Util: VFile backed by memory

src/util/vfs.h

@@ -38,6 +38,7 @@ struct VDir {
 
 struct VFile* VFileOpen(const char* path, int flags);
 struct VFile* VFileFromFD(int fd);
+struct VFile* VFileFromMemory(void* mem, size_t size);
 
 struct VDir* VDirOpen(const char* path);
 

src/util/vfs/vfs-mem.c

@@ -0,0 +1,139 @@
+/* Copyright (c) 2013-2015 Jeffrey Pfau
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include "util/vfs.h"
+
+struct VFileMem {
+	struct VFile d;
+	void* mem;
+	size_t size;
+	size_t offset;
+};
+
+static bool _vfmClose(struct VFile* vf);
+static off_t _vfmSeek(struct VFile* vf, off_t offset, int whence);
+static ssize_t _vfmRead(struct VFile* vf, void* buffer, size_t size);
+static ssize_t _vfmWrite(struct VFile* vf, const void* buffer, size_t size);
+static void* _vfmMap(struct VFile* vf, size_t size, int flags);
+static void _vfmUnmap(struct VFile* vf, void* memory, size_t size);
+static void _vfmTruncate(struct VFile* vf, size_t size);
+static ssize_t _vfmSize(struct VFile* vf);
+
+struct VFile* VFileFromMemory(void* mem, size_t size) {
+	if (!mem || !size) {
+		return 0;
+	}
+
+	struct VFileMem* vfm = malloc(sizeof(struct VFileMem));
+	if (!vfm) {
+		return 0;
+	}
+
+	vfm->mem = mem;
+	vfm->size = size;
+	vfm->offset = 0;
+	vfm->d.close = _vfmClose;
+	vfm->d.seek = _vfmSeek;
+	vfm->d.read = _vfmRead;
+	vfm->d.readline = VFileReadline;
+	vfm->d.write = _vfmWrite;
+	vfm->d.map = _vfmMap;
+	vfm->d.unmap = _vfmUnmap;
+	vfm->d.truncate = _vfmTruncate;
+	vfm->d.size = _vfmSize;
+
+	return &vfm->d;
+}
+
+bool _vfmClose(struct VFile* vf) {
+	struct VFileMem* vfm = (struct VFileMem*) vf;
+	vfm->mem = 0;
+	free(vfm);
+	return true;
+}
+
+off_t _vfmSeek(struct VFile* vf, off_t offset, int whence) {
+	struct VFileMem* vfm = (struct VFileMem*) vf;
+
+	size_t position;
+	switch (whence) {
+	case SEEK_SET:
+		position = offset;
+		break;
+	case SEEK_CUR:
+		if (offset < 0 && ((vfm->offset < (size_t) -offset) || (offset == INT_MIN))) {
+			return -1;
+		}
+		position = vfm->offset + offset;
+		break;
+	case SEEK_END:
+		if (offset < 0 && ((vfm->size < (size_t) -offset) || (offset == INT_MIN))) {
+			return -1;
+		}
+		position = vfm->size + offset;
+		break;
+	default:
+		return -1;
+	}
+
+	if (position > vfm->size) {
+		return -1;
+	}
+
+	vfm->offset = position;
+	return position;
+}
+
+ssize_t _vfmRead(struct VFile* vf, void* buffer, size_t size) {
+	struct VFileMem* vfm = (struct VFileMem*) vf;
+
+	if (size + vfm->offset >= vfm->size) {
+		size = vfm->size - vfm->offset;
+	}
+
+	memcpy(buffer, vfm->mem + vfm->offset, size);
+	vfm->offset += size;
+	return size;
+}
+
+ssize_t _vfmWrite(struct VFile* vf, const void* buffer, size_t size) {
+	struct VFileMem* vfm = (struct VFileMem*) vf;
+
+	if (size + vfm->offset >= vfm->size) {
+		size = vfm->size - vfm->offset;
+	}
+
+	memcpy(vfm->mem + vfm->offset, buffer, size);
+	vfm->offset += size;
+	return size;
+}
+
+void* _vfmMap(struct VFile* vf, size_t size, int flags) {
+	struct VFileMem* vfm = (struct VFileMem*) vf;
+
+	UNUSED(flags);
+	if (size > vfm->size) {
+		return 0;
+	}
+
+	return vfm->mem;
+}
+
+void _vfmUnmap(struct VFile* vf, void* memory, size_t size) {
+	UNUSED(vf);
+	UNUSED(memory);
+	UNUSED(size);
+}
+
+void _vfmTruncate(struct VFile* vf, size_t size) {
+	// TODO: Return value?
+	UNUSED(vf);
+	UNUSED(size);
+}
+
+ssize_t _vfmSize(struct VFile* vf) {
+	struct VFileMem* vfm = (struct VFileMem*) vf;
+	return vfm->size;
+}