分段错误循环fgets

Question

我遇到了分段错误，我怀疑它在while循环中，因为注释while循环允许它以一行读取运行。该程序的目标是采用3个参数，一个文本文件名，一个单词和一个单词来替换第一个单词。所以./this文本旧的NEW将用NEW，全部大写替换所有每行旧单词的第一个实例。根据说明，我只对每行的第一个实例感兴趣。

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
int main(int argc, char *argv[])
{
    FILE *fp;           // file pointer
    char output[400];       // we put a limit on the size of our string so we don't go overboard
    char term[40];          // our term to search for
    char newTerm[40];       // the replacement term
    char filename[40];      // the name of the file we examine
    char curr[150];         // the current line of text read
    char currWord[40];      // current token
    char *cp;           // char pointer
    int replaceCounter;     // count how many strings were replaced
    int i = 0;          // index counter
    strncpy(filename, argv[1], 40); // assign the first argument to the filename
    strcat(filename, ".txt");   
    strncpy(term, argv[2], 40);
    strncpy(newTerm, argv[3], 40);
    fp = fopen(filename, "r");
    if(fp != NULL)
    {
        printf("File opened successfully!\n");  
        while(fgets(curr, 150, fp) != NULL)
        {
            if((cp = strstr(curr, term)) != NULL);
                strncpy(cp, newTerm, strlen(newTerm));
            printf("%s\n", curr);
            fflush(fp);
        }

    }   
    else
    {
        printf("Error opening file: %s", filename);
        return 0;
    }
    fclose(fp);
    return 0;   

}

使用Ubuntu和gcc进行编译，所以我没有得到更具体的内容，比如调试。任何帮助表示赞赏。