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#include <stdio.h>
#include <assert.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#define MAX_DATA 512
#define MAX_ROWS 100
struct Address {
int id;
int set;
char name[MAX_DATA];
char email[MAX_DATA];
};
struct Database {
struct Address rows[MAX_ROWS];
};
struct Connection {
FILE *file;
struct Database *db;
};
void Database_close(struct Connection *conn)
{
if(conn) {
if(conn->file) fclose(conn->file);
if(conn->db) free(conn->db);
free(conn);
}
}
void die(const char *message, struct Connection *conn)
{
if(errno) {
perror(message);
} else {
printf("ERROR: %s\n", message);
}
Database_close(conn);
exit(1);
}
void Address_print(struct Address *addr)
{
printf("%d %s %s\n",
addr->id, addr->name, addr->email);
}
void Database_load(struct Connection *conn)
{
int rc = fread(conn->db, sizeof(struct Database), 1, conn->file);
if(rc != 1) die("Failed to load database", conn);
}
struct Connection* Database_open(const char *filename, char mode)
{
struct Connection *conn = malloc(sizeof(struct Connection));
if(!conn) die("Memory Error", conn);
conn->db = malloc(sizeof(struct Database));
if(!conn->db) die("Memory Error", conn);
if(mode == 'c') {
conn->file = fopen(filename, "w");
} else {
conn->file = fopen(filename, "r+");
if(conn->file) {
Database_load(conn);
}
}
if(!conn->file) die("Failed to open the file", conn);
return conn;
}
void Database_write(struct Connection *conn)
{
rewind(conn->file);
int rc = fwrite(conn->db, sizeof(struct Database), 1, conn->file);
if(rc != 1) die("Failed to write to database", conn);
rc = fflush(conn->file);
if(rc == -1) die("Cannont flush database", conn);
}
void Database_create(struct Connection *conn)
{
int i = 0;
for(i=0; i < MAX_ROWS; i++) {
// make a prototype & initialize it
struct Address addr = {.id = i, .set = 0};
// then just assign it
conn->db->rows[i] = addr;
}
}
void Database_set(struct Connection *conn, int id, const char *name, const char *email)
{
struct Address *addr = &conn->db->rows[id];
if(addr->set) die("Already set, delete it first", conn);
addr->set = 1;
// FIXME
char *res = strncpy(addr->name, name, MAX_DATA);
// demonstrate strncopy bug
if(!res) die("Name copy failed", conn);
res = strncpy(addr->email, email, MAX_DATA);
if(!res) die("Email copy failed", conn);
}
void Database_get(struct Connection *conn, int id)
{
struct Address *addr = &conn->db->rows[id];
if(addr->set) {
Address_print(addr);
} else {
die("ID is not set", conn);
}
}
void Database_delete(struct Connection *conn, int id)
{
struct Address addr = {.id = id, .set = 0};
conn->db->rows[id] = addr;
}
void Database_list(struct Connection *conn)
{
int i = 0;
struct Database *db = conn->db;
for(i = 0; i < MAX_ROWS; i++) {
struct Address *cur = &db->rows[i];
if(cur->set) {
Address_print(cur);
}
}
}
int main(int argc, char *argv[])
{
if(argc < 3) die("Usage: ex17 <dbfile> <action> [action params]", NULL);
char *filename = argv[1];
char action = argv[2][0];
struct Connection *conn = Database_open(filename, action);
int id = 0;
if(argc > 3) id = atoi(argv[3]);
if(id >= MAX_ROWS) die("There's not that many records", conn);
switch(action) {
case 'c':
Database_create(conn);
Database_write(conn);
break;
case 'g':
if(argc != 4) die("Please provide an ID", conn);
Database_get(conn, id);
break;
case 's':
if(argc != 6) die("Need IF, name, email to set", conn);
Database_set(conn, id, argv[4], argv[5]);
Database_write(conn);
break;
case 'd':
if(argc != 4) die("Need id to delete", conn);
Database_delete(conn, id);
Database_write(conn);
break;
case 'l':
Database_list(conn);
break;
default:
die("Invailid action, only c=create, g=get, s=set, d=del, l=list", conn);
}
Database_close(conn);
return 0;
}
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