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我正在用C语言编写代码混淆器。调试器在代码中未显示任何错误，但是程序在编译后崩溃。我猜想它与while循环和从文件中读取文本有关，但是我不确定如何解决它？提前致谢。
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
// list off all replaced elements
typedef struct ReplaceList
{
char *from; // from string
char *to; // to string (random)
struct ReplaceList *next;
} ReplaceList;
// ANSI C keywords that can't be changed
typedef struct Data
{
char *kword;
struct Data *next;
} Data;
// add keyword to list
Data* AddToList(Data **head, Data *d)
{
d->next = *head;
*head = d;
return d;
}
// delete all elements from list
void FreeList(Data *head)
{
Data *prev;
while (head != NULL)
{
prev = head;
head = head->next;
free(prev);
}
}
// Generating random numbers
int random1()
{
return ((rand() % 6) + 1);
}
// return other characters from file and erase comments
char *getOtherCharacters(FILE *file){
char *buf = (char*)malloc(sizeof(char));
char a;
int n=0;
while(!feof(file)){
a= fgetc(file);
if(
(!((a >= 'a') && (a<='z'))) &&
(!((a >= 'A') && (a <= 'Z'))) &&
(a != '_')
)
{
// comment
if(a == '/'){
a = fgetc(file);
// until end of line
if(a == '/'){
while(!feof(file)){
a = fgetc(file);
if(a == '\n')
break;
}
}
else if(a == '*'){
while(!feof(file)){
a = fgetc(file);
if(a=='*'){
a = fgetc(file);
if(a == '/')
break;
else
fseek(file,ftell(file)-1,SEEK_SET);
}
}
}
// other chars
else{
buf = (char*)realloc(buf,++n);
buf[n-1] = a;
}
}
else{
buf = (char*)realloc(buf,++n);
buf[n-1] = a;
}
}
else{
fseek(file,ftell(file)-1,SEEK_SET);
buf = (char*)realloc(buf,++n);
buf[n-1] = '\0';
return buf;
}
}
return NULL;
}
// return word from file
char *getWord(FILE *file){
char *buf = (char*)malloc(sizeof(char));
int n=0;
char a;
int ok = 0;
while(!feof(file)){
a = fgetc(file);
if(
((a >= 'a') && (a<='z')) ||
((a >= 'A') && (a <= 'Z')) ||
( (ok==1)&& (a>='0') && (a<='9')) ||
(a == '_')
)
{
ok = 1;
buf = (char*)realloc(buf,++n);
buf[n-1] = a;
}
else if(ok==1){
if(!feof(file))
fseek(file,ftell(file)-1,SEEK_SET);
buf = (char*)realloc(buf,++n);
buf[n-1] = '\0';
return buf;
}
else
return NULL;
}
return NULL;
}
// check if word exist in ReplaceList
ReplaceList *checkWord_ReplaceList(char *word,ReplaceList *Head){
ReplaceList *replaceList;
replaceList = Head;
while(replaceList != NULL){
if(strcmp(word, replaceList->from) == 0){
return replaceList;
}
replaceList = replaceList->next;
}
return NULL;
}
// check if word exist in Data struct
Data *checkWord_Data(char *word,Data *Head){
Data *data;
data = Head;
while(data != NULL){
if(strcmp(word, data->kword) == 0){
return data;
}
data = data->next;
}
return NULL;
}
// generate new element of ReplaceList and return it instance
ReplaceList *newReplaceListElement(ReplaceList *begin, char *from){
int random;
ReplaceList *tmp;
int i;
tmp = (ReplaceList*)malloc(sizeof(ReplaceList));
tmp->to = (char*)malloc(sizeof(char)*11);
for(i=0; i<10;i++)
tmp->to[i] = rand()%26 + 'a';
tmp->to[i] = '\0';
tmp->from = from;
tmp->next = begin;
begin = tmp;
return tmp;
}
int main(int argc, char *argv[])
{
FILE * input;
FILE * output;
FILE *kwords;
Data *dataBegin = NULL;
ReplaceList *replaceListBegin = NULL;
int a, i=0;
char c;
srand(time(NULL));
a = random1();
kwords = fopen("ckeywords.txt","r");
// get all magic words
if(kwords != NULL){
// read data to the first list
while (!feof(kwords))
{
Data *d;
d = (Data *) malloc( sizeof(Data)); // allocate new element
d->kword = getWord(kwords);
fscanf(kwords,"\n");
AddToList(&dataBegin, d);
}
fclose(kwords);
}
input = fopen("inputcode.txt","r");
output = fopen("outputcode.txt","w");
// parse file
if(input != NULL){
while(!feof(input)){
char *word;
Data* data;
word = getWord(input);
if(word != NULL){
data = checkWord_Data(word,dataBegin);
if(data!=NULL){
fprintf(output,"%s",word);
}
else{
ReplaceList *replaceList;
replaceList = checkWord_ReplaceList(word,replaceListBegin);
if(replaceList == NULL){
replaceList = newReplaceListElement(replaceListBegin,word);
}
fprintf(output,"%s",replaceList->to);
}
}
else{
word = getOtherCharacters(input);
fprintf(output,"%s",word);
}
}
}
fclose(input);
fclose(output);
if (strcmp(argv[i], "-i") == 0)
while (!feof(input))
{
c=(char)fgetc(input);
printf("%c", c);
}
if (strcmp(argv[i], "-o") == 0)
while (!feof(output))
{
c=(char)fgetc(output);
printf("%c", c);
}
return 0;
}
我在这里看到一个问题。您首先要使用fclose（）关闭文件描述符“输入”和“输出”，然后在while循环中再次使用“输入”和“输出”。这有点令人困惑。
fclose(input);
fclose(output);
if (strcmp(argv[i], "-i") == 0)
while (!feof(input))
{
c=(char)fgetc(input);
printf("%c", c);
}
if (strcmp(argv[i], "-o") == 0)
while (!feof(output))
{
c=(char)fgetc(output);
printf("%c", c);
}
fclose（）函数将对文件描述符执行close（）
与流指向的流相关联。之后
调用fclose（）时，对流的任何使用都会导致未定义的行为。
http://pubs.opengroup.org/onlinepubs/007908799/xsh/fclose.html