/**
* befs_find_key - Search for a key within a node
* @sb: Filesystem superblock
* @node: Node to find the key within
* @findkey: Keystring to search for
* @value: If key is found, the value stored with the key is put here
*
* Finds exact match if one exists, and returns BEFS_BT_MATCH.
* If there is no match and node's value array is too small for key, return
* BEFS_BT_OVERFLOW.
* If no match and node should countain this key, return BEFS_BT_NOT_FOUND.
*
* Uses binary search instead of a linear.
*/
static int
befs_find_key(struct super_block *sb, struct befs_btree_node *node,
const char *findkey, befs_off_t * value)
{
int first, last, mid;
int eq;
u16 keylen;
int findkey_len;
char *thiskey;
fs64 *valarray;
befs_debug(sb, "---> %s %s", __func__, findkey);
findkey_len = strlen(findkey);
/* if node can not contain key, just skip this node */
last = node->head.all_key_count - 1;
thiskey = befs_bt_get_key(sb, node, last, &keylen);
eq = befs_compare_strings(thiskey, keylen, findkey, findkey_len);
if (eq < 0) {
befs_debug(sb, "<--- node can't contain %s", findkey);
return BEFS_BT_OVERFLOW;
}
valarray = befs_bt_valarray(node);
/* simple binary search */
first = 0;
mid = 0;
while (last >= first) {
mid = (last + first) / 2;
befs_debug(sb, "first: %d, last: %d, mid: %d", first, last,
mid);
thiskey = befs_bt_get_key(sb, node, mid, &keylen);
eq = befs_compare_strings(thiskey, keylen, findkey,
findkey_len);
if (eq == 0) {
befs_debug(sb, "<--- %s found %s at %d",
__func__, thiskey, mid);
*value = fs64_to_cpu(sb, valarray[mid]);
return BEFS_BT_MATCH;
}
if (eq > 0)
last = mid - 1;
else
first = mid + 1;
}
/* return an existing value so caller can arrive to a leaf node */
if (eq < 0)
*value = fs64_to_cpu(sb, valarray[mid + 1]);
else
*value = fs64_to_cpu(sb, valarray[mid]);
befs_error(sb, "<--- %s %s not found", __func__, findkey);
befs_debug(sb, "<--- %s ERROR", __func__);
return BEFS_BT_NOT_FOUND;
}
/**
* befs_find_key - Search for a key within a node
* @sb: Filesystem superblock
* @node: Node to find the key within
* @key: Keystring to search for
* @value: If key is found, the value stored with the key is put here
*
* finds exact match if one exists, and returns BEFS_BT_MATCH
* If no exact match, finds first key in node that is greater
* (alphabetically) than the search key and returns BEFS_BT_PARMATCH
* (for partial match, I guess). Can you think of something better to
* call it?
*
* If no key was a match or greater than the search key, return
* BEFS_BT_NOT_FOUND.
*
* Use binary search instead of a linear.
*/
static int
befs_find_key(struct super_block *sb, befs_btree_node * node,
const char *findkey, befs_off_t * value)
{
int first, last, mid;
int eq;
u16 keylen;
int findkey_len;
char *thiskey;
fs64 *valarray;
befs_debug(sb, "---> befs_find_key() %s", findkey);
*value = 0;
findkey_len = strlen(findkey);
/* if node can not contain key, just skeep this node */
last = node->head.all_key_count - 1;
thiskey = befs_bt_get_key(sb, node, last, &keylen);
eq = befs_compare_strings(thiskey, keylen, findkey, findkey_len);
if (eq < 0) {
befs_debug(sb, "<--- befs_find_key() %s not found", findkey);
return BEFS_BT_NOT_FOUND;
}
valarray = befs_bt_valarray(node);
/* simple binary search */
first = 0;
mid = 0;
while (last >= first) {
mid = (last + first) / 2;
befs_debug(sb, "first: %d, last: %d, mid: %d", first, last,
mid);
thiskey = befs_bt_get_key(sb, node, mid, &keylen);
eq = befs_compare_strings(thiskey, keylen, findkey,
findkey_len);
if (eq == 0) {
befs_debug(sb, "<--- befs_find_key() found %s at %d",
thiskey, mid);
*value = fs64_to_cpu(sb, valarray[mid]);
return BEFS_BT_MATCH;
}
if (eq > 0)
last = mid - 1;
else
first = mid + 1;
}
if (eq < 0)
*value = fs64_to_cpu(sb, valarray[mid + 1]);
else
*value = fs64_to_cpu(sb, valarray[mid]);
befs_debug(sb, "<--- befs_find_key() found %s at %d", thiskey, mid);
return BEFS_BT_PARMATCH;
}
