             } else if (n_arg > p->max_args) {
                 VLOG_FATAL("'%s' command takes at most %d arguments",
                            p->name, p->max_args);
             } else {
-                p->handler(argc, argv);
+                p->handler(ctx);
                 if (ferror(stdout)) {
                     VLOG_FATAL("write to stdout failed");
                 }
@@ -124,7 +130,7 @@ ovs_cmdl_run_command(int argc, char *argv[], const struct ovs_cmdl_command comma
         }
     }
 
-    VLOG_FATAL("unknown command '%s'; use --help for help", argv[0]);
+    VLOG_FATAL("unknown command '%s'; use --help for help", ctx->argv[0]);
 }
 
 /* Process title. */

lib/command-line.h

@@ -23,18 +23,30 @@
 
 struct option;
 
+/* Command handler context */
+struct ovs_cmdl_context {
+    /* number of command line arguments */
+    int argc;
+    /* array of command line arguments */
+    char **argv;
+    /* private context data defined by the API user */
+    void *pvt;
+};
+
+typedef void (*ovs_cmdl_handler)(struct ovs_cmdl_context *);
+
 struct ovs_cmdl_command {
     const char *name;
     const char *usage;
     int min_args;
     int max_args;
-    void (*handler)(int argc, char *argv[]);
+    ovs_cmdl_handler handler;
 };
 
 char *ovs_cmdl_long_options_to_short_options(const struct option *options);
 void ovs_cmdl_print_options(const struct option *options);
 void ovs_cmdl_print_commands(const struct ovs_cmdl_command *commands);
-void ovs_cmdl_run_command(int argc, char *argv[], const struct ovs_cmdl_command[]);
+void ovs_cmdl_run_command(struct ovs_cmdl_context *, const struct ovs_cmdl_command[]);
 
 void ovs_cmdl_proctitle_init(int argc, char **argv);
 #if defined(__FreeBSD__) || defined(__NetBSD__)

ovsdb/ovsdb-tool.c

@@ -55,10 +55,13 @@ static const char *default_schema(void);
 int
 main(int argc, char *argv[])
 {
+    struct ovs_cmdl_context ctx = { .argc = 0, };
     set_program_name(argv[0]);
     parse_options(argc, argv);
     fatal_ignore_sigpipe();
-    ovs_cmdl_run_command(argc - optind, argv + optind, get_all_commands());
+    ctx.argc = argc - optind;
+    ctx.argv = argv + optind;
+    ovs_cmdl_run_command(&ctx, get_all_commands());
     return 0;
 }
 
@@ -187,10 +190,10 @@ check_ovsdb_error(struct ovsdb_error *error)
 }
 
 static void
-do_create(int argc, char *argv[])
+do_create(struct ovs_cmdl_context *ctx)
 {
-    const char *db_file_name = argc >= 2 ? argv[1] : default_db();
-    const char *schema_file_name = argc >= 3 ? argv[2] : default_schema();
+    const char *db_file_name = ctx->argc >= 2 ? ctx->argv[1] : default_db();
+    const char *schema_file_name = ctx->argc >= 3 ? ctx->argv[2] : default_schema();
     struct ovsdb_schema *schema;
     struct ovsdb_log *log;
     struct json *json;
@@ -272,20 +275,20 @@ compact_or_convert(const char *src_name_, const char *dst_name_,
 }
 
 static void
-do_compact(int argc, char *argv[])
+do_compact(struct ovs_cmdl_context *ctx)
 {
-    const char *db = argc >= 2 ? argv[1] : default_db();
-    const char *target = argc >= 3 ? argv[2] : NULL;
+    const char *db = ctx->argc >= 2 ? ctx->argv[1] : default_db();
+    const char *target = ctx->argc >= 3 ? ctx->argv[2] : NULL;
 
     compact_or_convert(db, target, NULL, "compacted by ovsdb-tool "VERSION);
 }
 
 static void
-do_convert(int argc, char *argv[])
+do_convert(struct ovs_cmdl_context *ctx)
 {
-    const char *db = argc >= 2 ? argv[1] : default_db();
-    const char *schema = argc >= 3 ? argv[2] : default_schema();
-    const char *target = argc >= 4 ? argv[3] : NULL;
+    const char *db = ctx->argc >= 2 ? ctx->argv[1] : default_db();
+    const char *schema = ctx->argc >= 3 ? ctx->argv[2] : default_schema();
+    const char *target = ctx->argc >= 4 ? ctx->argv[3] : NULL;
     struct ovsdb_schema *new_schema;
 
     check_ovsdb_error(ovsdb_schema_from_file(schema, &new_schema));
@@ -295,10 +298,10 @@ do_convert(int argc, char *argv[])
 }
 
 static void
-do_needs_conversion(int argc, char *argv[])
+do_needs_conversion(struct ovs_cmdl_context *ctx)
 {
-    const char *db_file_name = argc >= 2 ? argv[1] : default_db();
-    const char *schema_file_name = argc >= 3 ? argv[2] : default_schema();
+    const char *db_file_name = ctx->argc >= 2 ? ctx->argv[1] : default_db();
+    const char *schema_file_name = ctx->argc >= 3 ? ctx->argv[2] : default_schema();
     struct ovsdb_schema *schema1, *schema2;
 
     check_ovsdb_error(ovsdb_file_read_schema(db_file_name, &schema1));
@@ -309,9 +312,9 @@ do_needs_conversion(int argc, char *argv[])
 }
 
 static void
-do_db_version(int argc, char *argv[])
+do_db_version(struct ovs_cmdl_context *ctx)
 {
-    const char *db_file_name = argc >= 2 ? argv[1] : default_db();
+    const char *db_file_name = ctx->argc >= 2 ? ctx->argv[1] : default_db();
     struct ovsdb_schema *schema;
 
     check_ovsdb_error(ovsdb_file_read_schema(db_file_name, &schema));
@@ -320,9 +323,9 @@ do_db_version(int argc, char *argv[])
 }
 
 static void
-do_db_cksum(int argc OVS_UNUSED, char *argv[])
+do_db_cksum(struct ovs_cmdl_context *ctx)
 {
-    const char *db_file_name = argc >= 2 ? argv[1] : default_db();
+    const char *db_file_name = ctx->argc >= 2 ? ctx->argv[1] : default_db();
     struct ovsdb_schema *schema;
 
     check_ovsdb_error(ovsdb_file_read_schema(db_file_name, &schema));
@@ -331,9 +334,9 @@ do_db_cksum(int argc OVS_UNUSED, char *argv[])
 }
 
 static void
-do_schema_version(int argc, char *argv[])
+do_schema_version(struct ovs_cmdl_context *ctx)
 {
-    const char *schema_file_name = argc >= 2 ? argv[1] : default_schema();
+    const char *schema_file_name = ctx->argc >= 2 ? ctx->argv[1] : default_schema();
     struct ovsdb_schema *schema;
 
     check_ovsdb_error(ovsdb_schema_from_file(schema_file_name, &schema));
@@ -342,9 +345,9 @@ do_schema_version(int argc, char *argv[])
 }
 
 static void
-do_schema_cksum(int argc, char *argv[])
+do_schema_cksum(struct ovs_cmdl_context *ctx)
 {
-    const char *schema_file_name = argc >= 2 ? argv[1] : default_schema();
+    const char *schema_file_name = ctx->argc >= 2 ? ctx->argv[1] : default_schema();
     struct ovsdb_schema *schema;
 
     check_ovsdb_error(ovsdb_schema_from_file(schema_file_name, &schema));
@@ -371,15 +374,15 @@ transact(bool read_only, int argc, char *argv[])
 }
 
 static void
-do_query(int argc, char *argv[])
+do_query(struct ovs_cmdl_context *ctx)
 {
-    transact(true, argc, argv);
+    transact(true, ctx->argc, ctx->argv);
 }
 
 static void
-do_transact(int argc, char *argv[])
+do_transact(struct ovs_cmdl_context *ctx)
 {
-    transact(false, argc, argv);
+    transact(false, ctx->argc, ctx->argv);
 }
 
 static void
@@ -495,9 +498,9 @@ print_db_changes(struct shash *tables, struct shash *names,
 }
 
 static void
-do_show_log(int argc, char *argv[])
+do_show_log(struct ovs_cmdl_context *ctx)
 {
-    const char *db_file_name = argc >= 2 ? argv[1] : default_db();
+    const char *db_file_name = ctx->argc >= 2 ? ctx->argv[1] : default_db();
     struct shash names;
     struct ovsdb_log *log;
     struct ovsdb_schema *schema;
@@ -558,13 +561,13 @@ do_show_log(int argc, char *argv[])
 }
 
 static void
-do_help(int argc OVS_UNUSED, char *argv[] OVS_UNUSED)
+do_help(struct ovs_cmdl_context *ctx OVS_UNUSED)
 {
     usage();
 }
 
 static void
-do_list_commands(int argc OVS_UNUSED, char *argv[] OVS_UNUSED)
+do_list_commands(struct ovs_cmdl_context *ctx OVS_UNUSED)
 {
      ovs_cmdl_print_commands(get_all_commands());
 }

tests/ovstest.c

@@ -60,7 +60,7 @@ flush_help_string(struct ds *ds)
 }
 
 static void
-help(int argc OVS_UNUSED, char *argv[] OVS_UNUSED)
+help(struct ovs_cmdl_context *ctx OVS_UNUSED)
 {
     const struct ovs_cmdl_command *p;
     struct ds test_names = DS_EMPTY_INITIALIZER;
@@ -92,7 +92,7 @@ add_top_level_commands(void)
 }
 
 void
-ovstest_register(const char *test_name, ovstest_func f)
+ovstest_register(const char *test_name, ovs_cmdl_handler f)
 {
     struct ovs_cmdl_command test_cmd;
 
@@ -125,7 +125,11 @@ main(int argc, char *argv[])
 
     add_top_level_commands();
     if (argc > 1) {
-        ovs_cmdl_run_command(argc - 1, argv + 1, commands);
+        struct ovs_cmdl_context ctx = {
+            .argc = argc - 1,
+            .argv = argv + 1,
+        };
+        ovs_cmdl_run_command(&ctx, commands);
     }
     cleanup();
 

tests/ovstest.h

@@ -19,6 +19,8 @@
 
 #include "compiler.h"
 
+#include "command-line.h"
+
 /* Overview
  * ========
  *
@@ -41,7 +43,8 @@
  */
 
 typedef void (*ovstest_func)(int argc, char *argv[]);
-void ovstest_register(const char *test_name, ovstest_func f);
+
+void ovstest_register(const char *test_name, ovs_cmdl_handler f);
 
 /* Usage
  * =====
@@ -72,8 +75,13 @@ void ovstest_register(const char *test_name, ovstest_func f);
  * OVSTEST_REGISTER("my-test", my_test_main);
  */
 #define OVSTEST_REGISTER(name, function) \
+    static void \
+    ovstest_wrapper_##function##__(struct ovs_cmdl_context *ctx) \
+    { \
+        function(ctx->argc, ctx->argv); \
+    } \
     OVS_CONSTRUCTOR(register_##function) { \
-        ovstest_register(name, function); \
+        ovstest_register(name, ovstest_wrapper_##function##__); \
     }
 
 #endif

tests/test-bitmap.c

@@ -121,17 +121,17 @@ run_test(void (*function)(void))
 }
 
 static void
-run_tests(int argc OVS_UNUSED, char *argv[] OVS_UNUSED)
+run_tests(struct ovs_cmdl_context *ctx OVS_UNUSED)
 {
     run_test(test_bitmap_equal);
     run_test(test_bitmap_scan);
     printf("\n");
 }
 
 static void
-run_benchmarks(int argc OVS_UNUSED, char *argv[])
+run_benchmarks(struct ovs_cmdl_context *ctx)
 {
-    int n_iter = strtol(argv[1], NULL, 10);
+    int n_iter = strtol(ctx->argv[1], NULL, 10);
     struct timeval start;
 
     xgettimeofday(&start);
@@ -157,8 +157,13 @@ static const struct ovs_cmdl_command commands[] = {
 static void
 test_bitmap_main(int argc, char *argv[])
 {
+    struct ovs_cmdl_context ctx = {
+        .argc = argc - 1,
+        .argv = argv + 1,
+    };
+
     set_program_name(argv[0]);
-    ovs_cmdl_run_command(argc - 1, argv + 1, commands);
+    ovs_cmdl_run_command(&ctx, commands);
 }
 
 OVSTEST_REGISTER("test-bitmap", test_bitmap_main);