vfs: Block devices

2026-10-25 19:07:58 +01:00
parent c0767b4631
commit 9991c1ddcb
10 changed files with 1346 additions and 0 deletions
@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: ISC
+
+#include <zinnia/alloc.h>
+#include <zinnia/blockdev.h>
+#include <string.h>
+
+struct [[__packed]] gpt_header {
+    char signature[8];
+    uint32_t revision;
+    uint32_t header_size;
+    uint32_t header_crc32;
+    uint32_t reserved;
+    uint64_t my_lba;
+    uint64_t alternate_lba;
+    uint64_t first_usable_lba;
+    uint64_t last_usable_lba;
+    struct guid disk_guid;
+    uint64_t partition_entry_lba;
+    uint32_t num_partition_entries;
+    uint32_t partition_entry_size;
+    uint32_t partition_entry_array_crc32;
+};
+
+struct [[__packed]] gpt_entry {
+    struct guid type_guid;
+    struct guid unique_guid;
+    uint64_t start_lba;
+    uint64_t end_lba;
+    uint64_t attributes;
+    uint16_t name[36];
+};
+
+constexpr size_t GPT_MAX_ENTRIES = 1024;
+
+errno_t gpt_scan(struct blockdev* dev, struct gpt_partition** out, size_t* out_count) {
+    struct gpt_header header;
+    size_t read;
+    errno_t status = vmo_read(&dev->cache, dev->lba_size, &header, sizeof(header), &read);
+    if (status)
+        return status;
+    if (read != sizeof(header) || memcmp(header.signature, "EFI PART", 8) != 0)
+        return ENODATA;
+    if (header.partition_entry_size < sizeof(struct gpt_entry) || header.num_partition_entries > GPT_MAX_ENTRIES)
+        return EINVAL;
+
+    struct gpt_partition* parts = mem_alloc(MAX(header.num_partition_entries, 1) * sizeof(struct gpt_partition), 0);
+    if (!parts)
+        return ENOMEM;
+
+    size_t count = 0;
+    const uint64_t base = header.partition_entry_lba * dev->lba_size;
+    for (size_t i = 0; i < header.num_partition_entries; i++) {
+        struct gpt_entry entry;
+        status = vmo_read(&dev->cache, base + i * header.partition_entry_size, &entry, sizeof(entry), &read);
+        if (status || read != sizeof(entry))
+            break;
+        if (guid_is_zero(&entry.type_guid))
+            continue;
+
+        struct gpt_partition* part = &parts[count++];
+        part->type_guid = entry.type_guid;
+        part->unique_guid = entry.unique_guid;
+        part->start_lba = entry.start_lba;
+        part->end_lba = entry.end_lba;
+    }
+
+    *out = parts;
+    *out_count = count;
+    return 0;
+}