xml.c: support numerically indexed elements in wimlib_{get,set}_image_property()

[wimlib] / src / xml.c

diff --git a/src/xml.c b/src/xml.c
index 8280e8edfc496f014029d3abcb25560c5c89f100..d46470653ab4149d15fa5dfef347844034e32363 100644 (file)
--- a/src/xml.c
+++ b/src/xml.c
@@ -342,6 +342,32 @@ alloc_wim_xml_info(void)
        return info;
 }
 
+static bool
+parse_index(xmlChar **pp, uint32_t *index_ret)
+{
+       xmlChar *p = *pp;
+       uint32_t index = 0;
+
+       *p++ = '\0'; /* overwrite '[' */
+       while (*p >= '0' && *p <= '9') {
+               uint32_t n = (index * 10) + (*p++ - '0');
+               if (n < index)
+                       return false;
+               index = n;
+       }
+       if (index == 0)
+               return false;
+       if (*p != ']')
+               return false;
+       p++;
+       if (*p != '/' && *p != '\0')
+               return false;
+
+       *pp = p;
+       *index_ret = index;
+       return true;
+}
+
 static int
 do_xml_path_walk(xmlNode *node, const xmlChar *path, bool create,
                 xmlNode **result_ret)
@@ -362,34 +388,44 @@ do_xml_path_walk(xmlNode *node, const xmlChar *path, bool create,
 
        if (*p == '/')
                goto bad_syntax;
-       if (strchr(p, '[')) /* reserved for future use */
-               goto bad_syntax;
        c = *p;
 
        while (c != '\0') {
                const xmlChar *name;
                xmlNode *child;
+               uint32_t index = 1;
 
                /* We have another path component.  */
 
                /* Parse the element name.  */
                name = p;
-               while (*p != '/' && *p != '\0')
+               while (*p != '/' && *p != '\0' && *p != '[')
                        p++;
                if (p == name) /* empty name?  */
                        goto bad_syntax;
+
+               /* Handle a bracketed index, if one was specified.  */
+               if (*p == '[' && !parse_index(&p, &index))
+                       goto bad_syntax;
+
                c = *p;
                *p = '\0';
 
                /* Look for a matching child.  */
                node_for_each_child(node, child)
-                       if (node_is_element(child, name))
+                       if (node_is_element(child, name) && !--index)
                                goto next_step;
 
                /* No child matched the path.  If create=false, the lookup
                 * failed.  If create=true, create the needed element.  */
                if (!create)
                        return 0;
+
+               /* We can't create an element at index 'n' if indices 1...n-1
+                * didn't already exist.  */
+               if (index != 1)
+                       return WIMLIB_ERR_INVALID_PARAM;
+
                child = xmlNewChild(node, NULL, name, NULL);
                if (!child)
                        return WIMLIB_ERR_NOMEM;