fix: improve error handling (#14)

Author: mnahkies

.editorconfig

@@ -0,0 +1,12 @@
+# EditorConfig helps maintain consistent coding styles across editors and IDEs
+
+root = true
+
+[*]
+indent_style = space
+indent_size = 4
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+max_line_length = 80

.gitignore

@@ -1,2 +1,5 @@
 .idea
 .env.sh
+compile_commands.json
+*.o
+*.so

README.md

@@ -62,6 +62,15 @@ docker exec -it postgres psql -U postgres postgres
 docker exec -it postgres psql -U any_username any_database_name
 ```
 
+## Development
+
+You can use [bear](https://github.com/rizsotto/Bear) to generate a `compile_commands.json` which is 
+understood by IDE's like CLion.
+
+```shell
+bear -- make
+```
+
 ## References
 
 See https://github.com/taminomara/psql-hooks for the unofficial documentation of Postgresql hooks

ensure_role_and_database_exists.c

@@ -1,47 +1,79 @@
-#include <stdlib.h>
-
 #include "postgres.h"
 #include "fmgr.h"
 
 #include "libpq/auth.h"
-#include <unistd.h>
+#include "executor/spi.h"
+#include "miscadmin.h"
 
 PG_MODULE_MAGIC;
 
 static ClientAuthentication_hook_type original_client_auth_hook = NULL;
 
+static void execute_command(const char *cmd) {
+    int result = system(cmd);
+
+    if (result != 0) {
+        ereport(ERROR, (
+                    errmsg("command failed"),
+                    errdetail("Command: %s\nExit code: %d", cmd, WEXITSTATUS(result))
+                )
+        );
+    }
+}
+
 static void ensure_role_and_database_exists(Port *port, int status) {
-    char *cmd;
-    char *postgres_user;
-    char *role_attributes;
+    char *cmd = NULL;
+    const char *postgres_user = getenv("POSTGRES_USER");
+    const char *role_attributes = getenv("POSTGRES_ROLE_ATTRIBUTES");
 
     if (original_client_auth_hook) {
         original_client_auth_hook(port, status);
     }
 
-    postgres_user = getenv("POSTGRES_USER");
+    if (!postgres_user) {
+        ereport(ERROR, errmsg("POSTGRES_USER environment variable is not set."));
+    }
 
-    fprintf(stderr, "handling connection for username '%s' to database '%s'\n", port->user_name, port->database_name);
+    if (!role_attributes) {
+        ereport(ERROR, errmsg("POSTGRES_ROLE_ATTRIBUTES environment variable is not set."));
+    }
 
     // don't infinitely recurse when connecting as superuser
-    if (strcmp(port->database_name, postgres_user) == 0 && strcmp(port->user_name, postgres_user) == 0) {
+    if (strcmp(port->user_name, postgres_user) == 0 && strcmp(port->database_name, postgres_user) == 0) {
         return;
     }
 
-    role_attributes = getenv("POSTGRES_ROLE_ATTRIBUTES");
+    elog(LOG, "handling connection for username '%s' to database '%s'", port->user_name, port->database_name);
+
+    elog(LOG, "ensuring user_name '%s' exists with attributes '%s'", port->user_name, role_attributes);
+    if (asprintf(&cmd,
+                 "echo \"SELECT 'CREATE ROLE %s WITH %s' WHERE NOT EXISTS (SELECT FROM pg_roles WHERE rolname = '%s')\\gexec\" | psql -U %s -d %s",
+                 port->user_name,
+                 role_attributes,
+                 port->user_name,
+                 postgres_user,
+                 postgres_user
+    ) < 0) {
+        ereport(ERROR, errmsg("failed to allocate command string"));
+    }
 
-    fprintf(stderr, "ensuring user_name '%s' exists with attributes '%s'\n", port->user_name, role_attributes);
-    asprintf(&cmd,
-             "echo \"SELECT 'CREATE ROLE %s WITH %s' WHERE NOT EXISTS (SELECT FROM pg_roles WHERE rolname = '%s')\\gexec\" | psql -U %s -d %s",
-             port->user_name, role_attributes, port->user_name, postgres_user, postgres_user);
-    system(cmd);
+    execute_command(cmd);
     free(cmd);
 
-    fprintf(stderr, "ensuring database '%s' exists\n", port->database_name);
-    asprintf(&cmd,
-             "echo \"SELECT 'CREATE DATABASE %s WITH OWNER = %s' WHERE NOT EXISTS (SELECT FROM pg_database WHERE datname = '%s')\\gexec\" | psql -U %s -d %s",
-             port->database_name, port->user_name, port->database_name, postgres_user, postgres_user);
-    system(cmd);
+    elog(LOG, "ensuring database '%s' exists", port->database_name);
+
+    if (asprintf(&cmd,
+                 "echo \"SELECT 'CREATE DATABASE %s WITH OWNER = %s' WHERE NOT EXISTS (SELECT FROM pg_database WHERE datname = '%s')\\gexec\" | psql -U %s -d %s",
+                 port->database_name,
+                 port->user_name,
+                 port->database_name,
+                 postgres_user,
+                 postgres_user
+    ) < 0) {
+        ereport(ERROR, errmsg("failed to allocate command string"));
+    }
+
+    execute_command(cmd);
     free(cmd);
 }