用C语言写一个简单的文件系统，代码要求：具备基本的文件处理功能，包括实现文件的建立、打开、删除、关闭、复制、读、写、查询等功能。

以下是一个简单的基于C语言的文件系统的实现，具备基本的文件处理功能：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_FILENAME_LENGTH 100
#define MAX_FILE_SIZE 1000

typedef struct {
    char filename[MAX_FILENAME_LENGTH];
    int size;
    char* content;
} File;

File* files[10];
int num_files = 0;

void create_file(char* filename) {
    if (num_files == 10) {
        printf("Error: Maximum number of files reached.\n");
        return;
    }
    for (int i = 0; i < num_files; i++) {
        if (strcmp(files[i]->filename, filename) == 0) {
            printf("Error: File with same name already exists.\n");
            return;
        }
    }
    File* new_file = (File*) malloc(sizeof(File));
    strcpy(new_file->filename, filename);
    new_file->size = 0;
    new_file->content = (char*) malloc(sizeof(char) * MAX_FILE_SIZE);
    files[num_files] = new_file;
    num_files++;
    printf("File created successfully.\n");
}

File* find_file(char* filename) {
    for (int i = 0; i < num_files; i++) {
        if (strcmp(files[i]->filename, filename) == 0) {
            return files[i];
        }
    }
    return NULL;
}

void open_file(char* filename) {
    File* file = find_file(filename);
    if (file == NULL) {
        printf("Error: File not found.\n");
        return;
    }
    printf("File opened successfully.\n");
}

void close_file(char* filename) {
    File* file = find_file(filename);
    if (file == NULL) {
        printf("Error: File not found.\n");
        return;
    }
    printf("File closed successfully.\n");
}

void delete_file(char* filename) {
    File* file = find_file(filename);
    if (file == NULL) {
        printf("Error: File not found.\n");
        return;
    }
    for (int i = 0; i < num_files; i++) {
        if (files[i] == file) {
            for (int j = i; j < num_files-1; j++) {
                files[j] = files[j+1];
            }
            num_files--;
            free(file->content);
            free(file);
            printf("File deleted successfully.\n");
            return;
        }
    }
}

void copy_file(char* filename1, char* filename2) {
    File* file1 = find_file(filename1);
    if (file1 == NULL) {
        printf("Error: File 1 not found.\n");
        return;
    }
    File* file2 = find_file(filename2);
    if (file2 != NULL) {
        printf("Error: File 2 already exists.\n");
        return;
    }
    File* new_file = (File*) malloc(sizeof(File));
    strcpy(new_file->filename, filename2);
    new_file->size = file1->size;
    new_file->content = (char*) malloc(sizeof(char) * new_file->size);
    memcpy(new_file->content, file1->content, new_file->size);
    files[num_files] = new_file;
    num_files++;
    printf("File copied successfully.\n");
}

void read_file(char* filename) {
    File* file = find_file(filename);
    if (file == NULL) {
        printf("Error: File not found.\n");
        return;
    }
    printf("File contents:\n%s\n", file->content);
}

void write_file(char* filename, char* content) {
    File* file = find_file(filename);
    if (file == NULL) {
        printf("Error: File not found.\n");
        return;
    }
    if (strlen(content) > MAX_FILE_SIZE) {
        printf("Error: File size too large.\n");
        return;
    }
    file->size = strlen(content);
    strcpy(file->content, content);
    printf("File written successfully.\n");
}

void list_files() {
    printf("List of files:\n");
    for (int i = 0; i < num_files; i++) {
        printf("%s\n", files[i]->filename);
    }
}

int main() {
    char command[20], filename1[MAX_FILENAME_LENGTH], filename2[MAX_FILENAME_LENGTH], content[MAX_FILE_SIZE];
    while (1) {
        printf("> ");
        scanf("%s", command);
        if (strcmp(command, "create") == 0) {
            scanf("%s", filename1);
            create_file(filename1);
        } else if (strcmp(command, "open") == 0) {
            scanf("%s", filename1);
            open_file(filename1);
        } else if (strcmp(command, "close") == 0) {
            scanf("%s", filename1);
            close_file(filename1);
        } else if (strcmp(command, "delete") == 0) {
            scanf("%s", filename1);
            delete_file(filename1);
        } else if (strcmp(command, "copy") == 0) {
            scanf("%s", filename1);
            scanf("%s", filename2);
            copy_file(filename1, filename2);
        } else if (strcmp(command, "read") == 0) {
            scanf("%s", filename1);
            read_file(filename1);
        } else if (strcmp(command, "write") == 0) {
            scanf("%s", filename1);
            scanf("%s", content);
            write_file(filename1, content);
        } else if (strcmp(command, "list") == 0) {
            list_files();
        } else if (strcmp(command, "exit") == 0) {
            break;
        } else {
            printf("Invalid command.\n");
        }
    }
    return 0;
}

该文件系统使用一个File结构体来表示文件，其中包含文件名、大小和内容的指针。文件系统最多支持10个文件，文件内容最大为1000个字符。文件系统支持创建、打开、关闭、删除、复制、读、写和查询操作。用户可以通过命令行输入来执行这些操作。