From 26e0bbe445f8b96a33549d1a8d725c7e0ab7f4ea Mon Sep 17 00:00:00 2001
From: Martin Fiedler <keyj@emphy.de>
Date: Thu, 5 Sep 2024 22:10:11 +0200
Subject: [PATCH] bare minimum changes to compile (partly) on MSVC

Changes:
- made it possible to override ANSILOVE_EXTERN
  with something that's not GNU specific
- re-implemented strndup in compat/

This makes it possible to compile the core functionality
of libansilove (specifically, ansilove_ansi() and friends)
with MSVC, if some implementation of GD is available.
The _init(), _loadfile() and _clean() functions don't work
yet, as they are centered around POSIX-exclusive APIs.
This functionality is easily replaced by a few lines of
glue code though.
---
 CMakeLists.txt     |  5 +++++
 compat/strndup.c   | 22 ++++++++++++++++++++++
 compat/strndup.h   |  1 +
 include/ansilove.h |  2 ++
 src/loaders/ansi.c |  4 ++++
 5 files changed, 34 insertions(+)
 create mode 100644 compat/strndup.c
 create mode 100644 compat/strndup.h

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 095db79..b47e7e1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -15,6 +15,7 @@ include(CheckFunctionExists)
 include(GNUInstallDirs)
 
 # Check if system has strtonum
+check_function_exists(strndup HAVE_STRNDUP)
 check_function_exists(strtonum HAVE_STRTONUM)
 check_function_exists(reallocarray HAVE_REALLOCARRAY)
 
@@ -29,6 +30,10 @@ include_directories(${GD_INCLUDE_DIRS})
 set(SRC src/clean.c src/drawchar.c src/fonts.c src/error.c src/loadfile.c src/init.c src/output.c src/savefile.c)
 set(LOADERS src/loaders/ansi.c src/loaders/artworx.c src/loaders/binary.c src/loaders/icedraw.c src/loaders/pcboard.c src/loaders/tundra.c src/loaders/xbin.c)
 
+if(NOT HAVE_STRNDUP)
+  set(SRC ${SRC} compat/strndup.c)
+endif()
+
 if(NOT HAVE_STRTONUM)
   set(SRC ${SRC} compat/strtonum.c)
 endif()
diff --git a/compat/strndup.c b/compat/strndup.c
new file mode 100644
index 0000000..2ead4fe
--- /dev/null
+++ b/compat/strndup.c
@@ -0,0 +1,22 @@
+// SPDX-FileCopyrightText: 2024 Martin J. Fiedler <keyj@emphy.de>
+// SPDX-License-Identifier: MIT
+
+#include <stdio.h>
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "strndup.h"
+
+char *strndup(const char *str, size_t size) {
+    char *buffer;
+    size_t srclen = strlen(str);
+    if (srclen < size) { size = srclen; }
+    buffer = (char*) malloc(size + 1);
+    if (buffer) {
+        strncpy(buffer, str, size);
+    }
+    buffer[size] = '\0';
+    return buffer;
+}
diff --git a/compat/strndup.h b/compat/strndup.h
new file mode 100644
index 0000000..c65e9f2
--- /dev/null
+++ b/compat/strndup.h
@@ -0,0 +1 @@
+char *strndup(const char *str, size_t size);
diff --git a/include/ansilove.h b/include/ansilove.h
index e8d6970..e54e741 100644
--- a/include/ansilove.h
+++ b/include/ansilove.h
@@ -23,7 +23,9 @@
 extern "C" {
 #endif
 
+#ifndef ANSILOVE_EXTERN
 #define ANSILOVE_EXTERN __attribute__((visibility("default")))
+#endif
 
 /* Version number */
 #define ANSILOVE_VERSION "1.4.1"
diff --git a/src/loaders/ansi.c b/src/loaders/ansi.c
index eea5e23..04c1804 100644
--- a/src/loaders/ansi.c
+++ b/src/loaders/ansi.c
@@ -25,6 +25,10 @@
 #include "fonts.h"
 #include "output.h"
 
+#ifndef HAVE_STRNDUP
+#include "strndup.h"
+#endif
+
 #ifndef HAVE_STRTONUM
 #include "strtonum.h"
 #endif