feat: block partition support

[lunaix-os.git] / lunaix-os / kernel / block / blkpart_gpt.c

diff --git a/lunaix-os/kernel/block/blkpart_gpt.c b/lunaix-os/kernel/block/blkpart_gpt.c
new file mode 100644 (file)
index 0000000..4f9beec
--- /dev/null
+++ b/lunaix-os/kernel/block/blkpart_gpt.c
@@ -0,0 +1,84 @@
+#include <klibc/string.h>
+#include <lunaix/blkpart_gpt.h>
+#include <lunaix/block.h>
+#include <lunaix/mm/valloc.h>
+#include <lunaix/status.h>
+
+#include <lib/crc.h>
+
+#define GPT_BLKSIZE 512
+#define LBA2OFF(lba) (lba * GPT_BLKSIZE)
+#define ENT_PER_BLK (GPT_BLKSIZE / sizeof(struct gpt_entry))
+
+#define GPTSIG_LO 0x20494645UL
+#define GPTSIG_HI 0x54524150UL
+
+static u8_t NULL_GUID[16] = { 0 };
+
+int
+blkpart_parse(struct device* master, struct gpt_header* header)
+{
+    struct block_dev* bdev = (struct block_dev*)master->underlay;
+    if (!bdev)
+        return ENODEV;
+
+    int errno;
+    u32_t ent_lba = (u32_t)header->ents_lba;
+    struct gpt_entry* ents_parial = (struct gpt_entry*)valloc(GPT_BLKSIZE);
+
+    for (size_t i = 0; i < header->ents_len; i++) {
+        if (!(i % ENT_PER_BLK)) {
+            errno = master->read(
+              master, ents_parial, LBA2OFF(ent_lba++), GPT_BLKSIZE);
+            if (errno < 0) {
+                goto done;
+            }
+        }
+
+        struct gpt_entry* ent = &ents_parial[i % ENT_PER_BLK];
+
+        // assuming the entries are not scattered around
+        if (!memcmp(ent->pguid, NULL_GUID, 16)) {
+            break;
+        }
+
+        // Convert UEFI's 512B LB representation into local LBA range.
+        u64_t slba_local = (ent->start_lba * GPT_BLKSIZE) / bdev->blk_size;
+        u64_t elba_local = (ent->end_lba * GPT_BLKSIZE) / (u64_t)bdev->blk_size;
+
+        // we ignore the partition name, as it rarely used.
+        blk_mount_part(bdev, NULL, i, slba_local, elba_local);
+    }
+
+done:
+    vfree(ents_parial);
+    return errno;
+}
+
+int
+blkpart_probegpt(struct device* master)
+{
+    int errno;
+    struct gpt_header* gpt_hdr = (struct gpt_header*)valloc(GPT_BLKSIZE);
+
+    if ((errno = master->read(master, gpt_hdr, LBA2OFF(1), LBA2OFF(1))) < 0) {
+        goto done;
+    }
+
+    if (*(u32_t*)&gpt_hdr->signature != GPTSIG_LO ||
+        *(u32_t*)&gpt_hdr->signature[4] != GPTSIG_HI) {
+        return 0;
+    }
+
+    u32_t crc = gpt_hdr->hdr_cksum;
+    gpt_hdr->hdr_cksum = 0;
+    if (crc32b((void*)gpt_hdr, sizeof(*gpt_hdr)) != crc) {
+        // FUTURE check the backup header
+        return EINVAL;
+    }
+
+    errno = blkpart_parse(master, gpt_hdr);
+done:
+    vfree(gpt_hdr);
+    return errno;
+}
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