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// MIT License, Copyright (c) 2020 Marvin Borner
// EXT2 based filesystem
#include <assert.h>
#include <def.h>
#include <fs.h>
#include <ide.h>
#include <mem.h>
#include <print.h>
#include <str.h>
void *buffer_read(u32 block)
{
return ide_read(malloc(BLOCK_SIZE), block);
}
struct superblock *get_superblock(void)
{
struct superblock *sb = buffer_read(EXT2_SUPER);
if (sb->magic != EXT2_MAGIC)
return NULL;
return sb;
}
struct bgd *get_bgd(void)
{
return buffer_read(EXT2_SUPER + 1);
}
struct inode *get_inode(u32 i)
{
struct superblock *s = get_superblock();
assert(s);
struct bgd *b = get_bgd();
assert(b);
u32 block_group = (i - 1) / s->inodes_per_group;
u32 index = (i - 1) % s->inodes_per_group;
u32 block = (index * INODE_SIZE) / BLOCK_SIZE;
b += block_group;
u32 *data = buffer_read(b->inode_table + block);
struct inode *in =
(struct inode *)((u32)data + (index % (BLOCK_SIZE / INODE_SIZE)) * INODE_SIZE);
return in;
}
u32 read_indirect(u32 indirect, u32 block_num)
{
char *data = buffer_read(indirect);
return *(u32 *)((u32)data + block_num * sizeof(u32));
}
void *read_inode(struct inode *in)
{
assert(in);
if (!in)
return NULL;
u32 num_blocks = in->blocks / (BLOCK_SIZE / SECTOR_SIZE);
assert(num_blocks != 0);
if (!num_blocks)
return NULL;
/* u32 sz = BLOCK_SIZE * num_blocks; */
u32 sz = in->size;
void *buf = malloc(sz);
printf("Loading %dKiB\n", sz >> 10);
assert(buf != NULL);
u32 indirect = 0;
u32 blocknum = 0;
char *data = 0;
// TODO: Support triply indirect pointers
// TODO: This can be heavily optimized by saving the indirect block lists
for (u32 i = 0; i < num_blocks; i++) {
if (i < 12) {
blocknum = in->block[i];
data = buffer_read(blocknum);
memcpy((u32 *)((u32)buf + i * BLOCK_SIZE), data, BLOCK_SIZE);
} else if (i < BLOCK_COUNT + 12) {
indirect = in->block[12];
blocknum = read_indirect(indirect, i - 12);
data = buffer_read(blocknum);
memcpy((u32 *)((u32)buf + i * BLOCK_SIZE), data, BLOCK_SIZE);
} else {
indirect = in->block[13];
blocknum = read_indirect(indirect, (i - (BLOCK_COUNT + 12)) / BLOCK_COUNT);
blocknum = read_indirect(blocknum, (i - (BLOCK_COUNT + 12)) % BLOCK_COUNT);
data = buffer_read(blocknum);
memcpy((u32 *)((u32)buf + i * BLOCK_SIZE), data, BLOCK_SIZE);
}
/* printf("Loaded %d of %d\n", i + 1, num_blocks); */
}
return buf;
}
u32 find_inode(const char *name, u32 dir_inode)
{
if (!dir_inode)
return (unsigned)-1;
struct inode *i = get_inode(dir_inode);
char *buf = malloc(BLOCK_SIZE * i->blocks / 2);
memset(buf, 0, BLOCK_SIZE * i->blocks / 2);
for (u32 q = 0; q < i->blocks / 2; q++) {
char *data = buffer_read(i->block[q]);
memcpy((u32 *)((u32)buf + q * BLOCK_SIZE), data, BLOCK_SIZE);
}
struct dirent *d = (struct dirent *)buf;
u32 sum = 0;
do {
// Calculate the 4byte aligned size of each entry
sum += d->total_len;
if (strlen(name) == d->name_len &&
strncmp((void *)d->name, name, d->name_len) == 0) {
free(buf);
return d->inode_num;
}
d = (struct dirent *)((u32)d + d->total_len);
} while (sum < (1024 * i->blocks / 2));
free(buf);
return (unsigned)-1;
}
struct inode *find_inode_by_path(char *path)
{
if (path[0] != '/')
return 0;
path++;
u32 current_inode = EXT2_ROOT;
int i = 0;
while (1) {
for (i = 0; path[i] != '/' && path[i] != '\0'; i++)
;
if (path[i] == '\0')
break;
path[i] = '\0';
current_inode = find_inode(path, current_inode);
path[i] = '/';
if (current_inode == 0)
return 0;
path += i + 1;
}
u32 inode = find_inode(path, current_inode);
if ((signed)inode <= 0)
return 0;
return get_inode(inode);
}
void *file_read(char *path)
{
struct inode *in = find_inode_by_path(path);
if (in)
return read_inode(in);
else
return NULL;
}
u32 file_stat(char *path)
{
struct inode *in = find_inode_by_path(path);
if (!in)
return 0;
return in->size;
}
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