basic gpt support

Signed-off-by: Anna (navi) Figueiredo Gomes <navi@vlhl.dev>

1 files changed, 71 insertions, 0 deletions

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;
+}