--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/libmlk-core/core/zfile.c	Fri Oct 01 20:30:00 2021 +0200
@@ -0,0 +1,157 @@
+/*
+ * zfile.c -- load potentially ZSTD compressed file
+ *
+ * Copyright (c) 2020-2021 David Demelier <markand@malikania.fr>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "config.h"
+
+#include <sys/stat.h>
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+/*
+ * If not enabled, we still need to check if a file is in zstandard so we use
+ * the magic number defined in the zstd.h file or copy it if zstd is disabled.
+ */
+#if defined(MLK_WITH_ZSTD)
+#       include <zstd.h>
+#else
+#       define ZSTD_MAGICNUMBER 0xFD2FB528
+#endif
+
+/* Windows thing. */
+#if !defined(O_BINARY)
+#       define O_BINARY 0
+#endif
+
+#include <port/port.h>
+
+#include "zfile.h"
+
+static int
+is_zstd(int fd)
+{
+	uint32_t magic = 0;
+
+	read(fd, &magic, sizeof (magic));
+	lseek(fd, 0, SEEK_SET);
+
+#if SDL_BYTEORDER != SDL_LIL_ENDIAN
+	magic = SDL_Swap32(magic);
+#endif
+
+	return magic == ZSTD_MAGICNUMBER;
+}
+
+static int
+decompress(int fd, struct zfile *zf)
+{
+#if defined(MLK_WITH_ZSTD)
+	char *in = NULL;
+	unsigned long long datasz;
+	struct stat st;
+	ssize_t nr;
+
+	/* Load uncompressed data. */
+	if (fstat(fd, &st) < 0)
+		goto fail;
+	if (!(in = calloc(1, st.st_size)) || (nr = read(fd, in, st.st_size)) != st.st_size)
+		goto fail;
+
+	switch ((datasz = ZSTD_getFrameContentSize(in, st.st_size))) {
+	case ZSTD_CONTENTSIZE_ERROR:
+		errno = EINVAL;
+		goto fail;
+	case ZSTD_CONTENTSIZE_UNKNOWN:
+		errno = ENOTSUP;
+		goto fail;
+	default:
+		break;
+	}
+
+	/* Finally decompress. */
+	if (!(zf->data = calloc(1, datasz + 1)))
+		goto fail;
+	if (ZSTD_isError(ZSTD_decompress(zf->data, datasz, in, st.st_size))) {
+		errno = EINVAL;
+		goto fail;
+	}
+	if (!(zf->fp = fmemopen(zf->data, datasz, "r")))
+		goto fail;
+
+	close(fd);
+	free(in);
+
+	return 0;
+
+fail:
+	close(fd);
+	free(zf->data);
+	free(in);
+
+	return -1;
+#else
+	(void)fd;
+	(void)zf;
+
+	errno = ENOTSUP;
+
+	return -1;
+#endif
+}
+
+static int
+reopen(int fd, struct zfile *zf)
+{
+	if (!(zf->fp = fdopen(fd, "r")))
+		return close(fd), -1;
+
+	return 0;
+}
+
+int
+zfile_open(struct zfile *zf, const char *path)
+{
+	assert(zf);
+	assert(path);
+
+	int fd;
+
+	memset(zf, 0, sizeof (*zf));
+
+	if ((fd = open(path, O_RDONLY | O_BINARY)) < 0)
+		return -1;
+
+	return is_zstd(fd) ? decompress(fd, zf) : reopen(fd, zf);
+}
+
+void
+zfile_close(struct zfile *zf)
+{
+	assert(zf);
+
+	free(zf->data);
+
+	if (zf->fp)
+		fclose(zf->fp);
+
+	memset(zf, 0, sizeof (*zf));
+}