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#include <fcntl.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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struct Connection_t {
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int file_descriptor;
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};
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typedef struct Connection_t Connection;
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Connection* open_connection(char* filename) {
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int fd = open(filename,
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O_RDWR | // Read/Write mode
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O_CREAT, // Create file if it does not exist
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S_IWUSR | // Create file with user write permission
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S_IRUSR // Create file with user read permission
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);
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if (fd == -1) {
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printf("Unable to open file '%s'\n", filename);
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exit(EXIT_FAILURE);
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}
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Connection* connection = malloc(sizeof(Connection));
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connection->file_descriptor = fd;
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return connection;
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}
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char* get_db_filename(int argc, char* argv[]) {
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if (argc < 2) {
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printf("Must supply a filename for the database.\n");
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exit(EXIT_FAILURE);
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}
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return argv[1];
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}
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struct InputBuffer_t {
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char* buffer;
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size_t buffer_length;
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ssize_t input_length;
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};
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typedef struct InputBuffer_t InputBuffer;
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InputBuffer* new_input_buffer() {
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InputBuffer* input_buffer = malloc(sizeof(InputBuffer));
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input_buffer->buffer = NULL;
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input_buffer->buffer_length = 0;
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input_buffer->input_length = 0;
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return input_buffer;
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}
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void print_prompt() { printf("db > "); }
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void read_input(InputBuffer* input_buffer) {
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ssize_t bytes_read =
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getline(&(input_buffer->buffer), &(input_buffer->buffer_length), stdin);
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if (bytes_read <= 0) {
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printf("Error reading input\n");
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exit(EXIT_FAILURE);
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}
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// Ignore trailing newline
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input_buffer->input_length = bytes_read - 1;
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input_buffer->buffer[bytes_read - 1] = 0;
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}
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int main(int argc, char* argv[]) {
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char* db_filename = get_db_filename(argc, argv);
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Connection* connection = open_connection(db_filename);
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InputBuffer* input_buffer = new_input_buffer();
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while (true) {
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print_prompt();
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read_input(input_buffer);
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if (strcmp(input_buffer->buffer, ".exit") == 0) {
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exit(EXIT_SUCCESS);
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} else {
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printf("Unrecognized command '%s'.\n", input_buffer->buffer);
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}
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}
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}
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