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#3530: Upgrade bundled expat to 2.4.6

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This commit is contained in:
Günter Obiltschnig 2022-02-20 18:53:57 +01:00
parent 2b3662c854
commit 5239c4f023
2 changed files with 49 additions and 34 deletions
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2
XML/include/Poco/XML/expat.h
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@ -1041,7 +1041,7 @@ XML_SetBillionLaughsAttackProtectionActivationThreshold(
*/
#define XML_MAJOR_VERSION 2
#define XML_MINOR_VERSION 4
#define XML_MICRO_VERSION 5
#define XML_MICRO_VERSION 6
#ifdef __cplusplus
}

81
XML/src/xmlparse.cpp
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@ -1,4 +1,4 @@
/* 042615face2b8727e23bb27cf4f56baa292a1f91df47c1bca8f09dff49067888 (2.4.5+)
/* a30d2613dcfdef81475a9d1a349134d2d42722172fdaa7d5bb12ed2aa74b9596 (2.4.6+)
__ __ _
___\ \/ /_ __ __ _| |_
/ _ \\ /| '_ \ / _` | __|
@ -7393,39 +7393,58 @@ build_model(XML_Parser parser) {
*
* The iterative approach works as follows:
*
* - We use space in the target array for building a temporary stack structure
* while that space is still unused.
* The stack grows from the array's end downwards and the "actual data"
* grows from the start upwards, sequentially.
* (Because stack grows downwards, pushing onto the stack is a decrement
* while popping off the stack is an increment.)
* - We have two writing pointers, both walking up the result array; one does
* the work, the other creates "jobs" for its colleague to do, and leads
* the way:
*
* - A stack element appears as a regular XML_Content node on the outside,
* but only uses a single field -- numchildren -- to store the source
* tree node array index. These are the breadcrumbs leading the way back
* during pre-order (node first) depth-first traversal.
* - The faster one, pointer jobDest, always leads and writes "what job
* to do" by the other, once they reach that place in the
* array: leader "jobDest" stores the source node array index (relative
* to array dtd->scaffold) in field "numchildren".
*
* - The reason we know the stack will never grow into (or overlap with)
* the area with data of value at the start of the array is because
* the overall number of elements to process matches the size of the array,
* and the sum of fully processed nodes and yet-to-be processed nodes
* on the stack, cannot be more than the total number of nodes.
* It is possible for the top of the stack and the about-to-write node
* to meet, but that is safe because we get the source index out
* before doing any writes on that node.
* - The slower one, pointer dest, looks at the value stored in the
* "numchildren" field (which actually holds a source node array index
* at that time) and puts the real data from dtd->scaffold in.
*
* - Before the loop starts, jobDest writes source array index 0
* (where the root node is located) so that dest will have something to do
* when it starts operation.
*
* - Whenever nodes with children are encountered, jobDest appends
* them as new jobs, in order. As a result, tree node siblings are
* adjacent in the resulting array, for example:
*
* [0] root, has two children
* [1] first child of 0, has three children
* [3] first child of 1, does not have children
* [4] second child of 1, does not have children
* [5] third child of 1, does not have children
* [2] second child of 0, does not have children
*
* Or (the same data) presented in flat array view:
*
* [0] root, has two children
*
* [1] first child of 0, has three children
* [2] second child of 0, does not have children
*
* [3] first child of 1, does not have children
* [4] second child of 1, does not have children
* [5] third child of 1, does not have children
*
* - The algorithm repeats until all target array indices have been processed.
*/
XML_Content *dest = ret; /* tree node writing location, moves upwards */
XML_Content *const destLimit = &ret[dtd->scaffCount];
XML_Content *const stackBottom = &ret[dtd->scaffCount];
XML_Content *stackTop = stackBottom; /* i.e. stack is initially empty */
XML_Content *jobDest = ret; /* next free writing location in target array */
str = (XML_Char *)&ret[dtd->scaffCount];
/* Push source tree root node index onto the stack */
(--stackTop)->numchildren = 0;
/* Add the starting job, the root node (index 0) of the source tree */
(jobDest++)->numchildren = 0;
for (; dest < destLimit; dest++) {
/* Pop source tree node index off the stack */
const int src_node = (int)(stackTop++)->numchildren;
/* Retrieve source tree array index from job storage */
const int src_node = (int)dest->numchildren;
/* Convert item */
dest->type = dtd->scaffold[src_node].type;
@ -7447,16 +7466,12 @@ build_model(XML_Parser parser) {
int cn;
dest->name = NULL;
dest->numchildren = dtd->scaffold[src_node].childcnt;
dest->children = &dest[1];
dest->children = jobDest;
/* Push children to the stack
* in a way where the first child ends up at the top of the
* (downwards growing) stack, in order to be processed first. */
stackTop -= dest->numchildren;
/* Append scaffold indices of children to array */
for (i = 0, cn = dtd->scaffold[src_node].firstchild;
i < dest->numchildren; i++, cn = dtd->scaffold[cn].nextsib) {
(stackTop + i)->numchildren = (unsigned int)cn;
}
i < dest->numchildren; i++, cn = dtd->scaffold[cn].nextsib)
(jobDest++)->numchildren = (unsigned int)cn;
}
}