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Improve ext2 inode reading

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This commit is contained in:
mintsuki 2020-04-24 14:16:48 +02:00
parent bcfd9e5f91
commit ee38f8b4c9
3 changed files with 45 additions and 32 deletions
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16
Makefile
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@ -24,16 +24,18 @@ ext2-test: all
rm -rf test.img test_image/
mkdir test_image
dd if=/dev/zero bs=1M count=0 seek=64 of=test.img
parted -s test.img mklabel msdos
parted -s test.img mkpart primary 1 100%
parted -s test.img mklabel gpt
parted -s test.img mkpart primary 2048s 6143s
parted -s test.img mkpart primary 6144s 131038s
sudo losetup -Pf --show test.img > loopback_dev
sudo mkfs.ext2 `cat loopback_dev`p1
sudo mount `cat loopback_dev`p1 test_image
sudo cp test/test.elf test_image
sudo cp test/qloader2.cfg test_image
sudo mkfs.ext2 `cat loopback_dev`p2
sudo mount `cat loopback_dev`p2 test_image
sudo mkdir test_image/boot
sudo cp test/test.elf test_image/boot/
sudo cp test/qloader2.cfg test_image/
sync
sudo umount test_image/
sudo losetup -d `cat loopback_dev`
rm -rf test_image loopback_dev
./qloader2-install src/qloader2.bin test.img
./qloader2-install src/qloader2.bin test.img 2048
qemu-system-x86_64 -hda test.img -monitor stdio

BIN
qloader2.bin
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61
src/fs/ext2fs.c
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@ -185,6 +185,10 @@ struct ext2fs_dir_entry {
uint8_t type; // File type
} __attribute__((packed));
static int inode_read(void *buf, uint64_t loc, uint64_t count,
uint64_t block_size, struct ext2fs_inode *inode,
uint64_t drive, struct part *part);
// parse an inode given the partition base and inode number
static int ext2fs_get_inode(struct ext2fs_inode *ret, uint64_t drive, struct part *part, uint64_t inode, struct ext2fs_superblock *sb) {
if (inode == 0)
@ -226,16 +230,17 @@ next:
else
path++;
uint64_t offset = current_inode->i_blocks[0] * fd->block_size;
uint64_t stop = current_inode->i_size + offset;
while (offset < stop) {
for (uint32_t i = 0; i < current_inode->i_size; ) {
// preliminary read
read_partition(fd->drive, &fd->part, dir, offset, sizeof(struct ext2fs_dir_entry));
inode_read(dir, i, sizeof(struct ext2fs_dir_entry),
fd->block_size, current_inode,
fd->drive, &fd->part);
// name read
char *name = balloc(dir->name_len);
read_partition(fd->drive, &fd->part, name, offset + sizeof(struct ext2fs_dir_entry), dir->name_len);
inode_read(name, i + sizeof(struct ext2fs_dir_entry), dir->name_len,
fd->block_size, current_inode,
fd->drive, &fd->part);
int r = strncmp(token, name, dir->name_len);
@ -252,7 +257,7 @@ next:
}
}
offset += dir->rec_len;
i += dir->rec_len;
}
brewind(sizeof(struct ext2fs_inode));
@ -284,54 +289,60 @@ int ext2fs_open(struct ext2fs_file_handle *ret, int drive, int partition, const
}
int ext2fs_read(struct ext2fs_file_handle *file, void *buf, uint64_t loc, uint64_t count) {
// TODO: add support for the indirect block pointers
return inode_read(buf, loc, count,
file->block_size, &file->inode,
file->drive, &file->part);
}
static int inode_read(void *buf, uint64_t loc, uint64_t count,
uint64_t block_size, struct ext2fs_inode *inode,
uint64_t drive, struct part *part) {
for (uint64_t progress = 0; progress < count;) {
uint64_t block = (loc + progress) / file->block_size;
uint64_t block = (loc + progress) / block_size;
uint64_t chunk = count - progress;
uint64_t offset = (loc + progress) % file->block_size;
if (chunk > file->block_size - offset)
chunk = file->block_size - offset;
uint64_t offset = (loc + progress) % block_size;
if (chunk > block_size - offset)
chunk = block_size - offset;
uint64_t block_index;
if (block < 12) {
// Direct block
block_index = file->inode.i_blocks[block];
block_index = inode->i_blocks[block];
} else {
// Indirect block
block -= 12;
if (block * sizeof(uint32_t) >= file->block_size) {
if (block * sizeof(uint32_t) >= block_size) {
// Double indirect block
block -= file->block_size / sizeof(uint32_t);
uint32_t index = block / (file->block_size / sizeof(uint32_t));
if (index * sizeof(uint32_t) >= file->block_size) {
block -= block_size / sizeof(uint32_t);
uint32_t index = block / (block_size / sizeof(uint32_t));
if (index * sizeof(uint32_t) >= block_size) {
// Triple indirect block
panic("ext2fs: triply indirect blocks unsupported");
}
uint32_t offset = block % (file->block_size / sizeof(uint32_t));
uint32_t offset = block % (block_size / sizeof(uint32_t));
uint32_t indirect_block;
read_partition(
file->drive, &file->part, &indirect_block,
file->inode.i_blocks[13] * file->block_size + index * sizeof(uint32_t),
drive, part, &indirect_block,
inode->i_blocks[13] * block_size + index * sizeof(uint32_t),
sizeof(uint32_t)
);
read_partition(
file->drive, &file->part, &block_index,
indirect_block * file->block_size + offset * sizeof(uint32_t),
drive, part, &block_index,
indirect_block * block_size + offset * sizeof(uint32_t),
sizeof(uint32_t)
);
} else {
read_partition(
file->drive, &file->part, &block_index,
file->inode.i_blocks[12] * file->block_size + block * sizeof(uint32_t),
drive, part, &block_index,
inode->i_blocks[12] * block_size + block * sizeof(uint32_t),
sizeof(uint32_t)
);
}
}
read_partition(file->drive, &file->part, buf + progress, (block_index * file->block_size) + offset, chunk);
read_partition(drive, part, buf + progress, (block_index * block_size) + offset, chunk);
progress += chunk;
}