Making a mess of ex17 extra credit (NOT WORKING)

lcthw/.ex17ec.argv

@@ -0,0 +1,2 @@
+ex17ec.db
+l

lcthw/ex17ec.c

@@ -0,0 +1,305 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <errno.h>
+#include <string.h>
+
+#define DEFAULT_MAX_DATA 512
+#define DEFAULT_MAX_ROWS 100
+
+struct Address {
+	char *name;
+	char *email;
+};
+
+struct TableOfContents {
+	size_t n_rows;
+	size_t string_field_size;
+};
+
+struct Database {
+	struct Address *rows;
+};
+
+struct Connection {
+	FILE *file;
+	struct TableOfContents *toc;
+	struct Database *db;
+};
+
+void Database_close(struct Connection *conn);
+struct Address *Database_get(struct Connection *conn, const char *email);
+
+void die(struct Connection *conn, const char *message)
+{
+	Database_close(conn);
+
+	if (errno) {
+		perror(message);
+	} else {
+		printf("ERROR: %s\n", message);
+	}
+
+	exit(1);
+}
+
+void Address_print(struct Address *addr)
+{
+	if (!addr) {
+		return;
+	}
+
+	printf("%s %s\n", addr->name, addr->email);
+}
+
+size_t Database_addr_size(struct Connection *conn)
+{
+	return sizeof(struct Address) +
+		/* name */ conn->toc->string_field_size +
+		/* email */ conn->toc->string_field_size;
+}
+
+size_t Database_size(struct Connection *conn)
+{
+	return sizeof(struct Database) +
+		(conn->toc->n_rows * Database_addr_size(conn));
+}
+
+size_t Database_n_rows(struct Connection *conn)
+{
+	return sizeof(conn->db->rows) / Database_addr_size(conn);
+}
+
+void Database_load(struct Connection *conn)
+{
+	int rc = 0;
+
+	rc = fread(conn->toc, sizeof(struct TableOfContents), 1, conn->file);
+	if (rc != 1) {
+		die(conn, "Failed to load TableOfContents.");
+	}
+
+	rc = fread(conn->db, Database_size(conn), 1, conn->file);
+	if (rc != 1) {
+		die(conn, "Failed to load Database.");
+	}
+}
+
+struct Connection *Database_open(const char *filename, char mode, size_t string_field_size)
+{
+	struct Connection *conn = malloc(sizeof(struct Connection));
+
+	if (!conn) {
+		die(conn, "Memory error allocating Connection");
+	}
+
+	conn->toc = malloc(sizeof(struct TableOfContents));
+	if (!conn->toc) {
+		die(conn, "Memory error allocating TableOfContents");
+	}
+
+	conn->toc->string_field_size = string_field_size;
+
+	conn->db = malloc(sizeof(struct Database));
+	if (!conn->db) {
+		die(conn, "Memory error allocating Database");
+	}
+
+	if (mode == 'c') {
+		conn->file = fopen(filename, "w");
+
+		conn->toc->n_rows = 1;
+
+		conn->db->rows = malloc(Database_addr_size(conn));
+		if (!conn->db->rows) {
+			die(conn, "Memory error allocating Database rows");
+		}
+
+	} else {
+		conn->file = fopen(filename, "r+");
+
+		if (conn->file) {
+			Database_load(conn);
+		}
+	}
+
+	if (!conn->file) {
+		die(conn, "Failed to open file");
+	}
+
+	return conn;
+}
+
+void Database_close(struct Connection *conn)
+{
+	if (conn) {
+		if (conn->file) {
+			fclose(conn->file);
+		}
+
+		if (conn->toc) {
+			free(conn->toc);
+		}
+
+		if (conn->db) {
+			free(conn->db);
+		}
+
+		free(conn);
+	}
+}
+
+void Database_write(struct Connection *conn)
+{
+	rewind(conn->file);
+
+	int rc = 0;
+
+	rc = fwrite(conn->toc, sizeof(struct TableOfContents), 1, conn->file);
+	if (rc != 1) {
+		die(conn, "Failed to write TableOfContents.");
+	}
+
+	rc = fwrite(conn->db, sizeof(struct Database), 1, conn->file);
+	if (rc != 1) {
+		die(conn, "Failed to write Database.");
+	}
+
+	rc = fflush(conn->file);
+	if (rc == -1) {
+		die(conn, "Cannot flush");
+	}
+}
+
+void Database_set(struct Connection *conn, const char *name, const char *email)
+{
+	struct Address *addr = Database_get(conn, email);
+	if (!addr) {
+		addr = malloc(Database_addr_size(conn));
+		conn->db->rows[Database_n_rows(conn)+1] = *addr;
+	}
+
+	char *res = strncpy(addr->name, name, conn->toc->string_field_size);
+	if (!res) {
+		die(conn, "Name copy failed");
+	}
+
+	addr->name[conn->toc->string_field_size - 1] = '\0';
+
+	res = strncpy(addr->email, email, conn->toc->string_field_size);
+	if (!res) {
+		die(conn, "Email copy failed");
+	}
+
+	addr->email[conn->toc->string_field_size - 1] = '\0';
+}
+
+struct Address *Database_get(struct Connection *conn, const char *email)
+{
+	int i = 0;
+	struct Address *addr;
+
+	for (i = 0; i < Database_n_rows(conn); i++) {
+		addr = &conn->db->rows[i];
+
+		if (strcmp(addr->email, email) == 0) {
+			return addr;
+		}
+	}
+
+	return NULL;
+}
+
+void Database_delete(struct Connection *conn, const char *email)
+{
+	struct Address *addr = Database_get(conn, email);
+	if (!addr) {
+		// already deleted
+		return;
+	}
+
+	addr->email = NULL;
+	addr->name = NULL;
+}
+
+void Database_list(struct Connection *conn)
+{
+	int i = 0;
+	struct Database *db = conn->db;
+
+	for (i = 0; i < Database_n_rows(conn); i++) {
+		struct Address *cur = &db->rows[i];
+
+		Address_print(cur);
+	}
+}
+
+size_t get_string_field_size()
+{
+	size_t string_field_size = DEFAULT_MAX_DATA;
+
+	const char *string_field_size_string = getenv("EX17_MAX_DATA");
+	if (string_field_size_string) {
+		int string_field_size_int = atoi(string_field_size_string);
+		string_field_size = string_field_size_int;
+	}
+
+	return string_field_size;
+}
+
+int main(int argc, char *argv[])
+{
+	if (argc < 3) {
+		die(NULL, "USAGE: ex17 <dbfile> <action> [action params]");
+	}
+
+	char *filename = argv[1];
+	char action = argv[2][0];
+
+	size_t string_field_size = get_string_field_size();
+
+	struct Connection *conn = Database_open(filename, action, string_field_size);
+
+	switch (action) {
+		case 'c':
+			Database_write(conn);
+			break;
+
+		case 'g':
+			if (argc != 4) {
+				die(conn, "Need an `email` to get");
+			}
+
+			Address_print(Database_get(conn, argv[3]));
+			break;
+
+		case 's':
+			if (argc != 5) {
+				die(conn, "Need a `name` and `email` to set");
+			}
+
+			Database_set(conn, argv[3], argv[4]);
+			Database_write(conn);
+			break;
+
+		case 'd':
+			if (argc != 4) {
+				die(conn, "Need an `email` to delete");
+			}
+
+			Database_delete(conn, argv[3]);
+			Database_write(conn);
+			break;
+
+		case 'l':
+			Database_list(conn);
+			break;
+
+		default:
+			die(conn, "Invalid action: c=create, g=get, s=set, d=del, l=list");
+	}
+
+	Database_close(conn);
+
+	return 0;
+}