libplist API does not offer a way to clone or modify nodes
Reported by Martin S. | July 8th, 2009 @ 09:16 AM
Attempted to implement lockdown's get/set/remove value request
and came up with those signatures:
iphone_error_t lockdownd_get_value(lockdownd_client_t client, char domain, char key, plist_t value);
iphone_error_t lockdownd_set_value(lockdownd_client_t client, char domain, char key, plist_t value);
iphone_error_t lockdownd_remove_value(lockdownd_client_t client, char domain, char *key);
For instance lockdownd_get_value() returns the value plist subnode for the key named "Value". The issue here was that there is no way in libplist to copy/clone an existing node. This also becomes a problem for set_value(), which actually has to clone the passed value node to construct a lockdown request plist with the value node attached to send to lockdownd.
The intermediate solution was to use plist_to_bin() to serialize the plist subnode into a buffer, then use plist_from_bin() to unserialize the plist into a node again effectively ending up with a cloned node.
Also while thinking about implementing a plist GUI editor similar to the one on Mac OS X, libplist should also provide the necessary functions to deal with modifications of node trees.
I think the missing operations are:
- clone nodes (recurse deep copy) - needed to fix this bug
- modify node values (e.g.: for quick, plist load -> change <string> value, save modified plist)
- remove nodes (Does plist_free() also unlink the "destroyed" node from the parent tree?)
Another question is how far this functionality should make sure the strict "<key /><VALUE />" node structure is not compromised or whether allow the "freedom" to work on individual nodes.
Simple idea:
// Return a copy of passed node and it's children
PLIST_API plist_t plist_copy(plist_t node);
// modify value of a node
PLIST_API void plist_set_key_val(plist_t node, char val);
PLIST_API void plist_set_string_val(plist_t node, char val);
PLIST_API void plist_set_bool_val(plist_t node, uint8_t val);
PLIST_API void plist_set_uint_val(plist_t node, uint64_t val);
PLIST_API void plist_set_real_val(plist_t node, double val);
PLIST_API void plist_set_data_val(plist_t node, char *val, uint64_t length);
PLIST_API void plist_set_date_val(plist_t node, int32_t sec, int32_t usec);
Comments and changes to this ticket
-
Jonathan Beck July 8th, 2009 @ 05:49 PM
- State changed from “new” to “open”
- Assigned user set to “Jonathan Beck”
Hi Martin,
I updated libplist git HEAD with requested changes.
Please check that it fits your needs.Also I would like to ensure through API that dicts are always well formed (key/value pairs), but that would require to duplicate lots of functions in the API (as single node manipulation is still necessary to handle arrays), so I don't really know what to do here.
If you did not started yet, I will probably investigate making a GUI plist editor.
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Martin S. July 9th, 2009 @ 03:26 PM
Superb, thanks for looking into this. However I get empty nodes back...
static plist_t plist_copy_node(GNode * node, gpointer parent_node) { plist_t newnode = NULL; plist_data_t data = plist_get_data(node); plist_data_t newdata = plist_new_plist_data(); assert(data); // plist should always have data memcpy(newdata, data, sizeof(struct plist_data_s)); newnode = plist_new_node(newdata); if (parent_node) { g_node_append(parent_node, newnode); } g_node_children_foreach(node, G_TRAVERSE_ALL, plist_copy_node, newnode); } plist_t plist_copy(plist_t node) { plist_copy_node(node, NULL); }... as above obviously can't work returning void. :)
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Jonathan Beck July 9th, 2009 @ 04:33 PM
I obviously did that a bit too fast :). Strange gcc didn't moan about that though.
Should be fixed now.
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Martin S. July 10th, 2009 @ 05:07 PM
Attached patch fixes the last issue I encountered with this. After applying it everything works as expected. Thanks a lot.
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Martin S. July 17th, 2009 @ 05:47 PM
Well, forgot to also copy the string value for "key" which caused issues. Attached corrected patch to use instead of the one before.
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Jonathan Beck July 18th, 2009 @ 07:05 PM
- State changed from “open” to “resolved”
Changes applied and available in libplist-0.13
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A project around supporting the iPhone in Linux.
See http://libimobiledevice.org
Jonathan Beck
Martin S.