add save module: checked chunk files

2 files changed, 488 insertions, 0 deletions

diff --git a/kon/konsave.c b/kon/konsave.c
new file mode 100644
index 0000000..e351e5a
--- /dev/null
+++ b/kon/konsave.c
@@ -0,0 +1,389 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * konsave.c
+ *
+ * Copyright (c) 2026 KonAki
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "konsave.h"
+
+#include <stdio.h>
+#include <string.h>
+
+/*** checksum ***/
+
+static uint32_t crc32(const uint8_t *p, size_t n)
+{
+	uint32_t crc = 0xFFFFFFFFu;
+	size_t i;
+	int bit;
+
+	for (i = 0; i < n; i++) {
+		crc ^= p[i];
+		for (bit = 0; bit < 8; bit++) crc = (crc >> 1) ^ (0xEDB88320u & (0u - (crc & 1u)));
+	}
+	return ~crc;
+}
+
+/*** writing ***/
+
+static void putAt(uint8_t *p, uint32_t v)
+{
+	p[0] = (uint8_t)(v & 0xFF);
+	p[1] = (uint8_t)((v >> 8) & 0xFF);
+	p[2] = (uint8_t)((v >> 16) & 0xFF);
+	p[3] = (uint8_t)((v >> 24) & 0xFF);
+}
+
+static uint32_t getAt(const uint8_t *p)
+{
+	return (uint32_t)p[0] | ((uint32_t)p[1] << 8) | ((uint32_t)p[2] << 16) | ((uint32_t)p[3] << 24);
+}
+
+static int room(kon_saveWriter_t *w, size_t n)
+{
+	if (w->error) return 0;
+	if (!w->buf || n > w->cap - w->len) {
+		w->error = 1;
+		return 0;
+	}
+	return 1;
+}
+
+static void closeChunk(kon_saveWriter_t *w)
+{
+	if (!w->open || w->error) return;
+	if (w->len - w->chunk - 8 > 0xFFFFFFFFu) {
+		w->error = 1;
+		return;
+	}
+	putAt(w->buf + w->chunk + 4, (uint32_t)(w->len - w->chunk - 8));
+	w->open = 0;
+}
+
+void kon_saveBegin(kon_saveWriter_t *w, void *buf, size_t cap, uint32_t version)
+{
+	kon_saveWriter_t zero = {0};
+
+	*w = zero;
+	w->buf = buf;
+	w->cap = buf ? cap : 0;
+	if (!room(w, 8)) return;
+	memcpy(w->buf, "KONS", 4);
+	putAt(w->buf + 4, version);
+	w->len = 8;
+}
+
+void kon_saveChunk(kon_saveWriter_t *w, const char *tag)
+{
+	closeChunk(w);
+	if (!tag || strlen(tag) != 4 || !room(w, 8)) {
+		w->error = 1;
+		return;
+	}
+	w->chunk = w->len;
+	memcpy(w->buf + w->len, tag, 4);
+	putAt(w->buf + w->len + 4, 0);
+	w->len += 8;
+	w->open = 1;
+}
+
+void kon_savePutBytes(kon_saveWriter_t *w, const void *data, size_t n)
+{
+	if (!w->open) {
+		w->error = 1;
+		return;
+	}
+	if (!room(w, n)) return;
+	if (n) memcpy(w->buf + w->len, data, n);
+	w->len += n;
+}
+
+void kon_savePutU8(kon_saveWriter_t *w, unsigned v)
+{
+	uint8_t b = (uint8_t)(v & 0xFF);
+
+	kon_savePutBytes(w, &b, 1);
+}
+
+void kon_savePutU16(kon_saveWriter_t *w, unsigned v)
+{
+	uint8_t b[2];
+
+	b[0] = (uint8_t)(v & 0xFF);
+	b[1] = (uint8_t)((v >> 8) & 0xFF);
+	kon_savePutBytes(w, b, 2);
+}
+
+void kon_savePutU32(kon_saveWriter_t *w, uint32_t v)
+{
+	uint8_t b[4];
+
+	putAt(b, v);
+	kon_savePutBytes(w, b, 4);
+}
+
+void kon_savePutI32(kon_saveWriter_t *w, int32_t v)
+{
+	kon_savePutU32(w, (uint32_t)v);
+}
+
+void kon_savePutF32(kon_saveWriter_t *w, float v)
+{
+	uint32_t bits;
+
+	memcpy(&bits, &v, sizeof bits);
+	kon_savePutU32(w, bits);
+}
+
+void kon_savePutString(kon_saveWriter_t *w, const char *s)
+{
+	size_t n = s ? strlen(s) : 0;
+
+	if (n > 65535u) n = 65535u;
+	kon_savePutU16(w, (unsigned)n);
+	kon_savePutBytes(w, s, n);
+}
+
+void kon_savePutSwitches(kon_saveWriter_t *w, const uint8_t *switches, int count)
+{
+	int i;
+
+	if (count < 0 || !switches) count = 0;
+	kon_savePutU32(w, (uint32_t)count);
+	for (i = 0; i < count; i++) kon_savePutU8(w, switches[i] ? 1 : 0);
+}
+
+void kon_savePutVars(kon_saveWriter_t *w, const int32_t *vars, int count)
+{
+	int i;
+
+	if (count < 0 || !vars) count = 0;
+	kon_savePutU32(w, (uint32_t)count);
+	for (i = 0; i < count; i++) kon_savePutI32(w, vars[i]);
+}
+
+size_t kon_saveEnd(kon_saveWriter_t *w)
+{
+	closeChunk(w);
+	if (!room(w, 4)) return 0;
+	putAt(w->buf + w->len, crc32(w->buf, w->len));
+	w->len += 4;
+	return w->len;
+}
+
+/*** reading ***/
+
+int kon_saveOpen(kon_saveReader_t *r, const void *buf, size_t len)
+{
+	const uint8_t *p = buf;
+	size_t at;
+
+	memset(r, 0, sizeof *r);
+	if (!p || len < 12 || memcmp(p, "KONS", 4) != 0) return 0;
+	if (crc32(p, len - 4) != getAt(p + len - 4)) return 0;
+	at = 8;
+	while (at < len - 4) {
+		size_t size;
+
+		if (len - 4 - at < 8) return 0;
+		size = getAt(p + at + 4);
+		if (size > len - 4 - at - 8) return 0;
+		at += 8 + size;
+	}
+	r->buf = p;
+	r->len = len;
+	r->version = getAt(p + 4);
+	return 1;
+}
+
+int kon_saveFind(const kon_saveReader_t *r, const char *tag, kon_saveCursor_t *c)
+{
+	size_t at = 8;
+
+	c->p = c->end = NULL;
+	c->error = 0;
+	if (!r->buf || !tag || strlen(tag) != 4) {
+		c->error = 1;
+		return 0;
+	}
+	while (at + 8 <= r->len - 4) {
+		size_t size = getAt(r->buf + at + 4);
+
+		if (memcmp(r->buf + at, tag, 4) == 0) {
+			c->p = r->buf + at + 8;
+			c->end = c->p + size;
+			return 1;
+		}
+		at += 8 + size;
+	}
+	c->error = 1;
+	return 0;
+}
+
+void kon_saveGetBytes(kon_saveCursor_t *c, void *out, size_t n)
+{
+	if (c->error || !c->p || (size_t)(c->end - c->p) < n) {
+		c->error = 1;
+		if (out) memset(out, 0, n);
+		return;
+	}
+	if (n) memcpy(out, c->p, n);
+	c->p += n;
+}
+
+unsigned kon_saveGetU8(kon_saveCursor_t *c)
+{
+	uint8_t b = 0;
+
+	kon_saveGetBytes(c, &b, 1);
+	return b;
+}
+
+unsigned kon_saveGetU16(kon_saveCursor_t *c)
+{
+	uint8_t b[2];
+
+	kon_saveGetBytes(c, b, 2);
+	return (unsigned)b[0] | ((unsigned)b[1] << 8);
+}
+
+uint32_t kon_saveGetU32(kon_saveCursor_t *c)
+{
+	uint8_t b[4];
+
+	kon_saveGetBytes(c, b, 4);
+	return getAt(b);
+}
+
+int32_t kon_saveGetI32(kon_saveCursor_t *c)
+{
+	uint32_t v = kon_saveGetU32(c);
+
+	return v > 0x7FFFFFFFu ? -(int32_t)(0xFFFFFFFFu - v) - 1 : (int32_t)v;
+}
+
+float kon_saveGetF32(kon_saveCursor_t *c)
+{
+	uint32_t bits = kon_saveGetU32(c);
+	float v;
+
+	memcpy(&v, &bits, sizeof v);
+	return v;
+}
+
+void kon_saveGetString(kon_saveCursor_t *c, char *out, size_t size)
+{
+	size_t n = kon_saveGetU16(c);
+
+	if (c->error || (size_t)(c->end - c->p) < n) {
+		c->error = 1;
+		if (out && size) out[0] = '\0';
+		return;
+	}
+	if (out && size) {
+		size_t keep = n < size - 1 ? n : size - 1;
+
+		memcpy(out, c->p, keep);
+		out[keep] = '\0';
+	}
+	c->p += n;
+}
+
+int kon_saveGetSwitches(kon_saveCursor_t *c, uint8_t *switches, int count)
+{
+	uint32_t saved = kon_saveGetU32(c);
+	uint32_t i;
+
+	for (i = 0; i < saved; i++) {
+		unsigned v = kon_saveGetU8(c);
+
+		if (c->error) break;
+		if (switches && i < (uint32_t)count) switches[i] = v ? 1 : 0;
+	}
+	for (i = saved; switches && i < (uint32_t)count; i++) switches[i] = 0;
+	return c->error ? 0 : (saved > 0x7FFFFFFFu ? 0x7FFFFFFF : (int)saved);
+}
+
+int kon_saveGetVars(kon_saveCursor_t *c, int32_t *vars, int count)
+{
+	uint32_t saved = kon_saveGetU32(c);
+	uint32_t i;
+
+	for (i = 0; i < saved; i++) {
+		int32_t v = kon_saveGetI32(c);
+
+		if (c->error) break;
+		if (vars && i < (uint32_t)count) vars[i] = v;
+	}
+	for (i = saved; vars && i < (uint32_t)count; i++) vars[i] = 0;
+	return c->error ? 0 : (saved > 0x7FFFFFFFu ? 0x7FFFFFFF : (int)saved);
+}
+
+/*** files ***/
+
+int kon_saveWriteFile(const char *path, const void *buf, size_t len)
+{
+	char temp[1024];
+	FILE *f;
+	size_t n;
+
+	if (!path || (!buf && len)) return 0;
+	n = strlen(path);
+	if (n + 5 > sizeof temp) return 0;
+	memcpy(temp, path, n);
+	memcpy(temp + n, ".tmp", 5);
+	f = fopen(temp, "wb");
+	if (!f) return 0;
+	if ((len && fwrite(buf, 1, len, f) != len) || fflush(f) != 0) {
+		fclose(f);
+		remove(temp);
+		return 0;
+	}
+	if (fclose(f) != 0) {
+		remove(temp);
+		return 0;
+	}
+	if (rename(temp, path) != 0) {
+		remove(path);
+		if (rename(temp, path) != 0) {
+			remove(temp);
+			return 0;
+		}
+	}
+	return 1;
+}
+
+long kon_saveReadFile(const char *path, void *buf, size_t cap)
+{
+	FILE *f;
+	size_t n;
+	int extra;
+
+	if (!path || (!buf && cap)) return -1;
+	f = fopen(path, "rb");
+	if (!f) return -1;
+	n = cap ? fread(buf, 1, cap, f) : 0;
+	extra = fgetc(f);
+	fclose(f);
+	if (extra != EOF || n > 0x7FFFFFFFu) return -1;
+	return (long)n;
+}
diff --git a/kon/konsave.h b/kon/konsave.h
new file mode 100644
index 0000000..45e45c1
--- /dev/null
+++ b/kon/konsave.h
@@ -0,0 +1,99 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * konsave.h
+ *
+ * Copyright (c) 2026 KonAki
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef KONSAVE_H
+#define KONSAVE_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+/*** definition ***/
+
+/* a save is a list of tagged chunks, so each part of a game writes and reads its own and a menu can read just
+the little META chunk of every slot. whole thing is checked with a crc, a damaged or cut short file is refused. numbers
+are little endian whatever the machine. it all happens in a buffer you own, the file functions are at the end */
+
+typedef struct kon_saveWriter {
+	uint8_t *buf;
+	size_t cap, len, chunk;
+	int error, open;
+} kon_saveWriter_t;
+
+typedef struct kon_saveReader {
+	const uint8_t *buf;
+	size_t len;
+	uint32_t version; /* the number you gave kon_saveBegin, to change old saves into new ones */
+} kon_saveReader_t;
+
+typedef struct kon_saveCursor {
+	const uint8_t *p, *end;
+	int error; /* reading past the end gives 0s and sets this */
+} kon_saveCursor_t;
+
+/*** writing ***/
+
+void kon_saveBegin(kon_saveWriter_t *w, void *buf, size_t cap, uint32_t version);
+void kon_saveChunk(kon_saveWriter_t *w, const char *tag); /* four characters, ends the chunk before it */
+void kon_savePutU8(kon_saveWriter_t *w, unsigned v);
+void kon_savePutU16(kon_saveWriter_t *w, unsigned v);
+void kon_savePutU32(kon_saveWriter_t *w, uint32_t v);
+void kon_savePutI32(kon_saveWriter_t *w, int32_t v);
+void kon_savePutF32(kon_saveWriter_t *w, float v);
+void kon_savePutBytes(kon_saveWriter_t *w, const void *data, size_t n);
+void kon_savePutString(kon_saveWriter_t *w, const char *s); /* up to 65535 bytes */
+void kon_savePutSwitches(kon_saveWriter_t *w, const uint8_t *switches, int count);
+void kon_savePutVars(kon_saveWriter_t *w, const int32_t *vars, int count);
+
+/* how many bytes the save is, or 0 if it did not fit in the buffer */
+size_t kon_saveEnd(kon_saveWriter_t *w);
+
+/*** reading ***/
+
+/* 0 if it is not a save, is damaged or is cut short */
+int kon_saveOpen(kon_saveReader_t *r, const void *buf, size_t len);
+int kon_saveFind(const kon_saveReader_t *r, const char *tag, kon_saveCursor_t *c);
+
+unsigned kon_saveGetU8(kon_saveCursor_t *c);
+unsigned kon_saveGetU16(kon_saveCursor_t *c);
+uint32_t kon_saveGetU32(kon_saveCursor_t *c);
+int32_t kon_saveGetI32(kon_saveCursor_t *c);
+float kon_saveGetF32(kon_saveCursor_t *c);
+void kon_saveGetBytes(kon_saveCursor_t *c, void *out, size_t n);
+void kon_saveGetString(kon_saveCursor_t *c, char *out, size_t size); /* always ends with a 0, cut if it does not fit */
+
+/* into what you have, if the save had more they are dropped and if fewer the rest are 0. return how many the save had */
+int kon_saveGetSwitches(kon_saveCursor_t *c, uint8_t *switches, int count);
+int kon_saveGetVars(kon_saveCursor_t *c, int32_t *vars, int count);
+
+/*** files ***/
+
+/* written beside the real name first and then moved over it, so a crash leaves the old save. on Windows the old one
+is removed just before the move. 1 if it worked */
+int kon_saveWriteFile(const char *path, const void *buf, size_t len);
+
+/* how many bytes were read, or -1 if it could not be opened or does not fit in cap */
+long kon_saveReadFile(const char *path, void *buf, size_t cap);
+
+#endif /* KONSAVE_H */