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Re: [Qemu-devel] [PATCH V15 3/6] Create four QemuOptsList related functi


From: Dongxu Wang
Subject: Re: [Qemu-devel] [PATCH V15 3/6] Create four QemuOptsList related functions
Date: Fri, 31 May 2013 10:26:11 +0800
User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130509 Thunderbird/17.0.6

On 2013/5/31 5:43, Eric Blake wrote:
On 05/30/2013 03:55 AM, Dongxu Wang wrote:
From: Dong Xu Wang <address@hidden>

This patch will create 4 functions, count_opts_list, qemu_opts_append,

s/will create/creates/ - commit messages make the most sense when
written in present tense

qemu_opts_free and qemu_opts_print_help, they will be used in following
commits.


Again, this portion...

v12->v13:
1) simply assert that neither argument has merge_lists set.
2) drop superfluous paranthesesis around p == first.

v11->v12:
1) renmae functions.
2) fix loop styles and code styles.
3) qemu_opts_apend will not return NULL now.
4) merge_lists value is from arguments in qemu_opts_append.

v6->v7:
1) Fix typo.

v5->v6:
1) allocate enough space in append_opts_list function.

...belongs after '---', and


Signed-off-by: Dong Xu Wang <address@hidden>
Signed-off-by: Dongxu Wang <address@hidden>

your s-o-b is unusual.


+
+static size_t count_opts_list(QemuOptsList *list)
+{
+    size_t i = 0;
+
+    for (i = 0; list && list->desc[i].name; i++) {

No need to initialize i to 0 in two places.

Okay.
+        ;
+    }
+
+    return i;
+}
+
+/* Create a new QemuOptsList and make its desc to the merge of first
+ * and second. It will allocate space for one new QemuOptsList plus
+ * enough space for QemuOptDesc in first and second QemuOptsList.
+ * First argument's QemuOptDesc members take precedence over second's.
+ * The result's name and implied_opt_name are not copied from them.
+ * Both merge_lists should not be set. Both list can be NULL.
+ */
+QemuOptsList *qemu_opts_append(QemuOptsList *first,
+                               QemuOptsList *second)
+{
+    size_t num_first_opts, num_second_opts;
+    QemuOptsList *dest = NULL;
+    int i = 0;
+    int index = 0;
+    QemuOptsList *p = first;
+
+    num_first_opts = count_opts_list(first);
+    num_second_opts = count_opts_list(second);
+
+    dest = g_malloc0(sizeof(QemuOptsList)
+        + (num_first_opts + num_second_opts + 1) * sizeof(QemuOptDesc));
+
+    dest->name = "append_opts_list";
+    dest->implied_opt_name = NULL;
+    assert((!first || !first->merge_lists)
+        && (!second || !second->merge_lists));
+    QTAILQ_INIT(&dest->head);
+
+    for (i = 0; p && p->desc[i].name; i++) {

Again, a double-initialization of i [1]
Okay.

+        if (!find_desc_by_name(dest->desc, p->desc[i].name)) {
+            dest->desc[index].name = g_strdup(p->desc[i].name);
+            dest->desc[index].help = g_strdup(p->desc[i].help);
+            dest->desc[index].type = p->desc[i].type;
+            dest->desc[index].def_value_str =
+                g_strdup(p->desc[i].def_value_str);

Do we really have to strdup these elements, or are we guaranteed that
the scope of the original first/second list is always larger than the
scope of the merged list, and can thus share the existing pointer rather
than creating copies? [2]
I think yes, will use pointer directly in next version.

+            index++;
+        }
+        if (p == first && p && !p->desc[i].name) {
+            p = second;
+            i = 0;
+        }
+    }
+    dest->desc[index].name = NULL;
+    return dest;
+}
+
+/* free a QemuOptsList, can accept NULL as arguments */
+void qemu_opts_free(QemuOptsList *list)
+{
+    int i = 0;
+
+    for (i = 0; list && list->desc[i].name; i++) {

[1] and again for double initialization of i

+        g_free((char *)list->desc[i].name);
+        g_free((char *)list->desc[i].help);
+        g_free((char *)list->desc[i].def_value_str);

[2] The fact that you have to cast away const is a sign that maybe you
shouldn't be storing strdup'd data in these pointers in the first place.

+    }
+
+    g_free(list);
+}
+
+void qemu_opts_print_help(QemuOptsList *list)
+{
+    int i = 0;
+    printf("Supported options:\n");
+    for (i = 0; list && list->desc[i].name; i++) {

[1] and another

+        printf("%-16s %s\n", list->desc[i].name,
+            list->desc[i].help ?
+                list->desc[i].help : "No description available");
+    }
+}






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