Copying over the ex17 bits so that I can revert the main file to pre-extra-credit state
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Dan Buch
parent
a3133a8672
commit
40a718203c
239
ex17-ec.c
Normal file
239
ex17-ec.c
Normal file
@ -0,0 +1,239 @@
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#include <stdio.h>
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#include <assert.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <string.h>
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#define DEFAULT_MAX_DATA 512
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#define DEFAULT_MAX_ROWS 100
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struct Address {
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int id;
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int set;
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char *name;
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char *email;
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};
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struct Database {
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size_t size;
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int max_data;
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int max_rows;
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struct Address *rows;
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};
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struct Connection {
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FILE *file;
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struct Database *db;
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};
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void Database_close(struct Connection *conn);
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void die(const char *message, struct Connection *conn)
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{
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if(errno) {
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perror(message);
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} else {
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printf("ERROR: %s\n", message);
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}
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Database_close(conn);
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exit(1);
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}
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void Address_print(struct Address *addr)
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{
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printf("%d %s %s\n",
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addr->id, addr->name, addr->email);
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}
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void Database_load(struct Connection *conn)
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{
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rewind(conn->file);
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int rc = fread(&conn->db->max_rows, sizeof(int), 1, conn->file);
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if(rc != 1) die("Failed to load database max_rows.", conn);
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rc = fread(&conn->db->max_data, sizeof(int), 1, conn->file);
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if(rc != 1) die("Failed to load database max_data.", conn);
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rc = fread(conn->db->rows, sizeof(struct Address), conn->db->max_rows, conn->file);
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if(rc != 1) die("Failed to load database rows.", conn);
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}
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struct Connection* Database_open(const char *filename, char mode, int max_rows)
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{
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struct Connection *conn = malloc(sizeof(struct Connection));
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if(!conn) die("Memory error", conn);
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conn->db = malloc(sizeof(struct Database));
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if(!conn->db) die("Memory error", conn);
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size_t rowsize = max_rows * sizeof(struct Address);
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conn->db->size = rowsize;
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conn->db->rows = malloc(rowsize);
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if(!conn->db->rows) die("Memory error", conn);
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if(mode == 'c') {
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conn->file = fopen(filename, "w");
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} else {
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conn->file = fopen(filename, "r+");
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if(conn->file) {
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Database_load(conn);
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}
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}
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if(!conn->file) die("Failed to open the file", conn);
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return conn;
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}
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void Database_close(struct Connection *conn)
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{
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if(conn != NULL) {
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if(conn->file) fclose(conn->file);
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if(conn->db) free(conn->db);
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free(conn);
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}
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}
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void Database_write(struct Connection *conn)
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{
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rewind(conn->file);
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int rc = fwrite(&conn->db->size, sizeof(size_t), 1, conn->file);
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if(rc != 1) die("Failed to write database size.", conn);
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rc = fwrite(&conn->db->max_rows, sizeof(int), 1, conn->file);
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if(rc != 1) die("Failed to write database max_rows.", conn);
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rc = fwrite(&conn->db->max_data, sizeof(int), 1, conn->file);
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if(rc != 1) die("Failed to write database max_data.", conn);
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rc = fwrite(conn->db->rows, conn->db->size, 1, conn->file);
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if(rc != 1) die("Failed to write database rows.", conn);
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rc = fflush(conn->file);
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if(rc == -1) die("Cannot flush database.", conn);
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}
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void Database_create(struct Connection *conn, int max_rows, int max_data)
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{
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int i = 0;
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conn->db->max_rows = max_rows;
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conn->db->max_data = max_data;
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for(i = 0; i < conn->db->max_rows; i++) {
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// make a prototype to initialize it
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struct Address addr = {.id = i, .set = 0};
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// then just assign it
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conn->db->rows[i] = addr;
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}
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}
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void Database_set(struct Connection *conn, int id, const char *name, const char *email)
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{
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int max_data = conn->db->max_data;
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struct Address *addr = &conn->db->rows[id];
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if(addr->set) die("Already set, delete it first", conn);
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addr->set = 1;
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char *res = strncpy(addr->name, name, max_data);
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if(!res) die("Name copy failed", conn);
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addr->name[max_data - 1] = '\0';
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res = strncpy(addr->email, email, max_data);
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if(!res) die("Email copy failed", conn);
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addr->email[max_data - 1] = '\0';
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}
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void Database_get(struct Connection *conn, int id)
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{
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struct Address *addr = &conn->db->rows[id];
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if(addr->set) {
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Address_print(addr);
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} else {
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die("ID is not set", conn);
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}
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}
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void Database_delete(struct Connection *conn, int id)
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{
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struct Address addr = {.id = id, .set = 0};
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conn->db->rows[id] = addr;
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}
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void Database_list(struct Connection *conn)
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{
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int i = 0;
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struct Database *db = conn->db;
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for(i = 0; i < conn->db->max_rows; i++) {
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struct Address *cur = &db->rows[i];
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if(cur->set) {
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Address_print(cur);
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}
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}
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}
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int main(int argc, char *argv[])
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{
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if(argc < 3) die("USAGE: ex17 <dbfile> <action>[:max_data,max_rows] [action params]", NULL);
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char *filename = argv[1];
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int max_data = DEFAULT_MAX_DATA;
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int max_rows = DEFAULT_MAX_ROWS;
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char action = argv[2][0];
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if(':' == argv[2][1]) {
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sscanf(argv[2], "%c:%d,%d", &action, &max_data, &max_rows);
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}
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struct Connection *conn = Database_open(filename, action, max_rows);
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int id = 0;
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if(argc > 3) id = atoi(argv[3]);
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if(id >= max_rows) die("There's not that many records.", conn);
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switch(action) {
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case 'c':
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Database_create(conn, max_rows, max_data);
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Database_write(conn);
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break;
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case 'g':
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if(argc != 4) die("Need an id to get", conn);
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Database_get(conn, id);
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break;
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case 's':
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if(argc != 6) die("Need id, name, email to set", conn);
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Database_set(conn, id, argv[4], argv[5]);
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Database_write(conn);
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break;
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case 'd':
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if(argc != 4) die("Need id to delete", conn);
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Database_delete(conn, id);
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Database_write(conn);
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break;
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case 'l':
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Database_list(conn);
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break;
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default:
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die("Invalid action, only: c=create, g=get, s=set, d=del, l=list", conn);
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}
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Database_close(conn);
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return 0;
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}
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