2 files changed, 146 insertions, 0 deletions
diff --git a/src/kernel/arch/i386/driver/fsroot.c b/src/kernel/arch/i386/driver/fsroot.c
new file mode 100644
index 0000000..49cecc9
--- /dev/null
+++ b/src/kernel/arch/i386/driver/fsroot.c
@@ -0,0 +1,144 @@
+#include <kernel/arch/i386/ata.h>
+#include <kernel/mem/virt.h>
+#include <kernel/panic.h>
+#include <kernel/proc.h>
+#include <kernel/util.h>
+#include <kernel/arch/i386/driver/fsroot.h>
+#include <shared/mem.h>
+#include <stdbool.h>
+
+enum {
+	HANDLE_ROOT,
+	HANDLE_VGA,
+	HANDLE_ATA_ROOT,
+	HANDLE_ATA,
+	_SKIP = HANDLE_ATA + 4,
+};
+
+static bool exacteq(struct vfs_request *req, const char *str) {
+	size_t len = strlen(str);
+	assert(req->input.kern);
+	return req->input.len == len && !memcmp(req->input.buf_kern, str, len);
+}
+
+/* truncates the length */
+static void req_preprocess(struct vfs_request *req, size_t max_len) {
+	if (req->offset < 0) {
+		// TODO negative offsets
+		req->offset = 0;
+	}
+
+	if (req->offset >= capped_cast32(max_len)) {
+		req->input.len = 0;
+		req->output.len = 0;
+		req->offset = max_len;
+		return;
+	}
+
+	req->input.len  = min(req->input.len,  max_len - req->offset);
+	req->output.len = min(req->output.len, max_len - req->offset);
+
+	assert(req->input.len + req->offset <= max_len);
+	assert(req->input.len + req->offset <= max_len);
+}
+
+
+static int handle(struct vfs_request *req) {
+	assert(req->caller);
+	switch (req->type) {
+		case VFSOP_OPEN:
+			if (exacteq(req, "/"))		return HANDLE_ROOT;
+			if (exacteq(req, "/vga"))	return HANDLE_VGA;
+
+			if (exacteq(req, "/ata/"))	return HANDLE_ATA_ROOT;
+			if (exacteq(req, "/ata/0"))
+				return ata_available(0) ? HANDLE_ATA+0 : -1;
+			if (exacteq(req, "/ata/1"))
+				return ata_available(1) ? HANDLE_ATA+1 : -1;
+			if (exacteq(req, "/ata/2"))
+				return ata_available(2) ? HANDLE_ATA+2 : -1;
+			if (exacteq(req, "/ata/3"))
+				return ata_available(3) ? HANDLE_ATA+3 : -1;
+
+			return -1;
+
+		case VFSOP_READ:
+			switch (req->id) {
+				case HANDLE_ROOT: {
+					// TODO document directory read format
+					const char src[] =
+						"vga\0"
+						"com1\0"
+						"ps2\0"
+						"ata/";
+					int len = min((size_t) req->output.len, sizeof(src));
+					virt_cpy_to(req->caller->pages, req->output.buf, src, len);
+					return len;
+				}
+				case HANDLE_VGA: {
+					char *vga = (void*)0xB8000;
+					req_preprocess(req, 80*25*2);
+					virt_cpy_to(req->caller->pages, req->output.buf,
+							vga + req->offset, req->output.len);
+					return req->output.len;
+				}
+				case HANDLE_ATA_ROOT: {
+					// TODO offset
+					char list[8] = {};
+					size_t len = 0;
+					for (int i = 0; i < 4; i++) {
+						if (ata_available(i)) {
+							list[len] = '0' + i;
+							len += 2;
+						}
+					}
+					len = min((size_t) req->output.len, len);
+					virt_cpy_to(req->caller->pages, req->output.buf, list, len);
+					return len;
+				}
+				case HANDLE_ATA:   case HANDLE_ATA+1:
+				case HANDLE_ATA+2: case HANDLE_ATA+3: {
+					if (req->offset < 0) return 0;
+					char buf[512];
+					uint32_t sector = req->offset / 512;
+					size_t len = min(req->output.len, 512 - ((size_t)req->offset & 511));
+					ata_read(req->id - HANDLE_ATA, sector, buf);
+					virt_cpy_to(req->caller->pages, req->output.buf, buf, len);
+					return len;
+				}
+				default: panic_invalid_state();
+			}
+
+		case VFSOP_WRITE:
+			switch (req->id) {
+				case HANDLE_VGA: {
+					void *vga = (void*)0xB8000;
+					req_preprocess(req, 80*25*2);
+					virt_cpy_from(req->caller->pages, vga + req->offset,
+							req->input.buf, req->input.len);
+					return req->input.len;
+				}
+				default: return -1;
+			}
+
+		case VFSOP_CLOSE:
+			return 0;
+
+		default: panic_invalid_state();
+	}
+}
+
+static void accept(struct vfs_request *req) {
+	if (req->caller) {
+		vfsreq_finish(req, handle(req));
+	} else {
+		vfsreq_finish(req, -1);
+	}
+}
+
+static bool is_ready(struct vfs_backend *self) {
+	return true;
+}
+
+static struct vfs_backend backend = BACKEND_KERN(is_ready, accept);
+void vfs_root_init(void) { vfs_mount_root_register("", &backend); }
diff --git a/src/kernel/arch/i386/driver/fsroot.h b/src/kernel/arch/i386/driver/fsroot.h
new file mode 100644
index 0000000..dd72202
--- /dev/null
+++ b/src/kernel/arch/i386/driver/fsroot.h
@@ -0,0 +1,2 @@
+#pragma once
+void vfs_root_init(void);