vshReadlineParse: Use string list

It's better to fetch list of either commands or options just once
and then iterate over it. Moreover, it makes future completers
way simpler as they will return string lists too.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

tools/vsh.c

@@ -2605,25 +2605,25 @@ vshTreePrint(vshControl *ctl, vshTreeLookup lookup, void *opaque,
  * -----------------
  */
 
-/*
- * Generator function for command completion.  STATE lets us
- * know whether to start from scratch; without any state
- * (i.e. STATE == 0), then we start at the top of the list.
+/**
+ * vshReadlineCommandGenerator:
+ * @text: optional command prefix
+ *
+ * Generator function for command completion.
+ *
+ * Returns a string list of commands with @text prefix,
+ * NULL if there's no such command.
  */
-static char *
-vshReadlineCommandGenerator(const char *text, int state)
+static char **
+vshReadlineCommandGenerator(const char *text)
 {
-    static unsigned int grp_list_index, cmd_list_index;
-    static size_t len;
+    size_t grp_list_index = 0, cmd_list_index = 0;
+    size_t len = strlen(text);
     const char *name;
     const vshCmdGrp *grp;
     const vshCmdDef *cmds;
-
-    if (!state) {
-        grp_list_index = 0;
-        cmd_list_index = 0;
-        len = strlen(text);
-    }
+    size_t ret_size = 0;
+    char **ret = NULL;
 
     grp = cmdGroups;
 
@@ -2638,8 +2638,16 @@ vshReadlineCommandGenerator(const char *text, int state)
                 if (cmds[cmd_list_index++].flags & VSH_CMD_FLAG_ALIAS)
                     continue;
 
-                if (STREQLEN(name, text, len))
-                    return vshStrdup(NULL, name);
+                if (STREQLEN(name, text, len)) {
+                    if (VIR_REALLOC_N(ret, ret_size + 2) < 0) {
+                        virStringListFree(ret);
+                        return NULL;
+                    }
+                    ret[ret_size] = vshStrdup(NULL, name);
+                    ret_size++;
+                    /* Terminate the string list properly. */
+                    ret[ret_size] = NULL;
+                }
             }
         } else {
             cmd_list_index = 0;
@@ -2647,23 +2655,17 @@ vshReadlineCommandGenerator(const char *text, int state)
         }
     }
 
-    /* If no names matched, then return NULL. */
-    return NULL;
+    return ret;
 }
 
-static char *
-vshReadlineOptionsGenerator(const char *text, int state, const vshCmdDef *cmd_parsed)
+static char **
+vshReadlineOptionsGenerator(const char *text, const vshCmdDef *cmd)
 {
-    static unsigned int list_index;
-    static size_t len;
-    static const vshCmdDef *cmd;
+    size_t list_index = 0;
+    size_t len = strlen(text);
     const char *name;
-
-    if (!state) {
-        cmd = cmd_parsed;
-        list_index = 0;
-        len = strlen(text);
-    }
+    size_t ret_size = 0;
+    char **ret = NULL;
 
     if (!cmd)
         return NULL;
@@ -2672,7 +2674,7 @@ vshReadlineOptionsGenerator(const char *text, int state, const vshCmdDef *cmd_pa
         return NULL;
 
     while ((name = cmd->opts[list_index].name)) {
-        char *res;
+        size_t name_len;
 
         list_index++;
 
@@ -2685,28 +2687,40 @@ vshReadlineOptionsGenerator(const char *text, int state, const vshCmdDef *cmd_pa
         } else if (STRNEQLEN(text, "--", len)) {
             return NULL;
         }
-        res = vshMalloc(NULL, strlen(name) + 3);
-        snprintf(res, strlen(name) + 3,  "--%s", name);
-        return res;
-    }
 
-    /* If no names matched, then return NULL. */
+        if (VIR_REALLOC_N(ret, ret_size + 2) < 0) {
+            virStringListFree(ret);
             return NULL;
+        }
+
+        name_len = strlen(name);
+        ret[ret_size] = vshMalloc(NULL, name_len + 3);
+        snprintf(ret[ret_size], name_len + 3,  "--%s", name);
+        ret_size++;
+        /* Terminate the string list properly. */
+        ret[ret_size] = NULL;
+    }
+
+    return ret;
 }
 
 static char *
 vshReadlineParse(const char *text, int state)
 {
     static vshCmd *partial;
-    static const vshCmdDef *cmd;
-    char *res = NULL;
+    static char **list;
+    static size_t list_index;
+    const vshCmdDef *cmd = NULL;
+    char *ret = NULL;
 
     if (!state) {
         char *buf = vshStrdup(NULL, rl_line_buffer);
 
         vshCommandFree(partial);
         partial = NULL;
-        cmd = NULL;
+        virStringListFree(list);
+        list = NULL;
+        list_index = 0;
 
         *(buf + rl_point) = '\0';
 
@@ -2729,26 +2743,37 @@ vshReadlineParse(const char *text, int state)
         }
     }
 
+    if (!list) {
         if (!cmd) {
-        res = vshReadlineCommandGenerator(text, state);
+            list = vshReadlineCommandGenerator(text);
         } else {
-        res = vshReadlineOptionsGenerator(text, state, cmd);
+            list = vshReadlineOptionsGenerator(text, cmd);
+        }
+    }
+
+    if (list) {
+        ret = vshStrdup(NULL, list[list_index]);
+        list_index++;
     }
 
-    if (res &&
+    if (ret &&
         !rl_completion_quote_character) {
         virBuffer buf = VIR_BUFFER_INITIALIZER;
-        virBufferEscapeShell(&buf, res);
-        VIR_FREE(res);
-        res = virBufferContentAndReset(&buf);
+        virBufferEscapeShell(&buf, ret);
+        VIR_FREE(ret);
+        ret = virBufferContentAndReset(&buf);
     }
 
-    if (!res) {
+    if (!ret) {
         vshCommandFree(partial);
         partial = NULL;
+        virStringListFree(list);
+        list = NULL;
+        list_index = 0;
     }
 
-    return res;
+    return ret;
+
 }
 
 static char **