Fread为.txt和.jpeg文件获取不同的内容

Question

当我尝试读取整个文件时，我的缓冲区中只有4个字节（重量超过4B）。但是当我读取.txt文件时，我成功恢复了整个文件内容。

我在fopen man，malloc mand和fread man中搜索过，但我不明白为什么。

char* readFile(char* path)
{
    /*VARIABLES*/
    FILE *inFile;
    long inFileSize;
    long readSize;
    char *buffer = NULL;

    /*OPEN FILES*/
    inFile = fopen(path,"rb");

    /*ERROR HANDLING : FILES*/
    if(!inFile) {
        return "";
    }

    /*GETTING FILE SIZE*/
    fseek(inFile, 0, SEEK_END);
    inFileSize = ftell(inFile);
    rewind(inFile);

    printf("The file is %ld bytes long\n",inFileSize);

    /*ALLOCATING MEMORY*/
    buffer = (char*) malloc(sizeof(char) * (inFileSize + 1) );

    /*READ THE CONTENT AND PUT IT IN THE BUFFER*/
    readSize = fread(buffer, sizeof(char), inFileSize, inFile);

    /*ERROR HANDLING : readed size != to the file size*/
    if (inFileSize != readSize)
    {
        printf("Freeing buffer\n");
        free(buffer);
        buffer = NULL;
    }

    /*ADDING THE END STRING CODE*/
    buffer[inFileSize] = '\0';

    /*CLOSE THE FILE*/
    fclose(inFile);
    return buffer;
}

另外，当我将图片扩展名从.jpeg更改为.txt时，我仍然只能获得4个字节。

你能帮助我吗？