143 lines
4.2 KiB
C
143 lines
4.2 KiB
C
#include <fs/echfs.h>
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#include <stdint.h>
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#include <lib/libc.h>
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#include <lib/blib.h>
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#include <lib/print.h>
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#include <drivers/disk.h>
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#include <stdbool.h>
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#include <mm/pmm.h>
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struct echfs_identity_table {
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uint8_t jmp[4];
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char signature[8];
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uint64_t block_count;
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uint64_t dir_length;
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uint64_t block_size;
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uint32_t reserved;
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struct guid guid;
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} __attribute__((packed));
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#define ROOT_DIR_ID (~((uint64_t)0))
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#define END_OF_CHAIN (~((uint64_t)0))
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#define FILE_TYPE 0
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#define DIR_TYPE 1
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static bool read_block(struct echfs_file_handle *file, void *buf, uint64_t block, uint64_t offset, uint64_t count) {
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return volume_read(file->part, buf, (file->alloc_map[block] * file->block_size) + offset, count);
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}
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int echfs_read(struct echfs_file_handle *file, void *buf, uint64_t loc, uint64_t count) {
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for (uint64_t progress = 0; progress < count;) {
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uint64_t block = (loc + progress) / file->block_size;
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uint64_t chunk = count - progress;
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uint64_t offset = (loc + progress) % file->block_size;
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if (chunk > file->block_size - offset)
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chunk = file->block_size - offset;
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read_block(file, buf + progress, block, offset, chunk);
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progress += chunk;
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}
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return 0;
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}
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int echfs_check_signature(struct volume *part) {
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struct echfs_identity_table id_table;
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volume_read(part, &id_table, 0, sizeof(struct echfs_identity_table));
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if (strncmp(id_table.signature, "_ECH_FS_", 8)) {
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return 0;
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}
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return 1;
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}
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bool echfs_get_guid(struct guid *guid, struct volume *part) {
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struct echfs_identity_table id_table;
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volume_read(part, &id_table, 0, sizeof(struct echfs_identity_table));
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if (strncmp(id_table.signature, "_ECH_FS_", 8)) {
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return false;
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}
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*guid = id_table.guid;
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return true;
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}
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int echfs_open(struct echfs_file_handle *ret, struct volume *part, const char *path) {
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ret->part = part;
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struct echfs_identity_table id_table;
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volume_read(ret->part, &id_table, 0, sizeof(struct echfs_identity_table));
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if (strncmp(id_table.signature, "_ECH_FS_", 8)) {
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print("echfs: signature invalid\n");
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return -1;
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}
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ret->block_size = id_table.block_size;
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ret->block_count = id_table.block_count;
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ret->dir_length = id_table.dir_length * ret->block_size;
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ret->alloc_table_size = DIV_ROUNDUP(ret->block_count * sizeof(uint64_t), ret->block_size) * ret->block_size;
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ret->alloc_table_offset = 16 * ret->block_size;
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ret->dir_offset = ret->alloc_table_offset + ret->alloc_table_size;
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// Find the file in the root dir.
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uint64_t wanted_parent = ROOT_DIR_ID;
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bool last_elem = false;
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next:;
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char wanted_name[128];
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for (; *path == '/'; path++);
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for (int i = 0; ; i++, path++) {
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if (*path == '\0' || *path == '/') {
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if (*path == '\0')
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last_elem = true;
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wanted_name[i] = '\0';
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path++;
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break;
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}
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wanted_name[i] = *path;
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}
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for (uint64_t i = 0; i < ret->dir_length; i += sizeof(struct echfs_dir_entry)) {
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volume_read(ret->part, &ret->dir_entry, i + ret->dir_offset, sizeof(struct echfs_dir_entry));
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if (!ret->dir_entry.parent_id) {
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break;
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}
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if (!strcmp(wanted_name, ret->dir_entry.name) &&
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ret->dir_entry.parent_id == wanted_parent &&
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ret->dir_entry.type == (last_elem ? FILE_TYPE : DIR_TYPE)) {
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if (last_elem) {
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goto found;
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} else {
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wanted_parent = ret->dir_entry.payload;
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goto next;
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}
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}
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}
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return -1;
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found:;
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// Load the allocation map.
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uint64_t file_block_count = DIV_ROUNDUP(ret->dir_entry.size, ret->block_size);
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ret->alloc_map = ext_mem_alloc(file_block_count * sizeof(uint64_t));
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ret->alloc_map[0] = ret->dir_entry.payload;
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for (uint64_t i = 1; i < file_block_count; i++) {
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// Read the next block.
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volume_read(ret->part,
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&ret->alloc_map[i],
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ret->alloc_table_offset + ret->alloc_map[i-1] * sizeof(uint64_t),
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sizeof(uint64_t));
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}
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return 0;
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}
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