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/*
* Copyright 1993-1999 Bruno Haible, <haible@clisp.cons.org>
*
* This is free software distributed under the GNU General Public Licence
* described in the file COPYING. Contact the author if you don't have this
* or can't live with it. There is ABSOLUTELY NO WARRANTY, explicit or implied,
* on this software.
*/
#include "sigsegv.h"
#include <stddef.h> /* needed for NULL on SunOS4 */
#include <stdlib.h>
#ifdef _WIN32
#include <malloc.h>
#endif
/* C++ doesn't allow us to define a function called `delete'. */
#ifdef __cplusplus
#define delete my_delete
#endif
/*
* A dispatcher contains an AVL tree of non-empty intervals, sorted according
* to their starting address.
*/
typedef
struct node_t {
/* AVL tree management */
struct node_t * left;
struct node_t * right;
unsigned int height;
/* Representation of interval */
unsigned long address;
unsigned long len;
/* User handler */
sigsegv_area_handler_t handler;
void* handler_arg;
}
node_t;
#define empty ((node_t *) 0)
#define heightof(tree) ((tree)==empty ? 0 : (tree)->height)
#define MAXHEIGHT 41
static void rebalance (node_t*** nodeplaces_ptr, unsigned int count)
{
if (count > 0)
do {
node_t** nodeplace = *--nodeplaces_ptr;
node_t* node = *nodeplace;
node_t* nodeleft = node->left;
node_t* noderight = node->right;
unsigned int heightleft = heightof(nodeleft);
unsigned int heightright = heightof(noderight);
if (heightright + 1 < heightleft) {
node_t* nodeleftleft = nodeleft->left;
node_t* nodeleftright = nodeleft->right;
unsigned int heightleftright = heightof(nodeleftright);
if (heightof(nodeleftleft) >= heightleftright) {
node->left = nodeleftright; nodeleft->right = node;
nodeleft->height = 1 + (node->height = 1 + heightleftright);
*nodeplace = nodeleft;
} else {
nodeleft->right = nodeleftright->left;
node->left = nodeleftright->right;
nodeleftright->left = nodeleft;
nodeleftright->right = node;
nodeleft->height = node->height = heightleftright;
nodeleftright->height = heightleft;
*nodeplace = nodeleftright;
}
} else if (heightleft + 1 < heightright) {
node_t* noderightright = noderight->right;
node_t* noderightleft = noderight->left;
unsigned int heightrightleft = heightof(noderightleft);
if (heightof(noderightright) >= heightrightleft) {
node->right = noderightleft; noderight->left = node;
noderight->height = 1 + (node->height = 1 + heightrightleft);
*nodeplace = noderight;
} else {
noderight->left = noderightleft->right;
node->right = noderightleft->left;
noderightleft->right = noderight;
noderightleft->left = node;
noderight->height = node->height = heightrightleft;
noderightleft->height = heightright;
*nodeplace = noderightleft;
}
} else {
unsigned int height = (heightleft<heightright ? heightright : heightleft) + 1;
if (height == node->height) break;
node->height = height;
}
} while (--count > 0);
}
static node_t* insert (node_t* new_node, node_t* tree)
{
unsigned int key = new_node->address;
node_t** nodeplace = &tree;
node_t** stack[MAXHEIGHT];
unsigned int stack_count = 0;
node_t*** stack_ptr = &stack[0];
for (;;) {
node_t* node = *nodeplace;
if (node == empty) break;
*stack_ptr++ = nodeplace; stack_count++;
if (key < node->address)
nodeplace = &node->left;
else
nodeplace = &node->right;
}
new_node->left = empty;
new_node->right = empty;
new_node->height = 1;
*nodeplace = new_node;
rebalance(stack_ptr,stack_count);
return tree;
}
static node_t* delete (node_t* node_to_delete, node_t* tree)
{
unsigned long key = node_to_delete->address;
node_t** nodeplace = &tree;
node_t** stack[MAXHEIGHT];
unsigned int stack_count = 0;
node_t*** stack_ptr = &stack[0];
for (;;) {
node_t* node = *nodeplace;
if (node == empty) return tree;
*stack_ptr++ = nodeplace; stack_count++;
if (key == node->address) {
if (node != node_to_delete)
abort();
break;
}
if (key < node->address)
nodeplace = &node->left;
else
nodeplace = &node->right;
}
{
node_t** nodeplace_to_delete = nodeplace;
if (node_to_delete->left == empty) {
*nodeplace_to_delete = node_to_delete->right;
stack_ptr--; stack_count--;
} else {
node_t*** stack_ptr_to_delete = stack_ptr;
node_t** nodeplace = &node_to_delete->left;
node_t* node;
for (;;) {
node = *nodeplace;
if (node->right == empty) break;
*stack_ptr++ = nodeplace; stack_count++;
nodeplace = &node->right;
}
*nodeplace = node->left;
node->left = node_to_delete->left;
node->right = node_to_delete->right;
node->height = node_to_delete->height;
*nodeplace_to_delete = node;
*stack_ptr_to_delete = &node->left;
}
}
rebalance(stack_ptr,stack_count);
return tree;
}
void sigsegv_init (sigsegv_dispatcher* dispatcher)
{
dispatcher->tree = empty;
}
void* sigsegv_register (sigsegv_dispatcher* dispatcher,
void* address, unsigned long len,
sigsegv_area_handler_t handler, void* handler_arg)
{
if (len == 0)
return NULL;
else {
node_t* new_node = (node_t*) malloc(sizeof(node_t));
new_node->address = (unsigned long) address;
new_node->len = len;
new_node->handler = handler;
new_node->handler_arg = handler_arg;
dispatcher->tree = insert(new_node,(node_t*)(dispatcher->tree));
return new_node;
}
}
void sigsegv_unregister (sigsegv_dispatcher* dispatcher, void* ticket)
{
if (ticket != NULL) {
node_t* node_to_delete = (node_t*)ticket;
dispatcher->tree = delete(node_to_delete,(node_t*)(dispatcher->tree));
free(node_to_delete);
}
}
int sigsegv_dispatch (sigsegv_dispatcher* dispatcher, void* fault_address)
{
unsigned long key = (unsigned long) fault_address;
node_t* tree = (node_t*)(dispatcher->tree);
for (;;) {
if (tree == empty) return 0;
if (key < tree->address)
tree = tree->left;
else if (key - tree->address >= tree->len)
tree = tree->right;
else
break;
}
return (*tree->handler)(fault_address,tree->handler_arg);
}
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