Add function utf8_strndup to C plugin API

doc/en/dev/plugin_c_api.en.xml

@@ -1545,6 +1545,42 @@ char *weechat_utf8_pos (const char *string, int real_pos);
       </para>
     </section>
     
+    <section id="secPluginCApi_weechat_utf8_strndup">
+      <title>weechat_utf8_strndup</title>
+      
+      <para>
+        Prototype:
+<programlisting>
+char *weechat_utf8_strndup (const char *string, int max_chars);
+</programlisting>
+      </para>
+      <para>
+        Return duplicate string, with max N chars.
+      </para>
+      <para>
+        Arguments:
+        <itemizedlist>
+          <listitem>
+            <para>
+              <option>string</option>: string
+            </para>
+          </listitem>
+          <listitem>
+            <para>
+              <option>max_chars</option>: max chars
+            </para>
+          </listitem>
+        </itemizedlist>
+      </para>
+      <para>
+        Return value: duplicated string, NULL if error.
+      </para>
+      <para>
+        Example:
+        <screen>char *string = weechat_utf8_strndup ("chêne", 3); /* returns "chê" */</screen>
+      </para>
+    </section>
+    
   </section>
   
   <!-- ===========================[ directories ]========================== -->

src/core/wee-utf8.c

@@ -452,3 +452,26 @@ utf8_pos (const char *string, int real_pos)
     }
     return count;
 }
+
+/*
+ * utf8_strndup: return duplicate string, with max N UTF-8 chars
+ */
+
+char *
+utf8_strndup (const char *string, int max_chars)
+{
+    const char *end;
+    char *result;
+    
+    if (!string || (max_chars < 0))
+        return NULL;
+    
+    if (max_chars == 0)
+        return strdup ("");
+    
+    end = utf8_add_offset (string, max_chars);
+    if (!end || (end == string))
+        return strdup (string);
+
+    return string_strndup (string, end - string);
+}

src/core/wee-utf8.h

@@ -47,5 +47,6 @@ extern int utf8_char_size_screen (const char *string);
 extern char *utf8_add_offset (const char *string, int offset);
 extern int utf8_real_pos (const char *string, int pos);
 extern int utf8_pos (const char *string, int real_pos);
+extern char *utf8_strndup (const char *string, int max_chars);
 
 #endif /* wee-utf8.h */

src/plugins/plugin.c

@@ -360,6 +360,7 @@ plugin_load (const char *filename)
         new_plugin->utf8_add_offset = &utf8_add_offset;
         new_plugin->utf8_real_pos = &utf8_real_pos;
         new_plugin->utf8_pos = &utf8_pos;
+        new_plugin->utf8_strndup = &utf8_strndup;
         
         new_plugin->mkdir_home = &util_mkdir_home;
         new_plugin->mkdir = &util_mkdir;

src/plugins/weechat-plugin.h

@@ -171,6 +171,7 @@ struct t_weechat_plugin
     char *(*utf8_add_offset) (const char *string, int offset);
     int (*utf8_real_pos) (const char *string, int pos);
     int (*utf8_pos) (const char *string, int real_pos);
+    char *(*utf8_strndup) (const char *string, int max_chars);
     
     /* directories */
     int (*mkdir_home) (const char *directory, int mode);