From ddb15c409290ac5473ee36d5dc621a92f161cdfb Mon Sep 17 00:00:00 2001
From: "Anna (navi) Figueiredo Gomes" <navi@vlhl.dev>
Date: Thu, 6 Jun 2024 15:05:45 +0200
Subject: basic gpt support

Signed-off-by: Anna (navi) Figueiredo Gomes <navi@vlhl.dev>
---
 src/fs/gpt.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/nrvn.c   | 47 +++++++++++++++++++++++++++++++++++-----
 2 files changed, 113 insertions(+), 5 deletions(-)
 create mode 100644 src/fs/gpt.c

(limited to 'src')

diff --git a/src/fs/gpt.c b/src/fs/gpt.c
new file mode 100644
index 0000000..f9ff055
--- /dev/null
+++ b/src/fs/gpt.c
@@ -0,0 +1,71 @@
+#include <fs/gpt.h>
+#include <ahci.h>
+#include <mem.h>
+#include <memory.h>
+#include <vga.h>
+
+struct gpt_header *read_gpt_disk(struct disk *disk) {
+	uint16_t *gpt = kmalloc(512);
+	if (!read(disk->port, 1, 1, gpt))
+		return NULL;
+	struct gpt_header *part = (void*) gpt;
+	if (memcmp(part->sig, "EFI PART", 8) != 0) {
+		vga_puts("not gpt");
+		return NULL;
+	}
+	vga_puts("found gpt table on disk 0\n");
+
+	vga_puts("number of partitions: ");
+	vga_putn(part->number_partitions);
+	vga_putc('\n');
+
+	vga_puts("starting lba: ");
+	vga_putn(part->first_lba);
+	vga_putc('\n');
+
+	vga_puts("size per entry: ");
+	vga_putn(part->size_partitions);
+	vga_putc('\n');
+
+	return part;
+}
+
+struct gpt_entry *get_gpt_entry(struct disk *disk, struct gpt_header *header, size_t num) {
+	if (num >= header->number_partitions)
+		return NULL;
+	uint16_t *data = kmalloc(512);
+	if (!read(disk->port, header->first_lba + num, 1, data))
+		return NULL;
+	struct gpt_entry *entry = (void *) data;
+
+	/*
+	vga_puts("unique guid for first partition: ");
+	vga_putx(entry->guid);
+	vga_putc('\n');
+	*/
+
+	vga_puts("starting partition lba: ");
+	vga_putn(entry->lba.start);
+	vga_putc('\n');
+
+	vga_puts("ending partition lba: ");
+	vga_putn(entry->lba.end);
+	vga_putc('\n');
+
+	return entry;
+}
+
+char *read_gpt_entry(struct disk *disk, struct gpt_entry *entry) {
+	uint16_t *data = kmalloc(512 * (entry->lba.end - entry->lba.start));
+	uint16_t *ptr = data;
+	for (size_t lba = entry->lba.start; lba < entry->lba.end; lba += 1024) {
+		if (!read(disk->port, lba, entry->lba.end - lba < 1024 ? entry->lba.end - lba : 1024, ptr)) {
+			vga_puts("failed to read disk");
+			kfree(data);
+			return NULL;
+		}
+		ptr += 1024 * 256;
+	}
+
+	return (char *)data;
+}
diff --git a/src/nrvn.c b/src/nrvn.c
index 66a59df..3fcbc41 100644
--- a/src/nrvn.c
+++ b/src/nrvn.c
@@ -8,20 +8,33 @@
 #include <pic.h>
 #include <acpi.h>
 #include <ps2.h>
+#include <pci.h>
 #include <multiboot.h>
 #include <mem.h>
 #include <memory.h>
+#include <ahci.h>
+
+#include <fs/gpt.h>
 
 /* Check if the compiler thinks you are targeting the wrong operating system. */
 #if defined(__linux__)
 #	error "You are not using a cross-compiler, you will most certainly run into trouble"
 #endif
 
-/* This tutorial will only work for the 32-bit ix86 targets. */
 #if !defined(__x86_64__)
-#	error "This tutorial needs to be compiled with a ix86-elf compiler"
+#	error "nrvn needs to be compiled with a x86_64 compiler"
 #endif
 
+int oct2bin(char *str, int size) {
+	int n = 0;
+	while (size--) {
+		n *= 8;
+		n += *str - '0';
+		str++;
+	}
+	return n;
+}
+
 void kernel_main(void) {
 	vga_init();
 	vga_puts("hello world\n");
@@ -31,7 +44,6 @@ void kernel_main(void) {
 	idt_init();
 	vga_puts("interrupt tables initialized\n");
 
-
 	vga_puts("initializing the pic...");
 	pic_init();
 	vga_puts("pic initialized\n");
@@ -41,8 +53,6 @@ void kernel_main(void) {
 		vga_puts("memory pages allocated\n");
 	} else {
 		vga_puts("failed to allocate memory pages\n");
-		asm volatile ("cli");
-		asm volatile ("hlt");
 	}
 
 	vga_puts("initializing ps/2...\n");
@@ -56,5 +66,32 @@ void kernel_main(void) {
 		vga_puts("pci initialized.\n");
 	else
 		vga_puts("pci initialization failed.\n");
+
+	struct disk *disk = get_disk(0);
+
+	struct gpt_header *gpt = read_gpt_disk(disk);
+	if (!gpt)
+		while (1);
+
+	struct gpt_entry *entry = get_gpt_entry(disk, gpt, 0);
+	if (!entry)
+		while (1);
+
+	char *archive = read_gpt_entry(disk, entry);
+	while (!memcmp(archive + 257, "ustar", 5)) {
+		int size = oct2bin(archive + 0x7c, 11);
+		vga_puts(archive[156] == '0' ? "filename: " : "directory: ");
+		vga_puts(archive);
+		vga_puts(", size: ");
+		vga_putn(size);
+		vga_putc('\n');
+		if (size > 0) {
+			vga_puts("contents: ");
+			vga_puts(archive + 512);
+			vga_putc('\n');
+		}
+		archive += 512 + (size > 0 ? 512 : 0);
+	}
+
 	while (1);
 }
-- 
cgit v1.2.3