init(dbms): introduce Tanabata database management system (TDBMS)

Only basic database operations, only Unix domain sockets by now
2023-01-20 22:50:01 +03:00
parent 08da5aeb79
commit 871b76d43a
5 changed files with 701 additions and 0 deletions
@@ -0,0 +1,88 @@
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+
+#include "../../include/tdbms-client.h"
+
+int tdbms_connect(const char *domain, const char *addr) {
+    int socket_fd;
+    struct sockaddr_un sockaddr;
+    int domain_code;
+    if (strcmp(domain, "UNIX") == 0) {
+        domain_code = AF_UNIX;
+    } else {
+        fprintf(stderr, "ERROR: unexpected socket domain '%s'\n", domain);
+        return -1;
+    }
+    if (strlen(addr) > sizeof(sockaddr.sun_path) - 1) {
+        fprintf(stderr, "ERROR: too long socket address\n");
+        return -1;
+    }
+    socket_fd = socket(domain_code, SOCK_STREAM, 0);
+    if (socket_fd < 0) {
+        fprintf(stderr, "ERROR: failed to initialize socket\n");
+        return -1;
+    }
+    bzero(&sockaddr, sizeof(sockaddr));
+    sockaddr.sun_family = domain_code;
+    strcpy(sockaddr.sun_path, addr);
+    if (connect(socket_fd, (const struct sockaddr *) &sockaddr, sizeof(sockaddr)) < 0) {
+        fprintf(stderr, "ERROR: failed to connect the socket\n");
+        return -1;
+    }
+    return socket_fd;
+}
+
+int tdbms_close(int socket_fd) {
+    return close(socket_fd);
+}
+
+int tdb_query(int socket_fd, const char *db_name, char request_code, const char *request_body, char **response) {
+    if (socket_fd < 0 || db_name == NULL || request_body == NULL) {
+        return 1;
+    }
+    size_t req_size = 1 + strlen(db_name) + 1 + strlen(request_body) + 1, resp_size;
+    ssize_t nread, nwrite;
+    char *request = malloc(req_size);
+    char *buffer = request;
+    *buffer = request_code;
+    buffer++;
+    strcpy(buffer, db_name);
+    buffer += strlen(db_name) + 1;
+    strcpy(buffer, request_body);
+    for (buffer = request; (nwrite = write(socket_fd, buffer, req_size)) > 0;) {
+        buffer += nwrite;
+        req_size -= nwrite;
+        if (req_size == 0) {
+            break;
+        }
+    }
+    free(request);
+    if (nwrite <= 0) {
+        fprintf(stderr, "ERROR: failed to send request to server\n");
+        return -1;
+    }
+    *response = malloc(BUFSIZ);
+    resp_size = BUFSIZ;
+    buffer = malloc(BUFSIZ);
+    for (off_t offset = 0; (nread = read(socket_fd, buffer, BUFSIZ)) > 0;) {
+        if (offset + nread > resp_size) {
+            resp_size += BUFSIZ;
+            *response = realloc(response, resp_size);
+        }
+        memcpy(*response + offset, buffer, nread);
+        offset += nread;
+        if ((*response)[offset - 1] == 0) {
+            break;
+        }
+    }
+    free(buffer);
+    if (nread < 0) {
+        fprintf(stderr, "ERROR: failed to get server response\n");
+        return -1;
+    }
+    return 0;
+}