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Re: [Libguestfs] [PATCH v2] fish: show synopsis if command syntax is wrong



How about the following?  I've made it use a named value
(RUN_WRONG_ARGS == -2) instead of just the magic number.

Also I removed an incorrect hunk from the original patch (space before
synopsis string is required).

Rich.

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>From 4c65e5564c525e7b4ab5d3268f37547b853c0d03 Mon Sep 17 00:00:00 2001
From: Hu Tao <hutao cn fujitsu com>
Date: Mon, 1 Dec 2014 18:26:12 +0800
Subject: [PATCH] fish: show synopsis if command syntax is wrong

This patch lets guestfish show command synopsis if the syntax of command issued
by user is wrong, rather than telling user that the number of parameters is wrong.

Signed-off-by: Hu Tao <hutao cn fujitsu com>
---
 fish/cmds-gperf.h |  1 +
 generator/fish.ml | 48 +++++++++++++++++++++++++-----------------------
 2 files changed, 26 insertions(+), 23 deletions(-)

diff --git a/fish/cmds-gperf.h b/fish/cmds-gperf.h
index 74db69d..bcb3b5d 100644
--- a/fish/cmds-gperf.h
+++ b/fish/cmds-gperf.h
@@ -25,6 +25,7 @@
 struct command_entry {
   const char *name;             /* Short name. */
   const char *help;             /* Online help. */
+  const char *synopsis;         /* Synopsis. */
 
   /* The run_* function. */
   int (*run) (const char *cmd, size_t argc, char *argv[]);
diff --git a/generator/fish.ml b/generator/fish.ml
index 3f53ffa..b609ce9 100644
--- a/generator/fish.ml
+++ b/generator/fish.ml
@@ -98,6 +98,10 @@ let generate_fish_cmds () =
   pr "/* Valid suffixes allowed for numbers.  See Gnulib xstrtol function. */\n";
   pr "static const char *xstrtol_suffixes = \"0kKMGTPEZY\";\n";
   pr "\n";
+  pr "/* Return these errors from run_* functions. */\n";
+  pr "#define RUN_ERROR -1\n";
+  pr "#define RUN_WRONG_ARGS -2\n";
+  pr "\n";
 
   List.iter (
     fun { name = name } ->
@@ -129,6 +133,7 @@ let generate_fish_cmds () =
       pr "struct command_entry %s_cmd_entry = {\n" name;
       pr "  .name = \"%s\",\n" name2;
       pr "  .help = \"%s\",\n" (c_quote text);
+      pr "  .synopsis = NULL,\n";
       pr "  .run = run_%s\n" name;
       pr "};\n";
       pr "\n";
@@ -190,6 +195,7 @@ Guestfish will prompt for these separately."
       pr "struct command_entry %s_cmd_entry = {\n" name;
       pr "  .name = \"%s\",\n" name2;
       pr "  .help = \"%s\",\n" (c_quote text);
+      pr "  .synopsis = \"%s\",\n" (c_quote synopsis);
       pr "  .run = run_%s\n" name;
       pr "};\n";
       pr "\n";
@@ -337,7 +343,7 @@ Guestfish will prompt for these separately."
       pr "static int\n";
       pr "run_%s (const char *cmd, size_t argc, char *argv[])\n" name;
       pr "{\n";
-      pr "  int ret = -1;\n";
+      pr "  int ret = RUN_ERROR;\n";
       (match ret with
        | RErr
        | RInt _
@@ -393,30 +399,14 @@ Guestfish will prompt for these separately."
 
       if argc_minimum = argc_maximum then (
         pr "  if (argc != %d) {\n" argc_minimum;
-        if argc_minimum = 0 then (
-          pr "    fprintf (stderr, _(\"%%s should have no parameters\\n\"), cmd);\n";
-        ) else (
-          pr "    fprintf (stderr, ngettext(\"%%s should have %%d parameter\\n\",\n";
-          pr "                              \"%%s should have %%d parameters\\n\",\n";
-          pr "                              %d),\n"
-            argc_minimum;
-          pr "                     cmd, %d);\n"
-            argc_minimum;
-        )
+          pr "    ret = RUN_WRONG_ARGS;\n";
       ) else if argc_minimum = 0 then (
         pr "  if (argc > %d) {\n" argc_maximum;
-        pr "    fprintf (stderr, ngettext(\"%%s should have at most %%d parameter\\n\",\n";
-        pr "                              \"%%s should have at most %%d parameters\\n\",\n";
-        pr "                              %d),\n"
-          argc_maximum;
-        pr "                     cmd, %d);\n"
-          argc_maximum;
+        pr "    ret = RUN_WRONG_ARGS;\n";
       ) else (
         pr "  if (argc < %d || argc > %d) {\n" argc_minimum argc_maximum;
-        pr "    fprintf (stderr, _(\"%%s should have %%d-%%d parameter(s)\\n\"), cmd, %d, %d);\n"
-          argc_minimum argc_maximum;
+        pr "    ret = RUN_WRONG_ARGS;\n";
       );
-      pr "    fprintf (stderr, _(\"type 'help %%s' for help on %%s\\n\"), cmd, cmd);\n";
       pr "    goto out_noargs;\n";
       pr "  }\n";
 
@@ -694,16 +684,28 @@ Guestfish will prompt for these separately."
   pr "run_action (const char *cmd, size_t argc, char *argv[])\n";
   pr "{\n";
   pr "  const struct command_table *ct;\n";
+  pr "  int ret = -1;\n";
   pr "\n";
   pr "  ct = lookup_fish_command (cmd, strlen (cmd));\n";
-  pr "  if (ct)\n";
-  pr "    return ct->entry->run (cmd, argc, argv);\n";
+  pr "  if (ct) {\n";
+  pr "    ret = ct->entry->run (cmd, argc, argv);\n";
+  pr "    /* run function may return magic value -2 (RUN_WRONG_ARGS) to indicate\n";
+  pr "     * that this function should print the command synopsis.\n";
+  pr "     */\n";
+  pr "    if (ret == RUN_WRONG_ARGS) {\n";
+  pr "      fprintf (stderr, _(\"error: incorrect number of arguments\\n\"));\n";
+  pr "      if (ct->entry->synopsis)\n";
+  pr "        fprintf (stderr, _(\"usage: %%s\\n\"), ct->entry->synopsis);\n";
+  pr "      fprintf (stderr, _(\"type 'help %%s' for more help on %%s\\n\"), cmd, cmd);\n";
+  pr "      ret = -1;\n";
+  pr "    }\n";
+  pr "  }\n";
   pr "  else {\n";
   pr "    fprintf (stderr, _(\"%%s: unknown command\\n\"), cmd);\n";
   pr "    if (command_num == 1)\n";
   pr "      extended_help_message ();\n";
-  pr "    return -1;\n";
   pr "  }\n";
+  pr "  return ret;\n";
   pr "}\n"
 
 and generate_fish_cmds_h () =
-- 
2.1.0


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