[libvirt] [PATCHv2 11/15] virsh: add option aliases

[Eric Blake]

In the past, we have created some virsh options with less-than-stellar
names.  For back-compat reasons, those names must continue to parse,
but we don't want to document them in help output.  This introduces
a new option type, an alias, which points to a canonical option name
later in the option list.

I'm actually quite impressed that our code has already been factored
to do all option parsing through common entry points, such that I
got this added in relatively few lines of code!

* tools/virsh.c (VSH_OT_ALIAS): New option type.
(opts_echo): Hook up an alias, for easy testing.
(vshCmddefOptParse, vshCmddefHelp, vshCmddefGetOption): Allow for
aliases.
* tests/virshtest.c (mymain): Test new feature.
---

v2: no real change

 tests/virshtest.c |    6 ++++++
 tools/virsh.c     |   28 ++++++++++++++++++++++++++--
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/tests/virshtest.c b/tests/virshtest.c
index 6474c19..87b1336 100644
--- a/tests/virshtest.c
+++ b/tests/virshtest.c
@@ -386,6 +386,12 @@ mymain(void)
     DO_TEST(30, "--shell a\n",
             "echo \t '-'\"-\" \t --shell \t a");

+    /* Tests of alias handling.  */
+    DO_TEST(31, "hello\n", "echo", "--string", "hello");
+    DO_TEST(32, "hello\n", "echo --string hello");
+    DO_TEST(33, "hello\n", "echo", "--str", "hello");
+    DO_TEST(34, "hello\n", "echo --str hello");
+
 # undef DO_TEST

     VIR_FREE(custom_uri);
diff --git a/tools/virsh.c b/tools/virsh.c
index aef050f..77cf4ac 100644
--- a/tools/virsh.c
+++ b/tools/virsh.c
@@ -138,7 +138,8 @@ typedef enum {
     VSH_OT_STRING,   /* optional string option */
     VSH_OT_INT,      /* optional or mandatory int option */
     VSH_OT_DATA,     /* string data (as non-option) */
-    VSH_OT_ARGV      /* remaining arguments */
+    VSH_OT_ARGV,     /* remaining arguments */
+    VSH_OT_ALIAS,    /* alternate spelling for a later argument */
 } vshCmdOptType;

 /*
@@ -190,7 +191,8 @@ typedef struct {
     const char *name;           /* the name of option, or NULL for list end */
     vshCmdOptType type;         /* option type */
     unsigned int flags;         /* flags */
-    const char *help;           /* non-NULL help string */
+    const char *help;           /* non-NULL help string; or for VSH_OT_ALIAS
+                                 * the name of a later public option */
 } vshCmdOptDef;

 /*
@@ -15209,6 +15211,7 @@ static const vshCmdInfo info_echo[] = {
 static const vshCmdOptDef opts_echo[] = {
     {"shell", VSH_OT_BOOL, 0, N_("escape for shell use")},
     {"xml", VSH_OT_BOOL, 0, N_("escape for XML use")},
+    {"str", VSH_OT_ALIAS, 0, "string"},
     {"string", VSH_OT_ARGV, 0, N_("arguments to echo")},
     {NULL, 0, 0, NULL}
 };
@@ -17256,6 +17259,18 @@ vshCmddefOptParse(const vshCmdDef *cmd, uint32_t *opts_need_arg,
                 return -1; /* bool options can't be mandatory */
             continue;
         }
+        if (opt->type == VSH_OT_ALIAS) {
+            int j;
+            if (opt->flags || !opt->help)
+                return -1; /* alias options are tracked by the original name */
+            for (j = i + 1; cmd->opts[j].name; j++) {
+                if (STREQ(opt->help, cmd->opts[j].name))
+                    break;
+            }
+            if (!cmd->opts[j].name)
+                return -1; /* alias option must map to a later option name */
+            continue;
+        }
         if (opt->flags & VSH_OFLAG_REQ_OPT) {
             if (opt->flags & VSH_OFLAG_REQ)
                 *opts_required |= 1 << i;
@@ -17287,6 +17302,10 @@ vshCmddefGetOption(vshControl *ctl, const vshCmdDef *cmd, const char *name,
         const vshCmdOptDef *opt = &cmd->opts[i];

         if (STREQ(opt->name, name)) {
+            if (opt->type == VSH_OT_ALIAS) {
+                name = opt->help;
+                continue;
+            }
             if ((*opts_seen & (1 << i)) && opt->type != VSH_OT_ARGV) {
                 vshError(ctl, _("option --%s already seen"), name);
                 return NULL;
@@ -17465,6 +17484,9 @@ vshCmddefHelp(vshControl *ctl, const char *cmdname)
                             : _("[<%s>]...");
                     }
                     break;
+                case VSH_OT_ALIAS:
+                    /* aliases are intentionally undocumented */
+                    continue;
                 default:
                     assert(0);
                 }
@@ -17506,6 +17528,8 @@ vshCmddefHelp(vshControl *ctl, const char *cmdname)
                              shortopt ? _("[--%s] <string>") : _("<%s>"),
                              opt->name);
                     break;
+                case VSH_OT_ALIAS:
+                    continue;
                 default:
                     assert(0);
                 }
-- 
1.7.7.6