Minor fixes

include/db.h

@@ -1,42 +1,53 @@
-#ifndef _DB_H_
+#ifndef DB_H
-#define _DB_H_
+#define DB_H
+
+#include <stdio.h>
 
-#define MAX_TABLES 10
-#define MAX_COLUMNS 10
-#define MAX_ROWS 100
 #define MAX_QUERY_LENGTH 256
-#define MAX_NAME_LENGTH 50
+
+/* Default filename for saving/loading the database */
 #define DB_FILE "database.db"
 
-typedef struct
+
+typedef struct Column
 {
-    char name[MAX_NAME_LENGTH];
+    char *name;
-    char data[MAX_ROWS][MAX_NAME_LENGTH];
+    char **data; /* Array of string data for each row */
 } Column;
 
-typedef struct
+typedef struct Table
 {
-    char name[MAX_NAME_LENGTH];
+    char *name;
-    Column columns[MAX_COLUMNS];
-    int column_count;
     int row_count;
+    int column_count;
+    Column **columns;
 } Table;
 
-typedef struct
+typedef struct Database
 {
-    Table tables[MAX_TABLES];
     int table_count;
+    Table **tables;
 } Database;
 
+/* Database Operations */
 Database *create_db(void);
-void create_table(Database *db, const char *table_name, char *columns);
+void free_database(Database *db);
-void insert_into_table(Database *db, const char *table_name, char *values);
-void select_from_table(Database *db, const char *table_name);
-void parse_query(Database *db, const char *query);
-Table *find_table(Database *db, const char *table_name);
-void save_database_to_file(Database *db, const char *filename);
-void load_database_from_file(Database *db, const char *filename);
-int validate_ipv4_address(const char *ip);
-void trim_whitespace(char *str);
 
-#endif
+/* Table Operations */
+Table *find_table(Database *db, const char *table_name);
+void create_table(Database *db, const char *table_name, const char *columns_str);
+void insert_into_table(Database *db, const char *table_name, const char *values_str);
+void select_from_table(Database *db, const char *table_name);
+
+/* File Operations */
+void save_database_to_file(Database *db, const char *filename);
+Database *load_database_from_file(Database *db, const char *filename);
+
+/* Query Parsing */
+Database *parse_query(Database *db, const char *query);
+
+/* Utility Functions */
+int validate_ipv4_address(const char *ip);
+char *trim_whitespace(char *str);
+
+#endif /* DB_H */

src/db.c

@@ -2,42 +2,79 @@
 #include <stdlib.h>
 #include <string.h>
 #include <ctype.h>
-
 #include "db.h"
 
-void trim_whitespace(char *str)
+/* Writes a string to a file.
+ * The string is preceded by its length (including the null terminator).
+ */
+static void write_string(FILE *file, const char *str)
+{
+    int len = (int)strlen(str) + 1;
+    fwrite(&len, sizeof(int), 1, file);
+    fwrite(str, sizeof(char), len, file);
+}
+
+/* Reads a string from a file that was written using write_string.
+ * Returns a pointer to the heap-allocated string, or NULL on failure.
+ */
+static char *read_string(FILE *file)
+{
+    int len;
+    char *str;
+
+    if (fread(&len, sizeof(int), 1, file) != 1)
+    {
+        return NULL;
+    }
+
+    str = malloc(len);
+    if (str == NULL)
+    {
+        return NULL;
+    }
+
+    fread(str, sizeof(char), len, file);
+    return str;
+}
+
+/* Trims leading and trailing whitespace from a string in place.
+ * Returns a pointer to the trimmed string.
+ */
+char *trim_whitespace(char *str)
 {
     char *end;
 
+    /* Trim leading whitespace */
     while (isspace((unsigned char)*str))
     {
         str++;
     }
 
-    if (*str == 0)
+    if (*str == '\0')
     {
-        return;
+        return str;
     }
 
+    /* Trim trailing whitespace */
     end = str + strlen(str) - 1;
-
     while (end > str && isspace((unsigned char)*end))
     {
         end--;
     }
 
+    /* Write new null terminator */
     end[1] = '\0';
+    return str;
 }
 
+/* Validates if the provided string is in valid IPv4 format.
+ * Returns 1 if valid, 0 otherwise.
+ */
 int validate_ipv4_address(const char *ip)
 {
-    int segments;
+    int segments = 0;
-    int ch_count;
+    int ch_count = 0;
-    const char *ptr;
+    const char *ptr = ip;
-
-    segments = 0;
-    ch_count = 0;
-    ptr = ip;
 
     while (*ptr)
     {
@@ -47,7 +84,6 @@ int validate_ipv4_address(const char *ip)
             {
                 return 0;
             }
-
             segments++;
             ch_count = 0;
         }
@@ -59,7 +95,6 @@ int validate_ipv4_address(const char *ip)
         {
             ch_count++;
         }
-
         ptr++;
     }
 
@@ -67,217 +102,389 @@ int validate_ipv4_address(const char *ip)
     {
         return 0;
     }
-
     return 1;
 }
 
+/* Creates a new Database instance.
+ * Returns a pointer to the new Database or NULL on failure.
+ */
 Database *create_db(void)
 {
-    Database *db;
+    Database *db = malloc(sizeof(Database));
-
-    db = calloc(1, sizeof(*db));
     if (db == NULL)
     {
         printf("Failed to allocate memory for DB.\n");
         return NULL;
     }
 
+    db->tables = NULL;
     db->table_count = 0;
     return db;
 }
 
-Table *find_table(Database *db, const char *table_name)
+/* Frees all memory associated with the Database.
+ */
+void free_database(Database *db)
 {
-    int i;
+    if (db == NULL)
-
-    for (i = 0; i < db->table_count; i++)
     {
-        if (strcmp(db->tables[i].name, table_name) == 0)
-        {
-            return &db->tables[i];
-        }
-    }
-
-    return NULL;
-}
-
-void create_table(Database *db, const char *table_name, char *columns)
-{
-    Table *table;
-    char *token;
-
-    if (db->table_count >= MAX_TABLES)
-    {
-        printf("Error: Maximum table limit reached.\n");
         return;
     }
 
-    if (find_table(db, table_name))
+    for (int i = 0; i < db->table_count; i++)
+    {
+        Table *currTable = db->tables[i];
+        free(currTable->name);
+
+        for (int j = 0; j < currTable->column_count; j++)
+        {
+            Column *currColumn = currTable->columns[j];
+            free(currColumn->name);
+
+            for (int r = 0; r < currTable->row_count; r++)
+            {
+                free(currColumn->data[r]);
+            }
+            free(currColumn->data);
+            free(currColumn);
+        }
+        free(currTable->columns);
+        free(currTable);
+    }
+    free(db->tables);
+    free(db);
+}
+
+/* Searches for a table by name in the Database.
+ * Returns a pointer to the Table if found, or NULL otherwise.
+ */
+Table *find_table(Database *db, const char *table_name)
+{
+    for (int i = 0; i < db->table_count; i++)
+    {
+        if (strcmp(db->tables[i]->name, table_name) == 0)
+        {
+            return db->tables[i];
+        }
+    }
+    return NULL;
+}
+
+/* Creates a new table with the given name and comma-separated column definitions.
+ */
+void create_table(Database *db, const char *table_name, const char *columns_str)
+{
+    if (find_table(db, table_name) != NULL)
     {
         printf("Error: Table '%s' already exists.\n", table_name);
         return;
     }
 
-    table = &db->tables[db->table_count++];
+    Table *table = malloc(sizeof(Table));
-    strcpy(table->name, table_name);
+    if (table == NULL)
-    table->column_count = 0;
-    table->row_count = 0;
-
-    token = strtok(columns, ",");
-
-    while (token && table->column_count < MAX_COLUMNS)
     {
-        trim_whitespace(token);
+        printf("Error: Memory allocation failed for table '%s'.\n", table_name);
-        strcpy(table->columns[table->column_count++].name, token);
+        return;
+    }
+    table->name = strdup(table_name);
+    table->row_count = 0;
+    table->column_count = 0;
+    table->columns = NULL;
+
+    char *cols_copy = strdup(columns_str);
+    if (cols_copy == NULL)
+    {
+        printf("Error: Memory allocation failed for columns copy.\n");
+        free(table);
+        return;
+    }
+
+    char *token = strtok(cols_copy, ",");
+    while (token != NULL)
+    {
+        token = trim_whitespace(token);
+        Column *col = malloc(sizeof(Column));
+        if (col == NULL)
+        {
+            printf("Error: Memory allocation failed for column '%s'.\n", token);
+            free(cols_copy);
+            return;
+        }
+        col->name = strdup(token);
+        col->data = NULL;
+
+        table->columns = realloc(table->columns, sizeof(Column*) * (table->column_count + 1));
+        if (table->columns == NULL)
+        {
+            printf("Error: Memory allocation failed while adding column '%s'.\n", token);
+            free(col->name);
+            free(col);
+            free(cols_copy);
+            return;
+        }
+        table->columns[table->column_count++] = col;
         token = strtok(NULL, ",");
     }
+    free(cols_copy);
 
     if (table->column_count == 0)
     {
         printf("Error: No columns defined for table '%s'.\n", table_name);
-        db->table_count--;
+        free(table->name);
+        free(table);
         return;
     }
 
-    printf("Table '%s' with %d columns created successfully.\n", table_name, table->column_count);
+    db->tables = realloc(db->tables, sizeof(Table*) * (db->table_count + 1));
+    if (db->tables == NULL)
+    {
+        printf("Error: Memory allocation failed while adding table '%s'.\n", table_name);
+        free_database(db);
+        exit(EXIT_FAILURE);
+    }
+    db->tables[db->table_count++] = table;
+
+    printf("Table '%s' with %d columns created successfully.\n", table->name, table->column_count);
 }
 
-void insert_into_table(Database *db, const char *table_name, char *values)
+/* Inserts a new row into the specified table using comma-separated values.
+ */
+void insert_into_table(Database *db, const char *table_name, const char *values_str)
 {
-    Table *table;
+    Table *table = find_table(db, table_name);
-    char *token;
+    if (table == NULL)
-    int col_index;
-
-    table = find_table(db, table_name);
-
-    if (!table)
     {
         printf("Error: Table '%s' does not exist.\n", table_name);
         return;
     }
 
-    if (table->column_count == 0)
+    char *vals_copy = strdup(values_str);
+    if (vals_copy == NULL)
     {
-        printf("Error: Table '%s' has no columns defined.\n", table_name);
+        printf("Error: Memory allocation failed for values copy.\n");
         return;
     }
 
-    if (table->row_count >= MAX_ROWS)
+    char *token = strtok(vals_copy, ",");
+    int col_index = 0;
+    char **values = malloc(sizeof(char*) * table->column_count);
+    if (values == NULL)
     {
-        printf("Error: Maximum row limit reached for table '%s'.\n", table_name);
+        printf("Error: Memory allocation failed for values array.\n");
+        free(vals_copy);
         return;
     }
 
-    token = strtok(values, ",");
+    while (token != NULL && col_index < table->column_count)
-    col_index = 0;
-
-    while (token && col_index < table->column_count)
     {
-        trim_whitespace(token);
+        token = trim_whitespace(token);
-
+        /* Validate IPv4 address if required */
-        if (strcmp(table->columns[col_index].name, "IPv4") == 0)
+        if (strcmp(table->columns[col_index]->name, "IPv4") == 0)
         {
             if (!validate_ipv4_address(token))
             {
                 printf("Error: Invalid IPv4 address '%s'.\n", token);
+                free(vals_copy);
+                for (int i = 0; i < col_index; i++)
+                {
+                    free(values[i]);
+                }
+                free(values);
                 return;
             }
         }
-
+        values[col_index++] = strdup(token);
-        strcpy(table->columns[col_index].data[table->row_count], token);
         token = strtok(NULL, ",");
-        col_index++;
     }
+    free(vals_copy);
 
     if (col_index != table->column_count)
     {
         printf("Error: Column count mismatch for table '%s'.\n", table_name);
+        for (int i = 0; i < col_index; i++)
+        {
+            free(values[i]);
+        }
+        free(values);
         return;
     }
 
+    for (int i = 0; i < table->column_count; i++)
+    {
+        Column *col = table->columns[i];
+        col->data = realloc(col->data, sizeof(char*) * (table->row_count + 1));
+        if (col->data == NULL)
+        {
+            printf("Error: Memory allocation failed while inserting row.\n");
+            free(values);
+            return;
+        }
+        col->data[table->row_count] = values[i];
+    }
+    free(values);
     table->row_count++;
     printf("Row inserted into table '%s'.\n", table_name);
 }
 
+/* Displays the contents of the specified table.
+ */
 void select_from_table(Database *db, const char *table_name)
 {
-    Table *table;
+    Table *table = find_table(db, table_name);
-    int i;
+    if (table == NULL)
-    int j;
-
-    table = find_table(db, table_name);
-
-    if (!table)
     {
         printf("Error: Table '%s' does not exist.\n", table_name);
         return;
     }
 
     printf("Table: %s\n", table->name);
-
+    for (int i = 0; i < table->column_count; i++)
-    for (i = 0; i < table->column_count; i++)
     {
-        printf("%s\t", table->columns[i].name);
+        printf("%s\t", table->columns[i]->name);
     }
-
     printf("\n");
 
-    for (i = 0; i < table->row_count; i++)
+    for (int r = 0; r < table->row_count; r++)
     {
-        for (j = 0; j < table->column_count; j++)
+        for (int c = 0; c < table->column_count; c++)
         {
-            printf("%s\t", table->columns[j].data[i]);
+            printf("%s\t", table->columns[c]->data[r]);
         }
-
         printf("\n");
     }
 }
 
+/* Saves the database to a binary file.
+ */
 void save_database_to_file(Database *db, const char *filename)
 {
-    FILE *file;
+    FILE *file = fopen(filename, "wb");
-
+    if (file == NULL)
-    file = fopen(filename, "wb");
-
-    if (!file)
     {
         printf("Error: Could not open file '%s' for writing.\n", filename);
         return;
     }
 
-    fwrite(db, sizeof(Database), 1, file);
+    fwrite(&db->table_count, sizeof(int), 1, file);
+    for (int i = 0; i < db->table_count; i++)
+    {
+        Table *table = db->tables[i];
+        write_string(file, table->name);
+        fwrite(&table->column_count, sizeof(int), 1, file);
+        fwrite(&table->row_count, sizeof(int), 1, file);
 
+        for (int j = 0; j < table->column_count; j++)
+        {
+            Column *col = table->columns[j];
+            write_string(file, col->name);
+            for (int r = 0; r < table->row_count; r++)
+            {
+                write_string(file, col->data[r]);
+            }
+        }
+    }
     fclose(file);
     printf("Database saved to '%s'.\n", filename);
 }
 
-void load_database_from_file(Database *db, const char *filename)
+/* Loads a database from a binary file.
+ * Frees the current database and returns a new one loaded from the file.
+ */
+Database *load_database_from_file(Database *db, const char *filename)
 {
-    FILE *file;
+    FILE *file = fopen(filename, "rb");
-
+    if (file == NULL)
-    file = fopen(filename, "rb");
-
-    if (!file)
     {
         printf("Error: Could not open file '%s' for reading.\n", filename);
-        return;
+        return db;
     }
 
-    fread(db, sizeof(Database), 1, file);
+    free_database(db);
+    Database *new_db = create_db();
+    if (new_db == NULL)
+    {
+        fclose(file);
+        return NULL;
+    }
 
+    int table_count = 0;
+    fread(&table_count, sizeof(int), 1, file);
+    for (int i = 0; i < table_count; i++)
+    {
+        Table *table = malloc(sizeof(Table));
+        if (table == NULL)
+        {
+            printf("Error: Memory allocation failed while loading table.\n");
+            continue;
+        }
+
+        table->name = read_string(file);
+        fread(&table->column_count, sizeof(int), 1, file);
+        fread(&table->row_count, sizeof(int), 1, file);
+        table->columns = NULL;
+
+        for (int j = 0; j < table->column_count; j++)
+        {
+            Column *col = malloc(sizeof(Column));
+            if (col == NULL)
+            {
+                printf("Error: Memory allocation failed while loading column.\n");
+                continue;
+            }
+            col->name = read_string(file);
+            col->data = NULL;
+
+            for (int r = 0; r < table->row_count; r++)
+            {
+                char *cell = read_string(file);
+                col->data = realloc(col->data, sizeof(char*) * (r + 1));
+                if (col->data == NULL)
+                {
+                    printf("Error: Memory allocation failed while loading row data.\n");
+                    free(cell);
+                    continue;
+                }
+                col->data[r] = cell;
+            }
+            table->columns = realloc(table->columns, sizeof(Column*) * (j + 1));
+            if (table->columns == NULL)
+            {
+                printf("Error: Memory allocation failed while loading columns array.\n");
+                free(col);
+                continue;
+            }
+            table->columns[j] = col;
+        }
+        new_db->tables = realloc(new_db->tables, sizeof(Table*) * (i + 1));
+        if (new_db->tables == NULL)
+        {
+            printf("Error: Memory allocation failed while adding table to database.\n");
+            free(table);
+            continue;
+        }
+        new_db->tables[i] = table;
+        new_db->table_count++;
+    }
     fclose(file);
     printf("Database loaded from '%s'.\n", filename);
+    return new_db;
 }
 
-void parse_query(Database *db, const char *query)
+/* Parses and executes a query string.
+ * Supported commands: CREATE TABLE, INSERT INTO, SELECT, SAVE, LOAD.
+ */
+Database *parse_query(Database *db, const char *query)
 {
     char query_copy[MAX_QUERY_LENGTH];
-    char *command;
+    strncpy(query_copy, query, MAX_QUERY_LENGTH - 1);
-    char *table_name;
+    query_copy[MAX_QUERY_LENGTH - 1] = '\0';
-    char *columns;
 
-    strcpy(query_copy, query);
+    char *command = strtok(query_copy, " ");
-    command = strtok(query_copy, " ");
+    if (command == NULL)
+    {
+        printf("Error: Empty query.\n");
+        return db;
+    }
 
     if (strcmp(command, "CREATE") == 0)
     {
@@ -285,40 +492,37 @@ void parse_query(Database *db, const char *query)
         if (next_token == NULL || strcmp(next_token, "TABLE") != 0)
         {
             printf("Error: Invalid CREATE TABLE syntax.\n");
-            return;
+            return db;
         }
 
-        table_name = strtok(NULL, " ");
+        char *table_name = strtok(NULL, " ");
         if (table_name == NULL)
         {
             printf("Error: Table name is missing.\n");
-            return;
+            return db;
         }
 
-        columns = strchr(query, '(');
+        char *columns = strchr(query, '(');
         if (columns == NULL)
         {
             printf("Error: Missing column definitions.\n");
-            return;
+            return db;
         }
-
         columns++;
         char *closing_paren = strchr(columns, ')');
         if (closing_paren == NULL)
         {
             printf("Error: Missing closing parenthesis in column definitions.\n");
-            return;
+            return db;
         }
-
         *closing_paren = '\0';
-        trim_whitespace(columns);
 
+        columns = trim_whitespace(columns);
         if (strlen(columns) == 0)
         {
             printf("Error: No columns defined for table '%s'.\n", table_name);
-            return;
+            return db;
         }
-
         create_table(db, table_name, columns);
     }
     else if (strcmp(command, "INSERT") == 0)
@@ -327,53 +531,50 @@ void parse_query(Database *db, const char *query)
         if (next_token == NULL || strcmp(next_token, "INTO") != 0)
         {
             printf("Error: Invalid INSERT INTO syntax.\n");
-            return;
+            return db;
         }
 
-        table_name = strtok(NULL, " ");
+        char *table_name = strtok(NULL, " ");
         if (table_name == NULL)
         {
             printf("Error: Table name is missing.\n");
-            return;
+            return db;
         }
 
-        columns = strchr(query, '(');
+        char *values = strchr(query, '(');
-        if (columns == NULL)
+        if (values == NULL)
         {
             printf("Error: Missing values.\n");
-            return;
+            return db;
         }
-
+        values++;
-        columns++;
+        char *closing_paren = strchr(values, ')');
-        char *closing_paren = strchr(columns, ')');
         if (closing_paren == NULL)
         {
             printf("Error: Missing closing parenthesis in values.\n");
-            return;
+            return db;
         }
-
         *closing_paren = '\0';
-        trim_whitespace(columns);
 
-        if (strlen(columns) == 0)
+        values = trim_whitespace(values);
+        if (strlen(values) == 0)
         {
             printf("Error: No values provided for table '%s'.\n", table_name);
-            return;
+            return db;
         }
-
+        insert_into_table(db, table_name, values);
-        insert_into_table(db, table_name, columns);
     }
     else if (strcmp(command, "SELECT") == 0)
     {
-        strtok(NULL, " ");
+        /* Expected syntax: SELECT * FROM table_name */
-        strtok(NULL, " ");
+        strtok(NULL, " ");  // Skip '*'
-        table_name = strtok(NULL, " ");
+        strtok(NULL, " ");  // Skip 'FROM'
+        char *table_name = strtok(NULL, " ");
         if (table_name == NULL)
         {
             printf("Error: Table name is missing in SELECT query.\n");
-            return;
+            return db;
         }
-
         select_from_table(db, table_name);
     }
     else if (strcmp(command, "SAVE") == 0)
@@ -382,10 +583,12 @@ void parse_query(Database *db, const char *query)
     }
     else if (strcmp(command, "LOAD") == 0)
     {
-        load_database_from_file(db, DB_FILE);
+        db = load_database_from_file(db, DB_FILE);
     }
     else
     {
         printf("Error: Unsupported query.\n");
     }
-}
+
+    return db;
+}

src/main.c

@@ -1,15 +1,14 @@
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
-
 #include "linenoise.h"
 #include "db.h"
 
-int main()
+int main(void)
 {
     char *query;
     Database *db;
-
+    
     db = create_db();
 
     printf("Simple SQL-like Database\n");
@@ -34,12 +33,14 @@ int main()
 
         if (strlen(query) > 0)
         {
-            parse_query(db, query);
+            db = parse_query(db, query);
             linenoiseHistoryAdd(query);
         }
 
         free(query);
     }
 
+    free_database(db);
+    
     return 0;
-}
+}