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tree.c
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tree.c
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#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <unistd.h> /* getuid(), getgid() */
#include <sys/types.h>
#include "tree.h"
#include "globals.h"
/*Linux has a maximum filename length of 255 characters for most filesystems
(including EXT4), and a maximum path of 4096 characters. */
#define MAX_PATH_LENGTH 4096
//global variables declared in tree.h
TreeNode* root;
char new_entry_name[256];
unsigned int fs_size;
unsigned int curr_size;
TreeNode* create_node(char* name, mode_t mode, inode_type type, int size){
TreeNode* node = (TreeNode*)malloc(sizeof(TreeNode));
node->inode = (ram_inode*)malloc(sizeof(ram_inode));
strcpy(node->name, name);
node->inode->type = type;
node->inode->mode = mode;
node->inode->uid = getuid();
node->inode->gid = getgid();
node->inode->size = size;
node->data = NULL;
node->parent = NULL;
node->firstChild = NULL;
node->nextSibling = NULL;
time_t curr_time;
time(&curr_time);
node->inode->atime = curr_time;
node->inode->mtime = curr_time;
node->inode->ctime = curr_time;
//Update disk
curr_size += (sizeof(TreeNode) + sizeof(ram_inode));
return node;
}
TreeNode* create_dir_node(char* name, mode_t mode){
int size = MAX_PATH_LENGTH;
inode_type type = TYPE_DIR;
mode_t type_mode = S_IFDIR | 0755;
return create_node(name, type_mode, type, size);
}
TreeNode* create_file_node(char* name, mode_t mode){
int size = 0;
inode_type type = TYPE_FILE;
mode_t type_mode = S_IFREG | mode;
return create_node(name, type_mode, type, size);
}
/*
Validates the given path. Returns
a. 0, if the path exists
b. 1, if path till parent exists and a new node with last token needs to be created
c. -1, if even the parent path doesn't exist
*/
int validate_path(const char *path){
char path_copy[MAX_PATH_LENGTH];
strcpy(path_copy, path);
char *token = strtok(path_copy, "/");
//Root path found
if(token == NULL && (strcmp(path, "/") == 0)){
return 0;
}
//else
int found = 0;
TreeNode *start_node = root;
TreeNode *curr = NULL;
while(token != NULL) {
curr = start_node->firstChild;
while(curr) {
if(strcmp(token, curr->name) == 0 ){
found = 1;
break;
}
curr = curr->nextSibling;
}
token = strtok(NULL, "/");
if(found) {
if( token == NULL )
return 0;
}else{
if (token)
return -1;
else
return 1;
}
start_node = curr;
found = 0;
}
//If it reaches here, it's not found
return -1;
}
TreeNode* get_node_from_path(const char* path){
char path_copy[MAX_PATH_LENGTH];
strcpy(path_copy, path);
char* token = strtok(path_copy, "/");
//If path is root directory("/"), return root node
if(strcmp(path, "/") == 0 && token == NULL) {
return root;
}
//else
int found = 0;
TreeNode* start_node = root;
TreeNode* curr = NULL;
while(token){
curr = start_node->firstChild;
while(curr){
if(strcmp(token, curr->name) == 0 ){
found = 1;
break;
}
curr = curr->nextSibling;
}
if(found) {
token = strtok(NULL, "/");
if(token == NULL ){
return curr;
}
}else{
/* If entry not found(not in children of start_node)
1. Copy the token in a global variable for new entry
2. Return the parent(start_node)
This is required for mkdir,create etc. where last token is name of the directory
and path before that is the parent directory*/
strcpy(new_entry_name, token);
return start_node;
}
start_node = curr;
found = 0;
}
return NULL;
}
void add_child(TreeNode* parent, TreeNode* new_child){
if(parent == NULL || new_child == NULL)
return;
if(parent->firstChild != NULL){
TreeNode* curr = parent->firstChild;
while(curr->nextSibling != NULL){
curr = curr->nextSibling;
}
curr->nextSibling = new_child;
}else{
parent->firstChild = new_child;
}
new_child->parent = parent;
}
void detach_child(TreeNode* parent, TreeNode* node_to_delete){
//If node to delete is the first child
if(parent->firstChild == node_to_delete){
if(node_to_delete->nextSibling == NULL){
//If node to delete is the only child, remove linking
parent->firstChild = NULL;
}else{
//Make parent's first child to point to next sibling
parent->firstChild = node_to_delete->nextSibling;
}
}else{
//Iterate to reach the desired node
TreeNode* curr = parent->firstChild;
while(curr){
if(curr->nextSibling == node_to_delete){
curr->nextSibling = node_to_delete->nextSibling;
break;
}
curr=curr->nextSibling;
}
}
}