feat(builtin): add support for pgsql

Makefile

@@ -1,7 +1,7 @@
 SHELL := /bin/bash
 CC     = gcc
-SRC = main.c loop.c exec.c line.c builtin.c
-LINK= -lreadline
+SRC = main.c loop.c exec.c line.c builtin.c postgres.c
+LINK= -lreadline -lpq
 OBJ = $(SRC:.c=.ro)
 DBGOBJ = $(SRC:.c=.do)
 EXE  = dish

builtin.c

@@ -22,11 +22,11 @@ int dish_echo(char **args);
 int dish_laststatus(char **args);
 
 char *builtin_cmd[] = {"cd",     "help",     "exit", "clear",     "setenv",
-                       "getenv", "unsetenv", "echo", "laststatus"};
+                       "getenv", "unsetenv", "echo", "laststatus", defined_builtin};
 
 int (*builtin_func[])(char **) = {
     &dish_cd,     &dish_help,     &dish_exit, &dish_clear,     &dish_setenv,
-    &dish_getenv, &dish_unsetenv, &dish_echo, &dish_laststatus};
+    &dish_getenv, &dish_unsetenv, &dish_echo, &dish_laststatus, defined_builtin_func};
 
 int getBuiltinNum() { return sizeof(builtin_cmd) / sizeof(char *); }
 

builtin.h

@@ -8,6 +8,11 @@
 #define _BUILTIN_H_
 
 #include "config.h"
+
+#ifdef POSTGRES
+#include "postgres.h"
+#endif
+
 int getBuiltinNum();
 
 #endif

config.h

@@ -17,4 +17,11 @@
 #define ANSI_COLOR_CYAN    "\x1b[36m"
 #define ANSI_COLOR_RESET   "\x1b[0m"
 
+/* enable postgres support*/
+#define POSTGRES
+#ifdef POSTGRES
+#define defined_builtin "pg"
+#define defined_builtin_func &dish_pg
+#endif
+
 #endif

postgres.c

@@ -0,0 +1,114 @@
+#include "postgres.h"
+#include <libpq-fe.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include <sys/types.h>
+#include <unistd.h>
+#ifdef POSTGRES
+
+static PGconn *conn;
+
+int pg_connect(char *args) {
+  if (args == NULL) {
+    fprintf(stderr, "pg connect: need dbname\n");
+    return 1;
+  }
+  conn = PQsetdbLogin("localhost", "5432", NULL, NULL, args, "postgres", NULL);
+  if (PQstatus(conn) == CONNECTION_BAD) {
+    fprintf(stderr, "pg connect: Connection to database failed: %s",
+            PQerrorMessage(conn));
+    return 1;
+  }
+  return 0;
+}
+int pg_list() {
+  if (conn == NULL) {
+    fprintf(stderr, "pg list: not connected to database\n");
+    return 1;
+  }
+  PGresult *res =
+      PQexec(conn, "SELECT table_name FROM information_schema.tables WHERE "
+                   "table_schema = 'public'");
+  if (PQresultStatus(res) != PGRES_TUPLES_OK) {
+    fprintf(stderr, "pg list: No data retrieved\n");
+    PQclear(res);
+    return 1;
+  }
+  int rows = PQntuples(res);
+  for (int i = 0; i < rows; i++) {
+    if (i != 0)
+      printf(", ");
+    printf("%s ", PQgetvalue(res, i, 0));
+  }
+  printf("\n");
+  return 0;
+}
+
+int pg_show(char *args) {
+  if (conn == NULL) {
+    fprintf(stderr, "pg show: not connected to database\n");
+    return 1;
+  }
+  if (args == NULL) {
+    fprintf(stderr, "pg show: need table name\n");
+    return 1;
+  }
+  char *query = malloc(100);
+  sprintf(query, "SELECT * FROM %s", args);
+  PGresult *res = PQexec(conn, query);
+  if (PQresultStatus(res) != PGRES_TUPLES_OK) {
+    fprintf(stderr, "pg show: No data retrieved\n");
+    PQclear(res);
+    return 1;
+  }
+  int rows = PQntuples(res);
+  int cols = PQnfields(res);
+
+  //print header
+  for (int i = 0; i < cols; i++) {
+    if (i != 0)
+      printf(", ");
+    printf("%s ", PQfname(res, i));
+  }
+  printf("\n");
+  //print whole table
+  for (int i = 0; i < rows; i++) {
+    for (int j = 0; j < cols; j++) {
+      if (j != 0)
+        printf(", ");
+      printf("%s ", PQgetvalue(res, i, j));
+    }
+    printf("\n");
+  }
+
+
+  printf("\n");
+  free(query);
+  return 0;
+}
+
+int dish_pg(char **args) {
+  if (args[1] == NULL) {
+    fprintf(stderr, "pg: need arguments\n\
+    possible arguments:\n\
+    connect: connect to database\n\
+    list: list all tables\n\
+    show: show all contents of a table\n");
+    return 1;
+  }
+  if (strcmp(args[1], "connect") == 0) {
+    pg_connect(args[2]);
+  }
+  if (strcmp(args[1], "list") == 0) {
+    pg_list();
+  }
+  if (strcmp(args[1], "show") == 0) {
+    pg_show(args[2]);
+  }
+
+  return 0;
+}
+
+#endif

postgres.h

@@ -0,0 +1,10 @@
+#include "config.h"
+
+#ifdef POSTGRES
+#ifndef __POSTGRES_H__
+#define __POSTGRES_H__
+
+int dish_pg(char **args);
+
+#endif
+#endif