OS.rar_操作系统_文件管理

/* *模拟文件管理 */ #include<iostream> #include<string> #include<vector> #include<algorithm> #include<stdlib.h> #include<string.h> using namespace std; #define MAX 1000 /* *定义文件数据结构 */ typedef struct FCB { char file_name[20]; bool file_protect[3]; //只读、不可访问、不可删除 int head, tail; //文件指向存储位置的头尾 int file_length; bool isOpen; //是否已打开 FCB *next; }FCB; char space[10000]; //磁盘 int spaceSizeLeft = 10000; int fileCount = 0; int openCount = 0; //空闲表 typedef struct rest { int begin; int size; }rest; typedef struct restList { rest r[MAX]; int length; }restList; restList rl; bool createFile(FCB *head); bool deleteFile(FCB *head); bool readFile(FCB *head); bool writeFile(FCB *head); bool openFile(FCB *head); bool closeFile(FCB *head); void viewSpace(FCB *head); int cmp1(const void *a, const void*b); //按空闲区开始位置排序 int cmp2(const void *a, const void*b); //按空闲区大小排序 int main() { rl.length = 1; rl.r[0].begin = 0; rl.r[0].size = 10000; FCB *head = (FCB*)malloc(sizeof(FCB)); head->next = NULL; while (1) { cout << "欢迎使用文件管理系统" << endl; cout << "输入对应数字使用对应功能" << endl; cout << "1.创建文件" << endl; cout << "2.删除文件" << endl; cout << "3.打开文件" << endl; cout << "4.关闭文件" << endl; cout << "5.读文件" << endl; cout << "6.写文件" << endl; cout << "7.查看磁盘情况" << endl; int input; cin >> input; switch (input) { case 1: createFile(head); break; case 2: deleteFile(head); break; case 3: openFile(head); break; case 4: closeFile(head); break; case 5: readFile(head); break; case 6: writeFile(head); break; case 7: viewSpace(head); break; default: cout << "输入错误，请重新输入" << endl; } system("pause"); system("cls"); } } bool createFile(FCB* head) { char name[20]; bool protect[3]; int length; cout << "依次输入文件名，是否可修改，是否可访问，是否可删除，文件大小" << endl; cin >> name >> protect[0] >> protect[1] >> protect[2] >> length; if (length > spaceSizeLeft) { cout << "文件过大" << endl; return false; } FCB *q = head; FCB *p = head->next; while (p) { if (strcmp(name, p->file_name) == 0) { cout << "文件名已存在" << endl; return false; } q = p; p = p->next; } //算法： 最佳适应算法(best fit) //找一个空闲区 //对空闲表按空闲区大小排序 bool isFind = false; qsort(rl.r, rl.length, sizeof(rest), cmp2); int i; for (i = 0; i < rl.length; ++i) { if (rl.r[i].size >= length) { isFind = true; break; } } if (!isFind) { cout << "找不到空闲区，文件创建失败" << endl; return false; } FCB *newFile = (FCB*)malloc(sizeof(FCB)); newFile->next = NULL; newFile->head = rl.r[i].begin; newFile->tail = rl.r[i].begin + rl.r[i].size; strcpy(newFile->file_name, name); newFile->file_length = length; for (int k = 0; k < 3; ++k) { newFile->file_protect[k] = protect[k]; } fileCount++; //更新空闲表 if (rl.r[i].size == newFile->file_length) { for (int j = i; j < rl.length; ++j) { rl.r[j] = rl.r[j + 1]; } rl.length--; } else { rl.r[i].begin = rl.r[i].begin + newFile->file_length; rl.r[i].size = rl.r[i].size - newFile->file_length; } spaceSizeLeft -= newFile->file_length; cout << "文件" << newFile->file_name << "创建成功" << endl; q->next = newFile; newFile->isOpen = false; return true; } bool deleteFile(FCB *head) { char name[20]; cout << "输入删除的文件名" << endl; cin >> name; FCB *p = head->next; FCB *q = head; while (p) { if (strcmp(name, p->file_name) == 0) { break; } else { p = p->next; q = q->next; } } if (!p) { cout << "文件不存在" << endl; return false; } if (!p->file_protect[2]) { cout << "文件不可删除" << endl; return false; } if (p->isOpen) { cout << "文件未关闭" << endl; return false; } rl.r[rl.length].begin = p->head; rl.r[rl.length].size = p->file_length; rl.length++; fileCount--; q->next = p->next; free(p); cout << "文件" << name << "已删除" << endl; //TODO:合并空闲区 qsort(rl.r, rl.length, sizeof(rest), cmp1); for (int i = 0; i < rl.length - 1; ++i) { if (rl.r[i].begin + rl.r[i].size + 1 == rl.r[i + 1].begin) { rl.r[i].size = rl.r[i].size + rl.r[i + 1].size; for (int j = i; j < rl.length - 1; ++j) { rl.r[j] = rl.r[j + 1]; } --rl.length; } } return true; } void viewSpace(FCB *head) { cout << "当前磁盘文件数量:" << fileCount << endl; cout << "已打开的文件数量:" << openCount << endl; cout << "磁盘总空间:10000字节" << endl; cout << "磁盘已用空间:" << 10000 - spaceSizeLeft << "字节" << endl; cout << "磁盘可用空间:" << spaceSizeLeft << "字节" << endl; } bool openFile(FCB *head) { cout << "请输入打开的文件名" << endl; char name[20]; cin >> name; FCB *p = head->next; FCB *q = head; while (p) { if (strcmp(name, p->file_name) == 0) { break; } else { p = p->next; q = q->next; } } if (!p) { cout << "文件不存在" << endl; return false; } if (!p->file_protect[1]) { cout << "文件不可访问" << endl; return false; } cout << "文件" << name << "已经打开" << endl; p->isOpen = true; openCount++; return true; } bool closeFile(FCB *head) { cout << "请输入关闭的文件名" << endl; char name[20]; cin >> name; FCB *p = head->next; FCB *q = head; while (p) { if (strcmp(name, p->file_name) == 0) { break; } else { p = p->next; q = q->next; } } if (!p) { cout << "文件不存在" << endl; return false; } if (!p->isOpen) { cout << "文件未打开" << endl; return false; } p->isOpen = false; openCount--; cout << "文件" << name << "已关闭" << endl; return true; } bool writeFile(struct FCB *head) { cout << "请输入写入的文件名" << endl; char name[20]; cin >> name; FCB *p = head->next; FCB *q = head; while (p) { if (strcmp(name, p->file_name) == 0) { break; } else { p = p->next; q = q->next; } } if (!p) { cout << "文件不存在" << endl; return false; } if (!p->isOpen) { cout << "文件未打开" << endl; return false; } if (!p->file_protect[0]) { cout << "文件只读" << endl; return false; } cout << "请输入往文件写入的内容，不要超过文件长度" << endl; char* content = (char*)malloc(p->file_length * sizeof(char)); cin >> content; for (int i = 0; i < p->file_length; ++i) { space[p->head + i] = content[i]; } cout << "写入成功" << endl; return true; } bool readFile(FCB *head) { cout << "请输入读的文件名" << endl; char name[20]; cin >> name; FCB *p = head->next; FCB *q = head; while (p) { if (strcmp(name, p->file_name) == 0) { break; } else { p = p->next; q = q->next; } } if (!p) { cout << "文件不存在" << endl; return false; } if (p->isOpen == false) { cout << "文件未打开" << endl; return false; } char* content = (char*)malloc(p->file_length * sizeof(char)); for (int i = 0; i < p->file_length; ++i) { content[i] = space[p->head + i]; } cout << "文件" << name << "的内容是" << endl; cout << content << endl; return true; } int cmp1(const void *a, const void*b) { return (*(rest*)a).begin - (*(rest*)b).begin; } int cmp2(const void *a, const void*b) { return (*(rest*)a).size - (*(rest*)b).size; }