got basic mft parsing

stage23/fs/ntfs.h

@@ -7,8 +7,39 @@
 #include <lib/part.h>
 #include <lib/blib.h>
 
+struct ntfs_bpb {
+    uint8_t jump[3];
+    char oem[8];
+    uint16_t bytes_per_sector;
+    uint8_t sectors_per_cluster;
+    uint16_t reserved_sectors;
+    uint8_t fats_count;
+    uint16_t directory_entries_count;
+    uint16_t sector_totals;
+    uint8_t media_descriptor_type;
+    uint16_t sectors_per_fat_16;
+    uint16_t sectors_per_track;
+    uint16_t heads_count;
+    uint32_t hidden_sectors_count;
+    uint32_t large_sectors_count;
+    
+    // ntfs 
+    uint32_t sectors_per_fat_32;
+    uint64_t sectors_count_64;
+    uint64_t mft_cluster;
+} __attribute__((packed));
+
 struct ntfs_file_handle {
     struct volume *part;
+
+    struct ntfs_bpb bpb;
+    uint8_t mft_run_list[256];
+    uint8_t root_run_list[128];
+    uint8_t resident_index[256];
+    uint8_t attribute_list[256];
+
+    uint64_t mft_offset;
+
     uint32_t size_bytes;
 };
 

stage23/fs/ntfs.s2.c

@@ -1,31 +1,77 @@
 #include <fs/ntfs.h>
 
-struct ntfs_bpb {
-    uint8_t jump[3];
-    char oem[8];
-    uint16_t bytes_per_sector;
-    uint8_t sectors_per_cluster;
-    uint16_t reserved_sectors;
-    uint8_t fats_count;
-    uint16_t directory_entries_count;
-    uint16_t sector_totals;
-    uint8_t media_descriptor_type;
-    uint16_t sectors_per_fat_16;
-    uint16_t sectors_per_track;
-    uint16_t heads_count;
-    uint32_t hidden_sectors_count;
-    uint32_t large_sectors_count;
-    
-    // ntfs 
-    uint32_t sectors_per_fat_32;
-    uint64_t sectors_count_64;
-    uint64_t mft_cluster;
+#include <lib/print.h>
+
+#include <stdbool.h>
+
+struct mft_file_record {
+    char name[4];
+    uint16_t update_seq_offset;
+    uint16_t update_seq_size;
+    uint64_t log_seq_number;
+    uint16_t sequence_number;
+    uint16_t hard_link_count;
+    uint16_t attribute_offset;
+    uint16_t flags;
+    uint32_t real_size;
+    uint32_t allocated_size;
+    uint64_t base_record_number;
+} __attribute__((packed));
+
+struct file_record_attr_header {
+    uint32_t type;
+    uint32_t length;
+    uint8_t non_res_flag;
+    uint8_t name_length;
+    uint16_t name_offset;
+    uint16_t flags;
+    uint16_t attribute_id;
+} __attribute__((packed));
+
+#define     FR_ATTRIBUTE_LIST           0x00000020
+#define     FR_ATTRIBUTE_NAME           0x00000030
+#define     FR_ATTRIBUTE_VOLUME_NAME    0x00000060
+#define     FR_ATTRIBUTE_DATA           0x00000080
+#define     FR_ATTRIBUTE_INDEX_ROOT     0x00000090
+#define     FR_ATTRIBUTE_INDEX_ALLOC    0x000000A0
+
+struct file_record_attr_header_res {
+    struct file_record_attr_header header;
+    uint32_t info_length;
+    uint16_t info_offset;
+    uint16_t index_flag;
+} __attribute__((packed));
+
+struct file_record_attr_header_non_res {
+    struct file_record_attr_header header;
+    uint64_t first_vcn;
+    uint64_t last_vcn;
+    uint16_t run_offset;
+} __attribute__((packed));
+
+struct index_entry {
+    uint64_t mft_record;
+    uint16_t entry_size;
+    uint16_t name_offset;
+    uint16_t index_Flag;
+    uint16_t padding;
+    uint64_t mft_parent_record;
+    uint64_t creation_time;
+    uint64_t altered_time;
+    uint64_t mft_changed_time;
+    uint64_t read_time;
+    uint64_t alloc_size;
+    uint64_t real_size;
+    uint64_t file_flags;
+    uint8_t name_length;
+    uint8_t name_type;
+    wchar_t name[];
 } __attribute__((packed));
 
 int ntfs_check_signature(struct volume *part) {
-    struct ntfs_bpb bpb = { 0 };
-    if (volume_read(part, &bpb, 0, sizeof(bpb))) {
-        return 1;
+    struct ntfs_bpb bpb;
+    if (!volume_read(part, &bpb, 0, sizeof(bpb))) {
+        return 0;
     }
 
     //
@@ -33,29 +79,111 @@ int ntfs_check_signature(struct volume *part) {
     //
 
     if (strncmp(bpb.oem, "NTFS    ", SIZEOF_ARRAY(bpb.oem))) {
-        return 1;
+        return 0;
     }
 
     if (bpb.sector_totals != 0) {
-        return 1;
+        return 0;
     }
 
     if (bpb.large_sectors_count != 0) {
-        return 1;
+        return 0;
     }
 
     if (bpb.sectors_count_64 == 0) {
-        return 1;
+        return 0;
     }
 
     // this is a valid ntfs sector
-    return 0;
+    return 1;
 }
 
+/**
+ * Read the the directory's file record from the mft
+ */
+// static int ntfs_read_directory(struct ntfs_file_handle *handle, uint64_t mft_record, char *file_record) {
+
+// }
+
+/**
+ * Get an attribute from the given file record
+ */
+static bool ntfs_get_file_record_attr(uint8_t* file_record, uint32_t attr_type, uint8_t **out_attr) {
+    struct mft_file_record *fr = (struct mft_file_record *)file_record;
+
+    // get the offset to the first attribute
+    uint8_t* cur_attr_ptr = file_record + fr->attribute_offset;
+
+    while (true) {
+        if (cur_attr_ptr + sizeof(struct file_record_attr_header) > file_record + 4096)
+            panic("File record attribute is outside of file record");
+
+        struct file_record_attr_header *cur_attr = (struct file_record_attr_header *)cur_attr_ptr;
+
+        if (cur_attr->type == attr_type) {
+            *out_attr = cur_attr_ptr;
+            return true;
+        }
+
+        // we either found an attr with higher type or the end type
+        if (cur_attr->type > attr_type || cur_attr->type == 0xFF)
+            return false;
+
+        if (cur_attr->length == 0)
+            panic("File record attribute has zero length");
+
+        cur_attr_ptr += cur_attr->length;
+    }
+}
+
+/**
+ * Prepare for reading a file by reading the root directory into the file handle
+ */
+static void ntfs_read_root(struct ntfs_file_handle *handle) {
+    // calculate the offset for the mft
+    handle->mft_offset = (uint64_t)handle->bpb.mft_cluster * (uint64_t)handle->bpb.sectors_per_cluster * (uint64_t)handle->bpb.bytes_per_sector;
+
+    // read the mft file record, this should be the size of a sector
+    // but we will use 4096 since it should cover it 
+    uint8_t file_record_buffer[4096];
+    if (!volume_read(handle->part, file_record_buffer, handle->mft_offset, sizeof(file_record_buffer)))
+        panic("Failed to read MFT file record");
+
+    // get the file attribute
+    struct file_record_attr_header_non_res *attr;
+    if (!ntfs_get_file_record_attr(file_record_buffer, FR_ATTRIBUTE_DATA, (uint8_t **)&attr))
+        panic("MFT file record missing DATA attribute");
+
+    // verify the attr and run list are in the buffer
+    if ((uint8_t *)attr + sizeof(*attr) > file_record_buffer + sizeof(file_record_buffer))
+        panic("MFT file record attribute is outside of file record");
+    if ((uint8_t *)attr + attr->run_offset + 256 > file_record_buffer + sizeof(file_record_buffer))
+        panic("MFT Run list is outside of file record");
+
+    // save the run list
+    memcpy(handle->mft_run_list, (uint8_t *)attr + attr->run_offset, sizeof(handle->mft_run_list));
+
+    // TODO: read the root directory
+}
+
+// static int ntfs_find_file_in_directory(char *dir, size_t dir_size, short *name, struct index_entry* entry) {
+// }
+
 int ntfs_open(struct ntfs_file_handle *ret, struct volume *part, const char *path) {
-    (void)ret;
-    (void)part;
+    // save the part
+    ret->part = part;
+
+    // start by reading the bpb so we can access it later on
+    if (!volume_read(part, &ret->bpb, 0, sizeof(ret->bpb)))
+        panic("Failed to read the BPB");
+
+    // now prepare the root directory so we can search for 
+    // the rest of the stuff
+    ntfs_read_root(ret);
+
+    // TODO: search for the file we want
     (void)path;
+
     return 1;
 }