char和int比较

来源于南邮CTF whyvm1的数据比较,第一次看到就很疑惑

记录一次字符串过滤

下面我有几个操作,就是数据处理完后,不直接结束当前循环,而是从头再来判断一次

其实就怕数据监测的遗漏

...

比如你最后修改了某个内容,让指针移到新的节点,但是当前循环结束的时候也需要移动指针节点

所以就会导致一次多余的移动,同时你自己又不能少移动

所以你就不结束当前循环直接跳转到判断那里,再判断一次

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int ReadFileSize(char* filename);

int main()
{
	FILE* fp = 0;
	char fpname[] = "F:\\src.txt";
	int FileSize = 0;
	char* lp1 = 0;
	char* lp2 = 0;
	int i = 0,j=0;

	FileSize = ReadFileSize(fpname);
	fp = fopen(fpname, "rb+");
	if (fp == 0)
	{
		printf("wrong open\n");
		return -1;
	}
	//每一次删除0x23个字节
	//开始标志是d,结束标志是;

	lp1 = (char*)malloc(FileSize + 0x10);
	lp2 = (char*)malloc(FileSize + 0x10);
	if (lp1 == 0 || lp2==0)
	{
		printf("wrong malloc\n");
		fclose(fp);
		return 0;
	}
	memset(lp1, 0, FileSize + 0x10);
	memset(lp2, 0, FileSize + 0x10);
	fread(lp1, FileSize, 1,fp);
	fclose(fp);

	//删除多余项
	for (i = 0; i < FileSize;i++ )
	{

	check_again:
		if(!memcmp(&lp1[i],"dword",5))
		{
			while (1)
			{
				if (lp1[i] == 0xA)
				{
					lp1[i] = 0;
					i++;
					break;
				}
				lp1[i] = 0;
				i++;
			}
			goto check_again;
		}
	
		if (!memcmp(&lp1[i], "byte_6941", 9))
		{
			memset(&lp1[i], 0, 9);
			memcpy(&lp1[i], "a[0x", 4);
			lp1[i + 4 ] = lp1[i + 9];
			lp1[i + 5] =  lp1[i + 10];
			lp1[i + 6] = ']';
			lp1[i + 9] = 0;
			lp1[i + 10]=0;
			
		}
		if (!memcmp(&lp1[i], "input", 5))
		{
			memset(&lp1[i], 0, 5);
			memcpy(&lp1[i], "a[0]", 4);
			goto check_again;
		}
		if (lp1[i] == '+')
		{
			lp1[i] = '-';
			i++;
			goto check_again;
		}
		if (lp1[i] == '-')
		{
			lp1[i] = '+';
			i++;
			goto check_again;
		}
	}
	
	for (i = 0; i < FileSize; i++)
	{
		if (lp1[i]!=0)
		{
			lp2[j] = lp1[i];
			j++;
		}
	}
	//逆序读取
	//最后lp2以0xA结束
	//printf("%d %X", j, lp2[j]);
	j--;
	for (; j >= 0; j--)
	{
		if (lp2[j] == 0xD || lp2[j] == 0xA)
		{
			lp2[j] = 0;
		}
		if (!memcmp(&lp2[j], "--", 2))
		{
			printf("%s\n", &lp2[j]);

		}
		if (!memcmp(&lp2[j], "++", 2))
		{
			printf("%s\n", &lp2[j]);

		}
		if (!memcmp(&lp2[j], "a[", 2))
		{
			printf("%s\n", &lp2[j]);
		}
	}

	 
}
int ReadFileSize(char* filename)
{
	int size = 0;
	FILE* fp = fopen(filename, "r");
	if (!fp)
	{
		printf("wrong open\n");
		return -1;
	}
	fseek(fp, 0L, SEEK_END);
	size = ftell(fp);
	fclose(fp);

	return size;
}