From 1182412fd4ece0cb55c4b3ebefee78b22c8c15bd Mon Sep 17 00:00:00 2001
From: Don McCaughey <don@donm.cc>
Date: Tue, 26 Apr 2022 20:07:46 -0700
Subject: [PATCH] Add `ood_halt()` function.

Unify points where we print an error and exit before it gets messy by
introducting the `ood_halt()` and `ood_halt_on_error()` functions.  The
former prints a caller-provided message and halts; the latter prints the
system error message for the current value of `errno` and exits, using
`errno` as the process exit status value.
---
 src/dood/main.c           | 12 ++++--------
 src/dood/server.c         |  6 ++----
 src/libood/CMakeLists.txt |  2 ++
 src/libood/ood.h          |  1 +
 src/libood/ood/halt.c     | 37 +++++++++++++++++++++++++++++++++++++
 src/libood/ood/halt.h     | 12 ++++++++++++
 6 files changed, 58 insertions(+), 12 deletions(-)
 create mode 100644 src/libood/ood/halt.c
 create mode 100644 src/libood/ood/halt.h

diff --git a/src/dood/main.c b/src/dood/main.c
index 28c0cae..066ba1d 100644
--- a/src/dood/main.c
+++ b/src/dood/main.c
@@ -121,8 +121,7 @@ listener_on_read(struct ood_inet_socket *listener)
     while (server_can_accept_connections(server)) {
         struct ood_inet_socket *connection = NULL;
         if (!ood_inet_socket_accept(listener, &connection)) {
-            perror("dood");
-            exit(EXIT_FAILURE);
+            ood_halt_on_error();
         }
         if (!connection) return;
 
@@ -149,13 +148,11 @@ main(int argc, char *argv[]) {
     
     struct server *server = server_alloc(8);
     if (!server) {
-        perror("dood");
-        exit(EXIT_FAILURE);
+        ood_halt_on_error();
     }
 
     if (!server_add_listener(server, INADDR_LOOPBACK, port, backlog, listener_on_read, listener_on_error)) {
-        perror("dood");
-        exit(EXIT_FAILURE);
+        ood_halt_on_error();
     }
 
     printf("dood: ready\n");
@@ -166,8 +163,7 @@ main(int argc, char *argv[]) {
 
         bool interrupted;
         if (!ood_select_sets_select(&select_sets, timeout_millis, &interrupted)) {
-            perror("dood");
-            exit(EXIT_FAILURE);
+            ood_halt_on_error();
         }
 
         if (!interrupted) {
diff --git a/src/dood/server.c b/src/dood/server.c
index 912579e..8b84061 100644
--- a/src/dood/server.c
+++ b/src/dood/server.c
@@ -7,8 +7,7 @@
 void
 server_add_socket(struct server *server, struct ood_inet_socket *socket) {
     if (!ood_ptr_array_add(server->sockets, socket)) {
-        fprintf(stderr, "dood: unable to add socket\n");
-        exit(EXIT_FAILURE);
+        ood_halt("unable to add socket");
     }
 }
 
@@ -97,8 +96,7 @@ server_close_all_listeners(struct server *server)
 void
 server_close_socket(struct server *server, struct ood_inet_socket *socket) {
     if (!ood_ptr_array_clear(server->sockets, socket)) {
-        fprintf(stderr, "dood: unable to close socket\n");
-        exit(EXIT_FAILURE);
+        ood_halt("unable to close socket");
     }
     ood_inet_socket_free(socket);
 }
diff --git a/src/libood/CMakeLists.txt b/src/libood/CMakeLists.txt
index 15c0cc0..643a076 100644
--- a/src/libood/CMakeLists.txt
+++ b/src/libood/CMakeLists.txt
@@ -2,6 +2,8 @@ add_library(libood STATIC
         ood.h
         ood.c
 
+        ood/halt.c
+        ood/halt.h
         ood/ptr_array.c
         ood/ptr_array.h
         ood/result.h
diff --git a/src/libood/ood.h b/src/libood/ood.h
index 78d083a..18b8b91 100644
--- a/src/libood/ood.h
+++ b/src/libood/ood.h
@@ -2,6 +2,7 @@
 #define OOD_H_INCLUDED
 
 
+#include "ood/halt.h"
 #include "ood/ptr_array.h"
 #include "ood/result.h"
 #include "ood/select_sets.h"
diff --git a/src/libood/ood/halt.c b/src/libood/ood/halt.c
new file mode 100644
index 0000000..8680f74
--- /dev/null
+++ b/src/libood/ood/halt.c
@@ -0,0 +1,37 @@
+#include "halt.h"
+
+#include <errno.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+
+static void
+halt(char const *message, int status)
+{
+    fprintf(stderr, "ERROR: %s\n", message);
+    fflush(stderr);
+    exit(status);
+}
+
+
+void
+ood_halt(char const *message)
+{
+    if (message && message[0]) {
+        halt(message, EXIT_FAILURE);
+    } else {
+        halt("No message", EXIT_FAILURE);
+    }
+}
+
+
+void
+ood_halt_on_error(void)
+{
+    if (errno) {
+        halt(strerror(errno), errno);
+    } else {
+        halt("No error number", EXIT_FAILURE);
+    }
+}
diff --git a/src/libood/ood/halt.h b/src/libood/ood/halt.h
new file mode 100644
index 0000000..0acd548
--- /dev/null
+++ b/src/libood/ood/halt.h
@@ -0,0 +1,12 @@
+#ifndef OOD_HALT_H_INCLUDED
+#define OOD_HALT_H_INCLUDED
+
+
+void
+ood_halt(char const *message);
+
+void
+ood_halt_on_error(void);
+
+
+#endif
-- 
2.34.4